Nicotine may help with brain therapies

LOS ANGELES, Nov. 8 (UPI) - Scientists are beginning to unlock the powerful therapeutic secrets within nicotine, the substance infamous for its addictive properties in cigarettes.

Many research groups are finding nicotine and nicotine-like drugs are potentially effective in treating a number of disorders, from memory and learning problems to Parkinson's disease, schizophrenia, pain, attention deficit disorders, and possibly anxiety and depression.

A series of reports on nicotine compounds was presented today at the Society for Neuroscience meeting in Los Angeles.

In one major report, researchers demonstrated that a nicotine-like drug can improve learning and memory in rats, and can reverse the memory and learning loss in rats with brain damage mimicking that seen in Alzheimer's disease patients.

The rats with brain lesions performed poorly in maze tests compared with normal rats. But when they were injected with the nicotine-like compound AR-R 17779 before testing, the animals showed improved learning and "even a reversal of the impairment normally seen in these animals," reported Duke University behavioral pharmacologist Edward Levin.

He added, "We have also found nicotine itself will improve attention in Alzheimer's patients."

The AR-R 17779 compound, developed by Astra Arcus USA, of Worcester, Mass., is one of a new class of drugs aimed at combatting learning and memory disorders associated with Alzheimer's.

These drugs work by docking to specific sites of the surface of brain cells called acetylcholine receptors, long known to be important in learning and memory function. Nicotine and nicotine-like drugs can stimulate these receptors, specifically the nicotinic-type acetylcholine receptor.

Levin said, "Alzheimer's patients show a very substantial decline in nicotinic receptors."

Because AR-R 17779 docks with a specific nicotinic receptor, it acts selectively only on this subgroup of receptors, as opposed to nicotine itself, which acts on many systems throughout the body.

Levin and others think such selective nicotine compounds will have beneficial effects on cognition without the cardiovascular effects such as high blood pressure and increased heart rate.

"I don't recommend people take up or continue to smoke in order to improve their memory," Levin emphasizes. "The nicotine we use will be administered through skin patches. The other caveat is that the only currently approved use of nicotine on the market is to help people quit smoking, and other uses are still under investigation."

People should not rush out to get skin patches, he cautions. However, nicotine delivered in skin patches has not been found to be particularly addictive.

Levin's group also has done human studies looking at the effect of nicotine skin patches on adults with ADD and people with schizophrenia.

"They seem to show less cognitive symptoms, that is improved attention, with the skin patches," Levin said. Other groups and pharmaceutical companies are investigating the use of nicotinic compounds in the treatment of Parkinson's disease, pain relief and moods disorders. All indicate some potential benefit.

"We are at the beginning stage of what promises to be an exciting time in the exploration of these nicotine compounds," says Paul Newhouse, director of the Clinical Neuroscience Unit in the Department of Psychiatry at the University of Vermont in Burlington.

He said, "Due to some fine new developments in the chemistry of nicotine receptor molecules, we have a variety of new nicotine-based therapies we will be exploring for treating a variety of diseases in very specific ways.

Newhouse said, "There is a nicotinic drug in development that's good for pain, but doesn't do anything for cognition. And there are selective nicotinic compounds that work better for the motor problems of Parkinson's, and molecules that work better for cognition."

Whether these drugs turn out to be chemically useful is the key issue. Large studies still need to be done, and Newhouse added that what happens in the human trials "remains to be seen, but previous studies yield great hopes these drugs will have a positive impact on peoples' lives."

(Written by Kathleen Stein in New York City)