Smoking could predispose people to dementia, not protect them as has been suggested in the past. This is the conclusion from lab experiments in which rats with brain plaques developed further symptoms of Alzheimer鈥檚 when given nicotine.
In Alzheimer鈥檚 disease, the brain becomes riddled with amyloid protein plaques and tangles of tau proteins. Low doses of nicotine have been shown to reduce the number of plaques in rats, but till now little was known about the effect of nicotine on the protein tangles.
To find out, Yan-Jiang Wang鈥檚 team at the Third Military Medical University in Chongqing, China, injected amyloid plaques into the brains of healthy rats and gave some the equivalent of a smoker鈥檚 daily dose of nicotine for two weeks, while others received nothing.
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All the rats showed early signs of tau tangles and had difficulty navigating a maze, but the rats that were on nicotine did worse than those that were not.
Smokers take note
, of the Brain and Mind Research Institute at the University of Sydney, Australia, says the results are likely to have implications for humans.
Some previous studies, many of them funded by tobacco companies, have indicated that smokers are less likely to develop Alzheimer鈥檚. But when a team of researchers re-examined 43 studies earlier this year, discounting the industry-funded ones, they concluded that smoking actually increases the risk of Alzheimer鈥檚
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