Association between serum testosterone levels, body mass index (BMI) and insulin in male patients with schizophrenia treated with atypical antipsychotics--olanzapine or risperidone.

Objective: A sufficient amount of testosterone (T) is essential for adequate sexual functioning but also for cognitive and psychological well-being. Most recent studies have demonstrated that higher BMI and other symptoms of metabolic syndrome are associated with alterations in sex steroid hormone concentrations. Although, neuroleptics are known to cause a significant and sustained weight excess, the relationships between body mass index and the level of testosterone in psychiatric patients have not been thoroughly studied. The main purpose of the present study was to examine the correlations between testosterone, estradiol BMI, and insulin in male patients diagnosed with schizophrenia and treated with olanzapine or risperidone.

Methods: The study included 78 males diagnosed with schizophrenia according to the DSM-IV diagnostic classification hospitalized in psychiatric inpatient units (42 on risperidone and 36 on olanzapine). The initial and final evaluation of testosterone (T), estradiol, prolactin (PRL) and insulin serum levels were performed at week 3 and 8 after the onset of the new treatment, respectively.

Results: At week 3, the mean serum prolactin was markedly higher, whereas testosterone level was lower in risperidone patients compared to those treated with olanzapine. T level was negatively affected by the studied medication (risperidone), increased prolactin and a higher BMI. At week 8, the mean serum prolactin level was markedly higher in risperidone patients. Higher values of BMI and serum insulin were the most prominent factors independently associated with decreased plasma testosterone levels at that measurement point. Individual changes of T level between week 3 and 8 were positively correlated with the corresponding changes in estradiol levels.

Conclusions: T serum levels appear to be independently linked with BMI, insulin and prolactin in both investigated neuroleptics. Further research is needed to elucidate the relationship between reproductive hormones and metabolic parameters in patients with schizophrenia under neuroleptic treatment.