Relating mood to plasma glutathione and BDNF levels in patients with bipolar disorder

Objective To correlate self‐reported mood scores (depression and mania) with plasma levels of brain derived neurotrophic factor (BDNF) and glutathione in medicated bipolar patients. Methods BDNF (ELISA) and glutathione levels (enzymatic recycling, Ellman's reagent) were measured in plasma from 50 bipolar patients and matched healthy controls. The True Colours database (OXTEXT, University of Oxford) was used to determine mood‐monitoring scores for the bipolar group with the Quick Inventory of Depressive Symptomatology (QIDS) and the Altman Self‐Rating Mania Scale over an 8‐week period. Results Bipolar patients had significantly lower levels of reduced glutathione and higher levels of oxidized glutathione, while BDNF levels were not significantly different. 22% and 64% of the patients had scores ≥ 6 on the Altman scale and QIDS, respectively, but mood state did not correlate with antioxidant level. Discussion The results suggest that, despite medication, bipolar patients show higher levels of oxidative stress and that the majority still have depressive symptoms. The direction of effect is not established, but these observations appear to be consistent with studies that suggest N‐acetyl cysteine, an antioxidant, reduces depressive symptoms in bipolar patients. Hence, combining an antioxidant with other mood‐stabilizers may be therapeutically beneficial in the treatment of bipolar disorder.