Randomized, Double-blind, Placebo-controlled Study of Naltrexone for Impulse Control Disorders in Parkinson's Disease

Impulse control disorders (ICDs), including compulsive gambling, sexual behavior, buying, and eating, are increasingly recognized as a significant clinical problem in Parkinson's disease (PD), occurring in up to 15% of patients. Dopamine agonist (DA) treatment is thought to be the primary risk factor for the development of ICDs in PD. ICDs often lead to significant impairments in psychosocial functioning, interpersonal relationships, and quality of life. The management of ICDs in the context of PD can be complex. Patients may be reluctant to discontinue DA treatment due to the motor benefits derived from treatment, so patients often have chronic symptoms. Thus, additional treatment approaches are needed.

A medication shown to be efficacious for the treatment of ICDs with minimal impact on parkinsonism would allow many ICD patients to continue on full-dose DA treatment. Naltrexone, a long-acting opioid receptor antagonist, helps in the treatment of alcohol and opioid dependence. In addition, placebo-controlled studies have demonstrated that it helps in the treatment of pathological gambling in the general population. Opioids regulate dopamine pathways in areas of the brain linked with impulse control disorders, and opioid antagonists block opioid receptors in these regions. In this study, 48 PD patients with an ICD will be treated either with naltrexone (50-100 mg/day) or placebo for a period of 8 weeks. The study will assess if naltrexone improves ICD symptoms in PD and is well tolerated. To our knowledge, the proposed study is the first controlled trial of an agent to treat ICDs in PD.