Repetitive and impulsive behaviors in treated Parkinson disease

There are few disorders in which the interface between neurology and psychiatry has been more interesting, challenging, and illuminating, providing a greater portal into the physiology of behavior, than Parkinson disease (PD). Depression has been a major focus, but needs much more study. Dementia has attracted increasing attention, especially with the recognition of dementia with Lewy bodies as a common disorder. Anxiety, apathy, sleep disorders, fatigue, and personality also deserve more attention. In this issue, two articles^1,2 add important clinical information on yet another fascinating set of disorders, only recently recognized: repetitive behavior syndromes. These are, primarily, pathologic gambling, shopping, and hypersexuality, and are related to the drug treatment of the motor symptoms of PD, specifically treatment with dopamine agonists.^1,2

Repetitive behavior disorders with the drug treatment of PD have been recognized since 1994,³ with a report describing punding, a peculiar stereotyped behavior characterized by an intense fascination with a repetitive activity.⁴ Punding activities have been as varied as sorting collections, grooming, hoarding, repeatedly calculating sums, reading can labels in supermarkets, and reciting empty monologues. While initially considered rare, punding occurred in 17% of patients with PD taking high doses of dopaminergic drugs.⁵

Although hypersexuality was identified in the early days of l-dopa,^{6 …}