This is an observational study. This study will only recruit Parkinson's subjects with rises in systolic blood pressure exceeding 50% of baseline during motor off periods to select for subjects with severe blood pressure fluctuations. The clinical characteristics, including but not limited to, the degree of change of the motor tapping score, during an "off" period of this group of subjects with severe hypertension. There is a screening visit, a at home monitoring period, and a one-time 4-8 hour study visit for subjects that satisfy the inclusion criteria. The screening visit will assess Parkinson's motor state and review the inclusion/exclusion criteria. The at home monitoring period will measure blood pressure twice a levodopa cycle for 5 cycles (for most subjects, this will be for two days and is dependent on the subject's clinical levodopa cycle). Measurements will occur pre-levodopa dose (the maximal "OFF" time), and half-way through the cycle (maximal "ON" time). The percentage of change will be calculated and those that have a systolic change of greater than or equal to 50% will proceed to the outpatient visit. The outpatient visit will measure blood pressure, pulse, Parkinson's motor symptoms, and plasma levodopa levels.
