Decreased plasma levels of brain-derived neurotrophic factor (BDNF) during mixed episodes of bipolar disorder.
BACKGROUND
Brain-derived neurotrophic factor (BDNF) is a neurotrophin involved in neurogenesis and neuroplasticity. Decreased blood levels of BDNF have been found during acute manic and depressive states. BDNF has been proposed as a biomarker in illness phases of mood disorders. No information is available regarding BDNF levels during the mixed states of bipolar disorder (BD). The aim of this study was to evaluate BDNF levels during mixed episodes of BD patients and compare them with those of healthy subjects and depressed patients.


METHODS
Plasma BDNF levels were measured by an ELISA assay in 18 patients with major depressive episode (MDE), 19 patients with mixed episode (ME) and 15 healthy subjects (HS).


RESULTS
BDNF levels were significantly higher in HS, as compared with patients׳ samples (HS vs. MDE patients: p<001; HS vs. ME patients: p=.022). No significant differences were found between BDNF levels of ME and MDE patients. The severity of illness as assessed by CGI-S was significantly higher in ME than in MDE patients (p=.01).


LIMITATIONS
The small sample size may have weakened the power of statistical analyses. All patients received mood-stabilizing and antidepressant treatments which have been reported to influence peripheral BDNF levels.


CONCLUSIONS
Our results are consistent with previous studies showing reduced BDNF during both manic and depressive episodes. This finding supports the role of BDNF as a state-marker of mood episodes, and may represent a contribution to a unitary approach model between unipolar and BDs, as well as to the manic-depressive spectrum model.
['Piccinni|Armando|A|', 'Veltri|Antonello|A|', 'Costanzo|Davide|D|', 'Vanelli|Federica|F|', 'Franceschini|Caterina|C|', 'Moroni|Ilenia|I|', 'Domenici|Luciano|L|', 'Origlia|Nicola|N|', 'Marazziti|Donatella|D|', 'Akiskal|Hagop Souren|HS|', "Dell'Osso|Liliana|L|"]
D000328:Adult D000704:Analysis of Variance D015415:Biomarkers D001714:Bipolar Disorder D019208:Brain-Derived Neurotrophic Factor D003865:Depressive Disorder, Major D004797:Enzyme-Linked Immunosorbent Assay D005260:Female D006801:Humans D008297:Male D012720:Severity of Illness Index
BDNF Bipolar disorder Biomarkers Mixed state Bipolar spectrum DSM-5