OBJECTIVE: Associations between metabolic syndrome and its individual components with risk of incident dementia and its different subtypes are inconsistent. RESEARCH DESIGN AND METHODS: The 7,087 community-dwelling subjects aged > or =65 years were recruited from the French Three-City (3C) cohort. Hazard ratios (over 4 years) of incident dementia and its subtypes (vascular dementia and Alzheimer's disease) and association with metabolic syndrome (defined according to the National Cholesterol Education Program Adult Treatment Panel III criteria) and its individual components (hypertension, large waist circumference, high triglycerides, low HDL cholesterol, and elevated fasting glycemia) were estimated in separate Cox proportional hazard models. RESULTS: Metabolic syndrome was present in 15.8% of the study participants. The presence of metabolic syndrome increased the risk of incident vascular dementia but not Alzheimer's disease over 4 years, independent of sociodemographic characteristics and the apolipoprotein (apo) Eepsilon4 allele. High triglyceride level was the only component of metabolic syndrome that was significantly associated with the incidence of all-cause (hazard ratio 1.45 [95% CI 1.05-2.00]; P = 0.02) and vascular (2.27 [1.16-4.42]; P = 0.02) dementia, even after adjustment of the apoE genotype. Diabetes, but not impaired fasting glycemia, was significantly associated with all-cause (1.58 [1.05-2.38]; P = 0.03) and vascular (2.53 [1.15-5.66]; P = 0.03) dementia. CONCLUSIONS: The observed relation between high triglycerides, diabetes, and vascular dementia emphasizes the need for detection and treatment of vascular risk factors in older individuals in order to prevent the likelihood of clinical dementia.