This is the first controlled trial of an agent to treat impulse control disorders (ICDs) in Parkinson’s disease (PD). Naltrexone, which blocks opioid receptors, is FDA-approved for the treatment of alcohol dependence and has shown benefit for pathological gambling. This makes it an ideal candidate to explore for the treatment of ICDs in PD. In addition, naltrexone has been shown to be safe and well-tolerated in PD patients.
This is an eight-week study in which 48 PD patients diagnosed with one or more ICDs that developed during PD and in the context of dopamine agonist (DA) treatment will receive either naltrexone or placebo treatment in a blinded fashion. Recruitment will be such that all four common ICDs in PD (compulsive gambling, buying, sexual behavior and eating) are equally represented. Patients will be seen every other week during the course of the study, and treatment response and tolerability will be assessed at each visit.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
Up to 15 percent of dopamine agonist-treated patients experience an ICD at any given time, with usually pleasurable behaviors becoming uncontrollable and at sometimes leading to devastating personal, financial or physical outcomes. Thus, ICDs are a major clinical problem in PD. However, many patients are reluctant to make changes to their DA treatment, so patients typically have chronic symptoms. Thus, the clinical management of these patients is complicated, and additional treatment approaches are needed.
A medication shown to work as a treatment for ICDs with little impact on PD motor symptoms would allow many ICD patients to safely continue their DA treatment. This would have significant treatment implications for the relatively large number of PD patients suffering from one or more ICDs, who currently have no treatment option other than to stop or decrease their DA treatment.
The results of this study were negative for the efficacy of naltrexone for the treatment of impulse controls disorders (such as compulsive gambling, buying, sexual behavior and eating) in Parkinson’s disease (PD) using a clinician rating of general improvement, which was the primary outcome measure for the study. However, using a patient-completed, PD-specific assessment of impulse control disorder symptom severity, naltrexone treatment was associated with a significant decrease in symptoms compared with placebo treatment. The results of this preliminary study support further research with naltrexone or other opioid blockers for the treatment of these disorders in PD. In addition, other novel treatments to be considered for this condition include medications targeting glutamate (another brain chemical) and the possibility of deep brain stimulation.