Friday, February 16, 2007

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,
according to a report in the February issue of Archives of Neurology, one of
the JAMA/Archives journals. 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.