From the Journals

Impulse control disorders in Parkinson’s patients may be higher than thought

View on the News

Neurologists may miss the boat on impulse control disorders

Data from the study by Dr. Corvol and colleagues are robust and suggest neurologists may be “missing the boat or even harming patients” by underestimating the adverse effects associated with dopamine agonists, the authors of an editorial wrote.

The 5-year incidence of impulse control disorders approaching 50% suggests they are even more common than previously reported, according to editorial authors Laura S. Boylan, MD, and Vladimir S. Kostic, MD, PhD.Compulsive gambling, shopping, eating, sexual behaviors and other impulse control disorders at their worst can ruin finances, disrupt families, and have legal implications, Dr. Boylan and Dr. Kostic said in their editorial.

Neurologists are “often uncomfortable” with psychiatric disorders, they added, even though they are the ones managing movement disorder medications.

There is an absence of high-quality evidence on how to treat impulse control disorders, though one common approach, switching to levodopa, is in the wheelhouse of neurologists. However, “levodopaphobia” persists in some circles despite evidence debunking the notion that the medication is neurotoxic, according to Dr. Boylan and Dr. Kostic.

“Practice change in medicine, as in other areas, can be like turning a cruise ship,” they wrote, “but this study may help give a little push to the boat and, we hope, promote further basic and clinical research on nonmotor aspects of PD and other movement disorders.”

Dr. Boylan is with Essentia Health, Duluth, Minn., Albany-Stratton VA Medical Center, Albany, N.Y., and Bellevue Hospital/New York University. Dr. Kosticis with the Institute of Neurology CCS, School of Medicine University of Belgrade (Serbia). Dr. Kostic reported receiving speaker honoraria from Novartis, Teva, and Salveo. Their editorial accompanied Dr. Corvol and colleagues’ report (Neurology. 2018 Jun 20. doi: 10.1212/WNL.0000000000005806 ).



Nearly half of patients with Parkinson’s disease who were taking dopamine agonist treatment experienced impulse control disorders over a follow-up of 5 years, according to recently published results of a longitudinal study.

The 5-year cumulative incidence of impulse control disorders was approximately 45% in the study, which included 411 patients with a high prevalence of dopamine agonist use and disease duration of 5 years or less at baseline.

There was a strong association between dopamine agonist use and impulse control disorders in the study, which was conducted by Jean-Christophe Corvol, MD, of Publique Hôpitaux de Paris and his coinvestigators.

Impulse disorders increased in incidence with both duration and dose of dopamine agonists and resolved progressively after discontinuation of those agents, the investigators reported online June 20 in Neurology. The investigators used item 1.6 of part I of the Movement Disorder Society Unified Parkinson’s Disease Rating Scale to determine the presence of an impulse control disorder.

“Given the high cumulative incidence of impulse control disorders in patients with Parkinson’s disease, these adverse effects should be carefully monitored in patients ever treated with dopamine agonists,” Dr. Corvol and his coauthors wrote.

The results came from the ongoing Drug Interaction With Genes in Parkinson’s Disease (DIGPD) study, a longitudinal cohort study including Parkinson’s disease patients consecutively recruited between 2009 and 2013 at eight French hospitals. All patients had no more than 5 years of disease duration at recruitment, and follow-up included annual evaluations by movement disorder specialists.

At baseline, the majority of patients (302, or 73.5%) had taken dopamine agonists within the past 12 months.

Over the course of 5 years, the prevalence of impulse control disorders increased from 19.7% at baseline to 32.8%, Dr. Corvol and his colleagues reported.

Among 306 patients with no impulse control disorders at baseline, 94 developed one, for a 5-year cumulative incidence of 46.1%, they added. Only 4 of the 94 new cases occurred in patients who never used dopamine agonists.

Dopamine agonist use in the previous 12 months was associated with a 2.23-fold higher prevalence of impulse control disorders (P less than .001), with prevalence increasing along with average daily dose and cumulative dose duration over that time period, according to the investigators.

These findings suggests tools are needed to screen for impulse control disorders and identify high-risk patients, they said.

“Further studies are needed to understand the mechanisms involved in the relation between [dopamine agonists] and [impulse control disorders], in particular the role of apathy, anxiety, and depression,” they added.

The study was funded by grants from the French Ministry of Health and from the French Drug Agency. Dr. Corvol and many of his colleagues reported financial disclosures with many pharmaceutical companies.

SOURCE: Corvol J-C et al. Neurology. 2018 Jun 20. doi: 10.1212/WNL.0000000000005816.

Next Article: