Successful treatment with risperidone increases 5‐HT 3A receptor gene expression in patients with paranoid schizophrenia – data from a prospective study

INTRODUCTION: The relationship between peripheral 5‐HT3A receptor mRNA level and risperidone efficiency in paranoid schizophrenia patients is still unknown. METHODS: A total 52 first‐episode and drug‐naive paranoid schizophrenia patients who were treated with risperidone and 53 matched healthy controls were enrolled. Patients were naturalistically followed up for 8 weeks. Positive and Negative Syndrome Scale (PANSS) was applied to assess symptom severity of the patients at baseline and at the end of 8th week. RESULTS: There was no difference in 5‐HT3A receptor mRNA level between paranoid schizophrenia patients and healthy controls at baseline (p = .24). Among 47 patients who completed 8‐week naturalistic follow‐up, 37 were responders to risperidone treatment. 5‐HT3A receptor mRNA level of paranoid schizophrenia patients did not change in overall patients after 8‐week treatment with risperidone (p = .29). However, 5‐HT3A receptor mRNA level in responders increased significantly (p = .04), but not in nonresponders (p = .81). CONCLUSIONS: Successful treatment with risperidone increases 5‐HT3A receptor gene expression in patients with paranoid schizophrenia, indicating that 5‐HT3A receptor may be involved in the mechanism of risperidone effect.