Have you been waiting for a quick yet reliable test for early dementia? The AD8 might be your answer. The interview-based screening tool detects early cognitive impairment, has been validated against the clinical dementia rating scale and against neuropsychological tests, and is available in several languages. Indications are that, combined with a simple performance measure, such as recall of a word list, the AD8 is sufficiently sensitive and specific to serve as an initial screening tool in primary care. The Affordable Care Act, which comes into law beginning January 2011, stipulates that clinicians assess patients for cognitive impairment as part of their annual wellness visit. What tools will primary care physicians use to comply? Could the AD8 fit the bill?
On Tuesday, 30 November, Alzforum hosted a Webinar on the pros, cons, and potential uses of the AD8. Its developer, James Galvin, now at New York University, New York City, reviewed the latest data, including how AD8 scores correlated with AD-like biomarker signatures. Tracey Holsinger, the Durham Veteran Affairs Medical Center, North Carolina, discussed her recent finding that dementia screening is by and large well accepted among the elderly. Joining them for a panel discussion was Eric Tangalos, Mayo Clinic, Rochester, Minnesota. A geriatrician, Tangalos is the past president of the American Medical Directors Association, which promotes quality in long-term care. The Webinar was recorded for posterity and can now be viewed by clicking on the links below.
By Tom Fagan
The AD8 is the brainchild of Jim Galvin at New York University, New York City, and John Morris and Cathy Roe at Washington University, St. Louis, Missouri. Galvin demonstrated this brief, informant-based test for early cognitive impairment to the Alzforum audience in a previous Live Discussion in 2007, when he was at WashU, where the test was developed. The test began as a 55-item questionnaire to probe cognitive function, and was whittled down to a final eight items (Galvin et al., 2005). Initially developed in a research setting, the AD8 was subsequently tested in a community-based clinical setting. The researchers reported that the AD8 gives reliable results from test to test and when different raters administer it to the same person. They also found that it is valid and reliable in comparison to the Clinical Dementia Rating Scale and neuropsychological tests of memory and executive function (Galvin et al., 2006). When combined with a brief performance measure, for example, the CERAD 10-item Word List Recall, the AD8 scored at 94 percent sensitivity and 82 percent specificity in detecting early signs of dementia (Galvin et al., 2007).
Though the scientists initially designed the AD8 to be taken by a close relative or caregiver, it later turned out that when patients rated themselves, their scores matched well with what the informants had marked on their behalf (Galvin et al., 2007). This means that in the absence of a qualified informant, the test could still be used. In primary care practice, a qualified informant is often not at hand.
New data now strengthen the case that the test actually diagnoses AD, not another cognitive problem. In the September issue of Brain, Galvin and colleagues at WashU report that AD8 scores correlate with the same AD-like biomarker signature that ADNI and numerous previous studies at WashU and elsewhere have shown to precede and predict frank AD. In a sample of 257 volunteers, a score of 2 or higher on the AD8 (high scores are more predictive of dementia) correlated with positive PIB-PET imaging of amyloid plaques in the brain, with lower cerebrospinal fluid levels of Aβ42, and with higher CSF tau and phospho-tau levels than normal (Galvin et al., 2010).
Galvin and colleagues suggest that the AD8 could be a useful early screening tool in primary care settings. Both neuropsychological testing and CDR are widely used in research settings to identify people with early cognitive impairment, but neither may be particularly suitable for community testing. The MMSE, which is commonly used to screen for dementia, by broad scientific consensus lacks sensitivity to detect early changes. The MMSE and many other brief screening measures are performance based, comparing a person’s test score to accepted norms. These tests provide a cross-sectional “snapshot” of a person’s ability, or attention, at the time of examination but do not measure change within that person, or information on whether the scores relate to any impairment in the person’s activities of daily living. The CDR does measure change in cognitive function as well as interference with ADLs but is too time-consuming for primary care. Some performance tests, such as the MMSE, may also be biased based on age, education, language, race, and culture.
The AD8 is culturally neutral. It has been translated and validated into several languages, including Spanish, Chinese, Portuguese (Correia et al., under review), and Korean (Ryu et al., 2009). Versions in French, Czech, and the Philippine language Tagalog are currently undergoing validation. According to Galvin, the AD8 is being used at a growing number of centers abroad and, in the process, proving to work well in a variety of cultural settings.
Many practitioners are reluctant to screen for early dementia, citing lack of medicines that slow progression of the disease, or inaccuracies in screening (see, e.g., Brayne et al., 2007 and Bond et al., 2010). But attitudes toward screening may soon change. For one, recent work suggests that people and caregivers overwhelmingly favor screening for dementia (see Holsinger et al., 2010 and Bond et al., 2010). In addition, the Affordable Care Act, which comes into law beginning January 2011, stipulates that clinicians assess patients for cognitive impairment as part of their annual wellness visit (see healthcare.gov Fact Sheet for Seniors). Medicare billing codes have been set aside for tracking reimbursement for this cognitive checkup, but the Act provides no recommendations for how cognitive impairment in elders should be assessed.
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