Dopamine dysregulation syndrome in Parkinson's disease and restless legs syndrome

Abstract

Dopamine replacement therapy in Parkinson's disease (PD) improves the motor symptoms. However, it has recently been shown that a small sub-group of patients suffers from motor and behavioral disturbances associated with the use of dopamine agonists (DAs). The behavioral disorders are incentive- or reward-based repetitive symptoms regrouped under the term «dopamine dysregulation syndrome» (DDS). They include pathological gambling, hypersexuality, compulsive shopping, compulsive eating, punding, and compulsive medication use. Whether these behaviors are related to the dopaminergic medications interacting with an underlying individual vulnerability or whether the primary pathological features of Parkinson's disease play a role is not entirely understood. This review is devoted to the phenomenology of the DDS and factors influencing its susceptibility. We further review the literature studies that investigated the decision-making profile using the Iowa Gambling Task in Parkinson's disease, and the recent literature devoted to these abnormal behaviors in the restless legs syndrome (RLS). Given the potential substantial impact of the DDS on personal, familial, social, and financial well-being, patients with PD or RLS should be informed that DAs use may lead to the development of impulsive and compulsive disorders, and clinicians should include the investigation of these disorders as part of routine clinical care. The refinement of clinical strategies to predict, identify and manage DDS will help the future care of motor and non-motor symptoms of Parkinson's disease.