Elevated Brain-Derived Neurotrophic Factor Correlates Negatively with Severity and Duration of Major Depressive Episodes

Abstract

Major depressive disorder is a neuropsychiatric condition associated with neurochemical changes that alter levels of neurotrophins. We aimed to measure serum levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in patients experiencing their first episode of major depression and to examine those levels in relation to the severity and duration of the depressive episode. We recruited 85 participants: 44 drug-free patients with major depression (35 women, 9 men) and 41 healthy controls (32 women, 9 men). We used the Hamilton Rating Scale for Depression to assess the severity of the patients' depression. We assessed the controls' mental health according to Diagnostic and Statistical Manual of Mental Disorders, 4th ed, criteria. To assess all participants' stress levels, we used the Holmes and Rahe stress scale. We measured all participants' serum BDNF and NGF levels via enzyme-linked immunosorbent assay. The mean stress score was significantly higher in the patients than the controls (P=0.03). The patients had higher serum BDNF than the controls (P=0.001), but similar NGF levels. BDNF levels correlated negatively with symptom severity (r=-0.33, P=0.03) and duration (r=-0.2, P=0.06). NGF levels did not correlate with stress or with severity or duration of depressive episode. These findings suggest that an elevated serum BDNF level may contribute to the pathophysiology of major depressive disorder. The findings also indicate a possible role for BDNF in altering the clinical course of the condition.