This study is testing a medicine called Zoledronic Acid (ZA) to see if it helps prevent bone fractures in people aged 60 or older with Parkinson's disease or similar conditions. Parkinson's disease is a disorder that affects the brain and movement. In this study, participants will either get one dose of ZA or a placebo (a fake treatment) without knowing which one they receive.

Once you join, you'll get vitamin D pills to take daily for two months. A nurse will visit your home to check if you can continue in the study and give the ZA if you're eligible. You will be contacted every 4 months for at least 2 years to see if you've had any fractures.

• Duration: You will be part of the study for at least 2 years.
• Eligibility: You must be 60+ years, have Parkinson's or similar conditions, and be able to consent.
• Exclusions: Recent hip fracture or certain treatments might disqualify you.

For more information, visit the study website or contact the Parkinson's Foundation Helpline.