To assess the frequency and outcomes of impulsivity in study participants receiving bilateral subthalamic deep brain stimulation (STN-DBS) for the treatment of Parkinson’s Disease (PD).

The relationship between STN-DBS and impulse control disorders (ICD) has been complex and resulted in largely retrospective uncontrolled studies. These studies have yielded heterogeneous outcomes. Small retrospective studies evaluating participants before and after STN-DBS surgery have however revealed both positive and negative results. Many have shown potential for reduction of pre-existing behaviors and others have revealed worsening. De novo ICDs following STN-DBS have also been reported. There is limited knowledge regarding the factors and interactions accounting for these different outcomes.

INTREPID (ClinicalTrials.gov: NCT01839396) is a multi-center, prospective, double-blinded, randomized controlled trial. Participants with advanced PD were implanted bilaterally in the STN and completed a neuropsychological battery at screening (prior to DBS) and at follow-up (12-months). Impulsivity was examined using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease–Rating Scale (QUIP-RS). A higher QUIP-RS score indicated greater severity (frequency) of symptoms. Total QUIP-RS scores (ranged from 0-64) and ratings for individual ICD behavior(s) were also evaluated. Clinically significant ICD was defined as a QUIP-RS score >22.

At 1-year post STN-DBS, 32 of 160 participants (20%) reported >5 point improvement in QUIP-RS ICD scores, and 7 (4.3%) showed a >10-point improvement. Nineteen (11.8%) participants had a >5 point worsening, and 8 (5%) reported a worsening of > 10. Analysis of relevant demographic information, appearance of ICD and clinical factors including antiparkinsonian medications, lead location, programming settings and structural as well as functional connectivity will be presented.

The data  at 1-year follow-up following bilateral STN-DBS revealed both improvement and worsening in ICDs as well as some de novo cases. Clinicians should be aware of these critically important management issues and appropriate pre-operative counseling and post-operative monitoring should be employed.