Associations between lifestyle and cognitive function over time in women aged 40-79 years

Background: Smoking, excessive drinking, and physical inactivity are associated with reduced cognitive function but the independence, domain specific cognitive effects, and trajectories of these associations are not firmly established. Objective: Our aim was to examine these lifestyle-cognitive function associations in middle-to-older aged women across time. Methods: Cohort study design with repeat surveys (2001, 2005, and 2008). Participants were volunteers from a random sample of Australian women on the Brisbane electoral roll; mean (±SD) age 60 ± 11 years in 2001. Outcome measures were the Mini-Mental State Examination (MMSE), Auditory Delayed Index (ADI), Visual Delayed Index (VDI), Working Memory Index (WMI), and Processing Speed Index (PSI). Results: 489 women completed cognitive testing in 2001, 451 in 2005, and 376 in 2008. Mean (±SD) cognitive scores in 2001 were MMSE: 29.1 ± 1.2, ADI: 104.6 ± 13.4, VDI: 107.2 ± 14.0, WMI: 104.1 ± 12.3, and PSI: 102.7 ± 11.8. Multivariate adjusted mean scores (95% CI) over the 7-year study period were higher for moderate drinkers than non-drinkers for the MMSE (β = 0.32; 0.04, 0.61), the VDI (β = 4.33; 0.96, 7.70), and the WMI (β = 3.21; 0.34, 6.07). Current smokers performed worse than never-smokers for the MMSE (β = -0.35; 0.64, -0.06), the VDI (β = -3.91; -7.57, -0.26), the WMI (β = -3.42; -6.67, -0.18), and the PSI (β = -5.89; -8.91, -2.87). PSI was higher in women performing strenuous physical activity compared to inactive women (β = 2.14; 0.37, 3.90). None of the three lifestyle parameters influenced the changes in cognition across time. Conclusions: Alcohol and exercise were associated with selective protective effects and tobacco with selective harmful effects on cognitive function in middle-to-older aged women. Associations remained consistent across time.