Blood Levels of EPA and Decreased Risk of Dementia

Population studies have indicated that elderly individuals who are regular fish consumers (thereby having higher intakes of DHA/EPA) have a decreased risk for dementia and Alzheimer disease. Food records and dietary recalls often result in inaccurate and inconsistent estimations of omega-3 fatty acid intakes. Consequently, epidemiologists have often employed biomarkers for better assessing omega-3 status in the populations by measuring blood levels of EPA, DHA, and other fatty acids in blood serum samples. The present longitudinal study was conducted to determine whether plasma omega-3 fatty acids may possibly predict the eventual risk for incident dementia in a cohort of older persons independently of their depressive status.

The present study was conducted among participants from 3 cities in France and included 9294 community dwellers who had to be aged ≥65 years and not institutionalized. The baseline data collection included a wide range of informative parameters including neuropsychological testing and blood samplings with two follow-up examinations conducted at 2 and 4 years after the baseline examination. The diagnosis of dementia was derived from a 3-step procedure using trained psychologists who administered various neuropsychological tests at baseline and at follow-up including examination of all participants by a neurologist at baseline. Depressive symptomology was assessed using appropriate baseline home interviews and the validated Centre for Epidemiological Studies- Depression (CES-D) scale-considered to be a valid reliable measure of depressive symptomology in elderly persons. The results indicated that a higher level of EPA (eicosapentaenoic acid) in the plasma (lipid) samples was associated with a significantly lower incidence of dementia (by 31% overall, hazard ratio of 0.69) independently of depressive status and after adjusting for age, education, diabetes, and other parameters. Interestingly, the relations between DHA levels and total omega-3 fatty acid levels in plasma and incident dementia did not maintain statistical significance using multivariate models. However, higher ratios of arachidonic acid:DHA and n-6:n-3 fatty acids were related to an increased risk of dementia-particularly in depressive subjects. The investigators conclude that a high plasma EPA concentration may decrease the risk of dementia and that further research on the role of EPA in this condition is deserving of further research.