PARKINSON DISEASE AND GAMBLING

Problem Gambling in Parkinson's Patients Linked to Stimulation of Reward Network

NEW YORK (Reuters Health) Dec 10 - Pathological gambling that may occur in patients with Parkinson's disease may be a result of overstimulation by dopamine replacement therapy of a preserved reward-related mesocorticolimbic dopamine pathway, according to findings published in the December issue of the Archives of Neurology.

In a case-control study, Dr. Roberto Cilia, Istituti Clinici di Perfezionamento, Milano, Italy, and colleagues studied 11 Parkinson's disease (PD) outpatients with active pathological gambling (PG), 40 matched PD controls, and 29 age-matched healthy controls. The mean age of the PD patients was 57 years and all were receiving dopamine replacement therapy.

Perfusion single-photon emission computed tomography was performed on all participants. Parkinson's disease patients with PG showed several clusters of increased perfusion in a right hemisphere network that included the orbitofrontal cortex, the hippocampus, and the amygdala. Overactivity was also observed in the insula and the ventral pallidum. The team saw no areas of relative reduced perfusion.

"We found that normal dosages and types of drugs currently used to treat PD may induce PG by abnormal stimulation of a brain network involved in reward-related processes and impulse control," Dr. Cilia summed up in comments to Reuters Health.

"As we did not find any areas of reduced activity versus both control groups we conclude that this problem is not associated with a disease-related dysfunction but rather with an enhanced and pathological response of a relatively preserved neuronal system in vulnerable individuals," he elaborated.

"I believe that our findings give further insights to the mechanisms underlying this uncommon adverse event occurring in PD patients during standard daily dosage medication treatment," Dr. Cilia said. "The possible association with addictive disorders may widen therapeutic options for PG in PD."

He and his colleagues call for larger prospective controlled studies in order to investigate predisposing factors for the development of impulse control disorders in PD patients undergoing dopamine replacement therapy.