Droxidopa Treatment for Cognitive Impairment in Parkinson's Disease

Objective/Rationale:
Memory, concentration, and other cognitive operations are sometimes impaired in Parkinson's disease (PD), but available treatment options are very limited. This project will test a drug that enhances production of an important brain signaling chemical called norepinephrine to learn if this intervention can improve PD patients with mild cognitive impairment. The marked decrease in brain norepinephrine in PD might be responsible for impaired thinking.

Project Description:
Forty PD patients with mild cognitive deficits will receive droxidopa (a synthetic amino acid that can be converted in the brain to norepinephrine) or a placebo. Each patient will be switched for six-week trials of each regimen. Participants will undergo neuropsychological testing that emphasizes memory, reasoning ability, speed of solving problems and other similar tasks. The neuropsychological testing chosen for this clinical trial corresponds to circuitry of the brain where norepinephrine is actively involved.

Relevance to Diagnosis/Treatment of Parkinson’s Disease:
The study will use droxidopa as a probe of whether norepinephrine is important in impaired cognitive processes in PD. If so, this drug (and possibly other therapies also acting on norepinephrine) might become treatment options to help with a largely unmet need.

Anticipated Outcome:
Researchers expect a definitive answer as to whether increasing norepinephrine synthesis and release in the brain will improve various cognitive operations impaired in PD. If the study proves to be positive, then droxidopa might become a treatment option (since this drug is already under development for other medical uses).