Low plasma brain-derived neurotrophic factor and childhood physical neglect are associated with verbal memory impairment in major depression--a preliminary report.

BACKGROUND: Early life stress has been suggested to mediate vulnerability to affective disorders. Animal models of repeated maternal separation have shown reduced brain-derived neurotrophic factor (BDNF) levels in specific brain regions implicated with hypothalamic-pituitary-adrenal axis and memory formation. In addition, BDNF levels are also reduced in major depressive disorder (MDD) and bipolar disorder. The aim of this study was to investigate whether childhood physical neglect (CPN) and plasma BDNF levels would impact on memory performance in adult female subjects with recurrent major depression.
METHODS: Recurrent female MDD outpatients with CPN (MDD + CPN, n = 17) and without CPN (MDD, n = 17) and healthy control subjects (n = 15) were assessed for plasma BDNF content and verbal memory performance. Memory was assessed through the logical memory component of the Weschler Memory Scale-Revised for immediate and delayed recall. Brain-derived neurotrophic factor was assessed with enzyme-linked immunosorbent assays (ELISAs).
RESULTS: Major depressive disorder patients showed lower plasma BDNF concentrations than healthy control subjects (p < .001). Major depressive disorder + CPN had even lower BDNF levels compared with control subjects and MDD (p < .05). Brain-derived neurotrophic factor levels were negatively related to psychological morbidity and positively correlated to memory performance. Regression models showed that severity of self-reported CPN and low plasma BDNF predicted impairment on immediate verbal recall. Delayed recall impairment was predicted by severity of CPN and depression and memory retention by posttraumatic stress disorder (PTSD) severity symptoms.
CONCLUSIONS: Our data suggest that CPN and plasma BDNF are important factors associated with depression and verbal memory performance, particularly with encoding processes.