Serum levels of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) in depressed patients with schizophrenia

Aim: Brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are neurotrophins-proteins that induce the survival, development, and function of neurons. Their role in the development of schizophrenia and mood disorders is widely studied. This study was aimed to determine whether depression affects levels of BDNF and NT-3 in patients with schizophrenia. Methods: Data for 53 Caucasian adult hospitalized patients with chronic paranoid schizophrenia was compared with 27 healthy subjects. Clinical symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS) and positive, negative and general sub-scores, the Calgary Depression Scale for Schizophrenia (CDSS), the Hamilton Depression Rating Scale (HDRS), and the Clinical Global Impressions scale (CGI). Patients were defined as depressed (SHZ-DEP) with scores CDSS > 6 and HDRS > 7, otherwise they were included into the non-depressed group (SHZ-nonDEP). Results: In total, 17 patients (32.1%) with schizophrenia met criteria for depression. SHZ-DEP patients had higher scores in HDRS, CDSS, PANSS total, PANSS negative, PANSS general and CGI (p < 0.001 for all comparisons). There were no differences in BDNF or NT-3 levels between patients with schizophrenia and controls. BDNF levels were lower in SHZ-DEP compared to SHZ-nonDEP: 18.82 +/- 5.95 versus 22.10 +/- 5.31 ng/mL, p = 0.045. NT-3 levels were higher in SHZ-DEP compared to SHZ-nonDEP: 133.31 +/- 222.19 versus 56.04 +/- 201.28 pg/mL, p = 0.033. Conclusion: There were no differences in neurotrophin levels between patients with schizophrenia and controls. We found lower BDNF and higher NT-3 serum levels in depressed patients with schizophrenia.