Endocrine Abstracts

According to the novel concept bone remodeling is centrally regulated (CNS). Leptin the adipocyte derived hormone acts on hypothalamus and by increasing sympathetic activity acts on osteoblasts to regulate bone formation. In patients with schizophrenia several factors have influence on bone metabolism. Schizophrenia per se, as a disease of central nervous system is associated with increased occurence of osteoporosis. Hyperprolactinemia as consequence of antipsychotic treatment in these patients has impact on both bone mineral density (BMD) and bone metabolism by increasing bone resorption. On the other side, weight gain which is the commonly observed on antipsychotic therapy may be protective factor against osteoporosis.

Aim: The aim of our study was to investigate the effects of BMI and insulin on bone mineral density and markers of bone metabolism in 23 patients (12 males, mean age 32.2±1.3 years, BMI 29.2±1.0 kg/m²) with schizophrenia treated with atypical anypsychotic – depo risperidone 100 mg monthly, during 1.4±0.3 years. The control group included healthy 35 individuals sex, age and BMI matched (11 males, mean age 32.2±1.4 years, 28.0±1.2 kg/m²). After fasting in the morning serum leptin, prolactin-PRL, osteocalcin-OCL, ßcross laps-BCL, IGF 1, PTH and 25-OH-vitamin D levels were measured. Both groups were tested by oral glucose load (OGTT) with measuring insulin levels. In all patients DEXA (Hologic) was performed to measure bone mineral density-BMD. We used for statistical measurements General Linear Model for repeated measures. P values below 0.05 were regarded as significant.

Results: We did not find a statistical difference in serum levels of OCL, BCL, leptin, PTH and IGF1 between two groups (P>0.05). Vitamin D levels were lower (P<0.05) and prolactin levels were significantly increased in patients with schizophrenia (P<0.05). We found significant positive correlation between BMI and BMD in healthy control (P=0.051). BMI had positive correlation with Z score of the spine in controls (P=0.027). Correlation between insulin levels during OGTT (AUC) and parameters of BMD and Z score of spine in control (P<0.0001; P=0.001, respectively) was confirmed. On the other side in patients with schizophrenia no significant correlation between BMI and insulin levels (AUC) with BMD and Z score were found.

Conclusion: BMI and insulin levels did not affect bone mineral density and bone metabolism in patients with schizophrenia which is different from healthy control. Central control of bone remodeling might be disturbed in schizophrenia.