The Effect of Melatonin Adjuvant on Cognitive Function and Melatonin Levels in Schizophrenia Patients

Background: Schizophrenia is an important and serious mental disorder. It has been studied that serum melatonin levels were significantly decreased in schizophrenia patients. Objective: To investigate the effect of adjuvant melatonin on cognitive function and serum melatonin levels in schizophrenia patients receiving risperidone therapy Methods: This study used a randomized controlled double-blind design. Forty-four male schizophrenic patients were successfully enrolled and randomized into two groups: 22 treatment patients who received risperidone therapy (4-6 mg/day) and melatonin (5 mg/day) and 22 control patients who received risperidone and placebo. The Montreal Cognitive Assessment Indonesian version (MoCA-INA) scale and serum melatonin levels were measured before and after 8 weeks of therapy. Data were analyzed using chi-squared, independent samples t-test or Mann-Whitney and Spearman correlation tests. Results: Changes in MoCA-Ina scores were significantly different between the treatment and control groups (p<0.001), particularly in the visuospatial/executive, language, memory and orientation dimensions (p<0.05). The change in melatonin levels was also significantly different between groups (p<0.05). The decrease in melatonin levels in the treatment group was about three times lower than in the control group (-4.34 pg/mL vs. -13.61 pg/mL). There was no significant correlation between melatonin levels and MoCA-Ina scores. Conclusion: Adjuvant melatonin could improve cognitive function and slow the rate of melatonin decline in schizophrenia patients receiving risperidone.