Sex‐specific association of physical frailty and cognitive function in a population‐based cross‐sectional study of American older adults

Abstract

AbstractBackgroundWe hypothesized that the association between physical frailty and cognition would be modified by participant sex in a nationally representative sample of elderly adults in the United States.MethodsCross‐sectional data from the National Health and Nutrition Examination Survey (NHANES 2011‐2014) were obtained for participants age ≥60 years. Physical frailty was defined by four measures developed by Fried et al.: exhaustion, weakness, low body mass, and low physical activity, and then categorized into robust (None), pre‐frail (1‐2 measures), or frail (3‐4 measures). Cognitive test scores were converted to z‐scores based on the study sample means and standard deviations. To estimate global cognition, a composite z‐score was calculated by averaging the individual z‐scores. Linear regression models were fit to evaluate the association between frailty and cognition. In addition to the cognitive tests, we evaluated frailty as a risk factor for self‐reported memory complaint (SMC) using logistic regression. We used sampling weights to account for the NHANES design.ResultsA total of 2863 participants aged 60 years or older were included. According to the 4‐items frailty measures, 50.5% of participants were robust, 44.7% were pre‐frail, and 4.8% were frail. The majority of the participants were > 70 (58.9%), women (54.4%), and White (79.4%). After adjustment for age, sex, race/ethnicity, education, alcohol use, income, marital status, diabetes, hypertension, and history of stroke, compared to robust, being frail (β = ‐0.69, 95%CI: ‐0.90, ‐0.48) and pre‐frail (β = ‐0.11, 95%CI: ‐0.19, ‐0.02) was associated with lower global cognitive z‐scores. Compared to men, pre‐frail women had mean adjusted global cognitive z‐scores that were ‐0.33 standard deviations lower (95% confidence interval (CI): ‐0.23, ‐0.42; P<0.001). Similarly, compared to frail men, frail women had mean adjusted global z‐scores that were lower but the difference was not significant. There were no significant differences in odds of SMC by sex with regard to frailty.ConclusionsIn this population‐based cohort, our findings suggest frailty was associated with lower cognitive performance in older adults and modified by sex. Participants who did not meet criteria for 3‐4 measures of frailty but had 1‐2 measures showed similar lower cognitive performance.