Abstract
OBJECTIVES: To determine whether an objective measure of daytime movement is associated with better cognitive function in women in their 80s. DESIGN: Cross-sectional. SETTING: A study of health and aging. PARTICIPANTS: Two thousand seven hundred thirty-six older women without evidence of dementia. MEASUREMENTS: Daytime movement was assessed using actigraphy, which involved wearing a watch-like device that objectively quantified accelerometer motion over a mean of 3.0+/-0.8 days. Cognitive function was measured using the Trail-Making Test, Part B (Trails B) and the Mini-Mental State Examination (MMSE). Cognitive impairment was defined as performing 1.5 standard deviations (SDs) worse than the mean on a given test. RESULTS: Participants had a mean age of 83+/-4; 10% were African American. After adjustment for age, race, and education, women in the highest movement quartiles had better mean cognitive test scores (20+/-0.3 seconds faster on Trails B and 0.3+/-0.2 points higher on MMSE, both P<.001) than those in the lowest quartile and were less likely to be cognitively impaired (odds ratio (OR)=0.61, 95% confidence interval (CI)=0.41-0.92 for Trails B; OR=0.68, 95% CI=0.44-1.07 for MMSE). Associations were similar in different subgroups and were independent of self-reported walking, medical comorbidities, physical function, and other health-related behaviors. CONCLUSION: Daytime movement as measured objectively using actigraphy was associated with better cognitive function and lower odds of cognitive impairment in women in their 80s. Additional studies are needed to clarify the direction of the association and to explore potential mechanisms.