Serum level of brain derived neurotrophic factor (BDNF) among patients with bipolar disorder

There is a growing body of evidence that serum brain derived neurotrophic factor (BDNF) is altered during the episodes of bipolar disorder. The aim of this study was to investigate serum BDNF levels in bipolar disorder patients during manic and depressive episodes and its clinical utility in bipolar disorder compared to other psychiatric disorders.

The study was conducted on 80 Egyptian patients, who were classified into 4 groups: group Ia (25 patients with depressive episodes), group Ib (25 patients with manic episodes), group II (15 patients having Schizophrenia) as pathological controls and group III (15 healthy subjects) as controls. All subjects were diagnosed according to DSM-IV, assessed using the Hamilton Rating Scale for depression (HAM-D), and the Young Mania Rating Scale (YMRS). sBDNF concentrations were measured using the quantitative sandwich enzyme immunoassay technique.

sBDNF showed significantly lower levels in patients with depressive episodes or manic episodes. The best cut-off for sBDNF in discriminating depressed patient from healthy control was ≤33,000pg/ml (AUC=0.891, sensitivity of 84%, and specificity of 80%). Moreover, the best cut-off for sBDNF in discriminating mania patients׳ group from healthy control was ≤29,500pg/ml, (AUC=0.984, asensitivity of 96%, and specificity of 86.7%).

Only a small sample size was considered which included only drug free patients. BDNF was measured in serum not in CSF or brain tissue.

Low sBDNF levels are strongly associated with active phases of bipolar disorder, in depressive and manic episodes.