20 April 2000

Smoking Makes You Stupid

by Kate Melville

Smoking in later life seems to be linked to intellectual impairment over the age of 65, suggests research in the Journal of Neurology Neurosurgery and Psychiatry. Some previous studies have suggested that smoking may protect against of Alzheimer's disease and dementia, both of which are associated with ageing.

In a community survey of an area of North London, the research team from the Institute of Psychiatry, London, studied over 650 people aged 65 and over. Smoking and drinking habits were recorded at the beginning of the study. Their intellectual powers were also assessed. After excluding those who already had evidence of intellectual impairment, everyone else was followed up a year later to see if there was any evidence of a decline in intellect. The test used was similar to those used to screen for dementia and Alzheimer's disease.

Of the 417 people who could be retested at the end of the 12 month period, one in 16 had suffered significant intellectual decline. After adjusting for factors known to affect brain function in older people-depression, general health, alcohol use, and educational levels-the researchers found that smokers were up to four times more likely to have evidence of significant intellectual decline than either non-smokers or former smokers. Moderate drinkers before the age of 65 were marginally less likely to experience a decline in mental powers than either heavy, or non-, drinkers.

Smoking contributes to vascular disease and atherosclerosis, conditions which narrow and harden the arteries and impair blood supply to all parts of the body, including the brain, say the authors. They conclude that the lower risk among ex-smokers suggests that right through to older age, people should be actively encouraged to stop smoking to stave off mental decline.