See the assessment section of the Autism Spectrum Disorders Evidence Map for pertinent scientific evidence, expert opinion, and client/caregiver perspective.
In most cases, a stable diagnosis of ASD is possible before or around a child's second birthday (Chawarska, Klin, Paul, Macari, & Volkmar, 2009). An early, accurate diagnosis can help families access appropriate services, provide a common language across interdisciplinary teams, and establish a framework for families and caregivers within which to understand the child's difficulties. Any diagnosis of ASD, particularly of young children, is periodically reviewed, as diagnostic categories and conclusions may change as the child develops.
Interdisciplinary collaboration and family involvement are essential in assessing and diagnosing ASD; the SLP is a key member of a multidisciplinary team. In diagnosing ASD, it is important to have clinical experts agree that assessment results are consistent with the diagnostic characteristics of the disorder.
Assessment, intervention, and support for individuals receiving speech and language services are consistent with the World Health Organization's International Classification of Functioning, Disability, and Health (2001) framework. This framework considers impairments in body structures/functions, the individual's communication activities and participation, and contextual factors, including environmental barriers/facilitators and personal identity.
There is evidence to suggest that diagnostic features of ASD are evident in very young children. Most families/caregivers report observing symptoms within the first 2 years of life and typically express concern by 18 months of age. Studies of children with ASD have found
- parental reports of abnormalities in their children's language development and social relatedness were first noticed at about 14 months of age (Chawarska et al., 2007);
- displays of significantly fewer joint attention and communication behaviors at 1 year of age than shown by their typically developing same-age peers (Osterling & Dawson, 1994; Werner & Dawson, 2005);
- demonstrated atypical eye contact, passivity, decreased activity level, and delayed language by 12 months of age (Zwaigenbaum et al., 2005);
- subtle differences in sensory-motor and social behavior (Baranek, 1999) as well as differences in the use of communicative gestures (Watson et al., 2013) by 9 to 12 months of age;
- a decline (from normative levels) in eye fixation from 2 to 6 months of age not observed in infants who did not develop autism (Jones & Klin, 2013).
The identification of early behavioral indicators can help families obtain appropriate diagnostic referrals and access early intervention services, even before a definitive diagnosis is made (Woods & Wetherby, 2003). Furthermore, early intervention can improve long-term outcomes for many children (Dawson & Osterling, 1997; Harris & Handleman, 2000; Landa & Kalb, 2012).
There is research on the use of screening tools, including a broadband screener to identify communication delays (including ASD) in children from 9 to 24 months of age (Pierce et al., 2011; Wetherby, Brosnan-Maddox, Peace, & Newton, 2008) and questionnaire-based tools to screen for children at risk for ASD as early as 12 months of age (Turner-Brown, Baranek, Reznick, Watson, & Crais, 2012). There are also a number of algorithms and tools available to help physicians develop a strategy for early identification of children with ASD (Johnson & Myers, 2007).
Cultural and linguistic variables may contribute to challenges in identifying children with ASD and contribute to the disparity in the diagnosis of ASD among some racial/ethnic groups (Begeer, El Bouk, Boussaid, Terwogt, & Koot, 2009; Dyches, 2011). For example, Begeer et al. (2009) found that Dutch pediatricians might be inclined to attribute social and communication problems of non-European minority groups to their ethnic origin, while attributing these same characteristics to autistic disorders in children from majority groups.
While the core characteristics of ASD are common across cultures, parental response to the symptoms are not; these characteristics may be viewed through a cultural lens leading to under-, over-, or mis-diagnosis (Dyches, Wilder, & Obiakor, 2001). Signs and symptoms that are clearly "red flags" in the U.S. health care or educational system may not be viewed in the same way for someone from a culture that may not define the disorder.
One factor contributing to the inaccurate classification and diagnosis of students with autism is the "families' cultural and linguistic interpretation and reaction to receiving the diagnosis and to obtaining services" (Wilder, Dyches, Obiakor, & Algozzine, 2004, p. 106). Some cultures view disability in a negative light and feel that it is something that needs to be hidden from others, which may influence the type of care the family seeks. See cultural competence and the table of diverse perspectives on symptoms of autism [PDF] (Dyches, 2011).
Screening for ASD includes broadband screeners designed to detect developmental delays in the general pediatric population and autism-specific screening tools designed for either the general population or high-risk populations, such as children referred to the early intervention system. Any screening tool should have strong psychometric features to support its accuracy and be culturally and linguistically appropriate.
Screening typically includes
- norm-referenced parent and teacher report measures,
- competency-based tools, such as interviews and observations,
- hearing screening to rule out hearing loss as a contributing factor to communication and behavior difficulties.
Screening procedures evaluate the main characteristics that differentiate ASD from other developmental disorders, including difficulties in
- eye gaze,
- orienting to one's name,
- pointing to or showing objects of interest,
- pretend play,
- nonverbal communication,
- language development.
Social communication norms vary across cultures. When screening is conducted for non-linguistic aspects of communication, it is important to recognize when differences are related to cultural variances rather than secondary to a communication disorder. See cultural competence.
Loss of language or social skills at any age should be considered grounds for screening. In cases where children are being raised in a bilingual environment, consider whether language loss is attributable to language attrition. See bilingual service delivery.
Because children with ASD are often initially suspected of having a hearing problem, audiologists play a critical role in recognizing possible signs of ASD in children whose hearing they test and making appropriate referrals for screening and diagnosis of ASD.
Individuals suspected of having ASD based on screening results are referred to an SLP, and other professionals as needed, for a comprehensive assessment. Assessment of social communication skills should be culturally sensitive, functional, and sensitive to the wide range of acceptable social norms that exist within and across communities; and involve the collaborative efforts of families, caregivers, classroom teachers, SLPs, special educators, and psychologists as needed.
The SLP's role includes incorporating a family perspective into the assessment, effectively eliciting information from families about their concerns, beliefs, skills, and knowledge in relation to the individual being assessed. It is important to convey information to families clearly and empathetically, with an understanding that the assessment and diagnosis process is likely to be stressful and emotion-laden for family members (Marcus, Kunce, & Schopler, 2005).
The diagnostic evaluation for individuals at risk for ASD typically includes
- relevant case history, including information related to the child's health, developmental and behavioral history, and current medical status;
- a medical evaluation, including general physical and neurodevelopmental examination, as well as hearing and vision testing;
- medical and mental health history of the family;
- a comprehensive speech and language assessment.
In addition, diagnostic evaluation may include
- genetic testing, particularly if there is a family history of intellectual disability or genetic conditions associated with ASD (e.g., fragile X, tuberous sclerosis) or if the child exhibits physical features suggestive of a possible genetic syndrome;
- metabolic testing, if the child exhibits symptoms such as lethargy, cyclic vomiting, pica, or seizures.
Speech and Language Assessment
Depending on the individual's age and abilities, the SLP typically assesses
- receptive language;
- expressive language, including sound and word production and the frequency and function of verbal (vocalizations/verbalizations) and nonverbal (e.g., gestures) communication;
- literacy skills;
- social communication (See social communication disorders and social communication benchmarks [PDF]), including
- use of gaze,
- joint attention,
- initiation of communication,
- social reciprocity and the range of communicative functions,
- sharing affect,
- play behaviors,
- use of gestures;
- conversational skills, including
- topic management (initiating, maintaining, and terminating relevant, shared topics);
- providing appropriate amounts of information in conversational contexts;
- speech prosody.
Comprehensive assessment for ASD typically includes the following.
Standardized Assessment—an empirically developed evaluation tool with established reliability and validity. Formal testing may be useful for assessing the structure and form of language, but may not provide an accurate assessment of an individual's use of language (i.e., pragmatics). Standardized tests should be culturally and linguistically appropriate, and standard scores should not be determined if the norming sample is not representative of the individual assessed.
Parent/Teacher/Self-Report Measures—rating scales, checklists, and/or inventories completed by the family member(s)/caregiver, teacher, and/or individual. Findings from multiple sources (e.g., family vs. teacher vs. self-report) may be compared to obtain a comprehensive profile of communication skills. When possible, parent checklists should be provided in their native language to obtain the most accurate information.
Ethnographic Interviewing—an interview technique that uses open-ended questions, restatement, summarizing for clarification, and avoidance of leading questions and "why" questions in order to develop an understanding of the individual's and the family's perceptions, views, desires, and expectations. See cultural competence.
Analog Task(s)—observation of the individual in simulated or staged communication contexts that mimic real-world events, including peer-group activities and simulated workplace interactions.
Naturalistic Observation—observation of the individual in everyday social settings with others. Criterion-referenced assessments may be used during naturalistic observations to document an individual's functional use of language across social situations.
Dynamic Assessment—a method that seeks to identify an individual's skills as well as his or her learning potential. Dynamic assessment is highly interactive and emphasizes the learning process over time. It can be used in conjunction with standardized assessments and for ongoing assessment following the diagnosis of ASD.
Assessment may result in
- data that contribute to the diagnosis of ASD;
- description of the characteristics and severity of communication-related symptoms;
- recommendations for intervention, priorities and goals, and supports;
- referral to other professionals for further testing if other disorders/conditions are suspected or for additional data to confirm the diagnosis of ASD.
Need For Ongoing Assessment
Following a diagnosis of ASD, ongoing assessment focusing on the skills most essential for social and communication development is conducted to
- determine an individual's current profile of social communication skills,
- identify priority learning objectives within natural communication contexts,
- examine the influence of the communication partner and the environment on communication competence.
As part of the ongoing assessment process, dynamic assessment procedures can be used to identify the skills that an individual has achieved, those that may be emerging, and the contextual supports that enhance communication skills (e.g., AAC or modeling). See intervention goals associated with core challenges [PDF].
Special Considerations: Audiologic Assessment
Individuals with hearing loss may present with symptoms similar to those of ASD, particularly within the communication and socialization domains. For example, in the case of children with significant hearing loss or deafness,
- when compared to peers with normal hearing, their speech may differ, and they may rely more heavily on gestures (Worley, Matson, & Kozlowski, 2011);
- the inability to hear may limit social interaction with peers and lead to the kind of deficits in social skills often seen in children with ASD.
It is also possible for an individual to have both ASD and hearing impairment (Easterbrooks & Handley, 2005; Malandraki & Okalidou, 2007; Szymanski & Brice, 2008). The similarities in communication and socialization symptoms between hearing impairment and ASD populations, along with the possibility of dual diagnosis, can present challenges for differential diagnosis. An audiologic assessment is conducted when hearing loss and/or ASD are suspected.
Some characteristic behaviors associated with ASD may make it challenging to obtain valid and reliable hearing assessment results. These include comfort with sameness and aversion to novel situations; hypersensitivity to sensory input and negative behavioral responses; and communication differences, such as receptive language deficits and unreliable pointing gestures (Davis & Stiegler, 2010). Suggestions for assessing hearing in individuals with these and other challenging behaviors include
- minimizing distractions in the test suite;
- using visual schedules to support audiological testing sequence;
- partnering with parents and the managing SLP, who are more familiar with the individual's behaviors, interests, and needs;
- using the individual's primary/preferred language form (e.g., spoken language, sign, AAC devices, or picture symbols);
- increasing the individual's familiarity with assessment procedures prior to testing, such as through the use of social stories (Gray, White, & McAndrew, 2002), a visual schedule, and/or practicing with a favorite doll or stuffed animal;
- allowing the individual to touch and explore earphones that will be used during testing to help him or her overcome tactile sensitivity and related anxiety;
- incorporating flexibility in the assessment situation (e.g., testing order or earphone type);
- practicing appropriate motor movements in response to test stimuli;
- knowing what is reinforcing to the individual (e.g., food, clips from favorite videos, playing with a favorite toy) and using these reinforcers to reward appropriate behavioral responses to test stimuli;
- considering the use of multiple sessions to obtain complete results;
- being aware of the individual's signs of distress and terminating testing before the situation escalates (Brueggeman, 2012; Davis & Stieger, 2010);
- considering the need for auditory brainstem response (ABR) testing when behavioral audiometry is not possible.
Special Considerations in the School Setting
Within a public school setting, eligibility for services under the disability category of autism is based on the definition provided in the Individuals with Disabilities Education Improvement Act of 2004 (IDEA, 2004):
Autism means a developmental disability significantly affecting verbal and nonverbal communication and social interaction, generally evident before age 3, which adversely affects a child's educational performance. Other characteristics often associated with autism are engagement in repetitive activities and stereotyped movements, resistance to environmental change or change in daily routines, and unusual responses to sensory experiences. The term does not apply if a child's educational performance is adversely affected primarily because the child has an emotional disturbance as defined by IDEA criteria.
A child who manifests the characteristics of "autism" after age 3 could be diagnosed as having "autism" if the criteria in the preceding paragraph are met.
34 C.F.R. ß 300.7(c)(1)
By their very nature, severe social communication challenges impinge on participation and progress in the general education curriculum, extracurricular settings, and other nonacademic settings, as specified as the basis for eligibility of services by IDEA. Therefore, the pervasive nature of the social communication challenges in individuals with ASD supports the decision-making process to determine eligibility for language services in the schools (IDEA, 2004).
Individuals diagnosed with an ASD by means of other sources of clinical criteria, such as the DSM-5 (American Psychiatric Association, 2013), are likely to be eligible for special education services under the category of autism as defined above, due to the common challenges and deficits in social communication functioning across the various severity levels on the autism spectrum.
As mandated by IDEA, a priori criteria should be avoided when making decisions regarding eligibility for services. Such criteria include the following.
- Cognitive referencing. This practice of comparing IQ scores and language scores to determine eligibility for speech-language intervention is based on the assumption that language functioning cannot surpass cognitive levels.
- Chronological age. Research has shown that infants, toddlers, and preschoolers with ASD do benefit from communication services and supports ( Garfinkle & Schwartz, 2002; Lawton & Kasari, 2012; Pierce et al., 2011). In addition, individuals with autism can continue to develop communication abilities across their lifespan (Hamilton & Snell, 1993; Pickett, Pullary, O'Grady, & Gordon, 2009; Watanabe & Sturmey, 2003).
- Diagnostic label. A diagnostic label on its own typically reveals very little about the individual's communication abilities; however, in the case of the autism spectrum, social communication impairment is encompassed in its very definition (Baron-Cohen, Allen, & Gillberg, 1992; DiLavore, Lord, & Rutter, 1995; Lord & Corsello, 2005). Therefore, the diagnosis of ASD indicates the inclusion of communication services and supports rather than the exclusion of services.
- Absence of cognitive or other prerequisite skills. Research has shown that individuals (including those with ASD) who do not demonstrate supposed prerequisites can benefit from appropriate communication services and supports (Amato, Barrow, & Domingo, 1999; Bondy & Frost, 1998; Moes & Frea, 2002);
- Failure to benefit from previous communication services. Lack of progress may be tied to issues other than factors associated with the individual, such as inappropriate goals, unsuitable intervention methods, failure to incorporate assistive technology, or insufficient methods in measuring outcomes (National Joint Committee, 2003). Access to communication services and supports should not be denied merely because an individual failed to progress as a function of prior therapy; rather, previous experiences should be examined in order to determine ways in which communication services and supports could be better tailored to meet the individual's unique communication needs.
- Lack of funding or adequately trained personnel. Lack of funding and expertise often fuels exclusionary practices. If trained personnel are not available, there is an obligation either to find trained personnel or to train existing personnel (Timothy W. v. Rochester, NH School District, 1989). Similarly, lack of funding does not constitute a reason for exclusion from communication services and supports. IDEA states that identified needs have to be met.
High-functioning individuals with ASD pose particular challenges both for identification and for determining eligibility for services. These individuals often have either verbal or nonverbal intelligence within normal limits and appear to succeed in some or most academic subjects, particularly in early school years. As a result, many are not diagnosed until later school age, adolescence, or even adulthood. Long-term outcomes research for these individuals has shown that social communication deficits significantly affect their ability to adjust to new social demands in later academic and community settings and to achieve vocational goals (Gilchrist et al., 2001; Mueller, Schuler, Burton, & Yates, 2003; Tsatsanis, Foley, & Donehower, 2004). These findings suggest that it is important to provide intervention to address the gap between cognitive potential and social adaptive functioning.
Determining an individual's eligibility for educational services necessitates the use of a variety of strategies for gathering information, including standardized measures of social adaptive functioning, naturalistic observation across a range of social settings, and caregiver/teacher interviews or questionnaires. However, regardless of the assessment measures or tools used, the clinician needs to be aware of any subtle signs and symptoms consistent with a diagnosis of ASD.