Our open-label pilot study showed that supplementation with docosahexaenoic acid (DHA) increased serum brain-derived neurotrophic factor (BDNF) levels and that there might be an association between changes in serum BDNF levels and reduced psychological distress. Animal research has indicated that a DHA-enriched diet increases BDNF in the brain. In this randomized double-blind controlled trial of severely injured patients vulnerable to posttraumatic stress disorder (PTSD) and depression, we examined whether DHA increases serum BDNF levels and whether changes in BDNF levels are associated with subsequent symptoms of PTSD and depression. Patients received 1470 mg per day of DHA plus 147 mg per day of eicosapentaenoic acid (EPA; n = 53) or placebo (n = 57) for 12 weeks. Serum levels of mature BDNF and precursor pro-BDNF at baseline and 12-week follow-up were measured using enzyme-linked immunosorbent assay kits. At 12 weeks, we used the Clinician-Administered PTSD Scale to assess PTSD symptoms and depressive symptoms by the Montgomery-Åsberg Depression Rating Scale. We found a significant increase in serum BDNF levels during the trial in the DHA and placebo groups with no interaction between time and group. Changes in BDNF levels were not associated with PTSD severity but negatively associated with depression severity (Spearman's ρ = -0.257, P = 0.012). Changes in pro-BDNF were also negatively associated with depression severity (Spearman's ρ = -0.253, P = 0.013). We found no specific effects of DHA on increased serum levels of BDNF and pro-BDNF; however, evidence in this study suggests that increased BDNF and pro-BDNF have a protective effect by minimizing depression severity.
Trial registration: ClinicalTrials.gov NCT00671099.