Impulse control disorders in Parkinson's disease: Review of pathophysiology, epidemiology, clinical features, management, and future challenges

Impulsive–compulsive behavior (ICB) in Parkinson's disease (PD) suggests a combination of impulse control disorders (ICDs), such as pathological gambling, hypersexuality, compulsive eating, excessive buying, and compulsive behaviors, such as punding, dopamine dysregulation syndrome (DDS), hoarding, and hobbyism. Hypersexuality and gambling are common in male patients while compulsive buying is common in women patients. Recent studies reveal the prevalence of ICB to be more than 25% among the PD patients. The nigrostriatal, mesocortical, and mesolimbic dopaminergic pathways play a crucial role in the pathogenesis of ICDs in PD patients. The greater tonic release of dopamine creates a state of relative dopamine deficit and reduced reward sensation and impulsive behaviors. The major risk factors for ICB are the use of dopamine agonist (DA), male gender, young patient, depression, smoking, drug abuse, Parkin mutation, and family history of ICDs. Single nucleotide polymorphism in dopamine receptors D1, D2, and D3 also acts as a major risk factor. Questionnaire for impulsive–compulsive disorders in PD is the most widely adopted screening tool for the detection of ICB in PD. The major treatment for PD is to discontinue DAs and use prolonged release formulation of the DAs. The role of deep brain stimulation (DBS) and apomorphine in the treatment of ICB is still uncertain. Though DBS can reduce the risk of DDS, it can precipitate new ICBs such as hypersexuality.