Increase in Brain-derived Neurotrophic Factor in Patients with Schizophrenia Treated with Olanzapine: A Systemic Review and Meta-analysis

IntroductionStudies have shown reduced levels of brain-derived neurotrophic factor (BDNF) in patients with schizophrenia, but the effects of antipsychotic agents on BDNF levels have been inconsistent. The current study aimed to examine (1) whether the levels of peripheral BDNF in patients with schizophrenia change after antipsychotic treatment, and (2) whether the effect differs among antipsychotic drugs.MethodsMeta-analyses were performed using the random effects model. The results from 10 studies with 399 subjects were synthesized applying the random effects model.ResultsOverall, the study showed that the BDNF levels were mildly increased after antipsychotic treatment [standardized mean difference (SMD) = 0.171, 95% confidence interval (CI) = 0.008–0.334, p = 0.040]. When categorizing the subjects based on the antipsychotic drugs they used, BDNF levels were only significantly increased with olanzapine treatment (SMD = 0.635, 95% CI = 0.323–0.948, p = 0.0001), but not with risperidone (SMD = 0.005, 95% CI = −0.176 to 0.185, p = 0.612).DiscussionThese results suggested a differential effect of antipsychotic agents on BDNF levels in patients with schizophrenia. Peripheral BDNF may play a role in the disease process of a subset of patients, related to the use of antipsychotic agents.