Conditions: Parkinson's Disease
Keywords: donepezil parkinson's disease balance cholinesterase inhibitor
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 21
Healthy volunteers: no

Brief summary:
This study involves Parkinson's disease (PD). Symptoms include slow movement, tremor, and muscle rigidity. Current medications for the treatment of PD do not improve gait and balance difficulties in individuals with PD. Donepezil (study drug) has been found to reduce falls in individuals with PD. The mechanism in which this reduction of falls occurs is unclear. The investigators study will look at what aspects of gait and balance are improved by the study drug. The study drug is not approved to treat PD in the United States or other countries because we do not know enough about it.

Detailed description:
Parkinson's disease (PD) is a common neuro-degenerative disease affecting about 2% of the adult population in the United States over the age of 65. Some of the most disabling symptoms of Parkinson's disease are balance and gait dysfunction, leading to falls. These symptoms do not respond to current dopamine directed therapies. Evidence from both pathologic studies and advanced imaging has demonstrated that a cholinergic deficiency in the thalamus and basal ganglia is found in individuals with PD who fall compared to non-fallers. The central acting acetylcholine esterase inhibitor, donepezil, has been demonstrated to decrease falls in individuals with PD. The mechanism by which falls decreased is unknown. Our open label pilot data indicates that donepezil can improve quantitative measures of balance in individuals with PD. Suggesting that improvements in balance in the mechanism by which donepezil reduces falls. Our goal is to determine whether donepezil will:

* Improve quantitative measures of balance in subjects with Parkinson's disease compared to placebo.
* Improve quantitative measures of gait in subjects with Parkinson's disease compared to placebo.
* Improve cognitive measures in non-demented subjects with Parkinson's disease.

Arms:
arm 1: Donepezil 5 mg a day for weeks 1 - 3, if tolerated increased to 10 mg a day for weeks 4 - 6. After a washout period of 4 weeks, placebo 5 mg a day for weeks 1 - 3, if tolerated increased to 10 mg a day for weeks 4 - 6. arm 2: Placebo 5 mg a day for weeks 1 - 3, if tolerated increased to 10 mg a day for weeks 4 - 6.

After a washout period of 4 weeks, donepezil 5 mg a day for weeks 1 - 3, if tolerated increased to 10 mg a day for weeks 4 - 6.

Interventions: intervention 1: Donepezil intervention 2: Placebo
Intervention descriptions: intervention 1: Use 1 capsule (5 mg) of donepezil once per day for first 21 days than donepezil 10mg qday for 21 days. intervention 2: Use 1 capsule (5 mg) once per day for first 21 days than 10mg qday for 21 days.

Protocol document: