Parkinson's disease (PD) is a condition that affects movement and thinking. Medicines and surgeries often can't fully help. This study is looking at whether a special exercise, called Partnered Dance Aerobic Exercise (PDAE), can help people with PD more than just walking. PDAE is a fun way to exercise by dancing with a partner. It is believed that this kind of exercise can reduce "OFF-time" (when medications don't work well) and help with thinking. Researchers will compare PDAE with walking to see which helps better.

The study is for people over 40 with PD. It will last 16 months. Participants will be randomly chosen to either dance or walk. They'll do lessons twice a week for 3 months, then once a week for the next 13 months. Researchers will check changes in the brain using scans and ask participants about their symptoms and thinking skills at different times during the study.

• Participants will need to commit to a 16-month program.
• Participants will attend weekly sessions, starting with two per week.
• Participants will have brain scans and tests to track progress.