Didier Jambart, a French defence ministry employee, has been suing for damages of €400,000 after being prescribed with dopamine agonist drugs in a case that is being closely studied by lawyers representing Parkinson's sufferers in Britain, the US and Canada. Like Jambart, they claim that they were provided with minimal information about the disturbing side effects, estimated to affect up to 15 per cent of those taking the drugs.

'I could not have told this story even several months ago without breaking down,' said Jambart. 'I know of other dreadful examples here in France, including someone imprisoned as a result of their compulsive gambling, and of women who ended up prostituting themselves in mobile homes because of their sexual obsessions.' He ran up gambling debts of €130,000 while stealing from his family, friends and neighbours to fund his obsession. He even sold toys belonging to his two young sons.

Dopamine agonists, which mimic the mood chemical dopamine, are used in several branded drugs commonly prescribed for Parkinson's, a debilitating disease which affects some 120,000 people in Britain. In most cases, they successfully counter symptoms which include muscular tremors and slowness of movement.

But within a year of starting his medication, Jambart felt the first signs of what he calls 'a state of Jekyll and Hyde'. During the highs he began placing horse racing bets on the internet. But in December 2004, he made the first of three suicide attempts. The next year he began trawling gay internet sites for sexual partners whom he invited home.

'As soon as we saw him we knew immediately it was dopamine agonists,' said Philippe Damier, head of the neurology department at the Nantes CHU hospital. Jambart was given different medication and his disorders disappeared. He said: 'Without that, I would have killed myself or have ended up in prison.'

Bids for compensation in Britain were launched last month by two Parkinson's sufferers who claimed to have become gambling addicts after being prescribed Mirapexin.