New trials have shown that nicotine may be effective in the treatment of Parkinson's disease and Tourette's syndrome.

The preliminary studies were both revealed at the annual meeting of the American Association for the Advancement of Science, and follow earlier studies showing benefits from the tobacco-derived drug in Alzheimer's patients.

Paul Newhouse, at the University of Vermont College of Medicine, looked at the effect of nicotine on Parkinson's patients.

"We saw small effects immediately, but they were more significant later on," he said. "Even patients who were already optimally treated with existing Parkinson's drugs got some benefits."

Nicotine patch

The trial involved just 15 people and the patients knew they were receiving nicotine, either by injection or via a commercial nicotine patch.

No one can in any way use this work as an endorsement of cigarette smoking

Paul Newhouse

The benefits were seen simultaneously in three important areas: mental attentiveness, body control in walking and using the hands, and reducing anxiety. The effects began to reduce two weeks after the final dose.

Dr Newhouse admitted the effects were variable, but said: "Parkinson's is a remarkably variable disease, so that's not surprising. But one patient wrote to me saying his wife believed he was back to 'his old, pre-Parkinson's, totally cool self'."

He also added two warnings: "We don't know the long-term effects of this treatment yet, so it may be rash to recommend it now.

Blurted obscenities

"And no one can in any way use this work as an endorsement of cigarette smoking."

Some of the patients received the drug through a patch

The nicotine study on children with Tourette's syndrome - characterised by tics, blurted obscenities and rages - was done by neuroscientist Paul Sandberg at the University of South Florida.

"The two drugs currently used to treat Tourette's are major tranquilisers - they can make people appear 'parkinsonian'."

Dr Sanberg's study, currently in review with a scientific journal, shows that nicotine enhances the effect of one of these two drugs so that dose, and soporific side effects can be reduced.

Nicotine derivatives

The trial was conducted double-blind and had two groups of 35 children, aged 8 to 17, who received either a daily 7mg nicotine patch or a placebo.

The drug companies need to produce nicotine derivatives with fewer side effects

"There has been no problem with kids becoming addicted but there are problems with side effects - nausea and stomach upsets and itching under the patch."

Ken Lloyd, a consultant and visiting scientist with the Scripps Research Institute, said the next step was to develop nicotine derivatives that better target specific diseases and have fewer side effects.

He said an additional advantage of this approach for companies is that it would produce drugs that could be patented. He said all the major pharmaceutical companies were doing research in this area, including AstraZeneca, Merck, and Aventis. He believed phase II trials were underway in some areas.

Nicotine is believed to be effective in these and other neurological diseases, such as attention deficit hyperactivity disorder, because it acts on several brain receptors, including those relating to attentiveness and memory.