The effect of rTMS on auditory hallucinations: Clues from an EEG-rTMS study

OBJECTIVE Repetitive transcranial magnetic stimulation (rTMS) to the temporoparietal region has been proposed as a therapeutic option for auditory verbal hallucinations (AVH). However, most large randomized controlled trials failed to demonstrate a superior effect of rTMS treatment as compared to sham. Previous studies applied daily rTMS sessions for one or more weeks to summate its effects. However, the effect of a single rTMS treatment on AVH-severity has never been studied, making it unclear if there is an initial effect that could be increased by repeated treatment. METHODS In three separate sessions, twenty-four patients with a psychotic disorder received 1-Hz rTMS to the left temporoparietal cortex, its right-sided homologue or a centro-occipital control site. Severity of AVH was assessed before and after each rTMS session and resting-state EEGs were recorded to investigate the neuronal effects of rTMS. RESULTS Stimulation of the temporoparietal cortices was not more effective in reducing AVH-severity than control-site stimulation. In addition, EEG-related power and connectivity measures were not affected differently across stimulation sites and changes in neuronal activity did not correlate with changes in AVH-severity. CONCLUSIONS These results may suggest a placebo effect of a single session of 1-Hz rTMS treatment on AVH-severity.