Cigarette smoking and risk of disabling dementia in a Japanese rural community: a nested case-control study.
BACKGROUND
Previous prospective cohort studies have examined the association between smoking and the risk of dementia, but the results were inconsistent.


METHODS
A prospective, nested, case-control study was conducted to examine the association between cigarette smoking and risk of disabling dementia within the cohort of 6,343 men and women aged 35-85 years. Incident dementia was documented in 208 men and women (95 cases with and 113 cases without a history of stroke). Two control subjects per case were selected by matching for sex, age and year of examination.


RESULTS
The multivariable odds ratios (95% CI) for current versus never smokers were 2.3 (1.1-4.7) for total dementia, 2.6 (0.8-8.2) for dementia with a history of stroke and 2.2 (0.8-5.7) for dementia without it, yielding no effect of stroke history on the smoking-dementia association. A dose-response relationship was noted between the years of cigarette smoking and the risk of total dementia, and a significant excess risk was found for smoking duration of >or=45 years.


CONCLUSIONS
The present prospective study suggests that long-term cigarette smoking may raise the risk of disabling dementia.
Ikeda
Ai
A
Public Health, Department of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, Osaka, Japan.
Yamagishi
Kazumasa
K
Tanigawa
Takeshi
T
Cui
Renzhe
R
Yao
Masayuki
M
Noda
Hiroyuki
H
Umesawa
Mitsumasa
M
Chei
Choylye
C
Yokota
Kimiko
K
Shiina
Yumi
Y
Harada
Mitiko
M
Murata
Keiko
K
Asada
Takashi
T
Shimamoto
Takashi
T
Iso
Hiroyasu
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D015331:Cohort Studies; D003704:Dementia / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012307:Risk Factors; D012424:Rural Population; D012907:Smoking / Q000009:adverse effects*; D013997:Time Factors