Parkinson's disease (PD) is a difficult to treat condition that impairs mobility and thinking. It is not fully treated by drugs and surgery. Two priority issues for most people with PD are "OFF-time" and Cognitive impairment. Even under best medical management, 74% of people with PD experience "OFF-time," which is when medications are just not working right. OFF-time severely impacts both quality of life and thinking. Cognitive problems are found even in newly diagnosed people with PD and are very difficult to treat. However, the investigators' research has shown that partnered dance-aerobic exercise (PDAE) reduces OFF-time on the official test for OFF-time of the Movement Disorders Society, the Movement Disorders Society Unified Parkinson Disease Rating Scale-IV, (MDS-UPDRS-IV). PDAE improves other symptoms too. Benefits of the therapy have lasted for at least one-month after PDAE sessions stopped. PDAE provides aerobic exercise during an improvisational, cognitively-engaging physical activity. Cognitive engagement is a critical component of PDAE. Previous research showed PDAE improved spatial cognition, the ability to navigate, to mentally picture shapes and paths in the mind and to know the relationships between objects, people and places. Also, the investigators showed with imaging of the brain using a magnet in a scanner that twice weekly PDAE training increases activity in brain regions used in thinking and decision making. The investigators know that exercise benefits mobility and cognitive problems. The investigators even think exercise might protect brain cells in people with PD. But no one has really been able to show with biomarkers that exercise is protective of brain cells in humans.

The investigators will conduct a study in Veterans and non-Veterans with diagnosed PD to compare PDAE versus walking for OFF-time, cognition, and brain cell protection. The investigators will use a method like a coin flip to decide if the participants will be doing PDAE or walking. Importantly, the investigators will see if brain cells are protected using a brain scan that looks at the areas affected by PD to determine the relative amounts of different hormones in the brain that are related to having Parkinson's. The investigators will use these measurements of these hormones to chart the course of brain cell breakdown in patients with PD who have done walking or PDAE for 16 months. The investigators think that that PDAE will be better at lessening OFF-time and making cognition better than walking. The investigators think this because participants have to really use the mind during PDAE because the participants have so much to think about in terms of the steps and patterns. The investigators will assign 102 Veterans with mild-moderate PD to either 16 months of PDAE or walking. The investigators will use a coin toss or other similar method to determine who goes in what group. The investigators need participants to be in the classes for 16-months because it takes that long for us to see if anything changed in the brain with those hormones. Participants will do twice weekly classes for the first 3 months and then will switch down to taking lessons just 1 time per week for 13 months. The investigators will schedule appointments for participants to be seen by the research team before Veterans begin lessons, at 3 months (after the twice weekly schedule) and at 16 months after all the lessons are completed. The appointments will consist of asking the Veterans about their OFF-time having them take a few memory and thinking tests. The investigators will also ask them to lie in a scanner for about an hour. The participants can rest in the scanner for about a 1/2 hour and also do a thinking task. The investigators will be able to answer the questions, "Is PDAE better than walking at lessening OFF-time and spatial cognition and slowing down brain cell death? This study is using cutting edge imaging techniques for the first time to see if dance or walking are helpful for slowing brain cell death. This project combines patient-centered, clinical science and mechanistic aims to improve health care.

Inclusion Criteria:

• Age: older than 40 years (40 is upper limit for young onset PD)

• Montreal Cognitive Assessment (MoCA) score >17

• Able to walk with or without an assistive device at least 10 feet

• Best corrected/aided acuity better than 20/70 in the better eye

• Willingness to be randomized to either group

• H&Y stages I-III

• Report OFF times (reporting >0 on item 4.3 of the UPDRS-IV)

• Show clear symptomatic benefit from antiparkinsonian medications

  • e.g., alleviated rigidity, bradykinesia, and tremor

• Fluent in English to comprehend and participate

Exclusion Criteria:

• Untreated Major Depression and major psychiatric illness

• History of stroke, or traumatic brain injury

• Pure-tone threshold average sensitivity at 0.5, 1.0, and 2.0 kHz exceeds 40 dB

• Previous participation in PDAE or WAE classes.

• Alcohol abuse and/or use of antipsychotics

• Lives outside of the study site or is planning to move out of the area in next year or leave the area for >1 month during the next year

• Taking moderate to high doses of beta-blockers with a resting heart rate below 60 beats/min since exercise intensity is measured through target heart rate.

• Severe cardiac disease, including:

  • New York Heart Association (NYHA) Class III or IV congestive heart failure

  • clinically significant aortic stenosis

  • history of cardiac arrest, use of a cardiac defibrillator

  • uncontrolled angina

    • as discussed we are not planning to perform routine exercise tolerance tests prior to enrollment

• Other significant co-morbid disease that would impair ability to participate in the exercise-based intervention

  • e.g. renal failure on hemodialysis, excessive alcohol use (>14 drinks per wk)

• Any contraindications to MRI eg claustrophobia, etc