Introduction: Leptin, adipose-tissue-derived hormone has a prominent role in bone remodeling by activating, through CNS relay, the sympathetic tone which inhibits bone formation. Schizophrenia is a CNS disease associated with low bone mass and changes in bone remodeling. Risperidone, atypical antipsychotic, may be related to increase in body weight (BW). Increased BW is thought to be protective to the bone.
Aim: To determine relations between leptin, bone remodeling parameters (osteocalcin and C-terminal telopeptide of type I collagen-CTx), bone mineral density (BMD-lumbar spine et femoral neck) and BW in patients with schizophrenia treated with LAIR for at least 6 months up to 3 years.
Patients: Cross-sectional study, we investigated 26 out-patients(12 males, age 31.3±1.3 years, BMI 28.2±1.0 kg/m2) with stable schizophrenia in real-life conditions. They were treated with LAIR for mean 18.0±1.6 months with mean dose 38±2 mg/two weeks. Thirty-five matched subjects (11 males) served as healthy controls.
Results: The increase in BW was confirmed in 14(54%) patients treated with LAIR on average 8.7±1.6 kg. Leptin levels adjusted for BMI in females were significantly higher in patients than in healthy female subjects (P=0.018). Significant positive correlations between leptin and BW was found in patients and healthy controls. BMD tended to be lower but did not reach significance in patients with schizophrenia (p=0.094). CTx, was slightly increased in patients on LAIR (P=0.023). Significant negative correlation between leptin and osteocalcin (r=−0.376, P=0.050) was found only in patients with schizophrenia. Leptin did not correlate with BMD in schizophrenic patients while it did in healthy subjects (femoral neck r=0.366, P=0.031).
Conclusion: Higher serum leptin levels in female patients after adjusting for BMI may suggest leptin resistance. Leptin has been shown to inhibit bone formation so it is tempting to speculate that weight gain together with leptin resistance during long term therapy with LAIR may be protective to the bone in patients with schizophrenia.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This work was supported however funding details unavailable.