In 2004, radio/TV host Dave Iverson got confirmation of the bad news that his body had already been telling him: Like his father and brother before him, he had Parkinson’s disease. Frontline follows Iverson’s journey to understand the mysteries of the incurable illness that inexorably robs its victims of the ability to control their bodies—mysteries such as the possible connections between Parkinson’s and environmental toxins. High-profile Parkinson’s patients such as actor Michael J. Fox and writer Michael Kinsley add commentary, while the documentary reveals the emerging role of exercise in battling Parkinson’s symptoms and explores the potential for breakthrough discoveries from embryonic stem cell research (which may open up under the Obama administration). Tuesday, Feb. 3, at 9 p.m., PBS; check local listings