A report published by researchers at Albert Einstein College of Medicine of Yeshiva University in the August 20 issue of JAMA suggests that measuring how much an individual's performance varies across several neuropsychological tests enhances the accuracy of predicting whether older adults will develop dementia.
Developing strategies to improve the prediction and diagnosis of dementia has critical therapeutic and public health implications. "Typically, when neuropsychological tests are used for diagnostic purposes, an individual's level of performance on specific tests is measured against healthy individuals to determine cognitive impairment," says Dr. Roee Holtzer, assistant professor of neurology and psychology at Einstein and lead author of the study. "However, this approach does not take into account intra-individual variability in cognitive function." Intra-individual variability refers to inconsistency in performance measured in the same person.
Dr. Holtzer and Einstein colleagues evaluated 897 individuals, age 70 or older, who have taken part in The Einstein Aging Study, a longitudinal study of aging and dementia in Bronx, New York. Participants had follow-up visits every 12 to 18 months, during which they underwent detailed neurological and neuropsychological evaluations. The researchers included tests for verbal IQ, attention/executive function, and memory.
The study focused on whether within-person variability across several neuropsychological tests, assessed at the initial study visit, predicted future dementia. "We know that level of performance on tests of memory, attention and executive function predicts dementia. However, this study showed for the first time that the degree of variability in performance across neuropsychological tests, measured within a person, improved the prediction of dementia above and beyond one's level of performance on each test alone," says Dr. Holtzer.
In the follow-up visits, participants underwent extensive neurological and neuropsychological testing to determine whether individuals remained normal or became demented. "Of the 897 participants, there were 61 cases of dementia (6.8 percent) identified during the follow-up period, which, on average, was 3.3 years," says Dr. Holtzer. "This figure is in line with what we'd expect for the incidence of dementia in this population."
The study concluded that within-person variability across these tests predicted the development of dementia independently of how people performed on the tests. The authors recommend that their findings be replicated in different populations before they're applied in a clinical setting.
Other Einstein researchers involved in this study were: Drs. Joe Verghese, Cuiling Wang, Charles B. Hall, and Richard B. Lipton. The Einstein Aging Study is supported by a National Institute on Aging grant. Dr. Holtzer is supported by the National Institute on Aging Paul B. Beeson Award. Co-author Dr. Verghese is supported by a National Institute on Aging grant.
About Albert Einstein College of Medicine of Yeshiva University
The Albert Einstein College of Medicine of Yeshiva University is one of the nation's premier centers for research, medical education and clinical investigation. It is the home to some 2,000 faculty members, 750 M.D. students, 350 Ph.D. students (including 125 in combined M.D./Ph.D. programs) and 380 postdoctoral investigators. Last year, Einstein received more than $150 million in grant funding from the National Institutes of Health (NIH). In addition, the NIH funds major research centers at Einstein in diabetes, cancer, liver disease, and AIDS. Other areas where the College of Medicine is concentrating its efforts include developmental brain research, neuroscience, cardiac disease, and initiatives to reduce and eliminate ethnic and racial health disparities. Through its extensive affiliation network involving five hospital centers in the Bronx, Manhattan and Long Island – which includes Montefiore Medical Center, Einstein's officially designated University Hospital – the College runs one of the largest post-graduate medical training program in the United States, offering approximately 150 residency programs to more than 2,500 physicians in training. For more information, please visit www.aecom.yu.edu.
Journal
JAMA