BDNF protein levels are decreased in transformed lymphoblasts from lithium-responsive patients with bipolar disorder

Objective: Brain-derived neurotrophic factor (BDNF) is a key factor in neuroplasticity and has been implicated in the affective disorders; studies have demonstrated elevated BDNF in patients taking lithium and other mood stabilizers. The objective of our study was to analyze BDNF in lithium-responsive patients with bipolar disorder (BD) to further understand the role of BDNF in the pathophysiology of BD. Methods: Using enzyme-linked immunosorbent assay, we measured transformed B lymphocytes for BDNF protein. Results: BDNF levels were 36% lower in lymphoblasts from patients with BD ( n = 12), compared with matched control participants ( n = 13), and 55% lower when compared with their unaffected relatives ( n = 14). Lithium significantly decreased BDNF levels in patients with BD and healthy control participants, although BDNF levels remained lower (33%) in the BD group posttreatment. Conclusion: Decreased BDNF may constitute part of the pathophysiologic process of BD in a lithium-responsive subgroup of individuals with this disease. A compensatory mechanism protecting the genetically predisposed unaffected relatives from phenotypic expression of BD is suggested.