Drugs for Parkinson's disease turn patients into gambling addicts

A study of patients in the West of Scotland found that more than 10 per cent of those taking dopamine agonists to treat their condition had developed a problem with gambling.

Many went from spending only a few pounds a week before taking the drugs to forking out hundreds, or even thousands, on horses, scratch cards and internet betting sites.

One 71-year-old man lost a five-figure sum gambling on the internet.

The research team from Glasgow's Southern General Hospital, led by Dr Katherine Grosset, said patients given the drugs should be made aware of the potential side effects.

Their study looked at 251 Parkinson's patients taking different drug combinations. Of that total, 16 patients, all of whom had been taking the dopamine agonists, reported excessive gambling.

This meant that 10.3 per cent of those prescribed the drugs were thought to be problem gamblers.

"This classifies the problem as very common, according to EU guidelines," the researchers said. "All patients prescribed dopamine agonists should be made aware of this potential adverse effect, as it usually diminishes on dopamine agonist discontinuation."

One patient in the study went from spending about 10 a week on gambling before taking the drugs, to spending 1,500 on the internet and interactive TV.

Another, who spent 30 a week before treatment, went on to spend 1,300 on horse racing and football bets.

And one 65-year-old woman spent 4,000 on the internet and scratch cards.

Bingo, roulette and slot machines were also common forms of gambling used by patients.

Parkinson's patients have reduced levels of dopamine - a chemical that relays messages between brain cells - and may be given drugs to mimic its effects.

Low dopamine levels cause the classic symptoms of muscle rigidity and tremor in sufferers.

But dopamine is also known to play a role in helping the brain to recognise and seek sources of pleasure - the basis of addiction.

Anecdotal reports have suggested that taking dopamine agonists may also cause alcoholism or sex addiction.

However, changing over to other treatments usually stops the problem.

Dr Kieran Breen, the director of research at the Parkinson's Disease Society, said the Scottish research was one of the first studies to try to assess the extent of the link between gambling addiction and dopamine agonists.

"Dopamine is involved in reward and mood," he said.

"Some people's brain chemistry might make them more susceptible to the effects of dopamine agonists, meaning they may develop gambling problems or other addictions."

He said the charity was funding research to find out if these addiction problems could be avoided in Parkinson's patients.

"We must make people aware that this may be a side effect because there are other drugs they could take if they are having problems," Dr Breen said.

Robert Brown, a psychologist from Glasgow, said a person's environment meant they might react differently to the drugs.

If they had easy access to gambling, this could mean they were more likely to gamble than to turn to drink or drugs," he said.

"There is a tradition of gambling across the whole of Scotland, with more gamblers per head of population than in England and Wales. But people on these drugs could equally turn to alcohol or other ways of finding arousal or escape."

A spokesman for Gamblers Anonymous in Scotland said people with Parkinson's might be more at risk from internet gambling because it was easy to access without leaving home.

"We have seen a doubling of our membership in Scotland in the last 18 months and a lot of this has been due to a big surge in online gambling.

"Making it easy for people to gamble means they no longer have to go out to betting shops or dog tracks.

"But this can also mean that the problem remains hidden for longer," he said.

• Gamblers Anonymous in Scotland can be contacted on 0870 050 8881.