Cognitive and Cardiovascular Benefits of Docosahexaenoic Acid in Aging and Cognitive Decline

Abstract

Memory loss is a prominent health concern, second only to heart disease for older individuals. Docosahexaenoic acid (DHA), the principle omega-3 fatty acid in brain and heart, plays an important role in neural and cardiac function. Decreases in plasma DHA are associated with cognitive decline in healthy elderly and Alzheimer's patients. Higher DHA intake and plasma levels are inversely correlated with increased relative risk of Alzheimer's disease (AD) and fatal coronary heart disease. DHA provides well known cardiovascular benefits (e.g. lower triglycerides, increased HDL cholesterol, decreased resting heart rate) in older adults. Preclinically, DHA supplementation restores brain DHA levels, enhances learning and memory tasks in aged animals, and significantly reduces beta amyloid, plaques, and tau in transgenic AD models. To date, clinical studies with DHA+EPA supplementation have shown some positive effects in mild cognitive impairment but not in AD, suggesting that early intervention may be a key factor to providing effective therapies. A recent clinical study examined individual effects of 900mg/d algal DHA as a nutritional supplement for age-related cognitive decline (ARCD). This randomized, double blind, placebo controlled study (n=485) found significantly fewer CANTAB Paired Associate Learning errors with algal DHA at six months versus placebo (diff. score -1.63+/-0.76, p=0.03). Positive effects on Verbal Recognition Memory (p<0.02) and significant decreases in resting heart rate with DHA (p<0.03) were observed, indicating improved learning and episodic memory functions and cardiovascular benefits for ARCD. Collectively, data reveal a potentially beneficial role for DHA in preventing or ameliorating cognitive decline and cardiovascular disease in the aged.