According to an article published in the August 20 issue of JAMA, there is likely an association between within-person variability on neuropsychological testing and the development of dementia in older adults.
Roee Holtzer, Ph.D. (Albert Einstein College of Medicine, Yeshiva University, New York) and colleagues write that, “Developing strategies to improve the prediction and diagnoses of dementia has paramount therapeutic and public health implications.” They add: “When neuropsychological tests are used for diagnostic purposes, an individual’s level of performance on specific tests is measured against healthy normative samples to determine cognitive impairment. However, this approach does not take into account intra-individual variability in cognitive function.” This means that standard approaches fail to deal with inconsistency in cognitive performance within a person.
The study consisted of 897 individuals, age 70 or older, who are part of The Einstein Aging Study – a longitudinal study taking place in Bronx County, New York that focuses on aging and dementia. Every 12 to 18 months, participants had follow-up visits and underwent detailed neurological and neuropsychological evaluations. Participants were tested for verbal IQ, attention/executive function, and memory. The researchers were interested in finding out if within-person across-neuropsychological test variability could be used to predict future dementia.
“Of the 897 participants,” the authors find, “there were 61 cases of incident dementia (6.8 percent) … identified during the follow-up period (mean [average] 3.3 years).” They also report that, “On the basis of the consensus clinical diagnostic procedures, 47 participants developed incident dementia of the Alzheimer type and 18 participants developed incident vascular dementia. During the study, 128 individuals died, as expected for the age of this cohort. Of these, 18 had developed incident dementia.”
“In summary, within-person across-neuropsychological test variability was associated with development of dementia independently of performance of the neuropsychological tests. This finding needs to be replicated in different populations before it is applied in a clinical setting,” conclude the authors.
Within-Person Across-Neuropsychological Test Variability and Incident Dementia
Roee Holtzer; Joe Verghese; Cuiling Wang; Charles B. Hall; Richard B. Lipton
JAMA(2008). 300[7]: pp. 823-830.
Written by: Peter M Crosta