Smoking 'causes brain decline'
Smoking speeds up brain decline in the elderly, a study suggests.
The rate of decline is five times higher than in people who have never smoked, according to a group of European researchers.
Their study, published in Neurology, also found that smokers who quit greatly slowed their cognitive decline.
The findings contradict some earlier research which had suggested that nicotine could actually aid the brain.
The latest study ran a series of questions and tests called a mini-mental state examination (MMSE) designed to establish the cognitive function of men and women aged 65 and over.
Among those who never smoked, their MMSE declined .03 points a year, while for current smokers it was .16 points per year. For people who had previously quit, the MMSE declined .06 points.
Study author Alewjin Ott, of the Erasmus Medical Center, Rotterdam, in The Netherlands, said chronic tobacco use causes atherosclerosis and hypertension and that this, and other effects of smoking, increases the risk of stroke and small areas of tissue damage in the brain.
The greater the number of cigarettes smoked and the longer a person had been a smoker for, the greater the cognitive decline, Professor Ott found.
However, this was more significant for current smokers than those who had quit.
A family history of dementia did not influence the higher decline in smokers, said the researchers.
They studied data for 9,209 people in Denmark, France, The Netherlands and the UK for the European Community Concerted Action Epidemiology of Dementia (EURODEM) incidence research group.
Amanda Sandford, a spokeswoman for Action on Smoking and Health (ASH), said: "There has been other research suggesting nicotine might have some beneficial effects. It is quite a complex area."
Earlier studies had shown a positive effect against Alzheimer's, but Ms Sandford suggested this was because smokers did not live long enough.
She added: "The constant inhaling of a substance that is a poison is more likely to have a negative effect than a positive one."
Though smoking was more associated with damage to the heart and lungs, it also affected brain function, she said.
She welcomed the finding that those who had quit smoking also benefited as this emphasised that it was "never to late to quit".
However, Simon Clark, director of pro-smoking lobby Forest, said: "People will be very sceptical about these results. They will be put down to yet more scaremongering by the health industry.
"There have been so many weird reports recently and exaggerated claims that it is not going to have the slightest effect at all."