Objective: To investigate efficacy of repetitive transcranial magnetic stimulation (rTMS) on attention-deficit/hyperactivity disorder (ADHD).
Methods: Randomized sham-controlled trials (RCTs) were identified from major databases from the inception date of January 1990 to January 2023. Primary outcome was improvement in total symptoms of ADHD. Subgroup analysis focused on rTMS efficacy targeting different brain regions. Secondary outcomes were associations of rTMS with improvements in different symptoms of ADHD. Outcomes were expressed as effect size (ES) based on standardized mean difference (SMD) (continuous data), and odds ratios (ORs) with 95% confidence interval (CI) (categorical data).
Results: Meta-analysis of six RCTs involving 169 participants demonstrated no difference in total ADHD symptoms between rTMS-treated participants and sham controls (SMD=-0.24,p=0.17). Subgroup analysis revealed better efficacy of rTMS than sham controls when targeting right prefrontal cortex (rPFC) (SMD=-0.49,p=0.03), but not left prefrontal cortex (lPFC) (SMD= 0.01,p=0.67). rTMS treatment correlated with better improvement in symptoms of inattention (SMD=-0.76,p=0.0002), but not hyperactivity (p=0.86), impulsivity (p=0.41), and depression (p=0.95). The apparently higher risk of dropout in the rTMS group than sham controls was not statistically significant (OR=1.65,p=0.26).
Conclusions: Our study only supported the therapeutic efficacy of rTMS targeting rPFC for the symptoms of ADHD, especially inattention, but not that targeting lPFC. Further large-scale randomized sham-controlled trials are required to verify our findings.
Keywords: Repetitive transcranial magnetic stimulation; attention-deficit/hyperactivity disorder; meta-analysis.