Scientists at the OHSU Parkinson Center of Oregon found that methylphenidate, known commercially as Ritalin, bolsters the effects of levodopa, a drug converted in the brain to dopamine. Methylphenidate inhibits the reabsorption of dopamine into nerve cells, increasing the neurotransmitter's potency.
Parkinson's disease is caused by a deficiency of nerve cells that produce dopamine.
A parallel study by Parkinson center researchers found that paroxetine, a popular antidepressant best known under the brand name Paxil, doesn't augment the effects of levodopa and has little benefit in reducing physical symptoms of Parkinson's disease.
Paroxetine is a selective serotonin reuptake inhibitor, or SSRI, a class of antidepressants that block the reabsorption of another neurotransmitter, serotonin, into nerve cells. Researchers studied it because laboratory evidence has suggested the serotonin transporter, the system through which serotonin is reabsorbed into nerve cells, may take up dopamine as well.
"Both studies looked at the effects of these drugs on Parkinson's disease," said John "Jay" G. Nutt, M.D., professor of neurology, and physiology and pharmacology, OHSU School of Medicine, and director of the Parkinson center. He also is director of the Parkinson's Disease Research, Education, and Clinical Center (PADRECC) at the Portland Veterans Affairs Medical Center. The studies were presented last week at the 56th annual meeting of the American Academy of Neurology in San Francisco.
Ritalin, the drug used in the methylphenidate study, "increases the effects of levodopa," Nutt said, while paroxetine didn't affect Parkinson's disease symptoms. However, paroxetine, when taken without levodopa, did increase the walking speed of Parkin
Contact: Jonathan Modie
Oregon Health & Science University