Parkinson's Disease Not Linked to Impulse Control Disorders

Fran Lowry

January 11, 2013

Parkinson's disease (PD) itself does not increase the risk for compulsive gambling, shopping addictions, or other impulse control disorder (ICD) symptoms that have been seen in patients taking certain drugs for PD, a new study shows.

The finding, from the ongoing Parkinson's Progression Markers Initiative (PPMI) study, adds support to the idea that factors other than PD are responsible for the increase in ICDs seen once patients start treatment, lead author Daniel Weintraub, MD, from the University of Pennsylvania School of Medicine, Philadelphia, told Medscape Medical News.

"Our results suggest that Parkinson's disease itself does not confer an increased risk for experiencing ICDs and related disorders, but rather that the excess occurrence of these disorders in Parkinson's disease is likely driven by exposure to Parkinson's medications and other treatments, such as deep brain stimulation surgery," Dr. Weintraub said.

"These medications influence the dopamine system and in general these disorders are associated with alterations in the dopamine system, so there seems to be a subset of patients in whom dopaminergic therapy triggers these problems," he said.

Dr. Daniel Weintraub

About 20% of patients did report ICDs, however, on the initial screen. Dr. Weintraub believes that patients with PD who have impulse control symptoms before treatment may warrant close monitoring for development of the full-blown symptoms after initiation of drug therapy.

Their findings are published in the January 8 issue of Neurology.

Nonmotor Parkinson's Features

"The Parkinson's Progression Markers Initiative is a study of Parkinson's disease patients who were newly diagnosed and untreated and comparing them with healthy controls, so it is an opportunity to look at what in my case as a psychiatrist are some of the nonmotor features that are present at the time of diagnosis, before people are even treated," Dr. Weintraub explained.

Some research suggested that impulse control problems occurred with increased frequency in patients with PD and that this association seemed to be linked with certain Parkinson's medications.

"But what hasn't been clear is whether people at the time of diagnosis, before they are ever treated with medications, have symptoms at an increased frequency compared with the general population or whether they're just like everybody else," he said.

In this case-control study, Dr. Weintraub and his group administered the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (QUIP) to 168 patients with newly diagnosed, untreated PD and 143 healthy controls.

The QUIP, which was developed by Dr. Weintraub and his team at University of Pennsylvania, screens for a range of impulse control disorder symptoms and related behaviors, including compulsive gambling, compulsive buying, compulsive sexual behavior, compulsive eating, punding (repetitive manipulation of small objects or minor repetitive activities without any clear purpose), and hobbyism (repeating the same activity, such as writing or Internet use).

"It is true that certain things, like Internet use, are common in the general population as well. The difference here is that these are symptoms that the person typically has not experienced prior to the introduction of the medications for Parkinson's disease," Dr. Weintraub noted.

The researchers found that patients with PD were no more or less likely to have the impulse control symptoms than those without the disease.

"Our results showed that 18.5% of Parkinson's disease patients showed any impulse control or related behavior, compared with 20.3% of the healthy controls," Dr. Weintraub said. In multivariable models, there was no significant difference between patients with PD and controls on any particular impulsive behavior (P > .10 in all cases).

Table. Frequency of Impulsive Behaviors in Patients With PD vs Controls

Behavior Patients With PD (%) Controls (%)
Gambling 1.2 0.7
Compulsive buying 3.0 2.1
Sexual behavior 4.2 3.5
Compulsive eating 7.1 10.5
Punding 4.8 2.1
Hobbyism 5.4 11.9
Walkabout 0.6 0.7

 

Commenting on this study for Medscape Medical News, Anna DePold Hohler, MD, from Boston University School of Medicine in Massachusetts, agreed that this study suggests that de novopatients with PD do not have higher rates of ICDs than do healthy controls.

"It must be further expanded but may suggest that disease progression with concomitant parkinsonian medications may contribute to ICDs," Dr. Hohler, a spokesperson for the American Academy of Neurology, said.

Dr. Stephen D. Silberstein

Stephen D. Silberstein, professor of neurology at Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, pointed out that 20% of patients with PD did, in fact, screen positive for impulse control and related behavior symptoms.

"Is this a risk factor for drug-induced ICDs in PD?" Dr. Silberstein, a spokesperson for the American Academy of Neurology, asked. "Perhaps baseline screening should be done in PD patients."

This study was funded by The Michael J. Fox Foundation for Parkinson's Research. Dr. Weintraub reported financial relationships with the National Institutes of Health, The Michael J. Fox Foundation for Parkinson's Research, Novartis Pharmaceuticals, Teva Pharmaceuticals, Eli Lilly and Company, Lundbeck Inc., Biogen, Pfizer, Avanir Pharmaceuticals, and Merck & Co. Dr. Hohler and Dr. Silberstein have disclosed no relevant financial relationships.

Neurology. 2013;80:176-180. Abstract

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