Parkinson’s disease drug side effect revealed in study
BRISBANE: Doctors now know why treatment for Parkinson’s disease gives some people a high sex drive and makes others gambling addicts.
At 48, Mark Stephens was diagnosed with early-onset Parkinson’s disease.
If the news that he suffered an incurable disorder of his central nervous system was not bad enough, the treatment to ease symptoms made him develop addictions and paranoia.
“Yes, pretty tough,” Mr Stephens said of the condition he has now lived with for about eight years.
“I went through depression and anxiety as well as gambling addiction — I had a problem with the pokies.
“My car — I was way overspending on that not even realising what I was doing.”
He said he had spent about $85,000 working on his VW Beetle, which became an obsession he had felt eased his symptoms.
“It must be the adrenaline or something,” he said.
But last week, his wife — who he ran a successful courier business with — left him.
“[With] my mood swings and what-not … my wife said ‘I can’t take it anymore’ and she walked out on Tuesday.
“She said she needed some time to think … hopefully she decides to come back.”
Queensland researchers have now discovered why some people diagnosed with Parkinson’s disease develop highly impulsive or addictive behaviours in response to the key medication used to treat it.
Spending sprees and heightened sex drive are two of the potential side effects for the one in six people diagnosed with Parkinson’s disease who are treated with drugs to boost dopamine levels.
An expert in the condition said Parkinson’s disease was a movement disorder that made people slow and stiff in their movements.
Neuropsychiatrist Phil Mosley, from the Brisbane medical research institute QIMR Berghofer, said dopamine restored some of the neurotransmitters that were lost in the course of the neuro-degenerative disease.
Dr Mosley co-wrote a study that found patients who developed addictions differed in the way their brain structure reacted with the medication.
The institute studied 57 patients who had no history of addictive behaviours before their diagnosis and treatment.
Dr Mosely said 80,000 people in Australia were currently living with Parkinson’s disease.
“These types of addictive behaviours affect one in six people with the condition, so it’s huge really,” Dr Mosely said.
“They can range from problems with gambling, to having a high-sex drive, to using drugs and alcohol in a harmful way.
“They respond so badly to this medication and develop these addictions.”
The participants were given the chance to win money using special online gambling software.
Researchers tested their responses and scanned their brains at the Herston Imaging Research Facility in Brisbane.
They created a kind of wiring map of the brain and found that those who had negative behavioural reactions to the medication had one of two things in common.
“We took circuits in the brain that we know have underlying important behaviours and two of those behaviours are choosing and stopping.” Dr Mosley said.
People who had stronger choosing circuits or weaker stopping circuits were more likely to be impulsive.
Researchers envisage they would be able to warn people if they were susceptible to having a bad reaction to the medication and they could look at other ways of treating the disease, such as brain stimulation.
Mr Stephens, who has had deep brain stimulation (DBS) inserted into his head, said the study was a breakthrough.
“I hope this helps so that other people don’t have to go through this,” Mr Stephens said.
