Impulse control disorders with the use of dopaminergic agents in restless legs syndrome: a case-control study.

AN INCREASED FREQUENCY OF IMPULSE CONTROL DISORDERS (ICDS) HAS BEEN RECOGNIZED WITH THE USE OF DOPAMINERGIC AGENTS IN A SUBSET OF patients with Parkinson disease (PD). The central dopaminergic reward system has been implicated, possibly due to overstimulation of mesolimbic dopamine receptors.1 Recognized ICDs in this setting include pathologic gambling,2–7 hypersexuality,7–9 compulsive shopping,7,9 compulsive eating,10 punding,11–14 and compulsive medication use.15 Punding is characterized by complex, stereotyped, and often purposeless repetitive actions such as continued handling or sorting of common objects, manipulation of technical equipment, excessive grooming or cleaning, and hoarding.13,14 Several of these entities are formally designated as “impulse control disorders” in the Diagnostic and Statistical Manual of Mental Disorders (4th Edition),16 but this group of behaviors can be recognized as a whole by a common inability to resist impulses, drive, or temptation to engage in ultimately self-destructive acts. Controversy remains regarding their overall classification because of overlap with obsessive-compulsive and addiction processes. In patients with PD, ICDs are relatively common, with estimated lifetime prevalence rates of 3% to 8% for pathologic gambling, 2.5% to 7.2% for hypersexuality, and 0.4% to 1.5% for compulsive shopping.1,7 For comparison, the lifetime prevalence of pathologic gambling in the general population is between 0.3% and 2%.1,3,17–19 Similar data for other ICDs are less well established. One questionnaire-based study demonstrated an overall lifetime prevalence of pathologic gambling, hypersexuality, or compulsive shopping in patients with PD of 6.1% but a statistically significant heightened rate of 13.7% with the use of dopaminergic agonists in this population.9 The individual lifetime prevalence rates in the subset of patients using dopaminergic agonists in this study were 7.2% for pathologic gambling, 7.2% for hypersexuality, and 1.4% for compulsive shopping.9 A recent retrospective analysis of 267 local patients with PD found new-onset compulsive gambling or hypersexuality in 18.4% of subjects taking therapeutic doses of dopamine agonists (defined as ≥ 2 mg of pramipexole or 6 mg of ropinirole daily).20 Numerous reports in the literature confirm a similar striking relationship between ICDs and the use of dopaminergic agents in PD.1–10,12,15 A consistent dose effect has not been demonstrated.1 The relationship between ICDs and the use of dopaminergic medications in disease processes other than PD has not been as well studied. Several case reports suggest that pathologic gambling may have an increased frequency with the use of dopaminergic agonists in restless legs syndrome (RLS).19,21,22 A recent retrospective survey of 77 patients with idiopathic RLS actively taking dopaminergic medication found increased gambling in 6% and excessive sexual behaviors in 4% of the subjects.23 RLS is a common and important neurologic disorder. Epidemiologic studies suggest that 10% to 15% of adults in European and North American countries meet criteria for diagnosis, including 2.5% in which the condition seriously affects quality of life.24–27 Although the precise pathophysiology remains unknown, dysfunction of central dopaminergic systems has been implicated, and dopaminergic agents are widely used for treatment of symptoms.28 Given the potentially devastating psychosocial consequences of ICDs, a better understanding of the frequency of these behaviors is essential to improve medical management of RLS. We performed a prospective, case-control study to determine the frequency of ICDs in patients with RLS using dopaminergic agents. Our primary hypothesis was that the frequency would be higher than in a comparative group of patients with obstructive sleep apnea (OSA).