The research, “Improvement of impulse control disorders associated with levodopa-carbidopa intestinal gel treatment in advanced Parkinson’s disease,” was published in the Journal of Neurology.
Parkinson’s disease is characterized by the death of brain cells that produce the signaling molecule dopamine — a chemical that facilitates communication between nerve cells.
Dopamine replacement agents can reduce movement symptoms of the disease. The treatments can lead to side effects, however. One is impulse control disorders, such as compulsive gambling, buying, sexual behavior, and eating.
Duopa is an intestinal gel formulation of the carbidopa-levodopa combo that AbbVie developed to help manage Parkinson’s symptoms. It reduces the time when standard levodopa treatment wears off — periods known as off times.
Little is known about its non-movement side effects, however.
Spanish researchers wanted to know if Duopa would increase impulse control disorders in Parkinson’s patients. Their study involved 62 patients with an advanced form of the disease who received Duopa for six months. The patients had had symptoms a median of 13.5 years and movement problems a median of five years.
Duopa reduced patients’ off periods by almost six hours a day, or 79 percent. It failed to reduce the duration of patients’ uncontrolled movements, however. Duopa also improved patients’ ability to perform daily activities. In general, the treatment reduced the severity of the disease’s symptoms by 25 percent.
The treatment also led to signficant improvements in patients’ scores on an impulse control disorder index known as the Questionnaire for Impulsive–Compulsive Disorders in Parkinson’s disease. Patients’ scores fell by 54 percent over three months and by 64 percent over six months.
In terms of type of disorder, there were significant reductions in compulsive eating, in taking medication compulsively, in becoming compulsive hobby enthusiasts, and in compulsive punding, or engaging in repetitive mechanical tasks like assembling and disassembling things.
In contrast, Duopa led to no changes in compulsive gambling, sex, or buying.
Another finding was that the therapy led to significant reductions in psychosis, improved sleep quality and better social interactions.
“Currently, there is no consensus regarding treatment of impulse control disorders,” the researchers wrote. Key reasons are the variability of impulsive behavior symptoms and lack of clinical trials addressing the issue, they said.
As a whole, the study indicated that Duopa could be a good way to help people with advanced Parkinson’s disease manage their impulse control disorders.
Importantly, Duopa can significantly improve patients’ movement symptoms and sleep quality without a significant increase in levodopa dosage, the researchers wrote.
But additional studies are necessary to compare Duopa’s impact with that of other commonly used Parkinson’s treatment, the team added.