Scientists said they have found the first direct biological evidence that smoking destroys brain cells and stops others being produced.
Anti-smoking groups said this provided an even greater incentive to stop smoking.
French researchers led by Pier-Vincenzo Piazza and Djoher Nora Abrous, at the National Institute for Health and Medical Research (INSERM) let three groups of rats give themselves low, medium or high amounts of nicotine.
A fourth group was allowed no nicotine at all.
What is interesting is that they are saying they have found how tobacco smoking affects the body
The rats were allowed to absorb the nicotine for an hour a day for 42 days. They were then killed and their brains dissected.
Rodents that took the medium and higher doses suffered a 50% higher loss in the production of new brain cells than the non-nicotine group, as well as a significantly higher rate of brain cell death.
The researchers also found that all the rats taking nicotine suffered a fall in the protein PSA-NCAM.
This protein plays a vital part in the adaptibility of the brain and is related to an ability to learn and memorise.
The report, published in The Journal of Neuroscience said: “These results raise an important additional concern for the health consequences of nicotine abuse and open new insight on the possible neural mechanisms of tobacco addiction.”
The authors said their studies rebutted previous research in the 1990s that suggested that smoking could boost cognitive performance.
Amanda Sandford, of ASH, said the new findings should spur people to quit smoking.
“There are no great surprises there because tobacco is full of nasty chemicals.
“But what is interesting is that they are saying they have found how tobacco smoking affects the body.
“It is yet another reason for quitting at the earliest opportunity and dispels the myth that smoking helps concentration.”
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