The metabolic syndrome, diabetes, and Alzheimer's disease.

Background: The metabolic syndrome (MS) is a cluster of metabolic abnormalities that has been controversially associated with Alzheimer's disease (AD), so the purpose of this report was to investigate the association between these two chronic diseases a sample of older persons.
Methods: Case-control study of 90 consecutive outpatients with AD and 180 non-demented controls from a dementia clinic at a tertiary care hospital in Mexico City. Probable or possible AD was diagnosed according to the guidelines of the Consortium to Establish a Registry for Alzheimer's Disease, whereas control participants where those classified as normal by the same instrument. MS was defined according to the World Health Organization criteria. Patients were matched 1:2 by age, sex, and years of education. Conditional regression analysis was used to test the association between MS and AD.
Results: Compared to controls, MS was more frequent among AD patients (72.2% vs. 23.3%; P < 0.01). While all components of MS were more frequent among cases than control patients, only diabetes was statistically significant, whereas hypertriglyceridemia and low HDL cholesterol were marginally associated. Conditional regression analysis showed that among AD participants, the probability of having MS was about sevenfold higher than for their non-demented counterparts (OR 6.72, 95% CI 3.72-12.13; P < 0.01).
Conclusions: The MS is a clinical entity that encompasses a diverse range of chronic diseases, which could be a better risk indicator than any individual MS component for adverse health outcomes, like AD. Our findings underscore the harmful role of MS in the health status of the elderly.