Background Recently, the possibility of using non-invasive brain stimulation (NIBS) to treat mental disorders received considerable attention. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are considered effective treatments for depressive symptoms. However, no recommendation is available for anxiety disorders, suggesting that evidence is still limited.
Objective We systematically revised the existing literature, and quantitatively analyzed the effectiveness of rTMS and tDCS in anxiety disorders treatment.
Method Following PRISMA guidelines, 3 electronic databases were screened to the end of February 2020 to select English-written peer-reviewed articles including (i) a clinical sample of patients with anxiety disorders, (ii) the use of a NIBS technique, (iii) the inclusion of a control condition, and (iv) pre-post scores at a validated questionnaire measuring anxious symptoms.
Results Eleven papers met the inclusion criteria, comprising 154 participants assigned to the real stimulation condition and 164 to the sham or control group. The Hedge g for scores at disorder specific and general anxiety questionnaires before and after the treatment was computed as effect size and analyzed in two independent random-effects meta-analyses. Considering the well-known comorbidity between anxiety and depression, a third meta-analysis was run, analyzing depression scores outcomes. Results showed a significant effect of NIBS in reducing questionnaires scores in the real vs. control condition at specific and general anxiety measures, and depressive symptoms.
Conclusion Albeit preliminary, our findings highlighted that real stimulation reduced anxiety and depression scores compared to the control condition, suggesting that NIBS can alleviate clinical symptoms in patients with anxiety diseases.