Smoking and dementia in male British doctors: prospective study.
OBJECTIVE
To assess the possible association between smoking and dementia.


METHODS
Prospective study.


METHODS
Cohort of British male doctors followed up since 1951.


METHODS
34 439 male British doctors, with 24 133 deaths recorded.


RESULTS
For all types of dementia combined the relative risk was 0.96 (95% confidence interval 0.78 to 1.18), based on 473 deaths at a mean age of 81 years. For probable or definite Alzheimer's disease, the relative risk in continuing smokers was 0.99 (0.78 to 1.25), based on 370 deaths at a mean age of 82 years. In aggregate, however, the other prospective studies indicate a direct, although not clearly significant, association between smoking and the onset of dementia in general and of Alzheimer's disease in particular.


CONCLUSIONS
Contrary to previous suggestions persistent smoking does not substantially reduce the age specific onset rate of Alzheimer's disease or of dementia in general. If anything, it might increase rather than decrease the rate, but any net effect on severe dementia cannot be large in either direction.
Doll
R
R
Clinical Trial Service Unit and Epidemiological Studies Unit, Radcliffe Infirmary, Oxford OX2 6HE.
Peto
R
R
Boreham
J
J
Sutherland
I
I
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000209:etiology / Q000401:mortality; D002423:Cause of Death; D015331:Cohort Studies; D003704:Dementia / Q000209:etiology* / Q000401:mortality; D006801:Humans; D008297:Male; D010820:Physicians / Q000706:statistics & numerical data; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000401:mortality