Metabolic syndrome and risk of dementia in older adults.

Objectives: To investigate the association between metabolic syndrome (MetS; a clustering of cardiovascular risk factors including abdominal obesity, hypertension, dyslipidemia, and hyperglycemia, each of which has been individually associated with dementia) and incident dementia, Alzheimer's disease (AD), and vascular dementia (VaD) in older adults before and after the age of 75.

Design: Prospective population-based cohort.

Setting: An Italian municipality.

Participants: A community-based sample of 749 subjects aged 65 and older who, in 1999/2000, were free of cognitive impairment and, in 2003/04, underwent follow-up for incident dementia.

Measurements: The relationship between incident overall dementia, AD, and VaD and MetS. Dementia was defined according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. MetS was defined according to the National Cholesterol Education Program criteria.

Results: Risk of overall dementia and its subtypes was not associated with MetS or any MetS component in participants younger than 75. In participants aged 75 and older, MetS was associated with a lower risk of AD (hazard ratio (HR)=0.33, 95% confidence interval (CI)=0.12-0.94) but not of VaD, and abdominal obesity was associated with a lower risk of overall dementia (HR=0.53, 95% CI=0.28-0.98).

Conclusion: MetS measured in late life is not associated with risk of dementia. After age 75, persons with MetS may even be at lower risk for AD.