A Multicenter, Prospective, Longitudinal, Digital Assessment Study of Disease Progression in Subjects With Early, Untreated Parkinson Disease

1. Able to give written informed consent, as determined by the investigator.

2. Subjects must have at least two of the following: resting tremor, bradykinesia,
rigidity (must have either resting tremor or bradykinesia as one of two symptoms); OR
either asymmetric resting tremor or asymmetric bradykinesia.

3. Screening dopamine transporter (DAT) SPECT scan is consistent with dopamine
transporter deficit.

4. A diagnosis of Parkinson disease for 2 years or less at screening.

5. Modified Hoehn and Yahr stage I or II at screening.

6. Not expected to require PD medication for at least 6 months from baseline (includes
dopaminergics, MAO-B inhibitors, and anti-cholinergics used to treat PD-related
symptoms).

7. Male or female age 30 years or older at time of PD diagnosis.

8. Female subjects of childbearing potential must agree to be using highly effective
contraception within 30 days prior to DaTscan (e.g., oral contraceptives, a barrier
method of birth control (e.g., condoms with contraceptive foam, diaphragm with
contraceptive jelly), intrauterine device, partner with vasectomy or sexual
abstinence).

9. Male subjects who are fertile and have a partner of childbearing potential must agree
to use reliable contraception for 14 days following the administration of DaTscanTM
(e.g., condoms with contraceptive foam or sexual abstinence).

10. Fluent in English and able to read.

11. Able to perform all study activities (including walking tasks and timed up and go)

10. Willingness and ability to comply with study requirements.

Exclusion Criteria:

1. A diagnosis of atypical parkinsonism, drug-induced parkinsonism, essential tremor,
primary dystonia or other diagnoses that explain symptoms other than PD.

2. History of PD-related freezing episodes or falls.

3. A diagnosis of a significant CNS disease other than PD; history of repeated head
injury; history of epilepsy or seizure disorder other than febrile seizures as a child
that would interfere with ability to perform study assessments.

4. History of a brain magnetic resonance imaging (MRI) scan indicative of clinically
significant abnormality as determined by the investigator.

5. Concomitant disease, condition, medication, or laboratory abnormality that, in the
opinion of the investigator, could interfere with study conduct or analysis, or pose
an unacceptable risk to the participant. This could include neurologic, orthopedic or
cardiovascular diseases.

6. Has taken levodopa, dopamine agonists, MAO B inhibitors, amantadine, anticholinergics
or other medication for the treatment of PD or tremor within 60 days prior to
baseline, or for more than a total of 60 days.

7. For subjects taking any drugs that might interfere with dopamine transporter SPECT
imaging (modafinil, bupropion, methylphenidate, neuroleptics, metoclopramide, alpha
methyldopa, reserpine, or amphetamine derivative) must be willing and able from a
medical standpoint to withhold the medication for at least 14 days prior to screening
DaTscan imaging.

8. Montreal Cognitive Assessment (MoCA) score < 26 at baseline. 9. Is pregnant (or is planning to become pregnant during the study period) or lactating (includes a negative urine (or serum if required by site) pregnancy test on day of screening scan prior to injection of DaTscanTM 10. Known hypersensitivity to DaTscanTM or any of its excipients 11. Body habitus that would impede completion of DaTscanTM (subject weight above 158 kg should be discussed with the Clinical Monitor) 12. Resides in a nursing home or assisted care facility. 13. Use of investigational drugs (other than imaging agents) or devices (other than mobile/wearable devices used in this study) within 60 days or 5 half-lives of study agent prior to baseline and during the study period.