SERUM alpha-LINOLENIC ACID AND DISABLING DEMENTIA AMONG JAPANESE: THE CIRCULATORY RISK IN COMMUNITIES STUDY (CIRCS)

Background Information on the impact of fatty acid composition on dementia has not yet been elucidated. Methods We performed a nested case-control study based on a cohort of approximately 12 000 Japanese people from two communities in the CIRCS, aged 45–85 at baseline (1984–1994). Fatty acid compositions were measured for 350 dementia cases and 700 controls (age, sex, community and baseline-year matched). The subjects were followed-up from 1999 through 2008, and incident disabling dementia was defined as dependent individuals who had moderate to severe dementia-related behavioural disturbance and/or cognitive impairment. This criterion was previously validated with 5-cog test (specificity 90%, positive predictive value 71%). The conditional OR and 95% CI for disabling dementia was calculated according to one SD increment of each fatty acid with adjustment for body mass index, smoking status, alcohol consumption, systolic blood pressure, antihypertensive medication use, serum total cholesterol and diabetes. Results Serum α-linolenic acids were inversely associated with disabling dementia (OR=0.82 [0.70–0.95] for 1-SD increment). No associations were observed for other fatty acids: OR=1.07 [0.91–1.26] for saturated fatty acids, 0.99 [0.84–1.17] for monounsaturated fatty acids, 0.98 [0.83–1.15] for n−6 polyunsaturated fatty acids, 1.00 [0.87–1.16] for eicosapentaenoic acid, and 1.03 [0.87–1.22] for docosahexaenoic acid. Conclusions We found a significant inverse association between serum α-linolenic acid and incident disabling dementia.