1. Excitatory Noninvasive Brain Stimulation Intervention (NIBS) protocols over the left dorsolateral prefrontal cortex were associated with significantly large improvements in the severity of negative symptoms.

2. None of the investigated NIBS approaches was associated with significantly different changes in positive symptom severity compared to control groups.

Evidence Rating Level: 2 (Good)

According to the 2019 Global Burden of Disease Study, schizophrenia presents a significant burden worldwide. The negative symptoms of schizophrenia significantly impact patients’ quality of life and unfortunately, respond poorly to antipsychotics. As an alternative, noninvasive brain stimulation (NIBS) therapies may be successful in alleviating these symptoms, but their effectiveness has not yet been studied. As a result, the objective of the present study was to evaluate the efficacy of NIBS interventions in alleviating the negative symptoms of schizophrenia.

Of 4867 identified records, the present study included 48 randomized clinical trials (n=211, 30.6% females) from database inception to December 2021. Studies were included if they included patients with schizophrenia who underwent NIBS interventions. Studies were excluded if they did not investigate negative symptoms and included patients other than schizophrenia/schizoaffective disorder. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed. Pair-wise meta-analytic procedures were conducted using a random-effects model. Results demonstrated that NIBS treatments over the left dorsolateral prefrontal cortex were linked to a large reduction in the severity of negative symptoms. Furthermore, none of the investigated NIBS approaches was associated with significantly different changes in positive symptom severity.

Despite these findings, the study was limited by the heterogeneity of participants which may have underpowered the study. However, the present study demonstrated the potential for NIBS to relieve the negative symptoms of schizophrenia.

Click to read study in: JAMA Psychiatry

Image: PD

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