Incident impulse control disorder behaviors through the 5-year follow-up period were correlated with dopamine agonist use and depression, but not with age.
Maria L. Fantini, MD, PhD
Longitudinal data from the Parkinson’s Progression Markers Initiative (PPMI) revealed that probable rapid eye movement sleep behavior disorder (pRBD) is not associated with impulse control disorder behaviors (ICBs) symptom development in patients with early Parkinson disease (PD), compared with other factors such as depression, male sex, and dopamine agonist exposure.
After adjusting for covariates, both baseline pRBD and time-dependent (TD) pRBD were not associated with an increased risk for incident ICB symptoms, with adjusted hazard ratios (HRs) of 1.17 (P = .458) and 1.27 (P = .257), respectively.
Using a modified-TD pRBD model, research conducted by Maria L. Fantini, MD, PhD, Sleep and EEG Unit, Centre Hospitalier Universitaire de Clermond-Ferrand, and colleagues showed the risk for incident ICB symptoms was higher in pRBD in unadjusted models (HR, 1.48; P = .038), but not adjusted models (HR, 1.29; P = .202).
TD dopamine agonist use (HR, 1.64; P = .039), TD Generic Depression Scale (GDS-15) score (HR, 1.12; P <.001), and male sex (Year 3: HR, 2.10; P = .009; Year 4: HR, 3.04; P = .006; Year 5: HR, 4.40; P = .007) were associated with increased ICB symptom risk.
Fantini and colleagues wrote that, “While most previous cross-sectional studies found an association between ICBs and younger age, the few longitudinal studies conducted have reported conflicting results. The current study, performed on a large, de novo PD cohort with a long follow-up period, suggests that younger age is not a risk factor when controlling for confounding factors.”
Out of the 401 subjects included in the data, 213 (53.1%) did not change RBD status over the 5 years; of them, 43 (20.2%) subjects had pRBD at all their visits, and 170 (79.8%) never had pRBD.
The goal of PPMI is to identify biomarkers of PD progression in a large cohort of participants with early untreated PD at enrollment, compared with healthy controls (HC). It included and collected demographical and clinical data including sex, age, age of disease onset, duration of PD and current treatment in 401 newly diagnoses patients with PD.
RBD Screening Questionnaire (RBDSQ) was completed by all patients at baseline (BL), 6 months, and annually starting at year 1. A cut-off value >6 represents the best cut-off value for detecting RBD (sensitivity = 0.84; specificity = 0.96) in PD.
In addition to the RBDSQ, patients were evaluated on the same time points for ICB symptoms. The presence of ICB symptoms was defined by a score of >1 on any of the 4 items related to impulse control disorders (ICDs) such as gambling, hypersexuality, compulsive buying and compulsive eating, or related behaviors including hobbyism, punding, and walkabout.
Probable RBD status was measured at BL, month 6, and months 12, 24, 36, 48, and 60. Time-varying or TD pRBD was defined as patients who had pRBD status change at each of these time points.
“Our study failed to demonstrate a clear association between RBD and the development of ICBs. A possible explanation can be that ICB rates didn’t increase much over the 5 years, rising just from 20.7% at BL to 26.3% at year 5,” Fantini and colleagues concluded. Additionally, they noted that further longitudinal studies are needed to further elucidate the association between RBD and ICBs in this population.
Fantini ML, Fedler J, Pereira B, Weintraub D, A Marques, Durif F. Is RBD a risk factor for impulse control disorder in Parkinson’s disease? Ann Neurol. Published online May 28, 2020. doi: 10.1002/ana.25798.