tDCS efficacy and utility of anhedonia and rumination as clinical predictors of response to tDCS in major depressive disorder (MDD).

BACKGROUND: Anhedonia and rumination are mental disorders' transdiagnostic features but remain difficult to treat. Transcranial direct current stimulation (tDCS) is a proven treatment for depression, but its effects on anhedonia and rumination and whether anhedonia and rumination can be used as a predictive biomarker of treatment response is not well known. This study aimed to investigate the tDCS efficacy and identify the predictive role of anhedonia and rumination in response to tDCS in patients with MDD. METHODS: 182 patients received 10 tDCS sessions delivered at 2 mA to left (anode) dorsolateral prefrontal cortex (DLPFC). Hamilton Rating Scale for Depression (HRSD-17), Snaith-Hamilton Pleasure Scale (SHAPS), and the 10-item Ruminative Response Scale (RRS-10) was administered to patients with MDD before treatment, following it, and after two weeks of tDCS. RESULTS: There was an overall significant improvement in anhedonia from pre- to post-treatment. Regression analyses revealed that responders had higher baseline anhedonia and rumination (reflective pondering) scores. We found that the reduction in HRSD scores after tDCS was significantly associated with anhedonia's baseline values while no relation was found between baseline rumination and tDCS treatment response. CONCLUSION: These results provide new evidence that pronounced anhedonia may be a significant clinical predictor of response to tDCS. Patients with severe or low baseline rumination had an equal chance of achieving clinical response. Prospective tDCS studies are necessary to validate the predictive value of the derived model.

Clinical and demographic predictors of response to anodal tDCS treatment in major depression disorder (MDD).

Transcranial direct current stimulation (tDCS) of the prefrontal cortex is known as a promising intervention in major depression disorder (MDD). However, limited information on predictors of therapeutic response to tDCS are available. This study aimed to investigate clinical and demographic predictors of therapeutic response in patients taking no medications. For this purpose, the required data were collected from 2 independent tDCS trials on 116 MDD patients. Accordingly, 84 patients underwent 10 sessions of 2 mA tDCS daily each one lasted for 20 min and 32 patients received 10 twice sessions of 2 mA tDCS daily each one lasted for 20 min. Anodal electrode was located over the left dorsolateral prefrontal cortex (DLPFC), and cathode was over the right supraorbital region. Depression symptoms and the underlying clinical dimensions were assessed using the Beck Depression Inventory (BDI-II) at baseline and after the tDCS treatment. Of the included 116 patients, 47.4% showed an antidepressant response. Results of logistic regression analysis showed that the reduction in BDI-II scores after tDCS was associated with the baseline values of cognitive-affective symptoms factor, loss of pleasure, loss of interest, and sleep problems. Pronounced sleep disturbances and cognitive-affective symptoms were identified as the potential clinical predictors of response to tDCS. However, more prospective tDCS studies are necessary to validate the predictive value of the derived model.