Caroline Cassels

June 19, 2007

June 19, 2007 (Istanbul) — Like their counterparts with Parkinson's disease (PD), patients with restless legs syndrome (RLS) taking dopaminergic agonists (DA) are at increased risk for compulsive behaviors, new research suggests.

Presented here at the 11th International Congress of Parkinson's Disease and Movement Disorders, researchers from the Quebec Memory Motor Skills Disorders Clinic, in Quebec City, Quebec, found up to 10% of RLS patients had compulsive behaviors, including trichotillomania, a Tourette-like syndrome, and other impulse-control disorders, including shopping, overeating, and gambling.

"We are in the very beginning stages of describing this syndrome. However, it appears from our research there are differences in the risk factors and presentation of compulsive behaviors between PD and RLS patients," principal investigator Emmanuelle Pourcher, MD, told Medscape.

For instance, she said, compulsive behaviors in RLS patients taking DA are "insidious," such that patients tend not to link the compulsive behavior with the initiation of DA use.

Subtler Presentation

"In contrast to Parkinson's patients, it was less clear to RLS patients that the compulsive behavior they developed was due to the initiation of the drug," she said.

In addition, higher depression and stress scores were significantly associated with the development of compulsive behaviors, she said.

According to Dr. Pourcher, 2 recent reports have related impulse-control disorders in RLS patients to DA use. The aim of this current observational study, she said, was to examine the prevalence of and potential risk factors for impulse-control disorders and better describe the condition.

A questionnaire was sent to a population of 150 RLS patients attending a movement-disorders clinic at 3 different points in time over a 12-month period.

Included in the mailed assessment were the International Restless Leg Scale (IRLS) to measure RLS severity, the Beck Depression Inventory (BDI) to assess mood, a visual analog scale to assess stress, and the Medical Outcomes Study (MOS) Sleep Scale to measure sleep parameters.

Depression, Stress Equal Higher Risk

A total of 97 patients responded to all 3 mailings. Of these, 12 subjects — 8 men and 4 women — were found to have compulsive behaviors. None had a previous history of generalized anxiety disorder or obsessive-compulsive disorder.

Individuals with higher depression, stress, and poor-quality sleep were significantly more likely to develop compulsive behaviors compared with subjects without these conditions.

According to Dr. Pourcher, patients who developed compulsions showed more dysphoria with higher BDI scores and described themselves as "stressed" compared with RLS patients on DA therapy who did not have impulse-control behaviors. In addition, she said, the behaviors appeared to slowly but steadily progress over the course of the 12-month study period.

No Perfect Balance

According to Dr. Pourcher, reducing DA dosage can alleviate impulse-control disorders in these patients. However, she said, it comes at the expense of less effective control of RLS symptoms.

"It is very difficult to create a perfect balance in these patients. In RLS we are using these agents to stimulate the dopaminergic system, but by doing that we are creating an imbalance in other areas of the brain that are not dysfunctional," she said.

While more research needs to be done to better describe and determine the prevalence of DA-induced compulsions in RLS patients, it is important that clinicians — neurologists as well as general practitioners — are aware that this is a potential problem in this patient group.

In particular, she said, it may be worth screening patients for depression and stress, which in this study were significantly associated with an increased risk for impulse-control disorders.

"Over the past 5 years dopaminergic agonists have become the first-line treatment in RLS. Compulsions related to DA use in RLS may not occur as frequently as they do in PD, but it is important that clinicians are aware it is a possibility and that they screen their patients at every follow-up visit," she said.

11th International Congress of Parkinson's Disease and Movement Disorders: Oral Platform Presentation 2. Presented June 5, 2007.

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