Penn study suggests dopamine treatments may play role in increasing impulsivity
While approximately one in five Parkinson's disease patients experience impulse control disorder symptoms, the disease itself does not increase the risk of gambling, shopping, or other impulsivity symptoms, according to research from the Perelman School of Medicine at the University of Pennsylvania. A new study is the first to show in a large sample that people with untreated Parkinson's were no more likely to have an increased impulsivity than people without the disease. Published in the January 8, 2013, print issue of Neurology-, the medical journal of the American Academy of Neurology, this study is the strongest research to date reinforcing the reported association between disease medications and impulse control disorders in Parkinson's.
"When looking at newly diagnosed Parkinson's patients who had yet to be treated with drugs targeting the dopamine system, we saw no difference in impulsivity than what we found in healthy people without the disease," said lead study author Daniel Weintraub, MD, associate professor of Psychiatry and Neurology in the Perelman School of Medicine at the University of Pennsylvania. "Now knowing that the disease itself is not driving impulsive behaviors, we can follow newly diagnosed patients over time to see if we can predict how exposure to dopamine-related drugs and other factors play a role in impulse control disorders."
Using baseline data from 168 newly-diagnosed, untreated Parkinson's disease patients and 143 healthy control subjects, obtained upon enrollment into the Parkinson's Progression Markers Initiative (PPMI), the team also found that there was an increasing severity of depression associated with impulse control disorders among both groups, particularly with the presence of compulsive eating symptoms.
This is the first study to use an impulse control assessment tool developed and validated for use in PD, as well to enroll PD patients and healthy controls concurrently and to have both groups undergo an identical assessment process.
"For those with Parkinson's who screened positive for impulse control disorders at baseline, it will be interesting to follow the patients to see if treatment with dopamine agonists and other therapies will further increase risk over time," said Weintraub, also with the Parkinson's Disease and Mental Illness Research, Education and Clinical Center of the Philadelphia Veterans Affairs Medical Center.
This is the first data to be published from the Parkinson's Progression Markers Initiative, known as PPMI, a public-private partnership funded by The Michael J. Fox Foundation for Parkinson's Research and funding partners, including Abbott, Biogen Idec, F. Hoffman-La Roche Ltd., GE Healthcare, Genentech, and Pfizer Inc.