Patients with Parkinson's disease who are younger when they develop the condition, have a personality trait known as novelty-seeking or whose personal or family history includes alcohol abuse may be more likely to develop pathological gambling as a side effect of medications used to treat their condition, according to a report in the February issue of Archives of Neurology, one of the JAMA/Archives journals.

Behaviors associated with impulse control—including compulsive shopping, hypersexuality, binge eating and pathological gambling—have been associated with dopamine agonists, medications used to treat Parkinson's disease. In studies examining the relationship between dopamine agonists and compulsive gambling, the likelihood of gambling problems was unrelated to the medication dosage. This suggests that an underlying trait may interact with the drugs and make an individual more vulnerable to this adverse effect.

Valerie Voon, M.D., National Institute of Neurological Disorders and Stroke, Bethesda, Md., and colleagues compared the characteristics of 21 patients with Parkinson's disease who developed pathological gambling habits after beginning to take dopamine agonists with 42 patients with Parkinson's disease who did not develop compulsive behaviors. The participants, who all visited a clinic in Toronto, Canada, between June 2003 and October 2005, were examined by neurologists and completed assessment scales that measured their levels of impulsivity, substance abuse, mood and anxiety disorders. An additional inventory measured the extent to which the patients displayed novelty-seeking traits, characterized by impulsive and risk-taking behavior and excitement in response to new experiences.

"In keeping with our hypothesis, patients with Parkinson's disease who developed pathological gambling when receiving dopamine agonists had a younger age at Parkinson's disease onset, higher novelty-seeking scores, a personal or immediate family history of alcohol use disorders and impaired planning on an impulsivity scale," the authors write. "A robust association was found with medication-induced mania [a psychiatric disorder involving excessive physical and mental activity and impulsive behavior]." Pathological gambling was also weakly linked to younger age, Parkinson's disease that began in the brain's left hemisphere and a high score on a scale measuring the impulsiveness of behaviors.

"Screening for such features and advising those at higher risk may be warranted," the authors conclude.

Note: This article has been adapted from a news release issued by JAMA and Archives Journals.