One in one hundred people will experience schizophrenia in their lifetime. Schizophrenia can be managed well with a person-centred combination of therapy and medication and an emphasis on recovery. Many of us are likely to know people who are affected by the symptoms of schizophrenia but are still managing to lead fairly ordinary lives.
However, for others living with more severe symptoms, schizophrenia can be a distressing and highly debilitating experience. Symptoms experienced such as hearing voices or seeing things (hallucinations) often fail to respond to medication. Even when antipsychotic medication is effective, the side effects of weight gain, apathy, shaking or lack of drive are also debilitating. More effective drugs are urgently needed, however despite promising leads there has not been ground-breaking progress in drug development for schizophrenia for many decades.
One emerging non-drug therapy proposed for the treatment of schizophrenia and the symptom of hearing voices is transcranial magnetic stimulation (TMS). TMS is a device which involves the skilful application of a strong magnetic field close to the scalp surface. TMS is a relatively painless and non-invasive technique which stimulates parts of the brain. Researchers over the last decade have set about assessing whether this promising new therapy TMS could be an alternative treatment for people who do not respond, or do not cope well with medication.
Researchers have typically used ‘randomised controlled studies’ to assess the effectiveness of TMS. This has usually meant randomising people with schizophrenia – with their full consent – into an experiment of either having TMS or having ‘sham’ TMS (i.e. identical process without the magnet switched on). Therefore, randomised controlled studies are a way of comparing two groups of people with schizophrenia who are as identical as possible in every way except for the active ingredient of the TMS itself.
Although many of these study results have now been reported by researchers across the world, the results differed widely and there was no consensus on whether TMS should be routinely used in practice. Therefore we set out to achieve this consensus by reviewing all the reported TMS studies of schizophrenia using Cochrane methodology (the internationally recognised highest standard of review). The purpose of our Cochrane review was to assess the quality of all reported studies, and then combine the results into one analysis (a ‘meta-analysis’) to give summary estimates of whether TMS is effective, or not.
We found that from 41 reported studies (1473 people) there was some evidence to suggest TMS may improve certain symptoms such as hearing voices when compared with ‘sham’ TMS. However, because we also graded many of the studies as ‘low’ or ‘very low’ quality evidence, this meant we were uncertain that TMS was effective, and could not make firm conclusions about using TMS as routine treatment for schizophrenia.
To be clear, this is not the same as researchers doing low quality studies, but rather that frequently the way the study was conducted was not reported to a sufficient standard to rule out risks of bias. This is frustrating, and authors who are reporting on study results are urged to adopt clear reporting practices to remove ambiguity by using standards such as the CONSORT criteria. Journal editors should consider routinely recommending the use of CONSORT criteria and lift restrictions on word limits which inhibit full reporting.
In future, high quality research studies AND high quality reporting of these studies is very likely to have an important impact on whether we can confirm TMS alleviates some symptoms of schizophrenia, but for now we remain quite uncertain. It is important that the research community pursues this aim so that we can improve the quality of treatment provided to people who are living with the debilitating symptoms of schizophrenia.
1 October 2015
Dougall N, Maayan N, Soares-Weiser K, McDermott LM, McIntosh A. Transcranial magnetic stimulation (TMS) for schizophrenia. Cochrane Database of Systematic Reviews 2015, Issue 8. Art. No.:CD006081.