Predictors of Response to rTMS in Severe Mental Illnesses- Schizophrenia and Bipolar Disorder

Purpose of Review: Practice recommendations now include the use of repetitive transcranial magnetic stimulation (rTMS) in the treatment of various outcomes within schizophrenia and bipolar disorder. However, lack of data with respect to clinical, stimulation specific and neural predictors limits their translational potential in the clinics. We performed a scoping review of predictors for response to rTMS in schizophrenia and bipolar disorder. Recent Findings: Our review found that relatively small number of studies assess predictors or correlates of response compared to the vast pool of studies assessing the efficacy of rTMS in schizophrenia and bipolar disorder. Available literature suggests younger age and female gender for improvement in auditory verbal hallucinations (AVH) in schizophrenia; younger age for improvement in negative symptoms of schizophrenia; and younger age and less severe depression for bipolar depression have been found to be significant and well replicated predictors of rTMS response. Although some studies find various neural correlates of response to rTMS, they were not replicated. Summary: This scoping review screened 986 articles to finally conduct a detailed review of 71 articles for clinical, stimulation-specific and neural predictors of response to rTMS in various outcomes in schizophrenia and bipolar disorder. While younger age predicted response to rTMS treatment across various outcomes in both schizophrenia and bipolar disorder, additionally female gender for AVH in schizophrenia and less severe depression for bipolar depression were found to be significant predictors of rTMS response. We suggest that all clinical trials on rTMS must focus on assessing for predictors of response.