Background: Neuroimaging findings implicate bilateral superior temporal regions in the genesis of auditory-verbal hallucinations (AVH). This study aimed to investigate whether 1 Hz repetitive transcranial magnetic stimulation (rTMS) of the bilateral temporo-parietal region would lead to increased effectiveness in the management of AVH, compared to left rTMS or placebo.
Methods: 38 patients with schizophrenia (DSM-IV) and medication-resistant AVH were randomly assigned to 1 Hz rTMS treatment of the left temporo-parietal region, bilateral temporo-parietal regions, or placebo. Stimulation was conducted over 6 days, twice daily for 20 min, at 90% of the motor threshold. Effect measures included the Auditory Hallucination Rating Scale (AHRS), Positive and Negative Affect Scale (PANAS), and a score for hallucination severity obtained from the Positive and Negative Syndrome Scale (PANSS).
Results: All groups showed some improvement on the total AHRS. Hallucination frequency was significantly reduced in the left rTMS group only. The bilateral rTMS group demonstrated the most remarkable reduction in self-reported affective responsiveness to AVH. A modest, but significant decrease on the PANSS hallucination item was observed in the combined rTMS treatment group, whereas no change occurred in the placebo group. The left rTMS group showed a significant reduction on the general psychopathology subscale.
Conclusion: Compared to bilateral or sham stimulation, rTMS of the left temporo-parietal region appears most effective in reducing auditory hallucinations, and additionally may have an effect on general psychopathology. Placebo effects should however not be ruled out, since sham stimulation also led to improvement on a number of AVH parameters.