What does the research say?
The evidence for whether neurostimulation can actually reduce the frequency of voices is mixed. A study by Ralph Hoffman and colleagues in US in 2013 tested TMS with 83 voice-hearing participants (all with a diagnosis of schizophrenia), and reported that, compared to participants who didn’t receive the stimulation, participants reported their voices happening less often following the treatment. However, not all studies have found TMS to be effective. An analysis of 25 different studies, conducted by Christina Slotema, suggests that there may be a small benefit of TMS for voices.
There is less evidence about whether tDCS might be able to reduce the frequency of voices. The first study using this technique with voice-hearing participants was conducted by Jerome Brunelin and colleagues in France in 2012. They tested this technique with 30 voice-hearing participants and found a large reduction in the frequency of voices following treatment. However, other studies have not found tDCS to be effective, and an analysis of 5 studies by Fuyin Yang and colleagues in 2019 indicated no real reduction in voices following tDCS treatment.
One possibility is that neurostimulation techniques might work for some people but not others. One study by Sanne Koops and colleagues suggested that neurostimulation might work best for younger female participants – but we need much more evidence to know whether this is really the case.
