Heavy smoking doubles dementia riskQuitting lowers it
Heavy smoking in middle age more than doubles your risk of developing Alzheimers and other types of dementia, a large study has found.
Although smoking increases the risks of death and most diseases, its effect on brain health has not been extensively studied.
Researchers in Finland and the US tracked the health of more than 21,000 men and women aged between 50 and 60 for around 23 years.
Compared with non-smokers, those who smoked more than two packets of 20 cigarettes a day had more than a 157 per cent increased risk of vascular dementia.
Smoking was associated with a higher risk of dementia overall, as well as a higher risk of developing each of the sub-types.
Vascular dementia is the second most common form of dementia after Alzheimers disease, and is caused by conditions which affect the blood supply to the brain.
Former smokers, or those who smoked less than half a pack per day, did not appear to be at increased risk of disease.
The association between smoking and dementia was true after adjusting for race, gender, weight, high blood pressure, heart attack and other medical conditions.
As smoking is a well-known risk factor for stroke, a condition caused by an interrupted blood flow to the brain, it may also contribute to dementia risk through similar mechanisms, the researchers said. Smoking may also increase the risk of brain inflammation, increasing the risk of Alzheimers.
"This study shows that the brain is not immune to the long-term consequences of heavy smoking," said Dr Rachel Whitmer a research scientist at Kaiser Permanente's Division of Research in Oakland, California, who led the study.
"We have known that smoking is a risk factor for cancer, stroke and cardiovascular disease," she said. "This adds to the evidence that what is bad for the heart is bad for the brain."
This article was published on Tue 26 October 2010
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