The circadian syndrome is a predictor for cognition impairment in middle-aged adults: Comparison with the metabolic syndrome

Aims: Circadian syndrome (CircS) is considered a better predictor for cardiovascular disease than the metabolic syndrome (MetS). We aim to examine the associations between CircS and MetS with cognition in Chinese adults. Method: We used the data of 8546 Chinese adults aged >= 40 years from the 2011 China Health and Retirement Longitudinal Study. MetS was defined using harmonised criteria. CircS included the components of MetS plus short sleep and depression. The cut-off for CircS was set as >= 4. Global cognitive function was assessed during the face-to-face interview. Results: CircS and MetS had opposite associations with the global cognition score and self-reported poor memory. Compared with individuals without the CircS and MetS, the regression coefficients (95%CI) for global cognition score were -1.02 (-1.71 to -0.34) for CircS alone and 0.52 (0.09 to 0.96) for MetS alone in men; -1.36 (-2.00 to -0.72) for CircS alone and 0.60 (0.15 to 1.06) for MetS alone in women. Having CircS alone was 2.53 times more likely to report poor memory in men (95%CI 1.80-3.55) and 2.08 times more likely in women (95%CI 1.54-2.81). In contrast, having MetS alone was less likely to report poor memory (OR 0.64 (0.49-0.84) in men and 0.65 (0.52-0.81) in women). People with CircS and MetS combined were more likely to have self-reported poor memory. Conclusions: CircS is a strong and better predictor for cognition impairment than MetS in Chinese middle-aged adults. MetS without short sleep and depression is associated with better cognition.