The effects of anti-Parkinsonian medications on bone mineral density: A systematic review

Parkinson's disease (PD) is associated with elevated fracture risk, particularly at the hip. Antiparkinsonian medications have also been associated with increased fracture risk; although their direct effects on bone mineral density (BMD) remains unclear.

Investigate whether antiparkinsonian medications influence BMD.

A systematic search of four databases (Embase, MEDLINE, APA PsycINFO, Web of Science) was conducted up to 24/11/2025 using terms related to PD, antiparkinsonian medications and bone.

A total of 748 records were identified, with 543 screened following deduplication. Fourteen studies underwent full-text review, of which seven met inclusion criteria. Three studies assessed bone mineral content or surrogate measures at non-standard sites (hand radiographs or skull Hounsfield Units) and reported no associations with L-Dopa therapy. Four studies reported areal BMD (aBMD) from dual energy x-ray absorptiometry (DXA). One study showed negative correlations between L-Dopa dosage with aBMD at the hip and spine. Two studies (RCT and cross-sectional) implicated elevated serum homocysteine (Hcy) levels induced by L-Dopa as a potential mechanism for osteoporosis risk in PD. In the cross-sectional study, although L-Dopa therapy was associated with higher Hcy and lower aBMD, there were no causal associations between L-Dopa and hip aBMD. In the RCT, lower Hcy was associated with reduced annual aBMD loss with L-Dopa therapy. One further study found no associations between L-Dopa therapy and aBMD at any site.

The contribution of antiparkinsonian medication to low BMD in PD remains unclear. Despite plausible mechanisms of action, evidence of causal associations is lacking.