Incident impulse control disorder symptoms and dopamine transporter imaging in Parkinson disease

Abstract

Objective: To describe the incidence of, and clinical and neurobiological risk factors for, new-onset impulse control disorder (ICD) symptoms and related behaviours in early Parkinson disease (PD).

Methods: The Parkinson's Progression Markers Initiative is an international, multicenter, prospective study of de novo patients with PD untreated at baseline and assessed annually, including serial dopamine transporter imaging (DAT-SPECT) and ICD assessment (Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease short form, QUIP). Participants were included if they screened negative on the QUIP at baseline. Kaplan-Meier curves and generalised estimating equations examined frequency and predictors of incident ICD symptoms.

Results: Participants were seen at baseline (n=320), year 1 (n=284), year 2 (n=217) and year 3 (n=96). Estimated cumulative incident rates of ICD symptoms and related behaviours were 8% (year 1), 18% (year 2) and 25% (year 3) and increased each year in those on dopamine replacement therapy (DRT) and decreased in those not on DRT. In participants on DRT, risk factors for incident ICD symptoms were younger age (OR=0.97, p=0.05), a greater decrease in right caudate (OR=4.03, p=0.01) and mean striatal (OR=6.90, p=0.04) DAT availability over the first year, and lower right putamen (OR=0.06, p=0.01) and mean total striatal (OR=0.25, p=0.04) DAT availability at any post-baseline visit.

Conclusions: The rate of incident ICD symptoms increases with time and initiation of DRT in early PD. In this preliminary study, a greater decrease or lower DAT binding over time increases risk of incident ICD symptoms, conferring additional risk to those taking DRT.

Clinical trial registration: NCT01141023.

Figure 1

Estimated cumulative rate of initiation of dopamine replacement therapy. Rate of dopamine replacement therapy (DRT) initiation over time determined by Kaplan-Meier method. Censored data indicates that some participants at each visit had not initiated DRT by that visit and have not yet provided subsequent medication information.

Figure 2

Estimated cumulative rate of incident impulse control disorder (ICD) symptoms. Rate of incident ICD or related behaviour symptoms determined by Kaplan-Meier method. Censored data indicates that some participants at each visit had not developed ICD symptoms and have not yet completed subsequent ICD assessment.