Cardiometabolic multimorbidity, lifestyle behaviours, and cognitive function: a multicohort study

BACKGROUND: Little is known about the effect of lifestyle factors on cognitive decline related to cardiometabolic multimorbidity. We aimed to examine the association between cardiometabolic multimorbidity and cognitive decline, and the role of lifestyle factors in this association. METHODS: We did a pooled multi-cohort study using pooled data from four cohort studies (the Health and Retirement Study; the English Longitudinal Study of Ageing; the Survey of Health, Ageing and Retirement in Europe; and the China Health and Retirement Longitudinal Study) across 14 countries. Eligible participants were age 50 years and older, and those who were missing information on exposure and outcomes, or who had been diagnosed with dementia or Parkinson's disease, were excluded. Cardiometabolic multimorbidity was defined as the co-occurrence of two or three cardiometabolic diseases, including diabetes, heart disease, and stroke. The primary outcome of cognitive function was measured in three domains, on the basis of the mean and SD of the corresponding tests: memory, numeracy, and orientation, in all participants with available data. A global cognitive score was created by summing the individual scores. FINDINGS: The final sample consisted of 160 147 individuals across all four studies (73 846 [46·1%] men and 86 301 [53·9%] women) and participants had a mean age of 67·49 years (SD 10·43). An increasing number of cardiometabolic diseases was dose-dependently associated with the decline in cognitive function score (one disease, β=-0·15 [95% CI -0·17 to -0·13]; two diseases, β=-0·37 [-0·40 to -0·34]; three diseases, β=-0·57 [-0·64 to -0·50]), with comorbid diabetes and stroke (β=-0·23 [-0·29 to -0·17]) contributing most strongly to cardiometabolic disease-associated cognitive decline. Cognitive decline associated with cardiometabolic disease was accelerated with physical inactivity (one cardiometablic disease, p=0·020; two cardiometablic diseases, p=0·42; and three cardiometablic diseases, p=0·24), excessive alcohol use (one cardiometablic disease, p=0·016; two cardiometablic diseases, p=0·65; and three cardiometablic diseases, p=0·50), and the higher number of unhealthy lifestyle factors (one cardiometablic disease, p=0·79; two cardiometablic diseases, p=0·0050; and three cardiometablic diseases, p=0·888). INTERPRETATION: These findings indicated a targeted approach for simultaneously developing preventative interventions on lifestyles and integrated treatment for cardiometabolic comorbidities to delay cognitive decline in older people. FUNDING: Major Project of the National Social Science Fund of China, National Natural Science Foundation of China, China Medical Board, and Young Elite Scientists Sponsorship Program by CAST.