Theta Burst Stimulation Protocols for Schizophrenia: A Systematic Review and Network Meta-Analysis

To date, several theta burst stimulation (TBS) protocols, such as intermittent TBS (iTBS), have been proposed; however, previous systematic reviews have revealed inconsistent efficacy findings in individual TBS studies for schizophrenia.

To examine which TBS protocols are associated with the most favorable and acceptable outcomes in adults with schizophrenia.

The Cochrane Library, PubMed, and Embase databases were searched for studies published before May 22, 2024.

The inclusion criteria were as follows: (1) published and unpublished randomized clinical trials (RCTs) of any TBS treatment and (2) RCTs including individuals with schizophrenia spectrum disorders, other psychotic disorders, or both.

This study followed the Cochrane standards for data extraction and data quality assessment and used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline for reporting. The risk of bias of individual studies was assessed using the second version of the Cochrane risk of bias tool, and the Confidence in Network Meta-Analysis application was used to rate the certainty of evidence for meta-analysis results. At least 2 authors double-checked the literature search, data transfer accuracy, and calculations.

The primary outcome of this study was improvement in scores related to negative symptoms. Our frequentist network meta-analysis used a random-effects model. The standardized mean difference (SMD) or odds ratio for continuous or dichotomous variables, respectively, was calculated with 95% CIs.

A total of 30 RCTs of 9 TBS protocols, with 1424 participants, were included. Only iTBS over the left dorsolateral prefrontal cortex (L-DLPFC) was associated with reduced negative symptom scores (SMD, -0.89; 95% CI, -1.24 to -0.55), overall symptom scores (SMD, -0.81; 95% CI, -1.15 to -0.48), Positive and Negative Syndrome Scale general subscale scores (SMD, -0.57; 95% CI, -0.89 to -0.25), depressive symptom scores (SMD, -0.70; 95% CI, -1.04 to -0.37), and anxiety symptom scores (SMD, -0.58; 95% CI, -0.92 to -0.24) and improved overall cognitive impairment scores (SMD, -0.52; 95% CI, -0.89 to -0.15) compared with a sham. However, positive symptom score changes, all-cause discontinuation rate, discontinuation rate due to adverse events, headache incidence, and dizziness incidence did not significantly differ between any TBS protocols and sham.

In this network meta-analysis, iTBS over the L-DLPFC was associated with improved scores for negative, depressive, anxiety, and cognitive symptoms in individuals with schizophrenia and was well tolerated by the participants. Other forms of TBS were not associated with benefit. Further research is needed to assess the potential role of TBS in the treatment of schizophrenia.