Increases in compulsive behavior were clear in the use of L-dope in people with Parkinson's in the 60's, but the level of the problem is evident in this research....
The production of dopamine can be excessively stimulated by taking drugs such as alcohol, cocaine, or heroin.
So, the neurotransmitter is at the heart of addictions and impulse control disorders ranging from substance abuse to sex addiction and gambling.
Such impulse control issues have been found to be common in people with Parkinson's disease. Pathological gambling and compulsive shopping, as well as compulsive eating and sexual behavior, have all been documented among patients with Parkinson's.
The drugs often prescribed to people with Parkinson's are the main risk factor for such compulsive behavior. Because dopamine is deficient in Parkinson's, the go-to treatment is dopamine agonists — which are drugs that activate the brain's dopamine receptors — or the well known levodopa, which turns itself into dopamine.
The researchers investigated 411 people who had received a Parkinson's disease diagnosis 5 years or under before the study, and who were clinically followed for at least 3 years.
Dr. Corvol and his colleagues interviewed the participants about any symptoms of impulse control disorders, such as compulsive shopping, eating, gambling, or sexual behaviors.
Of the 411 participants, 356 (or almost 87 percent) had taken dopamine agonists at least once since their Parkinson's diagnosis. At baseline, 81 participants (almost 20 percent) reported an impulse control disorder.
Specifically, 11 percent reported binge eating, 9 percent reported compulsive sexual behavior, 5 percent said that they shopped compulsively, and 4 percent admitted to having a gambling problem.
Of the 306 participants who did not report having any impulse control problems at baseline, 94 developed such a problem during the study. According to the scientists, this amounts to a "5-year cumulative incidence" of impulse control disorders of 46 percent.
By comparison, those who had never taken the drugs had a 5-year incidence of 12 percent. What is more, 30 participants with compulsive behaviors stopped taking the drugs during the study, which put an end to their symptoms.
Finally, higher doses of dopamine agonists and the duration of the treatment correlated directly with the risk of developing impulse control disorders.