The purpose of this study was to investigate the relationship between metabolic syndrome (MetS), sleep duration and mild cognitive impairment (MCI) in community-dwelling older Chinese adults.

The study comprised of 1367 community-dwelling Chinese participants (563 men; mean age: 71.0 years) recruited from Tianjin and Shanghai, China who were invited to participate in a comprehensive geriatric assessment. The International Diabetes Federation metabolic syndrome guidelines were used to define MetS. The Mini-Mental State Examination (MMSE) and the Instrumental Activities of Daily Living (IADL) scale were used for the initial classification of patients with MCI. We divided sleep duration into five groups (≤6 h, 6–8 h which was used as the reference, 8–9 h, 9–10 h, and >10 h). Nutritional status was assessed by Mini Nutrition Assessment Short Form.

The overall incidence of metabolic syndrome was 46.7%, the overall incidence of mild cognitive impairment was 17.4%. In logistic regression analysis model, after adjusting for multiple confounding factors such as nutritional status and physical activity level, there was a significant positive association between long sleep duration (> 10h) and mild cognitive impairment in general population and metabolic syndrome population (p<0.05), but the association was not significant in non-metabolic syndrome group. In addition, in the long sleep duration group, the components of metabolic syndrome, elevated blood glucose were significantly associated with mild cognitive impairment (p<0.05).

Long sleep duration was significantly associated with increased risk of MCI in older adults with MetS, but not in those without MetS. The prevention of MCI may be more effective in the population of MetS with long sleep duration.