Subthalamic nucleus stimulation and compulsive use of dopaminergic medication in Parkinson's disease

Background Behavioural disorders associated with compulsive use of dopaminergic drugs for Parkinson's disease (PD) such as dopamine dysregulation syndrome (DDS) and impulse control disorders (ICDs) may have devastating consequences and are challenging to manage. Whether or not such patients should undergo subthalamic nucleus (STN) deep brain stimulation (DBS) is controversial. A few case reports and small series have reported contrasting effects of STN DBS on dopamine misuse and ICDs, while a recent prospective study found clear beneficial effects of STN DBS on these disorders. Methods We conducted an observational study on 110 consecutive parkinsonian patients scheduled for STN DBS surgery. Patients were assessed preoperatively through extensive behavioural and psychiatric evaluations and divided into two groups: with or without compulsive dopaminergic medication use. Evaluations were repeated 1 year after surgery in both groups. Results Before surgery 18 patients (16.3%) were compulsive dopamine users of whom 12 (10.9%) fulfilled all criteria for DDS. 90% of these patients also had at least one ICD compared to 20% in the group without compulsive dopamine use. One year after surgery, one patient had persistent compulsive dopamine use, while no new occurrences were reported in the group without the condition before surgery. STN DBS did not provoke any major psychiatric complications and ICDs were reduced in all patients. Conclusions Our results suggest that STN DBS may reduce compulsive use of dopaminergic medication and its behavioural consequences. Whether this improvement is the result of STN DBS or the consequence of better treatment management remains to be established.