Serum BDNF Levels in Suicide Attempters Related to Psychosocial Stressors: A Comparative Study with Depression

Although many studies have examined the neurobiological aspects of suicide, the molecular mechanisms and pathophysiologic mechanisms associated with suicide remain unclear. In this study, it is aimed to investigate whether there is a difference in serum brain-derived neurotrophic factor (BDNF) levels among suicide attempters without a major psychiatric disorder, compared to major depressive disorder patients and healthy subjects. It was undertaken with the hypothesis that suicide per se lowers serum BDNF levels, since it is a source of stress. The study was carried out in Celal Bayar University Hospital, Manisa, Turkey. Ten suicide attempters, 24 patients with major depressive disorder and 26 subjects without any psychiatric diagnosis and any psychiatric treatment were included in the study. All subjects were asked to give their written consent. Blood samples were collected at the baseline. Serum BDNF was kept at –70°C before testing, and assayed with an ELISA kit (Promega; Madison, Wisc., USA) after dilution with the block and sample solution provided with the kit. The data were subjected to the Kruskal-Wallis test for nonparametric analysis of variance. Mean serum BDNF levels were significantly lower in the suicide group (21.2 ± 12.4 ng/ml) and the major depressive disorder group (21.2 ± 11.3 ng/ml) than the control group (31.4 ± 8.8 ng/ml; p = 0.004). These results suggest that BDNF may play an important role in the neurobiology of suicidal behavior. BDNF levels may be a biological marker for suicidal behavior. To investigate the role of BDNF in suicide, further studies with a wider sample size and a variety of psychiatric diagnoses accompanying suicide attempt are needed.