A QIMR Berghofer study has discovered how drugs given to people with Parkinson's disease cause some patients to develop addictive behaviors such as gambling, binge eating, hypersexuality and excessive shopping.
Medications that increase dopamine levels in the brain are the cornerstone of the treatment of symptoms of Parkinson's disease. This neurodegenerative disorder damages nerve cells that produce dopamine in deep brain structures.
Dr. Phil Mosley, chief researcher of the QIMR Berghofer Medical Research Institute and neuropsychiatrist at St Andrews hospital, said that while dopamine replacement therapy was effective for most people diagnosed with Parkinson's disease, about one out of six people treated with the drug developed impulse control behaviors, such as gambling.
"We found that the people who developed these addictive behaviors differed in the way their brain structure interacted with dopamine-containing drugs, which gave rise to impulsive behavior," said Dr. Mosley.
"None of these people had a history of addictive behavior prior to diagnosis and developed it only after starting treatment with dopamine replacement drugs.
"At the moment it is not possible to predict which individuals are at risk of these terrible side effects".
More than 80,000 Australians live with Parkinson's disease, with most people diagnosed after age 65, although around 20% are of working age, according to Parkinson's Australia.
The dott. Mosley said the study recruited 57 people with Parkinson's disease from the St Andrews War Memorial Hospital in Brisbane, in collaboration with neurologist Professor Peter Silburn.
"We used an advanced brain imaging method, called magnetic resonance imaging, to reconstruct the connections between different brain regions, similar to the development of an individualized" brain "wiring diagram for each person in the study," he said. the dott. Mosley.
"We asked our participants to gamble in a virtual casino, which allowed us to read impulsive and risky behaviors in real time.
"By combining brain imaging data, virtual casino behavior and the effect of dopamine substitute drugs, we were able to identify people susceptible to impulse control behaviors.
"More generally, we found a clear link between the strength of connections in the brain, within circuits that we believe are crucial for making decisions and suppressing impulses and impulsive behavior, even in people without clinically significant behavioral control pulses."
The dott. Mosley said the study's findings indicate that brain imaging and computer-based tests could be used in the future to determine which individuals were at risk of developing these harmful behaviors when treated with dopamine replacement drugs.
"These disorders are often a second blow to people and their families living with Parkinson's disease. Some people suffer financial problems or disruptions due to these harmful behaviors," he said.
"We could offer an education targeted at individuals at risk or adapt their therapeutic regimen to minimize potential damage from these therapies."
Professor Michael Breakspear's co-author stated that the results could also have implications for other psychiatric conditions marked by impulsiveness, such as ADHD, alcohol and drug addiction.
The results of the research were published today in the journal Brain.
The study was funded by the Queensland Government's Advance Queensland Initiative and the Royal Australian and New Zealand College of Psychiatrists. Neuroimaging was performed at the Herston Imaging Research Facility.
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