Efficacy and Safety of Transcranial Direct Current Stimulation for Attention Deficit Hyperactivity Disorder: A Meta-Analysis.

Background: Attention deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders in children. Treatment strategies include psychotherapy, medication, education, and individual support. Recently, transcranial direct current stimulation (tDCS) has emerged as a potential therapeutic option. We undertook this meta-analysis and systematic review to evaluate the efficacy and safety of tDCS for ADHD. Methods: The PubMed, Embase, Cochrane Library, and Web of Science databases were systematically searched for randomized controlled trials (RCTs) assessing the efficacy of tDCS for ADHD. The search terms included "transcranial direct current stimulation" and "attention deficit hyperactivity disorder". The search was conducted with no language restrictions, up to the deadline of December 1, 2024. Impulsivity symptoms, inattention, adverse events, and correct responses were analyzed using Stata 15.0. Results: Seven studies with 290 patients were included. The results of this meta-analysis indicated that tDCS reduced impulsive symptoms [standardized mean difference (SMD) = -0.60, 95% CI (-1.04, -0.16)] as well as inattentive symptoms [SMD = -1.00, 95% CI (-1.95, -0.04)] in patients with ADHD, and did not increase adverse effects [odds ratio (OR) = 1.26, 95% CI (0.67, 2.38)]. Conclusions: tDCS can improve impulsive symptoms and inattentive symptoms in ADHD patients without increasing adverse effects, which is critical in clinical practice, especially when considering non-invasive brain stimulation. The study provided quantitative evidence that tDCS can be used for treating ADHD symptoms without adverse events. The PROSPERO Registration: This study was registered in PROSPERO (CRD42023451277), https://www.crd.york.ac.uk/PROSPERO/view/CRD42023451277.