Obesity and vascular risk factors at midlife and the risk of dementia and Alzheimer disease.

BACKGROUND Vascular risk factors play a role in the development of dementia, including Alzheimer disease (AD). However, little is known about the effect of body mass index and clustering of vascular risk factors on the development of dementia. OBJECTIVE To investigate the relation between midlife body mass index and clustering of vascular risk factors and subsequent dementia and AD. DESIGN AND SETTING Participants of the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) study were derived from random, population-based samples previously studied in a survey carried out in 1972, 1977, 1982, or 1987. After an average follow-up of 21 years, 1449 individuals (73%) aged 65 to 79 years participated in the reexamination in 1998. MAIN OUTCOME MEASURES Dementia and AD. RESULTS Obesity at midlife (body mass index>30 kg/m2) was associated with the risk of dementia and AD even after adjusting for sociodemographic variables (odds ratio [OR], 2.4 [95% confidence interval (CI), 1.2-5.1]). The association was somewhat modified by further adjusting for midlife blood pressure, total cholesterol level, and smoking (OR, 2.1 [95% CI, 1.0-4.6]) and also for apolipoprotein E genotype and history of vascular disorders (OR, 1.9 [95% CI, 0.8-4.6]). Midlife obesity, high total cholesterol level, and high systolic blood pressure were all significant risk factors for dementia with ORs of around 2 for each factor, and they increased the risk additively (OR, 6.2 for the combination). CONCLUSIONS Obesity at midlife is associated with an increased risk of dementia and AD later in life. Clustering of vascular risk factors increases the risk in an additive manner. The role of weight reduction for the prevention of dementia needs to be further investigated.