Objective: To verify whether high-frequency rTMS applied above the area of the left prefrontal cortex in 15 stimulation sessions with maximum stimulation intensity is able to modify negative symptoms of schizophrenia in a double-blind, randomized controlled study.
Methods: Twenty-two patients with schizophrenia stabilized on antipsychotic medication with prominent negative symptoms were included in the trial. They were divided into two groups: eleven were treated with effective rTMS and eleven with ineffective "sham" rTMS. The ineffectiveness of the sham rTMS was achieved through the stimulation coil position. Stimulation was applied to the left dorsolateral prefrontal cortex. The stimulation frequency was 10 Hz. Stimulation intensity was 110% of the motor threshold intensity. Each patient received 15 rTMS sessions on 15 consecutive working days. Each daily session consisted of 15 applications of 10-second duration and 30-second intervals between sequences. There were 1500 stimuli per session.
Results: During real rTMS treatment a statistically significant decrease of negative symptoms was found (approximately 29% reduction in the PANSS negative symptom subscale and 50% reduction in the SANS). No adverse events occurred during therapy except for a mild headaches. In sham rTMS treatment a decrease of negative symptoms was also identified, but to a lesser extent than in real rTMS (about 7% in negative subscale PANSS and 13% in SANS). The change in SANS achieved statistical significance. Mutual comparison revealed a greater decrease of negative symptoms in favor of real rTMS in contrast to sham rTMS.
Conclusion: The augmentation of rTMS enabled patients to experience a significant decrease in the severity of the negative symptoms. Our results support the therapeutic potential of rTMS at higher frequency for negative symptoms of schizophrenia.