Smoking doesn't lessen Alzheimer's disease risk

"If anything, persistent smoking may increase rather than decrease the (risk) of dementia," write Richard Doll and colleagues from Radcliffe Infirmary in Oxford, UK. But the researchers note that the effect in either direction is likely to be small.

Alzheimer's disease is a degenerative neurological illness characterized by deteriorations in memory, personality, and day-to-day functioning.

The investigators studied death certificates of 24,133 British doctors who participated in a long-term health study, looking for evidence associating smoking with the development of Alzheimer's disease or other forms of dementia. Their findings are published in the April 22nd issue of the British Medical Journal.

While admitting the difficulty distinguishing between the various types of dementia listed on death certificates, the authors report finding no significant relation between any dementia and smoking.

When they looked specifically at Alzheimer's disease, the investigators found no association, positive or negative, between smoking and dementia. The proportion of doctors who smoked was identical among the Alzheimer's cases and among the doctors without Alzheimer's.

Doll and colleagues conclude that "persistent smoking does not reduce the age specific onset rate of the disease or of dementia in general to any substantial extent."

"The public health message is clear," Carol Brayne of the Institute of Public Health in Cambridge, UK, concludes in a related editorial, "at the population level there is no protective effect of smoking in dementia."