Recognition of a dopamine replacement therapy dependence syndrome in Parkinson's disease: a pilot study

Patients with Parkinson's disease may use Dopamine Replacement Therapy (DRT) in excess of therapeutic need. We investigate whether a group of 10 patients with Parkinson's disease, provisionally diagnosed with "Hedonistic Homeostatic Dysregulation" because of their excessive use of DRT, met established operational psychiatric criteria for substance dependence, compared with 10 patients with Parkinson's disease compliant with prescribed DRT. Using a semi-structured questionnaire designed to distinguish between adaptive therapeutic dependence on DRT and a maladaptive pathological pattern of DRT use, in conjunction with the SCID-1, we found that seven of the patients deemed by their treating physicians to be misusing DRT fulfilled operational criteria for maladaptive dependence in contrast to none of the compliant group. The majority experienced dysphoric "withdrawal" symptoms in the "off" state and increased their dose of DRT in an effort to control their mood. They also continued to use high doses of DRT despite disabling dyskinesias and social difficulties. This study provides preliminary evidence that some patients with Parkinson's disease may become maladaptively dependent on DRT. This finding has both clinical relevance for the treatment of PD and further implicates dopaminergic pathways in the genesis of substance dependence.