Dopaminergic dysregulation syndrome in Parkinson's disease.

Parkinson's disease (PD) is a progressive neurodegenerative condition which requires gradually increasing doses of dopaminergic substances for adequate motor control. Some vulnerable patients increase their doses beyond those required for motor control. This may result in a pattern of compulsive drug taking which may be associated with typical behavioural changes which define dopaminergic dysregulation syndrome (DDS). This is frequently associated with impulse control disorders and a specific behavioural abnormality involving prolonged repetitive tasks, called punding. The pathophysiology of DDS likely involves a number of factors, including genetic and personality related risk factors, habit formation resulting from unpleasant OFF symptoms, fronto-striatal dysfunction and a sensitisation process due to repeated dopaminergic stimulation. Management includes attempts to reduce the dopaminergic dose; specific treatment options are currently unknown. Early detection and prevention are therefore essential.