Dopamine agonist therapy for Parkinson's disease may lead to problem gambling

Eleven patients with Parkinson's disease (PD) developed pathological gambling behavior following dopamine agonist therapy, a drug therapy to control movement problems caused by Parkinson's disease, according to a study posted online which will appear in the September print issue of Archives of Neurology.

Parkinson's disease, a degenerative disorder marked by the death of the neurons of an area of the brain called the substantia nigra, is primarily treated by drugs that restore or improve brain chemical signaling system dependent on dopamine, according to background information in the article. Brain dopamine, a chemical that helps regulate movement, balance and walking, also plays a central role in the behavioral reward system, reinforcing a myriad of behaviors. It has been implicated in the reward of gambling behavior.

M. Leann Dodd, M.D., of the Mayo Clinic, Rochester, Minn., and colleagues, present reports of eleven patients seen and evaluated between 2002 and 2004 in the Mayo movement disorders clinic with Parkinson's disease who had recently developed pathological gambling and review similar cases from the medical literature. Pathological gambling is defined as a failure to resist gambling impulses despite severe personal, family or vocational consequences

The researchers describe the clinical features of 11 patients. Pathological gambling developed in seven of these 11 patients within one to three months of either reaching the maintenance dose, or increasing their dose of a dopamine agonist, the researchers report. While the other four patients did not report compulsive gambling until 12 to 30 months after initiating the therapy, in all four the gambling resolved within months of discontinuing agonist treatment. "The relationship of pathological gambling to dopamine agonist therapy in these cases is striking," the researchers write.

Six of the patients developed additional behavioral problems simultaneously with the pathological gambling, which resolved as the gambling subsided. These included compulsive eating, increased alcohol consumption, increased spending and hypersexuality.

"In summary, dopamine agonist drugs appear to be uniquely implicated as a cause of pathological gambling," the authors conclude. "Both our series and prior reports have especially linked this to administration of the selective dopamine D3 agonist pramipexole. Disproportionate stimulation of dopamine D3 receptors might be responsible for pathological gambling in these PD cases."