PD brain networks for impulsivity mapped by MRI in virtual casino

Movement disorders

By Mardi Chapman

7 Nov 2019

Researchers have been able to distinguish which people with Parkinson’s disease are susceptible to developing impulsivity and compulsive behaviours when treated with dopamine-replacement drugs.

A Queensland-led study used high-resolution diffusion MRI to image the brains of 57 people with Parkinson’s disease in real time while they were gambling in a virtual casino.

The gambling task allowed for impulsive behaviours to be expressed in different ways such as increasing the size of the bets, switching slot machines, ’double or nothing’ gambles and cash outs.

Lead researcher and neuropsychiatrist Dr Phil Mosley, from QIMR Berghofer Medical Research Institute and St Andrew’s Hospital, said there was previously no way of predicting which individuals were at risk of treatment side-effects such as problem gambling.

“By combining data from brain imaging, behaviour in the virtual casino, and the effect of dopamine-replacement medication, we were able to identify people who were susceptible to impulse-control behaviours.”

“More broadly, we found a clear link between the strength of the connections in the brain, within circuits that we think are crucial for making decisions and suppressing impulses, and impulsive behaviour, even in people without clinically-significant impulse-control behaviours.”

The research, published in the journal Brain, offers the promise of identifying at-risk individuals and providing targeted education or adapting their treatment regimen to minimise the likelihood of side effects.

About one in six patients with Parkinson’s disease on dopamine-replacement therapies develop impulse-control behaviours, he told the limbic.

“The vast majority of people who are diagnosed with Parkinson disease and have motor symptoms are prescribed medications including dopamine and the dose of those needs to go up over time as the disease progresses.”

However with knowledge of a susceptibility to this type of addictive behaviours, patients might choose a type of therapy that has been associated with fewer such side effects.

“And they also might say to their neurologist that as their medication requirements go up, they might choose to have one of the surgical therapies like deep brain stimulation which allows treatment of their movement symptoms with electricity and removes the need for medication in a significant number of people.”

The research also has other implications for people with Parkinson’s disease, Dr Mosley said.

“I’m also interested in following people’s outcomes after deep brain stimulation for Parkinson’s disease and trying to see if we can improve the outcomes based on the targeting of the electrode and distribution of the stimulation within the brain.

“By learning about these networks in the brain that underlie these symptoms we can selectively stimulate them or not stimulate them,” he said.

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