Here's a perplexing medical irony: For Parkinson's disease patients, initiating certain voluntary movements such as walking and rising from a chair can be difficult. But the medications that help ease the challenging motor symptoms of Parkinson's seem to make it harder for some patients to halt certain behaviors that can be rewarding or pleasurable -- gambling, buying, eating, sexual stimulation.
While physicians have known about the link between Parkinson's medication and compulsive gambling since about 2005, little was known about how many patients are affected this way, whether the compulsive behavior went beyond gambling for some, and whether this is clearly a medication-induced problem. A study in the Archives of Neurology released Monday answers those questions.
Some 13.6% of Parkinson's Disease patients taking levodopa or one of the dopamine-agonist medications widely used for the movement disorder show clear signs of some impulse-control disorder. That rate was between 2 and 3.3 times higher among Parkinson's patients being treated with these medications than among patients who did not take them. About a quarter of those patients suffered from more than one type of compulsive behavior.
Compulsive buying was the most common manifestation of such impulse-control problems, affecting 5.9% of all medicated patients; 5% experienced problem or pathological gambling; 4.3% engaged in binge eating behaviors; and 3.5% engaged in compulsive sexual behavior.
Compulsive buying and binge eating were more common among women patients than among men; compulsive sexual behavior afflicted more men than women. The researchers also found some evidence that genetic inheritance might make some patients more vulnerable to these side effects of Parkinson's disease medicine: Patients were far more likely to develop compulsive buying, eating or gambling behaviors if they had a first-degree relative with a known gambling problem.
Finally, the study, which included 3,090 Parkinson's disease patients, found that those taking a combination of levodopa and one of the other dopamine-agonist medications (including pramipexole and ropinirole) were most likely to develop an impulse-control disorder; those on a dopamine agonist without levodopa were slightly less likely to develop such behavioral problems; and those on levodopa alone were about half as likely as the first two groups to develop impulse-control problems.
Researchers are gleaning insights into why and how some people become addicted to substances or behaviors from the experiences of Parkinson's patients. Here's a terrific overview of the curious link between Parkinson's medications and compulsion.
But you don't need to be a Parkinson's patient to have a compulsive behavior problem. Have a look here if gambling is your weakness; here if you compulsively seek out sexual stimulation; here if you buy or shop compulsively; and here if you think you might have a binge-eating problem.
-- Melissa Healy