Osteoporosis and low bone mass among schizophrenia and bipolar disorder: A cross-sectional study with newly diagnosed, drug-naïve subjects

Background: A growing body of data shows that schizophrenia (SCZ) and bipolar disorder (BD) have substantial metabolic risks; however, few studies have focused on bone metabolism. This study aimed to assess the prevalence and associated influencing factors of low bone mass and osteoporosis in SCZ and BD before pharmaco-logical effects occur. Methods: 108 healthy controls (HCs) and drug-naive individuals with SCZ (n = 56) and BD (n = 130) had their lumbar spine (L1-L4) and left femur (Neck/Trochanter/Ward's triangle) bone mineral density (BMD) determined using dual-energy X-ray absorptiometry. Besides, we measured bone turnover markers (BTMs) levels, including procollagen I N-terminal propeptide, osteocalcin, and C-terminal cross-linking telopeptide of type I collagen in different groups. Results: Individuals with SCZ and BD had significantly lower BMD and significantly higher prevalence of low bone mass and osteoporosis compared with HCs. In the main observation regions of the total lumbar (F =18.368, p < 0.001) and left femur (F = 14.790, p < 0.001), BMD was lower in individuals with SCZ and BD than HCs, with SCZ showing lower BMD than BD. The osteocalcin (H = 11.421, p = 0.003) levels were significantly higher in SCZ and BD than HCs. Binary regression analysis showed that SCZ or BD was an independent risk factor for low bone mass and osteoporosis. In addition, sex, age, and BTMs also influenced the occurrence of low bone mass and osteoporosis. Limitations: Cross-sectional study. Conclusion: The results findings of the study might contribute to our understanding of the increased risk of bone metabolism in SCZ and BD. Clinical trial registration: www.chictr.org.cn, identifier ChiCTR1900021379.