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12-05-2011 | Mental health | Article

BDNF may be biomarker of mood states in bipolar disorder


Free abstract

MedWire News: Results from a systematic review and meta-analysis of published studies suggest that brain-derived neurotrophic factor (BDNF) could be used as a biomarker of mood states and disease progression in patients with bipolar disorder.

Writing in the Journal of Psychiatric Research, Brisa Simões Fernandes (Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil) and team explain: "BDNF is a dimeric protein that plays a central role in synaptic plasticity and neuronal survival

"This neurotrophin is found throughout the brain with particular abundance in the hippocampus and cerebral cortex, brain areas thought to be critical for the control of mood, emotion, and cognition."

They add: "Some studies suggest that BDNF levels decrease during mood states and remain normal during euthymia, but other studies have contradicted this paradigm."

To investigate further, the team reviewed the literature for relevant cross-sectional studies of serum or plasma BDNF levels according to mood state in adults with bipolar disorder.

In total, 13 studies that included 548 patients with bipolar disorder and 565 controls met criteria for inclusion in the meta-analysis. Of these, six studies assessed BDNF levels during manic episodes, five assessed BDNF levels during depressive episodes, and six evaluated levels of the protein during euthymia.

Analysis of the pooled data revealed that BDNF levels were significantly lower in manic and depressed bipolar disorder patients compared with controls, with corresponding effect sizes (ES) of -0.81 and -0.97.

However, the decrease in BDNF levels in euthymic bipolar disorder patients relative to controls was not significant, at an ES of -0.20.

In euthymic patients, meta-regression analyses showed that age and illness duration influenced the variation in BDNF levels.

There was also an increase in BDNF levels following the treatment for acute mania, the researchers note.

Fernandes and team conclude: "These findings support the concept of peripheral BDNF levels as a biomarker of disease activity during mood episodes and as a possible biomarker of disease progression according to the staging model."

"Future studies are required to determine whether the measurement of serum or plasma BDNF can be used to guide clinical decision making."

They comment that the results "are of major importance to the field, considering the growing evidence of the involvement of neurotrophic factors in the pathophysiology of bipolar disorder."

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Mark Cowen

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