Methods: This systematic review was prospectively registered with PROSPERO (CRD42023426005) and the data collected in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The quality of reporting of included studies was evaluated in accordance with the CONSORT statement.
Results: Eleven randomized controlled trials were identified. Evaluation of the reviewed studies revealed low levels of overall compliance with the CONSORT statement highlighting the need for improved reporting. Key areas included insufficient information about - the intervention (for replicability), participant flow, recruitment, and treatment effect sizes. Study discussions did not fully consider limitations and generalizability, and the discussion/interpretation of the findings were often incongruent with the results and therefore misleading. Only two studies reported a significant difference between sham and active tDCS for OCD outcomes, with small effect sizes noted.
Conclusions: The variability in protocols, lack of consistency in procedures, combined with limited significant findings, makes it difficult to draw any meaningful conclusions about the effectiveness of tDCS for OCD. Future studies need to be appropriately powered, empirically driven, randomized sham-controlled clinical trials.
Keywords: CONSORT evaluation; Transcranial direct current stimulation (tDCS); obsessive-compulsive disorder (OCD); randomized controlled trial (RCT); systematic review.