BDNF levels ‘normalized’ in euthymic bipolar disorder patients
MedWire News: Euthymic bipolar disorder patients have similar serum brain-derived neurotrophic factor (BDNF) levels to those of healthy individuals, supporting the theory that treatment normalizes levels of the neurotrophin, say scientists.
Previous studies have indicated that BDNF plays a central role in the pathophysiology of bipolar disorder, and that BDNF-signaling pathway abnormalities may be associated with the cognitive decline seen in such patients.
To investigate further, Flávio Kapczinski, from Hospital de Clinicas de Porto Alegre in Brazil, and colleagues used an enzyme-linked immunosorbent assay to measure serum BDNF levels in 65 euthymic patients with bipolar I disorder and 50 healthy controls.
In addition, the team administered a neurocognitive battery to assess attention and mental control, perceptual–motor skills, executive function, verbal fluency, verbal abstraction, visuospatial attention, and memory function.
There were no significant differences in serum BDNF levels between patients and controls. In patients, there was a significant positive correlation between serum BDNF levels and illness duration, manic episodes, and depressive episodes, but only in female patients, at r values of 0.341, 0.557, and 0.610, respectively.
The results, published in the journal Bipolar Disorders, also show that serum BDNF levels were lower in patients treated with antipsychotics and/or lithium, and higher in patients receiving valproate and/or antidepressants. However, none of the differences were significant.
Even after taking into account age, education level, and mood symptoms, patients performed significantly worse than controls on 11 out of 16 neurocognitive tests. Serum BDNF levels were significantly positively correlated with a test of verbal fluency in patients, at an r value of 0.258. This phenomenon was also observed in healthy controls, among whom the r value was 0.279.
The team concludes: “Our finding showing no significant differences in serum BDNF levels in bipolar disorder type I euthymic patients as compared to healthy controls further supports the hypothesis that BDNF normalizes with mood stabilization and pharmacological treatment.”
They add: “The lack of association between serum BDNF levels and neurocognitive performance may be explained by the fact that we studied a sample of young and physically healthy patients, with relatively short illness duration and few mood episodes, even though their performance was overall significantly worse as compared to healthy controls.”
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By Liam Davenport