Spectrum of addictions in Parkinson’s disease: from dopamine dysregulation syndrome to impulse control disorders

There is an increasing awareness that addictive disorders may occur in Parkinson’s disease (PD), either typical substance-related addictions that are commonly known as dopamine dysregulation syndrome (DDS) or behavioral addictive syndromes, usually presenting as impulse control disorders (ICDs) that include pathological gambling, hypersexuality, compulsive eating and buying. DDS is characterized by the use of dopaminergic drugs in doses larger than those required to treat motor symptoms, despite the development of disabling dyskinesias. Case reporting and prospective studies have reported an association between ICDs and the use of dopamine-agonists (DAs) at greater doses, while DDS has been associated with levodopa at greater doses or short-acting DAs. Risk factors for addictions in PD include male sex, younger age or younger age at PD onset, history of substance use or bipolar disorder, and a personality profile characterized by impulsiveness. Functional neuroimaging studies such as functional MRI and PET have investigated in vivo the neurobiological basis of these pathologic behaviors. The management for clinically significant ICD symptoms should consist of modifications to dopamine replacement therapy (DRT), particularly DAs, which is usually associated with an improvement of ICDs, whereas there is no empiric evidence supporting the use of psychiatric drugs in ICDs in PD. Management of DDS is not easy, mainly because balancing the drugs in the long term could represent a difficult problem. Hypomanic and psychotic episodes are best managed with a reduction of DRT performed in hospital also by using atypical antipsychotics low dose.