Central obesity in midlife increases risk of dementia independent of diabetes and cardiovascular comorbidities. Fifty percent of adults have central obesity; therefore, mechanisms linking central obesity to dementia need to be unveiled.

OBJECTIVEType 2 diabetes confers a greater excess risk of cardiovascular disease in women than in men. Diabetes is also a risk factor for dementia, but whether the association is similar in women and men remains unknown. We performed a meta-analysis of unpublished data to estimate the sex-specific relationship between women and men with diabetes with incident dementia.RESEARCH DESIGN AND METHODSA systematic search identified studies published prior to November 2014 that had reported on the prospective association between diabetes and dementia. Study authors contributed unpublished sex-specific relative risks (RRs) and 95% CIs on the association between diabetes and all dementia and its subtypes. Sex-specific RRs and the women-to-men ratio of RRs (RRRs) were pooled using random-effects meta-analyses.RESULTSStudy-level data from 14 studies, 2,310,330 individuals, and 102,174 dementia case patients were included. In multiple-adjusted analyses, diabetes was associated with a 60% increased risk of any dementia in both sexes (women: pooled RR 1.62 [95% CI 1.45–1.80]; men: pooled RR 1.58 [95% CI 1.38–1.81]). The diabetes-associated RRs for vascular dementia were 2.34 (95% CI 1.86–2.94) in women and 1.73 (95% CI 1.61–1.85) in men, and for nonvascular dementia, the RRs were 1.53 (95% CI 1.35–1.73) in women and 1.49 (95% CI 1.31–1.69) in men. Overall, women with diabetes had a 19% greater risk for the development of vascular dementia than men (multiple-adjusted RRR 1.19 [95% CI 1.08–1.30]; P < 0.001).CONCLUSIONSIndividuals with type 2 diabetes are at ∼60% greater risk for the development of dementia compared with those without diabetes. For vascular dementia, but not for nonvascular dementia, the additional risk is greater in women.

Dementia prevalence in this ethnic group is similar to that reported in Canadian and European studies but lower than in Caribbean-Hispanics residing in the United States. The etiological fraction of dementia attributable to type 2 diabetes mellitus and stroke is substantial and points toward the need for intervention research and treatment with the goal of reducing neurological sequelae in groups with high prevalence of type 2 diabetes mellitus. The allele frequency of ApoE was similar to that in other published studies on Mexican Americans. The low frequency of the E4 allele may contribute to the difference in etiology of dementia in older Mexican Americans and older people of European background. Dementia in this ethnic group may be related to preventable causes, with a smaller genetic component than in Europeans.

Most healthy elderly people did not experience cognitive decline. Measures of subclinical CVD were modest predictors of cognitive decline. Those with any APOE epsilon4 allele in combination with atherosclerosis, peripheral vascular disease, or diabetes mellitus were at substantially higher risk of cognitive decline than those without the APOE epsilon4 allele or subclinical CVD. High levels of atherosclerosis increased cognitive decline independently of APOE genotype.

To examine the reasons for the association between socioeconomic status and poor health, the authors examined the nine-year mortality experience of a random sample of residents aged 35 and over in Oakland, California. Residents of a federally designated poverty area experienced higher age-, race-, and sex-adjusted mortality over the follow-up period compared with residents of nonpoverty areas (relative risk = 1.71, 95 per cent confidence interval 1.20-2.44). This increased risk of death persisted when there was multivariate adjustment for baseline health status, race, income, employment status, access to medical care, health insurance coverage, smoking, alcohol consumption, physical activity, body mass index, sleep patterns, social isolation, marital status, depression, and personal uncertainty. These results support the hypothesis that properties of the sociophysical environment may be important contributors to the association between low socioeconomic status and excess mortality, and that this contribution is independent of individual behaviors.