Methylphenidate and Parkinson's Disease

Parkinson's disease (PD) is a common disorder caused by the loss of dopamine-producing brain
cells. The disorder is generally treated with levodopa combined with carbidopa. Nerve cells
use levodopa to make dopamine. Carbidopa delays the conversion of levodopa into dopamine
until it reaches the brain. Motor fluctuations (the wearing off effects of levodopa
characterized by sometimes rapid changes between uncontrolled and normal movements) are a
common, and often difficult to manage, source of disability in people with PD.

In this trial researchers will study the effects of methylphenidate (MPD), also known as
Ritalin—a drug marketed in the U.S. to treat hyperactivity and narcolepsy—on
carbidopa/levodopa and other antiparkinson medications taken orally by individuals with
Parkinson's disease who experience motor fluctuations when they take levodopa. The overall
goal of this project is to develop better symptomatic therapies for PD.

After 2 screening visits to the treatment clinic to evaluate the wearing "on" and "off"
effects of levodopa, eligible participants will be scheduled for 3 admissions to the General
Clinical Research Center at Oregon Health & Science University during which they randomly
will receive the study drug, MPD, or placebo, along with their usual carbidopa/levodopa
therapy and/or other antiparkinson medications. Also, participants will have their
parkinsonism (tremor, rigidity, postural instability, and bradykinesia) rated and blood
pressure and pulse measured at regular intervals.

Duration of the study for participants is about 3 weeks and includes 2 outpatient clinic
visits (for screening) and 3 inpatient clinic visits (with overnight stays).

Inclusion Criteria:

- Idiopathic PD treated with levodopa and experiencing motor fluctuations

- At least 21 years of age

- Male or female.

Exclusion Criteria:

- Cardiovascular disease, psychosis, extreme anxiety, dementia and other unstable
medical conditions.