BDNF Dynamics During Early Antidepressant Treatment in Unipolar Depression

Abstract

Major depressive disorder frequently presents with prominent anxiety symptoms, reflecting overlapping disturbances in affective regulatory systems. Brain-derived neurotrophic factor (BDNF), a key mediator of synaptic plasticity, has been implicated in the neurobiological mechanisms underlying stress-related psychopathology. This longitudinal study examined whether changes in plasma BDNF concentrations during the first four weeks of antidepressant treatment were associated with improvements in depressive and anxiety symptom severity in patients with unipolar major depressive disorder. Twenty-six medication-free patients were evaluated at baseline and after four weeks using the Hamilton Depression and Hamilton Anxiety Rating Scales, and plasma BDNF levels were quantified by ELISA. Clinical improvement was accompanied by an increase in plasma BDNF concentrations. Greater reductions in depressive symptom severity were associated with larger BDNF increases, whereas no significant association was observed between anxiety symptom change and BDNF modulation. These findings suggest that BDNF dynamics may primarily reflect early neuroplastic adaptations related to depressive symptom improvement.