A double-blind dose-finding pilot study of docosahexaenoic acid (DHA) for major depressive disorder

We examined the antidepressant efficacy and dose–response pattern of the n−3 docosahexaenoic acid (DHA). Thirty-five depressed adult outpatients (46% women; mean age 42 ± 14 years) with a 17-item Hamilton-Depression Scale (HAM-D-17) score of > /= 18 were randomized into one of three double-blind dosing arms for 12 weeks. Group A (n = 14): 1 g/day of oral DHA; Group B (n = 11): 2 g/day; and Group C (n = 10): 4 g/day. We measured HAM-D-17 scores, plasma DHA, eicosapentaenoic acid (EPA), and n−6/n−3 ratio. Completer response rates (> /= 50% decrease in HAM-D-17 score) were 83% for Group A, 40% for Group B, and 0% for Group C; Groups A and B had significant decreases in HAM-D-17 scores (p < 0.05). For completers and intent-to-treat subjects, plasma DHA increased significantly (p < 0.05), EPA had little change (p > 0.05), and n−6/n−3 decreased significantly (p < 0.05). DHA may be effective for depression at lower doses.