Plasma Fatty Acid Profiles in Relation to Cognition and Gender in Alzheimer's Disease Patients During Oral Omega-3 Fatty Acid Supplementation: The OmegAD Study

Background: omega 3 fatty acids (omega 3 FAs) may slow the rate of decline in cognitive performance in mild forms of cognitive impairment and Alzheimer's disease (AD). However, the relationship between changes of plasma omega 3 FA levels and cognitive performance, as well as effects of gender, are poorly known. Objective: To study the effect of 6-month administration of DHA-rich omega 3 FA supplementation on plasma FA profiles in patients with mild to moderate AD in relation to cognitive performance and gender. This investigation is part of the OmegAD Study. Methods: 174 AD patients (74 +/- 9 years) were randomized to a daily intake of 2.3g omega 3 FA or placebo for 6 months; subsequently all received the omega 3 FA preparation for the next 6 months. Baseline as well as changes in plasma levels of the main omega 3 FAs in 165 patients, while receiving omega 3 FA supplementation for 6 months, were analyzed for association to cognitive performance (assessed by ADAS-cog and MMSE scores) as well as to gender. Results: Preservation of cognitive functioning, assessed by ADAS-cog or its sub-items (but not MMSE) scores, was significantly associated to increasing plasma omega 3 FA levels over time. Thus, the higher omega 3 FA plasma levels rose, the lower was the rate of cognitive deterioration. This effect was not related to gender; since although females displayed higher omega 3 FA plasma levels than did males after 6 months of supplementation, this difference disappeared when adjusted for body weight. Conclusions: Since our study suggests dose-response relationships between plasma levels of omega 3 FA and preservation of cognition, future omega 3 FA trials in patients with mild AD should consider exploring graded (and body weight adjusted) doses of omega 3 FA.