Association of dietary diversity and weight change with cognitive impairment among Chinese elderly: A prospective national cohort study

BACKGROUND: Dietary diversity is reported to be beneficial for cognitive function, while the effect may be offset by weight change status. We aimed to examine the association of dietary diversity and weight change with cognitive impairment among older adults. METHODS: We used three waves from 2008 to 2014 of the Chinese Longitudinal Survey of Health and Longevity, which included 16,954 participants for the subsequent screening and analysis. Dietary diversity information was collected from the food frequency questionnaire. Cognitive function was assessed using the Mini Mental State Examination. The relation of dietary diversity and weight change with cognitive impairment was investigated using Cox proportional hazards models and cubic spline regression. RESULTS: Compared with those reported poor dietary diversity at baseline, participants with good dietary diversity had a 16 % (hazard ratio [HR] = 0.84, 95 % confidence interval [CI]: 0.71-0.99) lower risk of cognitive impairment. The HR and 95 % CI of participants with consistently good dietary diversity from 2008 to 2011 was 0.71 (0.57-0.89) for cognitive impairment compared to those with consistently poor dietary diversity. Compared with the weight stable group, the HRs and 95 % CI for cognitive impairment were 1.34 (1.10-1.64) in weight loss group, and 1.08 (0.88-1.33) in weight gain group. Restricted cubic splines showed the risk of cognitive impairment decreased with higher dietary diversity score or less weight change, though no significant interaction between dietary diversity and weight change was found. LIMITATION: Given the observational nature of this study, there might be a reverse causation for the observed association. CONCLUSION: Establishing and maintaining good dietary diversity were associated with a lower risk of cognitive impairment regardless of weight change status, whereas weight loss was associated with increased cognitive impairment risk independently among older Chinese adults.