Serum glial cell derived neurotrophic factor (GDNF) as a predictor of response to HD-tDCS in bipolar affective disorder.

Serum glial cell line derived neurotrophic factor (GDNF) homeostasis within brain circuits represent target for focal neuromodulation techniques such as high-definition transcranial direct current stimulation (HD-tDCS). In current trial 37 inpatients with bipolar disorder (BD) received active (n = 18) or sham (n = 19) anodal HD-tDCS over right dorsolateral prefrontal cortex (DLPFC). Outcome measures evaluated by YMRS (p = 0.001, effect size=0.946), BPRS (p = 0.015, effect size=0.220) scales and serum GDNF (p = 0.003, effect size = 0.287) at baseline, before and after receiving HD-tDCS revealed significant improvement (active>sham) with modest effect size. However, the study findings are limited due to small sample size and shorter duration of follow-up.

Response Processes to Looming Appetitive and Aversive Cues in Euthymic Bipolar Patients and Their First-Degree Relatives: An Exploratory Study.

BACKGROUND: Patients with bipolar disorder demonstrate increased sensitivity to appetitive/rewarding stimuli even during euthymia. On presentation of arousing pictures, they show a peculiar response, suggesting heightened vigilance. While responding to looming arousing cues, studies show subjects with anxiety spectrum disorders exhibit increased reaction time (RT), explained by the "looming-vulnerability model." This study aimed to investigate the responses to looming arousing cues in euthymic bipolar patients and their first-degree relatives, as compared to healthy controls. METHOD: A looming appetitive and aversive cue paradigm was designed for assessing the RT of patients to process appetitive and aversive cues. The behavioral inhibition/activation and sensitivity to reward/punishment amongst the groups were also assessed. RESULTS: The bipolar group showed significantly longer RT to process appetitive cues irrespective of the looming condition. Aversive cues elicited significantly longer RT in both the bipolar group and in first-degree relatives, but only when presented with the looming condition. Significant looming bias was elicited in the bipolar group which suggested a particular cognitive style to looming cues. A composite measure of RT along with sensitivity to reward/punishment distinguishes the bipolar group and their first-degree relatives from the healthy controls. CONCLUSION: The looming vulnerability model may provide important insights for future exploration of cognitive endophenotypes in bipolar disorder.