PARIS – Transcranial magnetic stimulation guided by functional MRI reduced auditory hallucinations in patients with schizophrenia, but so did a sham treatment in a randomized, controlled study of 62 patients.
The findings were "an unpleasant surprise," Dr. Iris E.C. Sommer reported at the annual congress of the European College of Neuropsychopharmacology.
Even when the fMRI-guided group and the standard TMS group were pooled, results were not significantly better than with placebo
The severity of auditory hallucinations decreased by about 40% after 15 sessions of 20-minute treatments in each of three groups. One group received 1 Hz of transcranial magnetic stimulation (TMS) at 90% of the individual motor threshold, guided by functional MRI (fMRI) to the area of brain activity during hallucinations. A second group underwent nonguided fMRI aimed at the left temporoparietal cortex, and the third group had a placebo TMS coil placed perpendicular to the head.
The results contradict a meta-analysis of previous studies of TMS for hallucinations that reported a mean halving of hallucinations using 1 Hz TMS treatments (J. Clin. Psychiatry 2010;71:873-84). The earlier studies in the meta-analysis might have had a positive bias toward new technology, suggested Dr. Sommer of the department of psychiatry at University Medical Center Utrecht (the Netherlands).
The current study’s results are supported by three other studies that were not included in the meta-analysis, including one Canadian study with more than 100 patients, she added.
Dr. Sommer and her associates had hoped that guiding TMS via fMRI would make the treatment more effective. First, they used fMRI to localize brain activity during hallucinations and used the results to calculate hallucination "hot spots" in the brain. They repeated these steps in 33 patients because "fMRI is notorious for having low test-retest reliability," she said. The mean distance between hot spots in the first and second scans was less than 2 cm for all brain regions, averaging 1.4 cm, "which is large but still doable for TMS," she said.
The results suggest that fMRI guidance for hallucinations in single patients is feasible for TMS and possibly other symptoms with on/off states, such as obsessions, compulsions, tics, dystonia, or tardive dyskinesia.
However, the 1-HzTMS stimulation protocol was not effective enough for hallucinations, Dr. Sommer said. Even when the fMRI-guided group and the standard TMS group were pooled, results were not significantly better than with placebo (Biol. Psychiatry 2011;69:450-6).
It’s possible that results might differ with more effective TMS coils or other TMS stimulation paradigms such as burst frequencies.
Auditory hallucinations affect 70%-90% of patients with schizophrenia, and about 8% will have treatment-resistant auditory hallucinations. This represents 0.08% of the general population and can greatly affect quality of life and patients’ risks if they are hearing commands like, "You must burn down the library," she said.
Dr. Sommer said she has no relevant conflicts of interest.