Drug May Make People Less Impulsive


NEW ORLEANS — A drug used to treat Parkinson's disease may also make people less impulsive, a new study suggests.

After taking the drug, study participants were better able to delay gratification — or quell their impulse for an immediate reward, and hold out for a larger one — compared with before they took the drug.

The researchers said the drug could be used to help people with disorders of impulse control, such as gambling, substance abuse or compulsive stealing, said study researcher Dr. Andrew Kayser, an assistant professor of neurology at the University of California, San Francisco.

However, the study was conducted in a laboratory, and the situations participants faced were hypothetical. Kayser and colleagues are now conducting research to see if the drug can reduce impulsiveness in real-world settings.  

The study will be presented here this week at the American Academy of Neurology annual meeting.

The study involved 25 healthy people, ages 19 to 41. Participants answered a series of questions in which they had to choose between receiving a small amount of money immediately, or a larger amount of money later on. (While participants did not actually receive the money, research has demonstrated that more impulsive people tend to pick the smaller, more immediate reward over the larger, delayed reward.)

After taking the drug, called tolcapone, participants chose the immediate reward less often than they did when they were not on the drug. The greatest reduction in impulsivity was seen in people who were the most impulsive, Kayser said.

People who are impulsive are thought to have less dopamine — a chemical responsible for signaling feelings of reward and pleasure — available in their brain. The drug works by inhibiting the breakdown of dopamine in the brain's prefrontal cortex, which is responsible for inhibiting impulsive behaviors. By increasing dopamine in this region, the drug is thought to improve a person's ability to control their behaviors, Kayser said.

Unlike stimulants, which are sometimes used to improve attention and reduce impulsive behaviors, tolcapone does not produce a high, meaning it may have less potential for abuse, Kayser said.

However, people who take tolcapone need to be monitored to make sure the drug does not affect their liver function, and consuming alcohol with the drug can be dangerous, Kayser said.

Pass it on: A drug may be able to reduce impulsivity and help people with problems such as substance abuse and gambling.

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Rachael Rettner

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.