The relation between psychometric test performance and physical performance in older adults

Background. The relationship between cognitive function and physical disability in nondemented older adults is not well characterized. The purpose of this study was to determine the relationship between performance on psychometric measures and a modified Physical Performance Test (modified PPT) in older men and women. Methods. One hundred twenty-five men and women aged 75 years and older, who were enrolled in randomized, controlled trials of exercise or hormone replacement therapy, were recruited from the community- at-large and from congregate living sites. Measures obtained included Trailmaking A and B tests, Cancellation Random Figure tests, Weschler Associate Learning and 20-minute Delayed Recall, Verbal Fluency test, a modified PPT, and self-reports about performance of activities of daily living, medication use, and hospitalization in the previous year. Results. Simple regression analysis demonstrated that speed of performance on the Trailmaking B and Cancellation Random Figure tests was significantly associated with total modified PPT score (r = .29, p < .001 and r = .36, p < .001, respectively). A factor analysis of the psychometric test battery demonstrated that two factors, a cognitive speed factor and a memory factor, accounted for 55% of the variance in cognitive test performance. Hierarchical multiple regression analyses demonstrated that age, number of medications, and the cognitive speed factor were independent predictors of total modified PPT score. Conclusions. Cognitive processing speed is a significant component of physical frailty in this population, although it accounts for a small percentage of variance on a standardized physical performance test.