Aim: Bipolar disorder is associated with significant psychological and physical comorbidity. Yet little is known about the bone health of adults with bipolar disorder. Thus, we aimed to investigate the association between bipolar disorder and bone quality in women.
Method: Women with a history of bipolar disorder (n=117) were recruited from the Barwon Statistical Division. Controls, without bipolar disorder, were drawn from the Geelong Osteoporosis Study (n=909). Bipolar disorder was identified using a semi-structured clinical interview (SCID-I/NP). Bone quality was determined by Quantitative heel ultrasound (Achilles Express, GE Medical Systems) and included the following parameters: Speed of Sound (SOS), Broadband Ultrasound Attenuation (BUA) and Stiffness Index (SI). Weight and height were measured and information on medication use and lifestyle variables were obtained via questionnaire. Linear regression models were used to test associations, after adjusting for age and weight.
Results: Those with bipolar disorder were heavier, less active, more likely to smoke, take psychotropic medication and have lower SOS and SI compared to controls (all p<0.003); otherwise the groups were similar in age, height and BUA. After adjustments, bipolar disorder was associated with lower adjusted mean SOS [1559.1 (95%CI 1552.4-1565.8) vs 1576.2 (95%CI 1573.8-1578.6) m/sec, p=<0.001], BUA [109.2 (95%CI 106.5-111.8) vs 112.8 (95%CI 111.9-113.7) dB/MHz, p=0.01] and SI [88.7 (95%CI 85.4-92.1) vs 96.6 (95%CI 95.4-97.7) %, p=<0.001] compared to controls. These associations persisted after further adjustment for smoking, physical activity and psychotropic medications.
Conclusion: These population-based data suggest bipolar disorder is associated with poor bone quality, as measured by QUS, in women. Given the dearth of literature, replication and research into underlying mechanisms are warranted.