London, July 14 : Nicotine has toxic effects and carries a strong risk of addiction, but now scientists at King's College London have found that it may hold the key to new treatments for dementia.
Researchers have shown that nicotine-based drugs could boost learning, memory and attention.
The effect is small, but researchers believe it may help give dementia patients up to six extra months of independent living.
The King's team, based at the Institute of Psychiatry, demonstrated the positive effects of nicotine in experiments on rats.
They showed that nicotine boosted the animals' ability to carry out a task accurately - particularly when they were also distracted.
When able to give full concentration, the animals responded correctly to stimuli about 80 percent of the time. Nicotine boosted the accuracy rate by about 5 percent.
However, when distracted, the animals' success rate fell to about 55 percent. In this case nicotine brought it back up to around the 85 percent level.
Researchers studied the mechanisms, which underpin the effects produced by nicotine.
They showed how proteins on the surface of cells respond to the compound, and pinned down the role of several key chemicals in the brain, including dopamine and noradrenaline.
It transpired that there are only subtle biochemical differences in the way nicotine stimulates the brain, and triggers addiction.
Several nicotinic drugs are already in development, but the King's team hopes its work will speed up the discovery of agents, which give the brain a bigger boost than nicotine, with longer lasting effects.
"Nicotine, like many other drugs, has multiple effects, some of which are harmful, whereas others may be beneficial," BBC quoted lead researcher Professor Ian Stolerman, as saying.
"It may be possible for medicinal chemists to devise compounds that provide some of the beneficial effects of nicotine while cutting out the toxic effects," he added.