Challenges and future directions of Transcranial Direct Current Stimulation for Depression: insights from a systematic review and meta-analysis.

Objective: Depression is a common and debilitating disorder affecting millions of people. First-line treatments fail to achieve remission in approximately one-third of patients, highlighting a critical need for treatment. Transcranial direct current stimulation (tDCS) has emerged as a novel treatment for depression. Therefore, the aim of this review was to provide a comprehensive overview of the last decade of tDCS trials for depression and to suggest future research directions.

Methods: To synthesize studies from the past decade, we conducted a systematic review and meta-analysis of randomized clinical trials (RCTs) of tDCS for depression.

Results: A total of 21 RCTs were included, showing a moderate effect of active tDCS compared to placebo. We also provided a description of study designs, stimulation parameters, and patient characteristics. We then proposed possible strategies to improve clinical efficacy and reduce outcome variability, including 1) optimization/personalization of tDCS through spatial and temporal target localization, 2) optimized methodological strategies, including home-based, accelerated tDCS protocols and novel study designs, and 3) investigation of the patient profile to identify characteristics that may predict treatment response.

Conclusion: tDCS shows promise as a treatment for depression, but variability in study parameters and outcomes underscores the need for further optimization. Refinement and standardization of protocols may improve its efficacy.