Parkinson's disease (PD) is an incurable neurodegenerative disorder affecting approximately 1 million US adults and about 80,000 Veterans. PD causes significant morbidity due to motor and non-motor symptoms across its prolonged course with an annual economic burden of $14 billion in the US alone. Motor symptoms associated with loss of dopaminergic neurons in PD may be temporarily improved with dopamine replacing medicines, but disease-modifying therapies that delay or prevent neuronal loss are lacking and sorely needed. Exercise is promising as a disease-modifying therapy because it protects dopaminergic neurons in animal models of PD and has been associated with measures of neuroplasticity in PD patients. Unfortunately, more than half of dopaminergic neurons in the substantia nigra are lost before motor symptoms occur making it difficult to identify patients early enough to benefit from potentially disease-modifying therapies. Early "prodromal" PD can be identified using non-motor features including olfactory dysfunction and other biomarkers such as dopamine transporter (DaT) brain imaging abnormalities that are apparent years before motor symptoms. However, these strategies would be difficult and costly to implement on a population level without first identifying high-risk individuals for screening. Commonly prescribed dopamine blocking antipsychotic drugs cause debilitating PD-like motor dysfunction that is difficult to treat, and in some patients this finding may serve as a "stress test" for failing dopaminergic networks unmasking symptoms long before they would normally appear. Identifying prodromal PD among drug-induced parkinsonism patients offers a unique and unexplored opportunity for early intervention.