Long-Term Follow-Up of Impulse Control Disorders in Parkinson’s Disease
E. Mamikonyan, A. Siderowf, J. Duda, M. Potenza, S. Horn, M. Stern, D. Weintraub

Background: Dopamine agonists (DAs) are a first-line treatment for Parkinson’s disease (PD), but recent studies1;2 have linked DA usage with the development of impulse control disorders (ICDs) in PD. Recognition that ICDs occur in PD is relatively recent, so little is known about the long-term outcomes of affected patients.

Objective: To report on the long-term outcomes of ICDs in PD patients who were diagnosed as having an ICD during the course of PD.

Methods: PD subjects with an active ICD sometime during PD were identified using a database from a study examining the frequency and correlates of depression in PD. ICD subjects were re-contacted by telephone for a follow-up interview and (1) administered a modified Minnesota Impulse Disorder Interview (MIDI) for compulsive buying, gambling, and sexuality, and (2) asked to self-rate whether their ICD disorder was in full remission, in partial remission, or fully symptomatic. In addition, information on PD medication utilization at the time patients were symptomatic with their ICD, changes in pharmacotherapy over time, and possible ICD interventions was collected from subjects and verified by medical chart review.

Results: Of 18 subjects identified on initial assessment as having an ICD sometime during the course of PD, 15 (83.3%) were contacted and participated in the follow-up interview. The sample was primarily male (73.3%), with the following means: age =60.9 years, duration of PD =9.4 years, and educational level =14.8 years.

After a mean time period of 29.2 months, only one (6.7%) ICD patients remained fully symptomatic. At follow-up, patients were on a significantly lower DA levodopa equivalent daily dosage (LEDD) (Z=-3.1, P=.002) and a higher daily levodopa dosage (Z=-1.9, P=.05), but on a similar total LEDD dosage (Z=-.47, P=.64) at the two time points. As part of ICD management, twelve (80.0%) patients discontinued or decreased (>30% dosage reduction) DA treatment, all of whom (100.0%) experienced full or partial remission of ICD symptoms by self-report, and ten of whom (83.3%) no longer met diagnostic criteria for an ICD. Of the seven patients who discontinued DA treatment, none met diagnostic criteria for an ICD at follow-up. Of the three patients who were on the same DA dosage at follow-up, one was in full remission post DBS surgery and other medication adjustments, one was in partial remission, and one remained fully symptomatic.

Conclusion: This naturalistic follow-up of ICDs in PD suggests that discontinuation of or decrease in DA therapy is typically associated with partial or complete remission of ICD behaviors. However, outcomes of ICD patients continuing on the same dosage of DA therapy suggests that other factors may contribute to resolution or improvement in ICD symptoms.