Relationship between plasma levels of prolactin and the severity of negative symptoms in patients with schizophrenia

Objective: The aim of this study was to evaluate the relationship between plasma levels of prolactin and negative symptoms. Methods: One hundred fourteen patients with schizophrenia were included in this cross-sectional study. The patients were classified into groups with and without hyperprolactinemia. Plasma levels of prolactin and clinical features were compared between these groups. Results: Negative symptom scores in the group with hyperprolactinemia were significantly higher than in the non-hyperprolactinemic group. There was also a positive correlation between plasma levels of prolactin and negative symptom scores. However, there was no statistically significant difference between schizophrenia subtypes with regard to plasma prolactin levels. Patients treated with conventional neuroleptics or novel antipsychotics such as risperidone, paliperidone and amisulpride had higher prolactin levels than patients treated with aripiprazole, olanzapine, quetiapine, ziprasidone, and clozapine. Conclusion: This study indicated that we should be aware of prolactin levels, especially when negative symptoms are prominent in patients with schizophrenia. Plasma levels of prolactin could be an important biological marker for the severity of negative symptoms in the treatment of patients with schizophrenia. Thus, this finding may change the present pharmacotherapy for negative symptoms in schizophrenia based on prolactin levels.