Pathologic gambling in Parkinson's disease: a behavioral manifestation of pharmacologic treatment?

We describe 12 patients with Parkinson's disease and pathologic gambling. This association has apparently never been reported. The patients were selected from a Parkinson's disease unit of 250 patients. They met Diagnostic and Statistical Manual of Mental Disorders, 4th edition, criteria for pathologic gambling. All patients underwent a neurologic, psychiatric, and psychologic examination, specifically noting the presence or absence of psychopathology in the spectrum of impulse control disorder and the nature of the gambling. Ten patients started gambling after the onset of Parkinson's disease and treatment with levodopa. The pathologic behavior was exclusively present or was markedly increased in "on" periods in 11 patients. All patients had motor fluctuations at the time of the study. Slot machines were the preferred source of gambling for 10 patients, similar to the Spanish gambling population. That the gambling behavior appears more often in the "on" periods of motor fluctuations and that it begins after the onset of Parkinson's disease in most patients and worsens with levodopa therapy suggest that it could be related to the dopaminergic tone in patients with Parkinson's disease and motor fluctuations (that is, it could represent a behavioral manifestation of pharmacologic treatment).