WASHINGTON - Despite its evil image, new research suggests that nicotine is a surprisingly potent drug for a variety of diseases that afflict the brain, including Alzheimer's, Parkinson's and Tourette's syndrome.
Many small studies over the past decade have explored the possible benefits of this ubiquitous drug. But the field appears to be taking on fresh life as doctors test nicotine patches for neurological diseases in both children and the elderly, and drug companies race to concoct nicotine substitutes that carry fewer side effects.
At a conference Monday, doctors said the field's first gold-standard study - one in which dummy treatments are rigorously compared with the real thing - suggests the patch shows real promise in children with Tourette's syndrome, a strange affliction in which victims are beset by spates of tics, shouted obscenities and violent urges.
Still, nicotine has many drawbacks, including its unsavory reputation as the addictive grabber in cigarettes. Some experts believe nicotine's real future is in fake forms of the drug.
''The problem with nicotine is that it is nicotine. You're asking parents to put their kids on nicotine,'' said Dr. Paul R. Sanberg of the University of South Florida, who has tested the drug on more than 100 young Tourette's patients.
Typically, doctors treat Tourette's with Haldol, a powerful tranquilizer that is also used against schizophrenia. In the latest study, Sanberg and colleagues combined nicotine patches and Haldol in 70 children, half of whom got dummy patches.
The study found those on nicotine did better and were able to control their symptoms with lower than usual doses of Haldol. ''The data suggest that a low-dose nicotine patch may be useful in Tourette's syndrome,'' said Sanberg.
He and others experimenting with nicotine described their research at a conference in Washington sponsored by the American Association for the Advancement of Science.
Nicotine patches and gum are available in drugstores without prescriptions. They are intended to help smokers wean themselves off cigarettes.
The researchers cautioned that smoking is a bad way to get medical nicotine. Besides the obvious cancer risk, drug levels spike much higher in cigarettes.
They also say more research is needed before nicotine patches become routine to treat diseases. However, Sanberg said that if Tourette's patients cannot control their symptoms with standard drugs, a low-dose patch might be worth trying.
Nicotine has been tested for many years in small-scale experiments against Alzheimer's disease and more recently against Parkinson's disease. Parkinson's causes tremors, rigid limbs and a shuffling walk, and like Alzheimer's, it may also result in problems with memory and thinking.
Dr. Paul Newhouse of the University of Vermont tried nicotine patches on 15 Parkinson's patients. Although there was no comparison group, his pilot study suggested that nicotine substantially improved their movement and relieved their mental difficulties.
Newhouse also tested a synthetic form of nicotine, Abbott Laboratories' ABT-418, on six Alzheimer's patients. Despite its small size, Newhouse said patients showed ''a significant improvement in verbal learning and memory'' on standardized tests.
Since no drug firms have exclusive rights to nicotine, researchers say companies have little interest in paying for studies to prove its health benefits. However, several are working on nicotine substitutes that can be patented. These drugs could be more precisely targeted against specific disorders, carry fewer side effects and be available as pills rather than patches.
Nicotine is thought to work by regulating the brain's levels of message-carrying chemicals, such as dopamine and acetylcholine. Researchers say they see no sign that patients get hooked on the patch. The main side effects are nausea and itching around the patch.
Another drawback of the patch is the possibility it might trigger heart attacks, as the much higher nicotine in cigarettes can. Sanberg said that in his studies, children's heart rates rise about 10 percent, but they show no other obvious heart effects.
