The results discussed above must be considered with the view that most rTMS studies include subjects with very treatment-resistant forms of schizophrenia. Most studies include patients with medication-resistant auditory verbal hallucination, indicating a group with intractable symptomatology. Despite this, there is some evidence that patients with lower PANSS scores at baseline may respond better to rTMS in comparison with more severely ill patients. Previous research has linked schizophrenia with a failure to integrate activity in distributed neural circuits.[47–50] rTMS has the potential to induce changes in remote, functionally connected brain areas[51,52] in addition to local effects. The application of sequential stimulation, aimed at the areas of the PFC and temporoparietal cortex, seems to be an interesting approach, with some evidence for reduction in not only negative but also positive schizophrenia symptoms and potentially improved working memory. In this manner, targeting other brain areas, perhaps simultaneously or sequentially, may prove effective in targeting resistant symptoms of schizophrenia.
Although treatment with rTMS is generally well tolerated, it is quite difficult to recruit patients with prominent negative symptoms of schizophrenia to rTMS studies. Patients with negative symptoms are not motivated to undergo rTMS treatment, probably owing to the core negative symptoms such as anhedonia or loss of interest. Other patients are likely unaware of the minimal side-effect profile of rTMS, and associate brain stimulation with frightening, archaic protocols. Owing to low adherence to medications, as well as other factors, there is a high degree of pharmacoresistance associated with the disease, as well as clear deterioration of the socioeconomic status of patients, as schizophrenia progresses. There is, therefore, a medical imperative to develop new or augment existing treatments for schizophrenia and help the often intractable symptoms these patients deal with on a daily basis.
Expert Rev Neurother. 2013;13(10):1079-1082. © 2013 Expert Reviews Ltd.