Serum coenzyme Q10 and risk of disabling dementia: the Circulatory Risk in Communities Study (CIRCS).

To examine whether coenzyme Q10, a potent antioxidant, is associated with risk of dementia, which has not yet been elucidated. We performed a case-control study nested in a community-based cohort of approximately 6000 Japanese aged 40-69 years at baseline (1984-1994). Serum coenzyme Q10 was measured in 65 incident cases of disabling dementia with dementia-related behavioral disturbance or cognitive impairment incident between 1999 and 2004, and in 130 age-, sex- and baseline year-matched controls. Serum coenzyme Q10 was inversely associated with dementia: the multivariate odds ratios (95% confidence intervals) were 0.68 (0.26-1.78), 0.92 (0.33-2.56), and 0.23 (0.06-0.86) for individuals with the second, third, and highest quartiles of coenzyme Q10, respectively, as compared with the lowest quartile (P for trend = 0.05). A similar association was found for the coenzyme Q10/total cholesterol ratio: the respective ORs were 0.67 (0.25-1.78), 0.73 (0.28-1.92), and 0.21 (0.05-0.90) (P for trend = 0.04). Serum coenzyme Q10 levels were inversely associated with risk of disabling dementia.