Review of: Lorentzen R et al, Schizophrenia (Heidelb)2022;8(1):35

Study Type: Systematic review and meta-analysis 

The negative symptoms of schizophrenia—low motivation, paucity of thought, impoverished speech, and poor self-care—are notoriously difficult to treat with traditional pharmacologic methods. Given the success of transcranial magnetic stimulation (TMS) for major depression, which includes similar symptoms, there is growing interest in using TMS to target negative symptoms. A recent systematic review and meta-analysis synthesized the research on this topic. 

Included studies were double-blind, randomized, sham-controlled trials of TMS involving participants (≥18 years old) with schizophrenia, schizoaffective disorder, or other psychotic disorder, with outcomes measured using the Positive and Negative Syndrome Scale or the Scale for Assessment of Negative Symptoms. Studies that involved initiation of other treatments (eg, pharmacology) along with TMS were excluded. A total of 57 studies involving participants from 15 countries (n=2633) met criteria for analysis. The pooled analysis revealed superiority of TMS over sham in reducing the negative symptoms of schizophrenia (Cohen’s d=0.41, 95% confidence interval: 0.26–0.56, p<0.001, number needed to treat=5). Subgroup analysis found that TMS aimed at the left dorsolateral prefrontal cortex (Cohen’s d= 0.55 vs standardized mean difference [SMD] = 0.04, p = 0.0002) and using a stimulation frequency greater than 1 Hz (Cohen’s d= 0.51 vs SMD = 0.05, p = 0.003) may be the most effective. 

Limitations of the analysis included the substantial heterogeneity and risk for bias among the trials, including substantial differences in TMS modalities (ranging across unilateral, bilateral, rTMS, and deep TMS), total pulses (1,200–80,000), and different shams (coil repositioning vs sham coils vs undisclosed). 

Carlat Take

Despite a need for more consistent methodology in research, TMS shows promise for treating negative symptoms in schizo-spectrum disorders using similar treatment parameters as for ­depression.