Pathological gambling may be caused by Parkinson’s drugs

A study posted on the Internet and appearing in the September issue of Archives of Neurology revealed that 11 patients with Parkinson’s disease (PD) – a degenerative disorder marked by the death of the neurons of an area of the brain called the substantia nigra – developed pathological gambling behavior following dopamine agonist therapy, a drug therapy to control movement problems caused by PD.

According to background information in the article, PD is treated mainly by drugs that restore or improve brain chemical signaling system dependent on dopamine. Brain dopamine, a chemical that helps regulate movement, balance and walking, also plays a key role in the behavioral reward system, reinforcing a myriad of behaviors. It has been implicated in the reward of gambling behavior.

M. Leann Dodd, MD, of the Mayo Clinic, Rochester, Minn., and colleagues, presented reports of 11 PD patients seen and evaluated between 2002 and 2004 in the Mayo movement disorders clinic who had recently developed pathological gambling, and reviewed similar cases from the medical literature. Pathological gambling is defined as a failure to resist gambling impulses despite severe personal, family or vocational consequences

Pathological gambling developed in seven of  the 11 study patients within one-to-three months of either reaching the maintenance dose, or increasing their dose of a dopamine agonist, the researchers reported. While the other four patients did not report compulsive gambling until 12-to-30 months after initiating 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 observed.

Concurrent with the pathological gambling, six of the patients developed additional behavioral problems, which resolved as the gambling subsided, including 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 concluded. “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.”

SOURCE: Arch Neurol. 2005; 62:1-5.