Pathological gambling in Parkinson's disease. A comprehensive review

Pathological gambling (PG) and other Impulse Control Disorders (ICDs), such as hypersexuality, compulsive eating and buying, are often reported in Parkinson's disease (PD). The prevalence of PG is 2.2%-7% in treated PD patients, which is higher than the background population rate. As other non motor symptoms in PD, PG is frequently under-reported by patients and caregivers and may be under-recognized by the treating physicians. Factors associated with PG include male sex, younger age or younger age at PD onset, personal or family history of substance abuse or ICD, a personality profile characterized by impulsiveness, and treatment with dopamine agonists (DA) more than with levodopa (l-dopa). The DA effect seems to be a class effect and not specific for any DA. Neurofunctional studies suggest that medication-induced downregulation of frontostriatal connections and upregulation of striatum might combine to induce impulsive behavior. A dysfunction of fronto-subcortical circuits in PD patients with PG is also supported by neuropsychological findings of impaired executive control and monitoring abilities. Management of ICDs in PD is complex, and until now only discontinuation and/or tapering of DA treatment seem to be an effective management strategy for ICDs in PD. There is no empirical evidence supporting the use of psychiatric drugs for PG such as antipsychotics and antidepressants. Data regarding the effect of deep brain stimulation (DBS), particularly of subthalamic nucleus, on PG and ICDs in PD are still limited and sometimes conflicting since improvement of PG or new onset of PG after surgery have been reported.