Serum and plasma brain-derived neurotrophic factor and response in a randomized controlled trial of riluzole for treatment resistant depression

Background: Serum brain-derived neurotrophic factor (BDNF) is decreased in individuals with major depressive disorder (MDD). Pre-clinical and clinical reports suggest that the glutamate release inhibitor riluzole increases BDNF and may have antidepressant properties. Here we report serum (sBDNF) and plasma (pBDNF) levels from a randomized controlled, adjunctive, sequential parallel comparison design trial of riluzole in MDD. Methods: Serum and plasma BDNF samples were drawn at baseline and weeks 6 and 8 from 55 subjects randomized to adjunctive treatment with riluzole or placebo for 8 weeks. Results: Riluzole responders had lower baseline serum (19.08 ng/ml [SD 9.22] v. 28.80 ng/ml [9.63], p = 0.08) and plasma (2.72 ng/ml [1.07] v. 4.60 ng/ml [1.69], p = 0.06) BDNF compared to non-responders at a trend level. This pattern was nominally seen in placebo responders for baseline pBDNF to some degree (1.21 ng/ml [SD 1.29] v. 3.58 ng/ml [SD 1.67], p = 0.12) but not in baseline sBDNF. Limitations: A number of limitations warrant comment, including the small sample size of viable BDNF samples and the small number of riluzole responders. Conclusions: Preliminary evidence reported here suggests that lower baseline BDNF may be associated with better clinical response to riluzole.