Parkinson's disease sufferers could be adversely affected by the growth of betting on the web because they are more likely to become gambling addicts, says a doctor writing in today's BMJ.

Parkinson's disease is common. It is estimated to affect one in 200 people in the developed world. Dr Sui Wong says while the motor symptoms and signs of Parkinson's disease are well recognised, the behavioural disorders, such as problem gambling, are less well known.

It is estimated that 3.5% of people with Parkinson's disease are pathological gamblers. That figure rises to 7.2% if they are taking drugs known as dopamine agonists. By comparison, in the general population only 1% of people become pathological gamblers.

Characterised by excessive betting, pathological gambling is a chronic and progressive mental disorder which can have devastating effects. Dr Wong says her patients are often secretive about their gambling and may end up thousands of pounds in debt before the problem is discovered.

The reason for the greater incidence of pathological gambling among users of dopamine agonists is unclear, says Dr Wong, as the drugs should lessen the symptoms of Parkinson's. Many sufferers take dopamine agonists in the early stages of the disease. They work by directly stimulating the receptors in nerves in the brain which normally would be stimulated by dopamine.

Dr Wong goes on to warn about the effect easy accessibility to instant gambling on the internet could have on Parkinson's sufferers. Nearly 5.8 million people, or one in ten online users, log onto internet gambling sites each month. This figure is expected to rise as more households connect to the internet.

Dr Wong says many internet gambling companies actively lure gamblers with pop-ups to place free-bets. This proactive marketing technique is pervasive and she warns it can make it hard for vulnerable individuals to wean off gambling.

She says "the current debate on regulating gambling is relevant to this group of patients. This provides an ideal opportunity to deal with the problem through appropriate legislation to protect a small, though highly vulnerable, group in our society."

"Editorial: Pathological gambling in Parkinson's disease
BMJ Volume 334 pp 810-11

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