Dopamine dysregulation syndrome. Hypothetical application of reward system stimulation for the treatment of anhedonia in Parkinson's disease patients.

The management of motor symptoms in Parkinson's disease (PD), although imperfect, has already been standardized. However, patients often spend their time idly despite improvement in the elemental motor symptoms. The main cause of this may be anhedonia. Dopamine dysregulation syndrome (DDS) is a troublesome condition that can occur as a complication of dopamine replacement therapy in PD. As anhedonia and DDS may be converse syndromes in PD patients, it is very important to overcome anhedonia to improve patients' quality of life. In this article, the author proposes the possibility of stimulating patients' desire to participate in physical activity via the incentive of a reward system. Understanding the mechanism of DDS may help in the development of this type of approach.