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Intellectual Disability

The scope of this page is centralized content about individuals with an intellectual disability (ID) and associated communication difficulties across the life span.

See ASHAs Intellectual Disability evidence map for summaries of the available research on this topic.

Intellectual disability (ID) is characterized by

  • onset in the developmental period (before the age of 22 years; American Association on Intellectual and Developmental Disabilities [AAIDD], n.d.);
  • significant limitations in adaptive behavior (i.e., conceptual, social, and practical skills to function in daily life); and
  • significant limitations in intellectual functioning (e.g., learning, reasoning, and problem solving).

This definition of ID balances limitations with an equal emphasis on skills. Descriptive terminology and philosophy concerning ID focuses on levels of support necessary to maximize an individual’s ability, rather than strictly on functional limitations.

Diagnosis of ID is not made by a speech-language pathologist (SLP). However, information gathered during SLP evaluation and treatment may be useful to medical professionals who may diagnose ID. Assessment and treatment of disorders that fall under speech-language pathology scope of practice may be completed at any stage in an individual’s life. Treatment may begin as early as these disorders are detected, and early intervention is critical in identifying and providing services that will support both the child and the family (Guralnick, 2019).

Terminology

The definitions of ID and related terminology have evolved over time to reflect the legal and social gains made by individuals with such a disability and their families. See Changes in Services for Persons With Developmental Disabilities: Federal Laws and Philosophical Perspectives and Federal Programs Supporting Research and Training in Intellectual Disability. These changes reflect the movement away from a “medical model” and institutionalization and toward inclusive practices, self-advocacy, and self-determination. There has also been the movement toward recognizing the fundamental communication rights of people with severe disabilities. The Communication Bill of Rights—originally developed by the National Joint Committee for the Communication Needs of Persons With Severe Disabilities in 1992 and updated in 2016—recognizes the right of all people to participate fully in communication (Brady et al., 2016). For full participation, the Communication Bill of Rights identifies access to functioning augmentative and alternative communication (AAC) and other assistive technology services and devices as necessary at all times.

One of the major shifts in the early 1980s was a move toward person-first language, reflecting the idea that the disability does not define the person. Terms like individuals with intellectual disability have replaced the older terms of mentally retarded persons or the mentally retarded. Rosa’s Law, a federal law enacted in 2017, changed all prior references to “mental retardation” in federal law to “intellectual disability” or “intellectual disabilities.” Please see AAIDD’s page on Historical Context for further details. Terminology continues to evolve, with some individuals preferring identity-first language (e.g., “autistic person”). There is also an evolving cultural awareness of ableism (discrimination favoring able-bodied people). The American Speech-Language-Hearing Association (ASHA) aligns with the Disability section of the 7th edition of the American Psychological Association (2020) style manual, which says to use the terminology preferred by the individual. Definitions of ID have changed from being strictly IQ based to including strengths in adaptive behavior (Schalock et al., 2021; Tassé, 2017).

The AAIDD definition is consistent with the diagnostic criteria for Intellectual Disability (Intellectual Developmental Disorder) in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association [APA], 2013). However, AAIDD identifies the level of ID based on the level of supports needed for an individual to successfully function in activities of daily living. These levels of support are described as intermittent, limited, extensive, or pervasive. The DSM-5 uses severity level to define an individual with ID as mild, moderate, severe, or profound.

Limitations in adaptive functioning in specific skill areas are a necessary criterion for diagnosis under the AAIDD and DSM-5 definitions. The World Health Organization’s (WHO’s) International Classification of Functioning, Disability and Health (ICF) framework (WHO, 2001) and its Children & Youth version (WHO, 2007) recognize activity and participation limitations in addition to impairments in body functions and structures.

Developmental Disability

ID is a subset of developmental disability (DD). Per the Institute of Medicine (US) Committee on Nervous System Disorders in Developing Countries (2001), DD is a set of limitations that begin in infancy or childhood, with delays in reaching developmental milestones or limitations in one or more of the following domains:

  • cognition
  • motor performance
  • vision
  • hearing and speech
  • behavior

The Developmental Disabilities Assistance and Bill of Rights Act of 2000 defines or characterizes DD as follows:

  • a severe, chronic disability in an individual 5 years of age or older
  • onset before 22 years of age
  • results in substantial functional limitations in three or more areas of life activity such as
    • self-care,
    • receptive and expressive language,
    • learning,
    • mobility,
    • self-direction,
    • capacity for independent learning, and
    • economic self-sufficiency

Lifelong, early-onset conditions that result in substantial functional limitations—but not necessarily concomitant intellectual limitations—include autism spectrum disorder (ASD) or cerebral palsy. Individuals with these diagnoses who do not have significant limitations in adaptive behavior and intellectual functioning are considered to have DD without ID.

Co-Occurring Conditions and Disorders

Communication skills among individuals with ID can vary due to severity; co-occurring conditions; and other behavioral, emotional, and social factors. Conditions that commonly co-occur with ID include, but are not limited to, the following.

ASD

ASD is a neurologically based, heterogeneous condition, characterized by a range of social communication skills and the presence of restricted, repetitive behaviors, which are present in early childhood. These and other features include the following:

  • Persistent deficits in social communication and social interaction across multiple contexts (e.g., joint attention, social-emotional reciprocity, nonverbal and verbal communication skills, initiation of conversation; APA, 2013).
  • Restricted and repetitive use of language (e.g., echolalia, perseveration; APA, 2013).
  • Delay or absence of spoken communication (D. K. Anderson et al., 2007).
  • Difficulty with abstract language (Tager-Flusberg & Caronna, 2007).
  • Difficulty with narrative discourse (Colle et al., 2008).
  • May have a speech sound disorder (Shriberg et al., 2011).
  • May have feeding problems (Twachtman-Reilly et al., 2008).

Communication delays or limitations in social functioning may signal ASD, ID, or other conditions. A medical practitioner or team may have difficulty making a diagnosis of ID or ASD due to similarities and comorbidity between the two conditions. The SLP’s input may be useful to the medical team when considering comorbidity or differential diagnosis between the two disorders.   

Commonalities between ASD and ID include

  • onset during the developmental period,
  • difficulty with nonverbal communication modalities (e.g., gestural or facial expression),
  • speech patterns (e.g., prosody) as well as receptive and expressive pragmatic and sociolinguistic communication skills,
  • limitations in social participation,
  • attention and academic difficulties, and
  • difficulty with theory of mind (ToM).

Differences between ASD and ID include the following:

  • Individuals with ID have limitations in intellectual functioning and adaptive behavior, whereas individuals with ASD have a wide range of intellectual abilities and adaptive behavior.
  • Individuals with ID usually develop skills slower than their typically developing peers do, whereas individuals with ASD may not follow the typical developmental progression of skills across domains.
  • Individuals with both ASD and ID may have more difficulty with ToM than those with ID alone (Cáceres et al., 2014).

Please see ASHA’s Practice Portal page on Autism Spectrum Disorder for further information. 

Cerebral Palsy

Cerebral palsy is a motor disorder that may affect speech, language, and swallowing. Variable difficulties, depending on the area of the brain affected and the severity, are experienced, which may include the following:

  • Increased risk for language disorders (Pennington et al., 2005).
  • May have hearing loss (Rosenbaum & Rosenbloom, 2012).
  • Dysarthria is the most common speech disorder (McNeil, 2009).
  • Feeding and swallowing may be compromised (Sullivan, 2009).

Down Syndrome

Down syndrome is a genetic syndrome associated with intellectual disability, limitations in adaptive skills, and anatomical differences in tongue size (relative macroglossia). Other characteristics include the following:

  • Language comprehension is better than production, particularly syntax (J. E. Roberts et al., 2007).
  • Speech intelligibility problems, which may result from disturbances in voice, articulation, resonance, fluency, or prosody (Kent & Vorperian, 2013).
  • Stuttering is more prevalent (Eggers & Van Eerdenbrugh, 2018).
  • Persistent otitis media; conductive and sensorineural hearing loss is common (Shott, 2006).
  • Morphosyntax is more difficult than semantics (Fidler et al., 2009), with variability in vocabulary development compared to children with other intellectual disabilities or typical development (Loveall et al., 2016).
  • Social and pragmatic skill strengths that vary depending on executive function and ToM skills (Lee et al., 2017).

Fetal Alcohol Syndrome

Fetal alcohol syndrome is a congenital syndrome resulting from alcohol exposure in utero. It is a leading cause of developmental disabilities in the United States (Clarke & Gibbard, 2003). Characteristics may include the following:

  • Delayed speech and language acquisition (Cone-Wesson, 2005; Terband et al., 2018).
  • May have hearing loss (Cone-Wesson, 2005).
  • Receptive and expressive language problems (Wyper & Rasmussen, 2011).
  • Difficulties with narrative discourse, particularly errors in nominal reference (Thorne et al., 2007).
  • Difficulties with social communication (Coggins et al., 2007).

Fragile X Syndrome

Fragile X syndrome is the most common inherited cause of ID (Lozano et al., 2014). Deficits are more severe for boys than for girls (Haebig et al., 2020). Characteristics may include the following:

  • Delayed speech and language skills, particularly syntax, with relative strengths in vocabulary and language comprehension (J. E. Roberts et al., 2008).
  • Difficulties with articulation, fluency, and oral motor skills (J. E. Roberts et al., 2003).
  • Prolonged unintelligible speech, particularly in connected speech (Barnes et al., 2009). 
  • Social interaction and pragmatic difficulties similar to those associated with ASD (e.g., staying on topic, taking turns in conversation, echolalia, perseveration; Haebig et al., 2020).

Other conditions that may also co-occur with ID include the following:

  • anxiety disorder
  • attention-deficit/hyperactivity disorder
  • dysphagia (Chadwick & Joliffe, 2009)
  • depressive and bipolar disorder
  • impulse-control disorder
  • major depressive disorder (APA, 2013)

Associated Health Conditions

Individuals with ID may have more health problems than others in the general population, often because of inadequate health care, limited access to quality services (Krahn et al., 2006; van Schrojenstein Lantman-de Valk & Walsh, 2008), and communication limitations (Gentile et al., 2015).

Associated health conditions with higher prevalence in individuals with ID include the following:

  • anxiety disorders (Oeseburg et al., 2011)
  • hearing loss (Herer, 2012)
  • physical coordination and tone issues (Vuijk et al., 2010)
  • heart conditions (Patja et al., 2001)
  • obesity-related problems (Rimmer et al., 2010)
  • seizure activity (Oeseburg et al., 2011)
  • visual impairment (Warburg, 2001)

Addressing health inequalities as well as providing adequate health care and medical training may improve quality of life and increase longevity in individuals with ID.

Incidence refers to the number of new cases identified in a specified time period.

Prevalence refers to the number of people who are living with the condition in a given time period.

The incidence/prevalence data in this section pertain to United States–based populations.

The determination of incidence and prevalence of intellectual disability (ID) is complicated because researchers of ID do not use a uniform operational definition when selecting and identifying individuals with ID. In some cases, an IQ cutoff score is used (e.g., 70) as a criterion for diagnosis, whereas in other cases, the diagnostic criteria are more qualitative in nature (e.g., onset in childhood with limitations in adaptive behavior and intellectual functioning). Variations in study design, terminology definitions, sample size and characteristics, and diagnostic tools can also affect incidence and prevalence data. For example, some study authors use the terms “intellectual disability” and “developmental disability” interchangeably, the latter of which can include conditions like ASD and developmental language disorder. Keep these factors in mind when reviewing the incidence and prevalence data below.

Children and Adolescents

In the United States, the overall prevalence of ID was estimated to be 11.0–13.4 per 1,000 children and adolescents (L. L. Anderson et al., 2019). Of the children aged 6–21 years served under the Individuals with Disabilities Education Improvement Act of 2004 (IDEA), 6.7% of students were identified with ID (U.S. Department of Education, 2021).

Gender

Studies reported results based on gender; however, there were no indications whether the data collected were based on sex assigned at birth, gender identity, or both. Based on data from the 2011 meta-analysis of international studies, the female-to-male ratio of children and adolescents with ID varied between 0.4 and 1.0 (i.e., four to 10 females with ID for every 10 males with the condition; Maulik et al., 2013).

Race/Ethnicity and Disproportionality in Special Education

A lack of culturally and linguistically sensitive assessment measures and inherent assessment bias contribute to misrepresentation and disproportionality in the identification of individuals with ID. When examining data, use extreme caution: Consider the potential of bias in the testing as well as in the diagnostic and evaluation procedures.

Please see the section on Social Determinants of Health under Cultural and Linguistic Considerations in the Assessment section below for further information. 

According to the 42nd Annual Report to Congress on the Implementation of the Individuals with Disabilities Education Act (IDEA; U.S. Department of Education, 2021), the percentages of students, aged 6–21 years, receiving IDEA services under the category of ID within each racial/ethnic group are as follows:

  • American Indian/Alaska Native: 6.6%
  • Asian: 6.8%
  • Black/African American: 9.7%
  • Hispanic/Latino: 6.5%
  • Native Hawaiian or Other Pacific Islander: 6.8%
  • White: 5.8%
  • Two or more races: 5.3%

Co-Occurring Conditions

Of the children with autism spectrum disorder, 33% were identified with ID (Maenner et al., 2020). Data from the 2013–2014 Annual Survey of Deaf and Hard of Hearing Children and Youth revealed that 9.2% of students who are deaf and hard of hearing were also identified with ID (Office of Research Support and International Affairs, 2014). ID was present in 45% of children recorded in the cerebral palsy registry (Reid et al., 2018).

Adults

United States–based studies reported the prevalence of ID to be 7.9 per 1,000 adults (L. L. Anderson et al., 2019). Global prevalence based on international studies estimated the prevalence of ID in adults ranged from 0.05% to 0.08% (McKenzie et al., 2016).

Gender

Studies reported results based on gender; however, there were no indications whether the data collected were based on sex assigned at birth, gender identity, or both. Based on data from the 2011 meta-analysis of international studies, the female-to-male ratio of adults with ID varied between 0.7 and 0.9 (i.e., seven to nine females with ID for every 10 males with the condition; Maulik et al., 2013). Rates of co-occurring disorders in male and female adults with ID were similar, with 19% and 20%, respectively (Mazza et al., 2020).

Co-Occurring Conditions

Herer (2012) found that the prevalence of hearing loss in noninstitutionalized adults with ID was higher than for individuals in the general population and that the hearing loss occurred at a much younger age. Overall pooled prevalence of approximately 37% of adults with ID had a co-occurring psychiatric disorder. Mood disorders were found to be the most prevalent psychiatric disorder to co-occur in adults with ID (6.7%; Mazza et al., 2020). Mazza et al. (2020) also revealed that the following psychiatric disorders were also found to be prevalent in adults with ID:

  • anxiety disorders (5.5%)
  • schizophrenia (4.8%)
  • unspecified psychotic disorder (3.9%)
  • personality disorders (2.8%)

Defining Characteristics

It is important to distinguish signs and symptoms of intellectual disability (ID) from communication differences through case history and comprehensive assessment. Individuals with ID have intellectual deficits as well as deficits in adaptive functioning that include conceptual, social, and practical domains (APA, 2013).  

Intellectual Functioning

  • language development
  • reasoning
  • problem solving
  • planning
  • abstract thinking
  • judgment
  • academic learning
  • learning from experience

Adaptive Functioning

  • developmental and sociocultural standards for personal independence and community participation
  • independent functioning in one or more daily life activities (e.g., communication, social participation, and independent living) across settings

The level of support needed for adaptive functioning (i.e., performance of basic life skills) determines the severity level for ID. According to the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; APA, 2013), the signs and symptoms of deficits in adaptive functioning across domains may include the following.

Conceptual Domain

  • difficulty with language development
  • difficulties in pre-academic and academic learning (reading, writing, mathematics)
  • difficulty understanding concepts of time and money
  • problems with abstract thinking (concrete approach to problem solving)
  • difficulties in executive function such as
    • planning,
    • strategizing,
    • priority setting, and
    • cognitive flexibility
  • problems with short-term memory
  • difficulties with functional use of academic skills such as money management and time management

Social Domain

  • limitations in language and communication skills
    • more concrete and less complex spoken language (if used), compared with same-age peers
    • limited vocabulary and grammatical skills
    • receptive language that may be limited to comprehension of simple speech and gestures
    • communication that may occur through nonspoken means only—such as gestures, signs, facial expressions, or aided systems (e.g., AAC)
  • social skills
    • challenges with social judgment and decision making
    • difficulty understanding social cues and rules
    • emotional and behavioral regulation difficulties that may adversely affect social interactions

Practical Domain

  • requiring different levels of support for daily life activities such as
    • personal care,
    • complex tasks (e.g., shopping, transportation, care organization, meals, money management),
    • employment,
    • health care,
    • legal decisions,
    • household tasks, and
    • recreation

Communication Patterns

Individuals with ID and associated language and communication disorders may demonstrate signs and symptoms of spoken and written language disorders across the domains of phonology, morphology and syntax, semantics, and pragmatics. See ASHA’s Practice Portal pages on Spoken Language Disorders and Written Language Disorders for information related to language comprehension and production as well as multiple modes of communication via AAC. See ASHA’s Practice Portal page on Augmentative and Alternative Communication for further information. Individuals with ID accompanied by language and communication disorders may experience behavioral difficulties as well as social and emotional problems.

Communication abilities in individuals with ID vary and may be nonsymbolic (e.g., gestures, vocalizations, specific behaviors) and/or symbolic (e.g., words, signs, pictures). Please see Co-Occurring Conditions and Disorders section above for further information regarding ID in specific populations.

There are prenatal, perinatal, and postnatal causes of intellectual disability (ID). Some prenatal causes such as environmental influences (e.g., exposure to lead-based paint) may be preventable. Genetic causes account for 45% of ID (Batshaw et al., 2013). Down syndrome is the largest genetic cause of ID, and Fragile X syndrome is the largest inherited cause of ID. Fetal alcohol syndrome is the largest environmental cause of ID. Cultural beliefs may influence some individuals’ perceptions about the causes of ID (Allison & Strydom, 2009; Scior, 2011).

Prenatal

  • genetic syndromes (e.g., Down syndrome and Fragile X syndrome)
  • inborn errors of metabolism
  • brain malformation (e.g., microcephaly)
  • maternal disease (e.g., placental disease)
  • environmental influences (e.g., alcohol, other drugs, toxins, teratogens)

Perinatal

  • labor and delivery–related events (leading to neonatal encephalopathy)
  • anoxia at birth

Postnatal

  • hypoxic ischemic injury
  • traumatic brain injury
  • infections
  • demyelinating disorders
  • seizure disorders (e.g., infantile spasms)
  • severe and chronic social deprivation
  • toxic metabolic syndromes and intoxications (e.g., lead, mercury)

Speech-language pathologists (SLPs) do not diagnose intellectual disability (ID) but play a key role in assessing the communication and language skills of individuals with ID. SLPs may be part of a team making a differential diagnosis between ID and autism spectrum disorder or other conditions.

SLPs also play a role in enhancing adaptive communication functioning, as many of the adaptive skill areas rely on communication abilities. For example:

  • Conceptual skills include
    • receptive and expressive language,
    • reading, and
    • writing.
  • Social skills include
    • interpersonal skills,
    • following societal rules, and
    • problem solving.
  • Practical skills include
    • following routines or job tasks,
    • using telecommunications technologies (e.g., phone, Zoom),
    • using money,
    • using transportation, or
    • completing personal care procedures.

The professional roles and activities in speech-language pathology include clinical/educational services (assessment, planning, and treatment); prevention and advocacy; and education, administration, and research. See ASHA’s Scope of Practice in Speech-Language Pathology (ASHA, 2016b).

Appropriate roles for SLPs include the following.

Assessment

  • Screen individuals who may have hearing, speech, language, communication, and/or swallowing difficulties and determine the need for further assessment and/or referral for other services.
  • Conduct a culturally and linguistically relevant and age-appropriate assessment of speech, language, communication, and swallowing, using formal and informal tools.
  • Assess the need for AAC services and supports.
  • Determine eligibility for speech and language services.
  • Refer to other professionals to rule out other conditions, determine etiology, and facilitate access to comprehensive services (e.g., physical therapy, occupational therapy).

Treatment

  • Participate as a member of the school or adult service planning team to determine appropriate educational and/or community services. Team members may include parents/caregivers, general education teachers, special educators, counselors, job coaches, group home supervisors, and psychologists.
  • Make decisions about the management of communication disorders.
  • Develop culturally and linguistically responsive treatment plans for speech and language services, including social language goals and goals for assisting with self-regulatory and social interactive functions to enable participation in daily activities and curriculum to as great an extent as possible.
  • Provide treatment, document progress, and determine appropriate timelines for treatment and development of new treatment goals/targets for the individual’s continued development.
  • Plan for transitions from educational to community support services.

Counseling/Education

  • Promote early identification of risk for ID and help implement services to maximize the potential of young children.
  • Provide information to individuals and groups known to be at risk for ID, to their family members, and to individuals working with those at risk.
  • Partner with families in assessment and intervention with individuals with ID to develop individualized culturally and linguistically relevant plans for their family.
  • Collaborate with persons with ID and their families regarding communication-related issues and provide education aimed at enhancing communication development and preventing further complications related to ID.
  • Educate other professionals on the needs of persons with ID and the role of SLPs in diagnosing and managing communication disorders of those with ID.
  • Educate communication partners on effective strategies for supporting the use of AAC, where appropriate.
  • Collaborate with parents, teachers, caregivers, job coaches, peers, and others to promote communication development in individuals with ID.
  • Serve as an integral member of a team working with individuals with ID and their families/caregivers and, when appropriate, considering transition planning.
  • Support students with ID throughout their school years and in postsecondary education settings.
  • Support individuals with ID in vocational and community settings.
  • Consult and collaborate with other professionals, family members, caregivers, and others to facilitate program development and to provide supervision, evaluation, and/or expert testimony, as appropriate.
  • Remain informed of research related to ID and advance the knowledge base related to the nature and treatment of ID.
  • Advocate for individuals with ID and their families at the local, state, and national levels.
  • Provide quality control and risk management.

As indicated in the ASHA Code of Ethics (ASHA, 2016a), SLPs who serve individuals with ID should be specifically educated and appropriately trained to do so.

See the Assessment section of the Intellectual Disability evidence map for pertinent scientific evidence, expert opinion, and client/caregiver perspective.

Screening

SLPs screen for hearing, speech, language, communication, and swallowing problems. Screening does not result in a diagnosis of a disorder but, rather, determines the need for further assessment and/or referral for other services. Screening may not be a needed step for individuals with intellectual disability (ID), particularly those with more severe limitations in intellectual or adaptive functioning. For these individuals, a comprehensive assessment is likely to be the first step.

Screening may include the following:

  • Gathering information from parents, caregivers, teachers, and co-workers regarding skills and concerns about the dialect(s) and/or language(s) used.
  • Conducting a hearing screening to rule out hearing loss as a possible contributing factor to language difficulties.
  • Administering formal screening assessments that have normative data and/or cutoff scores and that have demonstrated evidence of adequate sensitivity and specificity.
  • Using informal measures, such as those designed by the clinician and tailored to the population being screened (e.g., age, developmental level, language[s] used).
  • Observing speech production, language comprehension and production, social communication, and literacy skills in natural environments.
  • Conducting a screening of swallowing function.

Comprehensive Assessment

Collaboration and Teaming

Assessment for individuals with ID involves multiple professionals due to the varying and far-reaching needs across developmental domains. Team models may be multidisciplinary, interdisciplinary, or transdisciplinary (see ASHA’s resource on collaboration and teaming).

Interprofessional collaborative practice consists of core ideals described by the WHO that include patient- and family-centered, community-oriented, and relationship-focused service delivery by a team of professionals working together with common goals for the individual with ID (WHO, 2010b). Please see ASHA’s resource on interprofessional collaborative practice for further information.   

Team members determine strengths and limitations in adaptive functioning and collaboratively determine the levels of support needed across conceptual, social, and practical domains.

Sensitivity to cultural and linguistic variables is necessary when selecting formal and informal assessment measures. Assessments address components within the International Classification of Functioning, Disability and Health (WHO, 2001) framework, including body structures/functions, activities/participation, and contextual factors. Findings from the communication and hearing assessments are analyzed in the context of findings from other professionals who assess and/or treat ID (e.g., psychologists).

Components of a Comprehensive Assessment

Both formal and informal assessment approaches can be used. Formal testing may be required if diagnosis or eligibility has yet to be determined. Informal testing may be useful to determine the individual’s achievement of developmental milestones. See ASHA’s resource on assessment tools, techniques, and data sources for items that may be used in a comprehensive communication assessment. Dynamic assessment may be used to identify nonsymbolic and symbolic communication behaviors and to evaluate individual learning potential (Snell, 2002).

A comprehensive assessment may include the following, depending on the age and functioning of individuals with ID and their needs:

  • Case history, including medical, educational, and vocational status as well as teacher, caregiver, employer, and client/patient perspectives.
  • Interview with family members about communication during daily routines.
  • Review of auditory, visual, motor, and cognitive status, including hearing screening.
  • Assessment of
    • nonsymbolic (e.g., gestures, vocalizations, problem behaviors) and/or symbolic (e.g., words, signs, pictures) communication,
    • play,
    • social interaction and social communication,
    • spoken language (listening and speaking),
    • written language (reading and writing),
    • speech production,
    • oral motor skills,
    • swallowing,
    • fluency, and
    • voice and resonance.
  • Assessment for AAC and/or other assistive technology.
  • Identification of the potential for effective intervention strategies and compensations.

Details regarding the components of a comprehensive assessment are available on the following Practice Portal pages:

See also ASHA’s Practice Portal pages on Autism Spectrum Disorder and Social Communication Disorder for relevant assessment considerations based on individual needs for individuals with autism spectrum disorder (ASD) and ID.

Information provided above under the Co-Occurring Conditions and Disorders section above may be helpful in developing an assessment protocol to document an individual performance profile. Examples of such considerations follow:

  • Children with Down syndrome often have specific limitations in expressive syntax relative to semantics. They also have difficulty with speech production due to low muscle tone and characteristic facial features (Berglund et al., 2001; J. E. Roberts et al., 2007). Therefore, children with Down syndrome may require a detailed evaluation of syntactic production relative to comprehension along with a speech intelligibility inventory.
  • Individuals with Fragile X syndrome often have pragmatic language difficulties (Abbeduto & Sterling, 2011). They may also benefit from a detailed evaluation of social communication relative to language structure and function.

Assessment may result in

  • the diagnosis of a communication disorder or delay secondary to ID;
  • a description of the characteristics and severity of the communication disorder or delay;
  • a determination of the effect of communicative situation/contexts on performance;
  • the identification of a possible hearing loss;
  • recommendations for intervention and support;
  • the recommendation of a communication system (e.g., speech-generating device);
  • a referral to other professionals as needed, such as
    • an audiologist,
    • an occupational therapist,
    • a physical therapist,
    • a physician,
    • a psychologist, or
    • a social worker;
  • recommendations for support for parents, caregivers, teachers, and employers; and
  • recommendations for support for transitions (e.g., early intervention into school age; school age into workplace).

Family-Centered Practices

Persons with ID and their families are integral to assessment, goal selection, and treatment. Families offer important information about the strengths, challenges, and needs for the individual with ID. Families also provide useful information about communication skills during daily routines. They also identify valued life outcomes for their children, such as

  • being safe and healthy,
  • having a home,
  • establishing meaningful relationships,
  • having choices and control, and
  • creating opportunities for meaningful activities across environments (Beadle-Brown et al., 2016; Brady et al., 2016).

Decisions about specific goals and objectives are made in collaboration with the family and the person with ID. The SLP recognizes that individual family values and available resources are central to the decision-making process.

See ASHA’s resource on family-centered practice for general guidelines.

Cultural and Linguistic Considerations

Culture and cultural identities are complex and dynamic. These identities interact in complex manners that influence life decisions and communication. These differing aspects of personal and social identity and how they converge are known as intersectionality. An individual’s total identities are considered during assessment and treatment. Please see the American Association on Intellectual and Developmental Disabilities’ page on Intersectionality for further details. 

Individuals with ID commonly experience stigmatization, discrimination, and health inequalities across cultures (Allison & Strydom, 2009). This may influence families’ willingness or desire to seek or accept services.

Careful consideration of language history (e.g., quality and duration of exposure to different languages) and linguistic abilities in all languages is necessary in the evaluation, particularly when working with individuals who are multilingual. See ASHA’s Practice Portal pages on Bilingual Service Delivery, Cultural Competence, and Collaborating With Interpreters, Transliterators, and Translators for additional information.

Assessment prompts and treatment materials are reviewed for relevance for each individual. Images, symbols, and depicted scenes are not universally meaningful or appropriate. For example, evaluators determine if failure to recognize a photo of a party reflects word retrieval challenges or is due to an unfamiliar representation of a “party” to an individual. SLPs are also mindful of gender presentations. Questions pertaining to gender and pronoun use must be relevant to that individual and their familial structures. SLPs ensure that symbols used with individuals who require AAC reflect the cultural and linguistic identity of the individual and are in line with the individual’s preference.

Social Determinants of Health

The WHO defines social determinants of health as facts related to how individuals experience the world, such as birthplace, where they live, where they work, and their age (WHO, 2013). Politics, economics, and social policies also influence how individuals receive and experience health care.

The focus of prior studies was to review and discuss health care disparities across racial/ethnic groups. While race/ethnicity influenced the likelihood of diagnosis, at best, it was unclear why. Current language examines these differences in rate of diagnosis as health care inequities suggesting avoidable failures to provide appropriate and responsive services.

Prior studies have highlighted over- and underrepresentation of ID and/or learning disability (LD) identification across race and ethnicity (e.g., Shifrer, 2018; Shifrer et al., 2011). Lack of linguistically appropriate measures and awareness of cultural influences on assessment, layered with the inherent bias in the evaluation process, results in disproportionality in “Black, Indigenous, and People of Color” (BIPOC) communities. Simply reporting data on health care disparities may leave the false impression that biological markers create those disparities. Audiologists and SLPs need to consider social determinants of health and their own implicit biases as both may influence assessment and treatment outcomes for ID. Bias should be addressed as it may affect quality of patient–provider interactions and has the potential to affect outcomes (Hall et al., 2015).

Eligibility for Services

Individuals with ID of all ages are eligible for SLP services because enhancement of communication skills is needed to function effectively, regardless of age or cognitive level relative to communication abilities. Eligibility is an area that has continued to evolve as the rights of individuals with ID have been increasingly well recognized. The National Joint Committee for the Communication Needs of Persons With Severe Disabilities (NJC) emphasizes that there are no prerequisites for communication (NJC, 2002a, 2002b).

Cognitive referencing is the practice of comparing IQ scores and language scores to help determine eligibility for SLP intervention. Cognitive referencing rests on the assumption that language skills cannot improve beyond cognitive ability. This assumption is a concern when applied to individuals with disabilities in general and to individuals with ID in particular (Casby, 1992; Cole et al., 1990; Notari et al., 1992). Relevant research indicates that language intervention benefits children with ID even when no language–cognition discrepancy exists (Carr & Felce, 2000; Cole et al., 1990; Snell et al., 2010).

The absence of prerequisite cognitive or other skills for determining eligibility is also of concern for individuals with ID. There are no prerequisites for communication supports and services, including the use of AAC (Brady et al., 2016; Romski & Sevcik, 2005). For example, some individuals with ID may be good candidates for immediate introduction of symbolic communication goals that target acquisition and use of words or symbols. Other goals may be appropriate for individuals with extremely limited functional communication (e.g., broader communication goals such as turn-taking and social participation).

For information about eligibility for services in the schools, see Eligibility and Dismissal in Schools, IDEA Part B Issue Brief: Individualized Education Programs and Eligibility for Services, and Current IDEA Part C Final Regulations (2011). See also Relation of Age to Service Eligibility and Relation of Developmental Age to Service Eligibility for the NJC position on eligibility.

Adolescents and Adults With ID

Individuals with ID continue to develop communication skills beyond the school years (e.g., Cheslock et al., 2008). As individuals with ID reaches adolescence and adulthood, their communication and functional needs change. For example, peer interactions, use of social media, and communication skills needed to optimize acceptance and relationship development may be important to teenagers with ID.

Individuals transitioning from school to employment need communication skills specific to the work setting (e.g., talking with co-workers and supervisors, interacting with customers).

SLPs work to maximize the participation and independence of individuals with ID as they experience life transitions that place new demands on communication. The speech-language assessment incorporates an evaluation of skills needed to support the individual’s changing communication needs. Please see NJC’s resource titled Myths About Adult Communicators With Severe Disabilities.

ID and Hearing Loss

Increased prevalence of hearing loss has been reported in individuals with ID as compared with the general population. See the Incidence and Prevalence section for more information.

Early detection of hearing loss and routine monitoring are essential for ensuring positive communication outcomes. Comprehensive assessment includes a hearing screening and referral for a complete audiological assessment if hearing concerns are indicated.

See ASHA’s Practice Portal pages on Permanent Childhood Hearing Loss and Hearing Loss (Ages 5+) for more information.

Challenging Behaviors

Comprehensive assessment of individuals with ID involves assessment of the function of challenging behaviors, also known as problem behaviors. Common challenging behaviors include aggressive, disruptive, self-injurious, and stereotypic behaviors.

Challenging behaviors may be used to

  • gain attention (social reinforcement),
  • express wants or needs (tangible reinforcement),
  • indicate frustration or a desire to avoid a nonpreferred activity or event (escape-avoidance), or
  • gain sensory input (sensory reinforcement).
  • Understanding the communicative intention of challenging behaviors serves as the basis for replacing problem behaviors with more appropriate communication skills, including AAC, that would serve the same functions (see the Functional Communication Training (FCT) subsection in the Treatment section). Please also see NJC’s resource titled Applied Behavior Analysis and Communication Services. Social expression and norms vary considerably. These variations and familial norms are considered when targeting new behaviors.

Differential Diagnosis

SLPs need to differentiate between ID and other disorders and conditions (e.g., spoken language disorders and hearing loss, selective mutism, and English as a second language) whose communication problems can be attributed mistakenly to ID (e.g., late language emergence and ASD). Developmental delay (DD), ASD, and LD may be conditions commonly considered when making a differential diagnosis.   

DD is commonly used as a temporary diagnosis in young children at risk for ID. It indicates a failure to achieve age-appropriate developmental milestones (Battaglia & Carey, 2003; Petersen et al., 1998). More severe disabilities are more likely to result in early identification of ID (Daily et al., 2000). Delayed language development is often the first sign of a developmental problem. Therefore, SLPs may help make a differential diagnosis between late language emergence and ID or another DD. See ASHA’s Practice Portal page on Late Language Emergence for further information.

ASD commonly co-occurs with ID (see the Incidence and Prevalence section above). Differential diagnosis between ASD and ID may be challenging as some of the core features of ASD related to social communication and language skills, and presence of restricted, repetitive behaviors may overlap with limitations noted in ID.  

ID is distinguished from LD, in that LD specifically refers to difficulty in at least one area of learning, such as reading, writing, and mathematics, with typical intellectual functioning. Additionally, LD is not characterized by intellectual limitations. However, it is possible for a person to have both LD and ID. 

See the Treatment section of the Intellectual Disability evidence map for pertinent scientific evidence, expert opinion, and client/caregiver perspective.

Each individual with intellectual disability (ID) has a unique profile, based on their level of language functioning as well as functioning in areas related to language and communication, including the following:

  • hearing ability
  • cognitive level
  • language(s) used or target language(s)
  • speech production skills
  • emotional status

Intervention considers strengths and needs in all areas to ensure individualized treatment and supports. Treatment also considers each individual’s peer group(s), family/caregiver, and social communities and provides opportunities to foster appropriate interaction within those settings, such as

  • teaching in natural contexts and
  • providing training for communication partners (including peers).

Please see Treatment Principles for Individuals with an Intellectual Disability for further information. 

The goal of treatment is to minimize the potential effects of disabilities on clients and their families and to maximize the likelihood of desirable outcomes.

Treatment Principles

Treatment typically encompasses a variety of techniques and approaches (Goldstein, 2006). Communication intervention for ID focuses on interactions that may occur within an individual’s natural environment to reflect social norms of their community. SLPs ensure that intervention provides ample opportunities for communication and incorporates

  • a variety of language functions, such as
    • greeting,
    • commenting, and
    • requesting;
  • multiple partners;
  • different forms and modalities, such as
    • speech
    • AAC; and
  • varied communication settings/contexts, such as
    • home;
    • educational settings;
    • recreational settings;
    • employment, as appropriate; and
    • community settings.

SLPs help ensure that communication partners recognize and respond to communication attempts and build on the interests, initiations, and requests of persons with ID. SLPs foster an appreciation for the importance of language in future learning and functioning when involving others in intervention activities. They also ensure the rights of each communicator in accordance with the National Joint Committee for the Communication Needs of Persons With Severe Disabilities’ Communication Bill of Rights (Brady et al., 2016).

See Treatment Principles for Individuals With an Intellectual Disability.

Treatment Targets and Contexts

Communication intervention is sensitive to cultural and linguistic diversity and addresses components within the International Classification of Functioning, Disability and Health (WHO, 2001) framework, including body structures/functions, activities/participation, and contextual factors (personal and environmental).

Intervention for individuals with ID involves a variety of communication partners (peers and adults) in different settings and may address the following areas:

  • early communication skills (e.g., pointing, turn-taking, joint attention)
  • social interaction and play
  • pragmatic conventions (spoken and nonspoken) for communicating appropriately in varied situations
  • spoken and written language for social, educational, and vocational functions
  • literacy
  • speech production
  • fluency
  • voice and resonance
  • increased complexity of spoken and written language for more effective communication
  • contextual factors that influence the individual’s relative success or difficulty in a given activity
  • compensatory communication techniques and strategies, including the use of AAC or other assistive technology
  • feeding and swallowing

Treatment programs often incorporate teaching or coaching models for communication partners, including peers, so they may support the individual’s language comprehension and expression. This training may include the use of communication intervention strategies, partner training in AAC, and/or assistive technology.

Interprofessional collaboration may also improve communication skills. For example, a physical therapist and an SLP may work together to improve respiratory support, which can, in turn, enhance speech production and intelligibility.

See ASHA’s Preferred Practice Patterns for a more detailed outline of the major components of communication intervention for individuals across the life span (ASHA, 2004).

Treatment Modes/Modalities

Treatment modes and modalities are technologies or other support systems that can be used in conjunction with or in the implementation of various treatment options. For example, video-based instruction is a form of intervention that uses technology and can be used in peer-mediated interventions to address social skills and other target behaviors.

Augmentative and Alternative Communication (AAC)

AAC involves supplementing, or using in the absence of, natural speech and/or writing with aided (e.g., picture communication symbols, line drawings, and tangible objects) and/or unaided (e.g., manual signs, gestures, and finger spelling) symbols. Aided symbols require a transmission device (e.g., a speech-generating device); unaided symbols require only the body to produce (Beukelman & Light, 2020). See ASHA’s Practice Portal page on Augmentative and Alternative Communication.

Activity Schedules/Visual Supports

Activity schedules/visual supports include objects, photographs, drawings, or written words that act as cues or prompts to help individuals

  • complete a sequence of activities,
  • attend to tasks,
  • transition between activities, or
  • act appropriately in various settings (e.g., Cohen & Demchak, 2018).

Written and/or visual prompts that initiate or sustain interaction are called scripts. Scripts are often used to promote social interaction but can also be used in a classroom setting to facilitate academic interactions and promote academic engagement (Hart & Whalon, 2008). Scripts are culturally and linguistically relevant.

Computer-Based Instruction

Computer technology (e.g., tablets) and/or computerized programs can be used to teach communication and social skills (e.g., Bernard-Opitz et al., 2001; Neely et al., 2013).

Video-Based Instruction

Video-based instruction (also called video modeling) is an observational mode of teaching that uses video recordings to provide a model of the target behavior or skill. Video recordings of desired behaviors are observed and then imitated by the individual (Darden-Brunson et al., 2008). The learner’s self-modeling can be videotaped for later review.

Treatment Options

Below are brief descriptions of treatment options commonly used to address communication problems associated with ID. The treatment modes/modalities described above (e.g., AAC) may be used to implement these treatment options. Intervention for individuals with ID typically incorporates a variety of options and techniques in combination. This list is not exhaustive, and the inclusion of any specific treatment approach does not imply endorsement from ASHA.

SLPs determine which options are appropriate by taking into consideration the individual’s age, language profile, communication needs, factors related to language functioning, the presence of coexisting conditions, communicative opportunities and partner supports, linguistic needs, cultural background and values, and available research evidence.

Other Practice Portal pages can serve as useful resources for treatment options, depending on the etiology of the ID. On the ASHA Practice Portal, see the Treatment sections of Autism Spectrum Disorder, Spoken Language Disorders, and Social Communication Disorder.

Behavioral Interventions

Behavioral interventions and techniques (e.g., differential reinforcement, prompting, fading, and modeling) are designed to reduce problem behaviors and teach functional alternative behaviors using the basic principles of behavior change. These methods are based on behavioral/operant principles of learning; they involve examining the antecedents that elicit a certain behavior, along with the consequences that follow that behavior, and then making adjustments in this chain to increase desired behaviors and/or decrease inappropriate ones. Behavioral interventions range from one-to-one, discrete trial instruction to naturalistic approaches.

Applied Behavior Analysis (ABA)

ABA is a treatment approach that uses principles of learning theory to bring about meaningful and positive change in behavior. ABA techniques have been used by SLPs in collaboration with ABA therapists to help build a variety of skills (e.g., communication, social skills, self-control, and self-monitoring) and help generalize these skills to other situations. The techniques can be used in both structured (e.g., classroom) and everyday (e.g., family dinnertime) settings and in one-on-one or group instruction. ABA has been used for individuals with ID, particularly those who also have ASD (e.g., Spreckley & Boyd, 2009).

Intervention is customized based on the individual’s needs, interests, and family situation. ABA techniques are often used in intensive, early intervention (before the age of 4 years) programs to address a full range of life skills (e.g., Frea & McNerney, 2008). Intensive programs total from 25 to 40 hr per week for 1–3 years. Qualifications for providing ABA therapy may vary by state; check with your state, as this may affect reimbursement.

SLPs should consider the role of ABA in communication intervention, particularly because difficulty with prompt dependency and generalization of communication interactions may result.

Environmental Arrangement

Environmental arrangement is a technique that involves arranging the environment to encourage communication by increasing interest in the environment and setting the occasion for communication. The SLP can build on the individual’s desire to request and comment on aspects of the environment using strategies such as

  • putting interesting materials in sight but out of reach;
  • sabotaging the situation with missing elements or providing inadequate portions; and
  • setting up choice-making, unexpected, or silly situations.
Functional Communication Training (FCT)

FCT is a behavioral intervention program that combines the assessment of the communicative functions of problem behavior with ABA procedures to teach alternative responses. Problem behaviors can be eliminated through extinction, the gradual weakening of a conditioned response (i.e., withholding reinforcers). Problem behaviors are then replaced with alternate, more appropriate forms of communicating needs or wants. FCT can be used across a range of ages and regardless of cognitive level or expressive communication abilities.

An FCT approach may be considered with students with ID to replace challenging behaviors with appropriate communication alternatives (Brady & Halle, 1997; Martin et al., 2005; Schmidt et al., 2014). FCT has a stepwise progression, as follows:

  1. Definition of the challenging behavior and the antecedent and consequent variables hypothesized to motivate them (Dunlap & Fox, 1999; Lucyshyn et al., 2002; Schwartz et al., 2001).
  2. Use of this information to identify and teach simple and potentially more efficient communication skills that serve the same functions.
  3. Expansion of those skills and ensuring that appropriate communication skills are used effectively in different contexts and that the challenging behavior is extinguished.
Incidental Teaching

Incidental teaching is a teaching technique that uses behavioral procedures to teach elaborated language; naturally occurring teaching opportunities are provided based on the individual’s interests. Following the individual’s lead, attempts to communicate are reinforced as these attempts get closer to the desired communication behavior (McGee et al., 1999). Incidental teaching requires initiation by the individual, which serves to begin a language teaching episode. If the person does not initiate, an expectant look and a time delay might be sufficient to prompt language use. The clinician can prompt with a question (e.g., “What do you want?”) or model a request (e.g., “Say ‘I need paint’”). The use of incidental teaching may be effective in increasing engagement in children with disabilities (Casey et al., 2012). 

Milieu Therapy

Milieu therapy is a range of methods (including incidental teaching, time delay, and mand-model procedures) that are integrated into a child’s natural environment. It includes training in everyday environments and activities, rather than only at therapy time. Milieu language teaching and other related procedures offer systematic approaches for prompting children to expand their repertoire of communication functions and to use increasingly complex language skills (Kaiser & Roberts, 2013). Prelinguistic milieu teaching applies natural environmental cues and prompts to promote development of gestures, gaze alternation, vocalizations, play, and other prelinguistic skills (Warren et al., 2008).

Time Delay

Time delay is fading the use of prompts during instruction. For example, the time delay between initial instruction and any additional instruction or prompting is gradually increased as the individual becomes more proficient at the skill being taught. Time delay can be used with individuals regardless of cognitive level or expressive communication abilities (e.g., Liber et al., 2008).

Literacy Interventions

It is important for individuals with ID to have the opportunity for literacy intervention, including a focus on phonological processing/word decoding and reading comprehension (Barker et al., 2013). Growth in early reading skills is influenced by environmental as well as genetic factors (Petrill et al., 2010). Development of literacy skills is important in any population; however, children with DD access literacy in different ways than nondisabled peers. Introduction of written language materials in SLP intervention may build upon already developing oral language skills (Koppenhaver et al., 1991). Additional information on literacy interventions can be found at the ASHA Practice Portal’s page on Written Language Disorders.

Peer-Mediated/Implemented Treatment

Peer-mediated/implemented treatment approaches incorporate peers as communication partners for children with disabilities to minimize isolation, provide effective role models, and boost communication competence. Typically developing peers are taught strategies to facilitate play and social interactions; interventions are commonly carried out in inclusive settings where play with typically developing peers naturally occurs (e.g., preschool setting). The following examples may be considered for children with ID.

Learning Experiences and Alternative Program (LEAP)

LEAP is a multifaceted program for preschool children with ASD and their parents (Strain & Hoyson, 2000). LEAP uses a variety of strategies and methods, including ABA, peer-mediated instruction, self-management training, prompting, and parent training. LEAP is implemented in a classroom setting consisting of children with ASD and typically developing peers and is designed to support child-directed play.

Circle of Friends

“Circle of friends” is a treatment approach that uses the classroom peer group to improve the social acceptance of a classmate with special needs by setting up a special group or “circle of friends.” The focus is on building behaviors that are valued in everyday settings. The application of skills to new and appropriate situations is reinforced as naturally as possible as such situations occur (Kalyva & Avramidis, 2005; Whitaker et al., 1998).

Integrated Play Groups

Integrated play groups is a treatment model designed to support children of different ages and abilities with ASD in play experiences with typical peers and siblings. Small groups of children play together under the guidance of an adult facilitator. The focus is on maximizing children’s potential and their intrinsic desire to socialize with peers (Wolfberg & Schuler, 1999).

Parent-Mediated/Implemented Treatment

Parent-mediated/implemented treatment approaches involve partnerships between SLPs, parents/caregivers, and other professionals and communication partners in supporting the natural communication behaviors of individuals with intellectual and other developmental disabilities (Guralnick, 2017; M. Y. Roberts & Kaiser, 2011). These can include parents implementing interventions described above, such as enhanced milieu teaching (Kaiser & Roberts, 2013), prelinguistic milieu teaching (Yoder & Warren, 2002), and AAC (Romski et al., 2010).

Hanen Programs

The Hanen programs are parent training approaches focused on supporting language and communication development in children with disabilities. Several Hanen Centre programs and guidebooks have been developed with research-based training for parents/caregivers of

  • children with language delays (It Takes Two to Talk; Girolametto et al., 1998),
  • children with autism (More Than Words; Carter et al., 2011), and
  • adults with ID (Allow Me; Ruiter, 2000).

Components of these programs include parent instruction, joint interaction with parents/caregivers and individuals with developmental delays and other deficits, and video coaching (Weitzman et al., 2017).

Focused Stimulation

Focused stimulation is a treatment approach in which a child is given multiple examples of a specific target (e.g., vocabulary item) within meaningful contexts. These approaches can be provided by SLPs and/or caregivers. As children with ID may have slowed receptive language processing compared to typically developing peers, they may benefit from an increase in frequency and intensity of examples (Ellis Weismer et al., 2017). 

Treatment Considerations

Target Behaviors for Specific Populations

Selection of target behaviors for individuals with ID has increased alongside understanding of the specific communication disorders associated with various diagnoses. This is especially the case in the most studied populations—Down syndrome and ASD. A variety of approaches may be selected based on individual strengths and needs.

Transitioning Youth

Individuals with ID may experience challenges in acquiring the skills necessary for independent living and achieving success in postsecondary education/training programs, employment settings, and social situations. They may need continued support to facilitate a successful transition to adulthood. SLPs are involved in transition planning and may be involved to varying degrees in other support services beyond high school. See ASHA’s Practice Portal page on Transitioning Youth for further details.

Aging Adults

The SLP helps maximize independent functioning in aging adults with ID. Adults with ID experience the same age-related health problems and functional decline observed in the general elderly population (Lazenby-Paterson & Crawford, 2014). However, the aging process may be premature in adults with ID as compared with the general population (e.g., Lin et al., 2011).

For example, individuals with Down syndrome may be at higher risk for earlier onset of dementia when compared with the general population (Burt et al., 2005; Hawkins et al., 2003). Speech and language skills may begin to decline in adults with ID from about the age of 50 years even when dementia is not taken into account (J. E. Roberts et al., 2007). SLPs may need to consider the possibility of mild cognitive impairment, a condition characterized by subtle cognitive decline that may lead to dementia (see ASHA’s Practice Portal page on Dementia), if treating adults with ID with new communication concerns.

Most healthy adults will not experience problems with eating, drinking, and swallowing, despite age-related changes in the muscles used for feeding and swallowing (Lazenby, 2008). However, some adults with ID—particularly those with psychomotor impairments or other comorbid conditions that affect feeding and swallowing—may experience dysphagia-related problems as they age (Lazenby-Paterson & Crawford, 2014).

Individuals With Challenging Behaviors

Challenging behaviors are reduced when individuals with ID are taught communication skills that serve efficiently and effectively as alternative behaviors (Kurtz et al., 2011).

Identifying and treating behaviors early in development may promote appropriate communication using alternative modes and prevent negative long-term consequences. Replacing challenging behaviors with appropriate and increasingly sophisticated communication skills has the potential to improve academic achievement, social relationships, and vocational outcomes.

SLPs typically educate team members about the communication functions of such behaviors and develop methods for replacing them with other forms of communication behavior.

Global Views of ID

Cultural differences in the attitudes, beliefs, and perceptions of individuals with ID are well documented within the United States and in other countries (Allison & Strydom, 2009; Scior, 2011; WHO, 2010a). At times, this may inhibit families from seeking services, resulting in either delays or lack of intervention. Societal norms within some communities may result in isolation of individuals with ID. Although there has been a global movement to encourage deinstitutionalization of individuals with ID and improve access to quality care and social integration, this is not yet a reality in all countries.

Cultural perspectives affect communication and the way care is provided. SLPs need to (a) be aware of culturally associated beliefs about the cause of ID, (b) provide person-centered care, (c) build working relationships with caregivers, and (d) address communication barriers (Allison & Strydom, 2009).

Working With Multilingual and/or Multidialectal Populations

Multilingual and multidialectal populations exist across the globe. Individuals who have ID may have a need to use multiple languages and/or dialects to communicate with loved ones and peers. Limiting communication means limiting access to peer groups and daily life activities. SLPs support the linguistic needs to facilitate those connections. Please see ASHA’s Practice Portal page on Cultural Competence for further information.

Service Delivery

See the Service Delivery section of the Intellectual Disability evidence map for pertinent scientific evidence, expert opinion, and client/caregiver perspective.

In addition to determining the type of speech and language treatment that is optimal for individuals with ID, SLPs consider other service delivery variables—including format, provider, timing, and setting—that may affect treatment outcomes. Service delivery decisions are made based on the individual’s communication needs relative to their family, community, school, or work setting.

Format

Format refers to the structure of the treatment session (e.g., group vs. individual; direct and/or consultative) provided.

Service delivery options include home-based, pull-out, classroom-based (e.g., push-in), and collaborative consultation. Selection of format type depends on each individual and their needs and goals.

Provider

Provider refers to the person offering the treatment (e.g., SLP, trained volunteer, caregiver).

Assessment and intervention are typically collaborative processes involving multiple providers. The multifaceted team also includes families, caregivers, and persons with disabilities. These teams establish and coordinate services that are family centered, culturally appropriate, comprehensive, and compassionate and that produce meaningful life outcomes.

Models of teaming require varying degrees of collaboration and engagement. See ASHA’s resource on collaboration and teaming.

Timing

Timing refers to the scheduling of intervention relative to the diagnosis.

The importance of early intervention for children who are at high risk for communication disorders cannot be overstated. For children with ID and other DDs, intervention may focus on factors influencing cognitive development and social competence (e.g., Guralnick, 2017; Mahoney & Perales, 2005).

Setting

Setting refers to the location of treatment (e.g., home, community-based, work).

More contextually based models of service delivery that occur in everyday contexts are consistent with the “natural environments” philosophy and the move toward inclusive educational programming (Paul-Brown & Caperton, 2001). Such models may serve to prepare persons with ID for transitions to independent living and working (White et al., 2010).

Intervention in multiple contexts allows the person with ID to practice functional skills in meaningful situations. Multiple communication partners besides the SLP may also be involved in service delivery across settings.

ASHA Resources

Other Resources

This list of resources is not exhaustive and the inclusion of any specific resource does not imply endorsement from ASHA.

Abbeduto, L., & Sterling, A. (2011). Language development and Fragile X syndrome. Perspectives on Language Learning and Education, 18(3), 87–97. https://doi.org/10.1044/lle18.3.87

Allison, L., & Strydom, A. (2009). Intellectual disability across cultures. Psychiatry, 8(9), 355–357. https://doi.org/10.1016/j.mppsy.2009.06.008

American Association on Intellectual and Developmental Disabilities. (n.d.). Definition of intellectual disability. https://www.aaidd.org/intellectual-disability/definition

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596

American Psychological Association. (2020). Publication manual of the American Psychological Association (7th ed.). https://doi.org/10.1037/0000165-000

American Speech-Language-Hearing Association. (2004). Preferred practice patterns for the profession of speech-language pathology [Preferred practice patterns]. https://www.asha.org/policy/

American Speech-Language-Hearing Association. (2016a). Code of ethics [Ethics]. https://www.asha.org/policy/

American Speech-Language-Hearing Association. (2016b). Scope of practice in speech-language pathology [Scope of practice]. https://www.asha.org/policy/

Anderson, D. K., Lord, C., Risi, S., DiLavore, P. S., Shulman, C., Thurm, A., Welch, K., & Pickles, A. (2007). Patterns of growth in verbal abilities among children with autism spectrum disorder. Journal of Consulting and Clinical Psychology, 75(4), 594–604. https://doi.org/10.1037/0022-006X.75.4.594

Anderson, L. L., Larson, S. A., MapelLentz, S., & Hall-Lande, J. (2019). A systematic review of U.S. studies on the prevalence of intellectual or developmental disabilities since 2000. Intellectual and Developmental Disabilities, 57(5), 421–438. https://doi.org/10.1352/1934-9556-57.5.421

Barker, R. M., Sevcik, R. A., Morris, R. D., & Romski, M. A. (2013). A model of phonological processing, language, and reading for students with mild intellectual disability. American Journal on Intellectual and Developmental Disabilities, 118(5), 365–380. https://doi.org/10.1352/1944-7558-118.5.365

Barnes, E., Roberts, J., Long, S. H., Martin, G. E., Berni, M. C., Mandulak, K. C., & Sideris, J. (2009). Phonological accuracy and intelligibility in connected speech of boys with Fragile X syndrome or Down syndrome. Journal of Speech, Language, and Hearing Research, 52(4), 1048–1061. https://doi.org/10.1044/1092-4388(2009/08-0001)

Batshaw, M. L., Roizen, N. J., & Lotrecchiano, G. R. (Eds.). (2013). Children with disabilities: A medical primer (7th ed.). Brookes.

Battaglia, A., & Carey, J. C. (2003). Diagnostic evaluation of developmental delay/mental retardation: An overview. American Journal of Medical Genetics, 117C(1), 3–14. https://doi.org/10.1002/ajmg.c.10015

Beadle-Brown, J., Leigh, J., Whelton, B., Richardson, L., Beecham, J., Baumker, T., & Bradshaw, J. (2016). Quality of life and quality of support for people with severe intellectual disability and complex needs. Journal of Applied Research in Intellectual Disabilities, 29(5), 409–421. https://doi.org/10.1111/jar.12200

Berglund, E., Eriksson, M., & Johansson, I. (2001). Parental reports of spoken language skills in children with Down syndrome. Journal of Speech, Language, and Hearing Research, 44(1), 179–191. https://doi.org/10.1044/1092-4388(2001/016)

Bernard-Opitz, V., Sriram, N., & Nakhoda-Sapuan, S. (2001). Enhancing social problem solving in children with autism and normal children through computer-assisted instruction. Journal of Autism and Developmental Disorders, 31(4), 377–384. https://doi.org/10.1023/A:1010660502130

Beukelman, D. R., & Light, J. C. (2020). Augmentative and alternative communication: Supporting children and adults with complex communication needs (5th ed.). Brookes.

Brady, N. C., Bruce, S., Goldman, A., Erickson, K., Mineo, B., Ogletree, B. T., Paul, D., Romski, M. A., Sevcik, R., Siegel, E., Schoonover, J., Snell, M., Sylvester, L., & Wilkinson, K. (2016). Communication services and supports for individuals with severe disabilities: Guidance for assessment and intervention. American Journal on Intellectual and Developmental Disabilities, 121(2), 121–138. https://doi.org/10.1352/1944-7558-121.2.121

Brady, N. C., & Halle, J. W. (1997). Functional analysis of communicative behaviors. Focus on Autism and Other Developmental Disabilities, 12(2), 95–104. https://doi.org/10.1177/108835769701200205

Burt, D. B., Primeaux-Hart, S., Loveland, K. A., Cleveland, L. A., Lewis, K. R., Lesser, J., Pearson, P. L., & MacLean, W. E., Jr. (2005). Aging in adults with intellectual disabilities. American Journal on Mental Retardation, 110(4), 268–284. https://doi.org/10.1352/0895-8017(2005)110[268:AIAWID]2.0.CO;2

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Acknowledgments

Content for ASHA's Practice Portal is developed through a comprehensive process that includes multiple rounds of subject matter expert input and review. ASHA extends its gratitude to the following subject matter experts who were involved in the development of the Intellectual Disability page:

  • Meher H. Banajee, PhD, CCC-SLP
  • Andrea Barton-Hulsey, PhD, CCC-SLP
  • Nancy C. Brady, PhD, CCC-SLP
  • Cynthia Cress, PhD, CCC-SLP
  • Amy S. Goldman, MS, CCC-SLP
  • Howard Goldstein, PhD, CCC-SLP
  • Jon F. Miller, PhD, CCC-SLP
  • Billy T. Ogletree, PhD, CCC-SLP
  • Patricia A. Prelock, PhD, CCC-SLP
  • MaryAnn Romski. PhD, CCC-SLP
  • Rose A. Sevcik, PhD
  • Krista M. Wilkinson, PhD

In addition, ASHA thanks the members of the Ad Hoc Committee to Review/Revise Current Practice and Policy Documents Related to Mental Retardation/Developmental Disabilities, whose work was foundational to the development of this content. Members of the Committee were Howard Goldstein (chair), Kevin Cole, Philip S. Dale, Jon F. Miller, Patricia A. Prelock, Krista M. Wilkinson, and Diane Paul (ex officio). Celia Hooper, ASHA vice president for professional practices in speech-language pathology (2003–2005), served as the Board liaison.

Citing Practice Portal Pages

The recommended citation for this Practice Portal page is:

American Speech-Language-Hearing Association. (n.d.). Intellectual Disability. (Practice Portal). Retrieved month, day, year, from www.asha.org/Practice-Portal/Clinical-Topics/Intellectual-Disability/.

Content Disclaimer: The Practice Portal, ASHA policy documents, and guidelines contain information for use in all settings; however, members must consider all applicable local, state and federal requirements when applying the information in their specific work setting.

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