Repetitive transcranial magnetic stimulation and cognitive function in schizophrenia: A randomized, controlled study

Abstract

Objective To investigate the influence of repetitive transcranial magnetic stimulation (rTMS) on the cognitive function of patients with schizophrenia. Methods Sixty-eight patients diagnosed as schizophrenic according to the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders were randomly assigned to either a real rTMS group (n=33) or a sham rTMS group (n=35). Both groups were given risperidone for 4 weeks, in addition to real or sham rTMS of the left dorsolateral prefrontal cortex at 10 Hz. The psychiatric symptoms of both groups were assessed using a Positive and Negative Syndrome scale (PANSS) before and after the 4 weeks of treatment. At the outset and at weeks 2 and 4 their cognition was evaluated using event-related potential P300 and the Wisconsin card sorting test (WCST). Results After 4 weeks of treatment the average negative symptoms score was significantly lower in rTMS group than in the sham group. The total score on the PANSS and the score of each factor were all significantly lower than before treatment in both groups. Both the average dose and the maximum dose of risperidone in the rTMS group were significantly higher than those in the sham group. Compared with before treatment, there were no significant differences in latency, P300 amplitude, completed categories (Cc), responses correct (Rc), response errors (Re), perseverative errors (Rpe) or non-perseverative errors (nRpe) in either group after 2 weeks of treatment. After 4 weeks, however, significantly shortened latency of P2, N2 and P3, significantly heightened amplitude of P2 and P3, significantly increased Cc and Rc, and significantly decreased Re, Rpe and nRpe were all observed in the rTMS group. In the sham group, significantly shortened P3 latency, significantly heightened P3 amplitude, significantly increased Cc, and significantly decreased Re and nRp were observed. The rTMS group showed significantly better improvement in P2 and N2 latency, more improved P3 amplitude, and better Cc, Rc, Re, Rpe and nRpe results than the sham group after 4 weeks of treatment. Conclusion 10 Hz rTMS may have a therapeutic effect on the cognitive dysfunctions of schizophrenia with a treatment duration of more than 2 weeks. It can reduce the dosage of antipsychotic drugs required. Key words: Schizophrenia; Transcranial magnetic stimulation; Cognition; Risperidone