Overall Research Project Description The purpose of this study is to acquire data on the gross and fine motor function of patients with Parkinson’s Disease when they are at peak dose of primary therapy and compare this with data collected at peak dose with a caffeine adjuvant of ~3mg/kg. The treatment standard for PD is dopamine replacement therapy (e.g. levodopa) to improve quality of life and reduce falls risk. Over time, patients may require increasing dose and frequency of levodopa therapy, which can precipitate side effects (e.g. dyskinesia) and hasten the rate of disease progression. To prevent this, researchers have been investigating adjuvants and supplements that can improve peak performance on levodopa. While the neuroprotective effects of caffeine are well established in the literature, the acute effects of caffeine on motor performance have not been sufficiently evaluated. In this study, we will examine the acute effects of caffeine as an adjuvant therapy during peak dose of primary therapy in Parkinson’s patients. Detailed analysis of the physical effects of caffeine is necessary to determine what, if any, role caffeine can play in the treatment and management of PD. This study is a double-blinded crossover study using randomized placebo-intervention to assess the effect of caffeine on motor performance.