[Associations of obesity and physical activity with cognition in people aged 50 and above in Shanghai]

Objective: To investigate the associations of obesity and physical activity with cognition in the elderly. Methods: A cross-sectional survey was conducted from October 2009 to June 2010 among people aged ≥50 years selected through multistage random cluster sampling in Shanghai. The subjects' body weight, body height, waist circumference and hip circumference were measured to calculate body mass index (BMI) and waist-hip ratio (WHR), and the data on self-reported physical activity level were collected through questionnaire survey. A comprehensive battery of cognitive tests was conducted to assess subjects' cognitive functions, including verbal recall, forward digit span (FDS), backward digit span (BDS), and verbal fluency (VF). General linear model was used to examine the associations of BMI, WHR and physical activity with cognition. Results: A total of 7 913 participants were included, with a median age of 60 years. Age, sex, education level, income level, BMI, WHR and physical activity level were significantly associated with cognitive scores in univariate analysis. After adjusted for age, sex, education level and income level, BMI was no longer significantly associated with cognitive scores in all cognitive functions (all P>0.01). WHR was significantly associated with VF score (P<0.01). Abdominally obese participants had lower VF score than non-abdominally obese participants (P<0.01). Physical activity level was significantly associated with all cognitive functions (P<0.01). Compared with participants with moderate physical activity level, participants with low physical activity level had lower scores in all cognitive functions (P<0.01). Conclusion: Abdominal obesity and low physical activity level were negatively associated with cognition level in the elderly, suggesting that waist circumference control and physical activity might help maintain cognition in the elderly.