Impulse Control Disorders in Parkinson's Disease: Too Much of a Good Thing?
Abstract & Commentary
By Melissa J. Nirenberg, MD, PhD, Assistant Professor, Neurology and Neuroscience, Weill Cornell Medical College. Dr. Nirenberg reports no financial relationship relevant to this field of study.
Synopsis: Treatment of Parkinson's disease with dopamine agonist medications may precipitate impulse-control disorders such as compulsive gambling, buying, and hypersexuality.
Source: Weintraub D, et al. Association of Dopamine Agonist Use With Impulse Control Disorders in Parkinson's Disease. Arch Neurol. 2006;63:969-973.
Recent reports have called attention to the fact that patients with Parkinson's disease (PD) have a higher incidence of impulse control disorders (ICDs) than the general population. These ICDs include compulsive gambling, buying, and hypersexual behavior. Prior studies have linked these disorders to the use of dopaminergic medications, particularly dopamine agonists.
This study reports the results of a cross-sectional screening and assessment study of ICDs in a series of 272 unselected, predominantly male PD patients seen at one of 2 outpatient movement disorders centers over the course of a year. Of these, approximately half (50.4%) were receiving active treatment with a dopamine agonist. Subjects were screened with a battery of open-ended questions regarding the occurrence of current or past compulsive gambling, buying, or sexual behaviors. Those who were positive for one or more of these ICDs then completed a modified Minnesota Impulsive Disorders Interview (MIDI) to confirm the presence of an ICD. A total of 18 subjects (6.6%) were identified who met MIDI criteria for having experienced an ICD during the course of PD. Of these, 11 (4%) had at least one active ICD at the time of screening. Of the 18 subjects who experienced an ICD during the course of PD, this fact had been recognized and recorded in the chart in only 3 (27.3%).
All subjects (18/18) who experienced an ICD during the course of PD had been concurrently taking a dopamine agonist medication; the ICDs subsequently remitted in 6/6 subjects in whom the dopamine agonist was subsequently discontinued or reduced in dose. Affected subjects were also more likely to have a premorbid history of ICDs (3.5% vs 36.4%). Subjects with ICDs tended to be younger (59.5 ± 9.4 years vs 68.6 ± 10.2 years) and to have had a longer duration of PD (11.2 ± 7.5 years vs 6.9 ± 5.8 years) than those without. In multivariate regression analysis, however, the only significant predictors of an active ICD were current dopamine agonist use and a history of ICD symptoms prior to the onset of PD. Increased risk of ICDs was associated with dopamine agonists as a class, and not with a specific medication.
Dopamine agonist-related ICDs have potentially devastating financial and psychosocial consequences. They include not only compulsive gambling, buying, and hypersexuality, as examined in this study, but also a wide range of other uncontrolled behaviors, including compulsive eating, hobbyism, and punding (repetitive, purposeless behaviors similar to those seen in the setting of amphetamine or cocaine use). The diagnosis of ICDs in PD is difficult because patients are not always forthcoming about their behaviors, particularly when they are embarrassing or socially inappropriate.
This study provides further evidence that ICDs in Parkinson's disease are an underrecognized, reversible side-effect of dopamine agonists. The findings highlight the importance of routine screening for ICDs in patients treated with dopamine agonists, so that these disorders can be identified and treated before secondary consequences emerge.