Repeated transcranial magnetic stimulation for treating the negative symptoms of schizophrenia

Objective To investigate the effect of repetitive transcranial magnetic stimulation (rTMS) on the negative symptoms of chronic schizophrenia and on the P300 component of schizophrenics′ event-related potentials (ERPs). Methods Ninety convalescing schizophrenia patients were randomly divided into a 5 Hz group, a 10 Hz group and a 15 Hz group, each of 30. The three groups were treated with the corresponding 5 Hz, 10 Hz or 15 Hz rTMS once a day, five times a week for five consecutive weeks. The P300 ERPs of all three groups were tested before and after the treatment. Any curative effect was evaluated using the scale for the assessment of negative symptoms (SANS). Results After the treatment, the average SANS score of the 10 Hz group was significantly different from that before the treatment and also from those of the other two groups after the treatment. After the treatment, significant improvement was also observed in the amplitude of P300 in the 10 Hz group. The treatment′s effectiveness was negatively correlated with age and longer course of the disease. Conclusion rTMS at 10 Hz is the most effective of the protocols tested for improving the negative symptoms of schizophrenia and improving cognitive functioning. Key words: Schizophrenia; Transcranial magnetic stimulation; Event-related potentials