Imagine if early identification of Alzheimer's disease, followed by quick intervention, could delay its full development by as much as five to 10 years, as early intervention can do in heart disease and diabetes. We could be steps closer to making this happen because of two forces:
- Advances in the field of cognitive aging and dementia provide a better understanding of the spectrum of age-related changes, from typical, age-related cognitive declines to profound Alzheimer's-related impairment.
- Findings from a recent working group of the National Institute on Aging and Alzheimer's Association identify new criteria for clinical diagnosis of mild cognitive impairment due to Alzheimer's.
Speech-language pathologists are acutely aware of the "graying of America." Population estimates from the U.S. Department of Health and Human Services, Administration on Aging, indicate that by 2030, nearly 20% of the U.S. population, or 71.5 million Americans, will be older adults [PDF]. And, predicts the Alzheimer's Association, the prevalence of Alzheimer's will triple by the year 2050, affecting more than 13.6 million people in the United States. The result could be a health care crisis costing up to $1.1 trillion by 2050.
But the crisis could be eased, at least somewhat, if health care providers, including speech-language pathologists, could identify older adults at the greatest risk for the disease and provide interventions that might delay its onset. The working group findings provide the framework for such an opportunity.
New Diagnostic Criteria
Clinical diagnostic criteria for Alzheimer's were first established in 1984 by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association. Soon, technical and scientific advances improved understanding of the disease's clinical spectrum and symptoms. By 2009, experts in academia and health care called for revision of the criteria.
In response, the National Institute on Aging and Alzheimer's Association formed three interdisciplinary working groups to focus on diagnostic criteria for the disease's dementia phase, identification of diagnostic criteria for the symptomatic, predementia phase, and a research agenda for the asymptomatic, preclinical phase. The overall charge to all three groups was to give health care providers the tools to screen, identify, and intervene at an earlier stage.
Working group findings were published in a series of four articles in Alzheimer's and Dementia (Albert et al., 2011; Jack et al., 2011; McKann et al., 2011; Sperling et al., 2011). Information on identification of diagnostic criteria for the symptomatic predementia phase, also known as mild cognitive impairment due to Alzheimer's, applies most directly to SLPs. In fact, it names SLPs as qualified to identify and treat mild cognitive impairment, and suggests the tools to use with older adults who appear on a trajectory toward full-blown Alzheimer's.
Historically, "mild cognitive impairment" has been used to describe myriad symptoms related to normal aging, traumatic brain injury, and substance abuse. In this case, however, it refers specifically to the symptomatic predementia phase of Alzheimer's, and is generally characterized by progressive cognitive decline greater than typical age-associated cognitive change, with preservation of independence in functional abilities.
As with Alzheimer's dementia, there is no laboratory test or neuroimaging that can diagnose mild cognitive impairment—it requires judgment of a clinician. Although it is nearly impossible to make sharp distinctions between different types of cognitive decline in aging, the working group proposes several core clinical criteria for diagnosing mild cognitive impairment (see chart [PDF]). According to Albert and colleagues (2011), these include:
- Concern about a change in cognition reported by the patient, someone who knows the patient well, or a skilled clinician observing the patient.
- Evidence of lowered performance in one or more cognitive domains (attention, memory, language, visuospatial skills, executive function) that is greater than would be expected for the patient's age and educational background.
- Reported or documented decline in episodic memory, found to be significantly predictive of Alzheimer's development.
- No difficulty with everyday functional activities.
- Decreased efficiency or accuracy in performing more complex tasks, such as paying bills or shopping.
Cognitive Screening and Assessment
The working group details the importance of documenting objective cognitive decline, and two elements are key to the cognitive screening and assessment of mild cognitive impairment:
- Longitudinal documentation of the cognitive decline.
- Formal cognitive testing to establish degree of cognitive decline. SLPs can use many cognitive screening tools that, when administered repeatedly over a period of time, can provide longitudinal evidence of cognitive decline (see chart [PDF]).
SLPs in skilled nursing facilities can also review a resident's Minimum Data Set—the federally mandated comprehensive functional assessment—for a longitudinal picture of the resident's cognitive function, although with no standardized comparison.
The working group suggests that standardized cognitive testing is optimal for objectively assessing the degree of cognitive dysfunction. People with mild cognitive impairment typically score 1 to 1.5 standard deviations below the mean for their education- and age-matched peers on formal cognitive assessments. Because of the predictive significance of an episodic memory deficit, the working group recommends using standardized tools—such as the Wechsler Memory Scale Revised Logical Memory I and II and the California Verbal Learning Test—to evaluate memory.
The group also recommends testing other domains of cognitive function, if possible, using appropriate validated measures such as the Boston Naming Test (language) and the Trail Making Test (attention and execution function). Because a full cognitive battery is not always feasible, the evaluator can quickly assess cognitive function using simple, informal techniques such as asking a patient to learn a street address and recall it after a delay. However, these informal approaches typically do not assess cognitive domains beyond memory and may not be sensitive enough to capture the subtle cognitive dysfunction associated with mild cognitive impairment.
The working group did not limit the ability to diagnose cognitive decline to a specific discipline, but rather indicated that many appropriately qualified clinicians can perform these assessments. Given that SLPs are included in this list of clinicians, the new guidelines offer SLPs the opportunity to take a lead role in early identification of mild cognitive impairment.
The new diagnostic criteria are a major step forward in addressing the growing incidence of Alzheimer's, but multiple challenges remain for SLPs and other health care providers. First, it remains unclear how quickly, consistently, and willingly the U.S. health care system will accept and implement these criteria. The criteria have been endorsed by both the National Institute on Aging and the Alzheimer's Association in the hope that they will lay a foundation for a fundamental shift toward earlier diagnosis and treatment of Alzheimer's. Although the American Medical Association announced and acknowledged the criteria, it remains unclear to what degree physicians have changed their practice in response. Without physicians willing and ready to document the diagnosis of mild cognitive impairment, reimbursement for speech-language pathology assessment and intervention will remain problematic.
Even with a documented diagnosis, reimbursement for provision of cognitive-communication intervention for this population remains an area of concern. Reimbursement models are based on evidence, and there needs to be more research documenting successful outcomes of intervention for predementia Alzheimer's.
SLPs, however, are in a unique position to be at the forefront of addressing the disease's increased incidence by arming themselves with the working group results, acting as qualified clinicians who can screen and assess cognitive decline according to the new criteria, and promoting a research agenda designed to identify evidence-based approaches for slowing decline in mild cognitive impairment.