Trends in prevalence of Alzheimer's disease and vascular dementia in a Japanese community: the Hisayama Study.
OBJECTIVE
To examine secular trends in the prevalence of Alzheimer's disease (AD) and vascular dementia (VD) in a general Japanese population.


METHODS
Four cross-sectional examinations were conducted among residents of a Japanese community aged >or=65 in 1985, 1992, 1998 and 2005.


RESULTS
The age- and sex-adjusted prevalence of all-cause dementia significantly increased with time (6.0% in 1985, 4.4% in 1992, 5.3% in 1998 and 8.3% in 2005; P for trend = 0.002). A similar trend was observed for AD (1.1%, 1.3%, 2.3% and 3.8% respectively; P for trend < 0.001), while the age- and sex-adjusted prevalence of VD and other/unclassified dementia showed J-shaped patterns (for VD: 2.3%, 1.5%, 1.5% and 2.5%, respectively, P for trend = 0.82; for other/unclassified dementia: 2.6%, 1.7%, 1.5% and 2.0%, P for trend = 0.26). The prevalence of AD was likely to increase with time from 1985 to 2005 among subjects aged 75 or older. The ratio of the prevalence of VD to that of AD decreased with time (2.1 in 1985, 1.2 in 1992, 0.7 in 1998 and 0.7 in 2005).


CONCLUSIONS
Our findings suggest that the prevalence of all-cause dementia and AD significantly increased over the past two decades in the general Japanese population.
Sekita
A
A
Department of Environmental Medicine, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka City, Japan.
Ninomiya
T
T
Tanizaki
Y
Y
Doi
Y
Y
Hata
J
J
Yonemoto
K
K
Arima
H
H
Sasaki
K
K
Iida
M
M
Iwaki
T
T
Kanba
S
S
Kiyohara
Yutaka
Y
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D015140:Dementia, Vascular / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D009483:Neuropsychological Tests; D011157:Population Dynamics; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012737:Sex Factors