Transcranial magnetic stimulation (TMS) was developed approximately 30 years ago by Barker et al. TMS has been applied as both a method to evaluate several neurophysiological processes and as a treatment for resistant psychiatric and neurological disorders. As a treatment, repetitive TMS (rTMS) has extensive evidence for efficacy in mood disorders[2,3] through the modulation of cortical excitability, inhibition and plasticity. In recent years, several studies have also explored the utility of rTMS as a treatment tool in schizophrenia with promising results. The heterogeneity of schizophrenia symptoms appears to be one of the main obstacles in developing treatments for this debilitating disorder. It may be prudent, therefore, for schizophrenia brain stimulation treatment studies to focus on specific symptom domains. In fact, some research has shown that rTMS appears more effective in the treatment of positive symptoms than negative symptoms, although one hypothesis is that this is due to fewer studies exploring the effects of rTMS on negative symptoms,[4,5] or due to the scales used to measure efficacy.[4,6] Moreover, rTMS appears to have significant efficacy for auditory hallucinations. rTMS can be applied as high (5–20 Hz) or low (1 Hz) frequency, with the former being usually excitatory and the latter being inhibitory.[8,9] Such selective modulation can have advantages when examined through the lens of fMRI characterization of hallucinations and negative symptoms. Simply put, the inhibitory stimulation frequency of 1 Hz has been used in studies examining treatment of positive symptoms and some of the more promising effects in negative symptoms used the excitatory stimulation frequencies of 10 or 15 Hz. Below, we will focus on evidence for the treatment of auditory hallucinations and more pervasive negative symptoms, before addressing future directions for the exploration of rTMS in the treatment of schizophrenia.
Expert Rev Neurother. 2013;13(10):1079-1082. © 2013 Expert Reviews Ltd.