Background: Antipsychotic medication, used in the treatment of schizophrenia, has been shown to be associated with lower bone mass. However, less is known about the impact of antipsychotic medications on bone quality. Thus, we aimed to investigate the association between antipsychotic use and bone quality in a population-based sample of adults.
Methods: Data were collected from antipsychotic users (n=16 men and n=15 women) and age- and sex-matched non-users (n=80 men and n=75 women) participating in the Geelong Osteoporosis Study. Bone quality was determined using quantitative ultrasound (QUS) of the left calcaneus and included: Broadband Ultrasound Attenuation (BUA), Speed of Sound (SOS) and Stiffness Index (SI). Medication use and lifestyle factors were self-reported, anthropometry measured, and socio-economic status (SES) determined. Linear regression analyses were used to test cross-sectional associations between bone quality and antipsychotic use, after adjusting for potential confounders.
Results: Antipsychotic users were more likely to smoke and use antidepressants, were less active and consumed less alcohol. Otherwise, the groups were similar in regards to height, weight, SES and use of hormone therapy and bone active medications and supplementations. After adjusting for weight, antipsychotic use was associated with a 6.0% difference in mean BUA [109.8 (103.9-115.6) vs. 116.8 (114.2-119.4) dB/MHz, p=0.03] and 7.0% difference in mean SI [91.6 (84.8-98.4) vs. 98.5 (95.5- 101.5) %, p=0.07] compared to non-users. Associations persisted following further adjustment for mobility, alcohol consumption, smoking, SES and medications known to affect bone. There was no difference in SOS between antipsychotic users and non-users (p=0.29).
Conclusion: Use of antipsychotics was associated with lower QUS values. Hence, the risk of osteoporosis should be considered when antipsychotics are prescribed.