Back in 1999, Ralph Hoffman and his collaborators working at Yale’s Department of Psychiatry published results from a study which tested low frequency ‘repetitive transcranial magnetic stimulation’ (rTMS) as a treatment for voice hearing. rTMS is a noninvasive brain stimulation technique, which basically uses a magnetic field to induce an electrical current in a small area of cortex. In these studies, the stimulation is generally aimed at the left temporoparietal cortex, based on what we know about voice hearing and parts of the brain that deal with language.

Image from Wikipedia – the highlighted region shows temporoparietal cortex

Three voice hearers (with a diagnosis of schizophrenia or schizo-affective disorder) took part, and Hoffman reported a dramatic decrease in the frequency of voices reported. Clearly, results from three patients are not enough to generalize to a wider population, so Hoffman expanded his sample size to incorporate 50 patients who reported hearing voices, and again reported a decrease in the frequency of voices. Since the initial study, many have sought to replicate his findings, but results have been mixed, with many finding no improvement whatsoever over the control condition. However, a recent meta-analysis by Christina Slotema and colleagues still concluded that rTMS may be a viable treatment option, finding a small effect size of 0.33.

I would make three points about these studies, and rTMS protocols in general:

This is not ECT.
Many people flinch when you mention altering brain activity with magnets and electric currents, probably because they’re reminded of portrayals of ECT such as in One Flew Over the Cuckoo’s Nest. A discussion of ECT is beyond the scope of this post, but the important point is that ECT & rTMS are very different techniques. rTMS is not unpleasant to receive – you simply feel a tapping sensation on your scalp, under the coil. Side effects of rTMS are also minimal, with not much more than occasional transient headaches, and some facial musculature twitching during stimulation being reported in published trials

We need better sham conditions in these studies.
An important downside of using rTMS experimentally is that it is hard to create an effective control condition. The sensation is not easy to replicate – some studies simply tilt the stimulating coil 45° away from the head, ensuring that the tapping sensation is to some extent present, whilst others use ‘sham coils’ which supposedly replicate the sensation without actually stimulating the brain. However, neither of these methods completely replicate the experience of rTMS, and many argue that improvements seen after rTMS treatment are actually a placebo effect. This is a serious point, and one that is hard to disprove, due to the subjective experience of voice hearing.

The more options we have available to help people, the better.
Many are understandably wary of biomedical treatments of voice-hearing, as they believe such approaches firstly, needlessly pathologise the experience of voice hearing and, secondly, resort to what are seen as extreme measures to simply ‘get rid’ of voices. I am sympathetic to these arguments. I agree that there is no need to pathologise the voice hearing experience itself, and in many cases we should be trying to get at other underlying problems, such as appraisals of the voices and the subsequent distress caused. However, the fact remains that we are not always capable of helping people as we would like to. Although many voice hearers say that they would prefer to keep their voices, a sizable proportion would prefer not to, according to a study conducted with members of the Dutch Resonance Foundation and members of a Voice Clinic. I would argue that the more potential ways of helping people, the better. As Nev Jones eloquently put it in a blog post earlier this year:

“Different narratives, different discursive horizons of experience, may be therapeutic, for different people, for different reasons”

Iris Sommer’s research group in Utrecht recently labelled rTMS treatment as ‘potentially useful’. Although I would agree with this assessment, in my opinion experimental studies of rTMS are nowhere near reaching a consensus – partly because of underpowered studies with inadequate control ‘sham’ conditions, and partly because, as we know, voice hearing is an extremely heterogeneous experience – what might work for some might not work for others.

References
Hoffman, R. E., Boutros, N. N., Berman, R. M., Roessler, E., Belger, A., Krystal, J. H., et al. (1999). Transcranial magnetic stimulation of left temporoparietal cortex in three patients reporting hallucinated “voices”. Biological Psychiatry, 46(1), 130-132.

Hoffman, R. E., Gueorguieva, R., Hawkins, K. A., Varanko, M., Boutros, N. N., Wu, Y. T., et al. (2005). Temporoparietal transcranial magnetic stimulation for auditory hallucinations: Safety, efficacy and moderators in a fifty patient sample. Biological Psychiatry, 58(2), 97-104.

Jenner, J. A., Rutten, S., Beuckens, J., Boonstra, N., & Sytema, S. (2008). Positive and useful auditory vocal hallucinations: prevalence, characteristics, attributions, and implications for treatment. Acta Psychiatrica Scandinavica, 118(3), 238-245.

Slotema, C. W., Aleman, A., Daskalakis, Z. J., & Sommer, I. E. (2012). Meta-analysis of repetitive transcranial magnetic stimulation in the treatment of auditory verbal hallucinations: Update and effects after one month. Schizophrenia Research, 142(1–3), 40-45.

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