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Second-hand smoke linked to dementia, study reveals

Exposure to second-hand smoke could increase the risk of developing dementia and other forms of cognitive impairment, according to new shock research published today.

The research, published by the British Medical Journal, highlighted a 44% increase in risk of cognitive impairment when exposed to high levels of second-hand smoke.

Previous research has highlighted the increased risk of dementia to active smokers, but this is the first time a link has been made |between second-hand smoke |exposure and development of |dementia and other neurological problems in elderly non-smokers.

Gerry McElwee, Head of Cancer Prevention at the Ulster Cancer Foundation (UCF), said: “This research adds further evidence to the already large volume of research into the damage caused to non-smokers by second-hand smoke.”

Mr McElwee said the report consolidates UCF's campaign to extend smokefree provision to protect people from second-hand smoke in public areas.

The research, carried out by Dr David Llewellyn and his colleagues at Cambridge University, measured levels of cotinine — a by-product of nicotine — in saliva samples of nearly 5,000 non-smoking adults over the age of 50, to ascertain levels of exposure to second-hand smoke.

Conducting a range of neuro-psychological tests, they were able to assess aspects of brain function including verbal memory and fluency, and numerical calculations.

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These results were added |together to provide a global score for cognitive function.

Those whose scores were in the lowest 10% were identified as suffering from cognitive impairment.

From their results, Dr Llewellyn and his team concluded exposure to second-hand smoke may be linked to an increased chance of developing dementia and other cognitive impairments.

There are believed to be a number of explanations for this, |including the fact that passive smoking increases the risk of heart disease and stroke — both of which are known to increase the likelihood of neurological problems like dementia.

Dr Llewellyn said: “Our results suggest that inhaling other people's smoke may damage the brain, impair cognitive functions such as memory, and make dementia more likely.

“Given that passive smoking is also linked to other serious health problems such as heart disease and stroke, smokers should avoid lighting up near non-smokers.”

The results join previous |research showing exposure to second-hand smoke can impair cognitive development in children and adolescents and a highly publicised anti-smoking campaign by the Health Promotion Agency.

Rebecca Wood, chief executive of the Alzheimer's Research Trust, said: “Previous research shows that smoking increases our risk of developing dementia, and this new study reveals that this danger exists even when the smoke is second-hand.

“Everyone can lower their risk of disease by stopping smoking, eating healthily and exercising.”

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