Among patients with early Parkinson disease, impulse control behaviors (ICBs) are common in the early stages of the disease, with a significant proportion having symptoms of subsyndromal impulse control disorders (ICDs), according to study findings published in Neurology.
The study was designed to describe risk factors, natural history, and prevalence for ICBs among patients with Parkinson disease and REM sleep behavior disorder. It was nested within the Oxford Parkinson Disease Centre Discovery cohort and participants were recruited between September 2010 and September 2014. Participants were longitudinally screened for ICBs using the Questionnaire for Impulsivity in Parkinson Disease Short Form at baseline, and every 18 months. Individuals found to have ICBs underwent semi-structured interviews with a follow-up 1 year later. ICB severity was assessed using the Parkinson Impulse Control Scale; associations and prevalence were estimated using multiple imputation and regression models.
Data from 921 patients with Parkinson disease were included at baseline, 768 at 18 months, and 531 at 36 months; 21% screened positive for ICB at baseline, 24% at 18 months, and 25% at 36 months. Interviews revealed 10% of those with ICBs met the formal criteria for ICD, while 33% met the criteria for subsyndromal ICD. The estimated prevalence of ICBs in those with Parkinson disease (including the full spectrum of severity), assuming the same proportion in those who did not have an in-depth interview and those who did, was 14.5% (95% CI 12.4–16.9). However, when data were combined using multiple imputation, Parkinson disease ICB prevalence was estimated to be 19.1% (95% CI, 10.1–28.2%), indicating ICBs were more common among nonresponders.
Although Parkinson disease ICD was associated with motor complications, dopamine agonist use, and apathy in the final model (area under the curve 0.75; 95% CI, 0.65–0.84), Parkinson disease REM sleep behavior disorder was not. ICB prevalence was slightly higher among REM sleep behavior disorder participants compared with controls (34% vs 21%). Of the 52% in the control group and 49% in the REM sleep behavior disorder group who were interviewed, researchers found a similar rate of ICDs in individuals among control participants and those in the REM sleep behavior group (0.7% and 1%, respectively).
Study limitations included 50% participation rate for the in-depth interview, relatively small absolute number of participants with ICBs in follow-up, and residual confounding differences for determining risk factors. Despite these limitations, study investigators concluded that “[t]his study highlights the importance and potential impact across the full spectrum of severity of [Parkinson Disease]-ICB symptoms.” They go on to note that, [l]ong-term management of these symptoms is challenging because symptoms persist and may even worsen, highlighting the need for holistic care, including nonpharmacologic therapies.”
Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Baig F, Kelly MJ, Lawton MA, et al. Impulse control disorders in Parkinson and RBD: A longitudinal study of severity Neurology. 2019;93(7).