The primary objective of the study is to determine the utility of blood plasma infrared spectroscopy (biospectroscopy) in distinguishing subjects with idiopathic Parkinson's disease from healthy controls.

Oxidative stress has been implicated as a factor in the pathogenesis of Parkinson's disease (PD). The overall goal of this proposal is to use a novel metabolomics platform, based on near infrared biospectroscopy, to detect oxidatively modified blood plasma constituents. These spectral findings can be used to model the degree of oxidative stress with a modeled "stress index" that may distinguish PD cases from healthy elderly controls.

Inclusion Criteria:

PD Subjects:

1. PostCEPT subjects with a diagnosis of PD based on UK Brain Bank criteria.
2. Willing and able to provide informed consent.

Healthy Controls:

1. No current diagnosis or known history of a neurological disease/disorder.
2. Non-blood relative of a patient or subject at the site who has diagnosis of PD (may include healthy controls from the PROBE study).
3. No first degree relatives with diagnosis of PD
4. MoCA score > 26.
5. Age > 45.
6. Willing and able to provide informed consent.

Parkinson's subjects: from pool of subjects currently enrolled in PostCEPT study Control subjects: general population