The influence of smoking on the risk of Alzheimer's disease.
OBJECTIVE
To investigate the relationship between cigarette smoking and Alzheimer's disease (AD) in a prospective community-based study in northern Manhattan.


BACKGROUND
Results from previous case-control studies suggest that there is a protective effect of smoking on AD. However, the recent prospective Rotterdam Study found that there was an increased risk of AD for smokers, particularly those without an apolipoprotein E (APOE)-epsilon4 allele.


METHODS
The authors examined data from a community-based longitudinal study of local elders residing in northern Manhattan to determine whether tobacco use increases or decreases the risk of AD. Information regarding the frequency of tobacco use was obtained in structured interviews at the baseline assessment. Standardized clinical assessments were subsequently completed on each subject at annual visits during which incident cases of AD were identified.


RESULTS
The relative risk (RR) of AD among former smokers was 0.7 (95% CI, 0.5 to 1.1). The RR among current smokers was 1.9 (95% CI, 1.2 to 3.0). Smokers without an APOE-epsilon 4 allele had the highest risk of AD (RR = 2.1; 95% CI, 2.1 to 3.7) compared with those with an APOE-epsilon 4 allele (RR = 1.4; 95% CI, 0.6 to 3.3).


CONCLUSIONS
Our results are consistent with the observation that smoking increases the risk of AD. However, we found that among previous smokers who quit smoking, there may be a slight reduction in the risk of AD.
Merchant
C
C
Gertrude H. Sergievsky Center, Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Tang
M X
MX
Albert
S
S
Manly
J
J
Stern
Y
Y
Mayeux
R
R
D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D000544:Alzheimer Disease / Q000209:etiology* / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*
D001057:Apolipoproteins E