International Journal of Alzheimer’s Disease

Review Article

Trends in the Prevalence of Dementia in Japan

Table 3

Prevalence of dementia (%) and its subtype by 10 years age group and by study site.


	Age 70–79		Age 80–89		Age 90 and older
Study name/site	Prevalence in percentage (95% CI)	AD/VaD ratio	Prevalence in percentage (95% CI)	AD/VaD ratio	Prevalence in percentage (95% CI)	AD/VaD ratio
(Study years)	(Number of subjects screened)	Number of cases: all subtypes combined/AD/VaD	(Number of subjects screened)	Number of cases: all subtypes combined/AD/VaD	(Number of subjects screened)	Number of cases: all subtypes combined/AD/VaD

Hisayama (1985)	3.41 (1.92–5.56)	AD/VaD = 0.13	19.50 (13.65–26.52)	AD/VaD = 0.75	57.14 (28.86–82.34)	AD/VaD = 2.50
Hisayama (1985)	(440)	15/1/8	(159)	31/6/8		8/5/2
Hisayama 992	3.35 (2.00–5.25)	AD/VaD = 0.22	13.39 (9.34–18.37)	AD/VaD = 1.44	46.43 (27.51–66.13)	AD/VaD = 6.00
Hisayama 992	(537)	18/2/9	(239)	32/13/9		13/6/1
Okinawa (1991-1992)	3.67 (2.32–5.02)	AD/VaD = 0.59	14.93 (10.97–18.89)	AD/VaD = 2.10	36.83 (28.08–45.58)	AD/VaD = 3.66
Okinawa (1991-1992)	(1481)*	45/16/27	(619)*	81/42/20		37/22/6
Hiroshima (1992–1996)	5.67 (4.09–7.66)	AD/VaD = 0.93	19.04 (14.97–23.87)	AD/VaD = 2.64	41.67 (26.97–61.50)	AD/VaD = 4.66
Hiroshima (1992–1996)	(741)	42/13/14	(	75/45/17		25/14/3
Hisayama (1998)	3.99 (2.65–5.76)	AD/VaD = 1.71	16.84 (12.76–21.59)	AD/VaD = 1.92	35.59 (23.55–49.13)	AD/VaD = 3.33
Hisayama (1998)	(676)	27/12/7	(	50/25/13		21/10/3
Tajiri (1998)	5.18 (3.80–6.93)	AD/VaD = N/A	22.33 (17.37–28.26)	AD/VaD = 1.50	51.52 (30.00–82.51)	AD/VaD = N/A
Tajiri (1998)	(908)	7/3/0^#		22/12/8^#	(	N/A
Hisayama (2005)	6.86 (5.13–8.94)	AD/VaD = 2.40	27.74 (20.50–29.37)	AD/VaD = 1.84	53.49 (42.41–64.32)	AD/VaD = 1.71
Hisayama (2005)	(729)	50/24/10		95/46/25		46/24/14
Ama-cho study (2008)	6.7 (4.12–9.02)	AD/VaD = 1.75	17.8 (14.81–26.41)	AD/VaD = 11.33	41.3 (26.51–61.52)	AD/VaD = 4.50
Ama-cho study (2008)	(432)	29/14/8		49/34/3		24/18/4

AD/VaD: the number of AD cases/the number of VaD cases.
^#Based on subsample analysis with MRI results.
N/A: sample size is too small to perform the calculation (AD + VaD cases < 5).
*Random sampling was used for screening. reported is not weighted. Prevalence, proportions of subtypes of dementia, and AD/VaD ratio used weighted frequencies to show those of the population at large.