Clustering of cardiometabolic risk factors and dementia incidence in older adults: a cross-country comparison in England, the USA and China.

BACKGROUND: There is mixed evidence for an association between cardiometabolic risk factors and dementia incidence. This study aimed to determine whether different latent classes of cardiometabolic conditions were associated with dementia risk in older adults across England, the USA and China.

METHODS: A total of 4511 participants aged 50 and older were drawn from the English Longitudinal Study of Ageing (ELSA), 5112 from Health and Retirement Study (HRS) and 9022 from China Health and Retirement Longitudinal Study (CHARLS). Latent class analyses were performed across each dataset utilising seven baseline cardiometabolic conditions: obesity, low high-density-lipoprotein (HDL) cholesterol, systolic and diastolic blood pressure (BP), hyperglycemia, diabetes, and inflammation. Confounder-adjusted Cox proportional hazards regressions were conducted to estimate dementia incidence by cardiometabolic latent classes.

RESULTS: Three similar cardiometabolic classes were identified across all countries: 1) 'relatively healthy/healthy obesity', 2) 'obesity-hypertension' and 3) 'complex cardiometabolic'. Across the three samples, a total of 1,230 individuals developed dementia over a median of 6.8-12.2 years. Among ELSA and HRS participants, the 'complex cardiometabolic' group had a higher dementia risk when compared to the 'healthy obesity' groups (England: AdjHR=1.62 [95%CI=1.11-2.37]; USA: AdjHR=1.31 [95%CI=1.02-1.68]). However, in CHARLS participants, the 'obesity-hypertension' group had a greater risk of dementia when compared to the 'relatively healthy' group (AdjHR=1.28 [95%CI=1.04-1.57]).

CONCLUSION: This study provides evidence that in western populations, complex cardiometabolic clusters are associated with higher rates of dementia incidence, whereas in a Chinese sample, a different cardiometabolic profile seems to be linked to an increased risk of dementia.