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Table 2 Age-specific prevalence of dementia and mild cognitive impairment at baseline among overall participants and by sex

From: Study design and baseline characteristics of a population-based prospective cohort study of dementia in Japan: the Japan Prospective Studies Collaboration for Aging and Dementia (JPSC-AD)

Age group, years

Number of subjects

Number of cases of dementia (prevalencea)

Number of cases of MCI (prevalencea)

Number of subjects with missing data (%)a

Overall

 65–69

3728

33 (0.9%)

314 (8.4%)

2 (0.05%)

 70–74

2758

65 (2.4%)

364 (13.2%)

4 (0.15%)

 75–79

2218

114 (5.1%)

494 (22.3%)

2 (0.09%)

 80–84

1462

231 (15.8%)

441 (30.2%)

1 (0.07%)

 85–89

816

279 (34.2%)

229 (28.1%)

3 (0.37%)

 ≥ 90

428

245 (57.2%)

92 (21.5%)

0 (0.00%)

Total

11,410

967 (8.5%)

1934 (17.0%)

12 (0.11%)

Men

 65–69

1648

15 (0.9%)

198 (12.0%)

2 (0.12%)

 70–74

1209

31 (2.6%)

205 (17.0%)

1 (0.08%)

 75–79

936

43 (4.6%)

242 (25.9%)

2 (0.21%)

 80–84

590

90 (15.3%)

186 (31.5%)

0 (0.00%)

 85–89

283

83 (29.3%)

85 (30.0%)

1 (0.35%)

 ≥ 90

116

53 (45.7%)

34 (29.3%)

0 (0.00%)

Total

4782

315 (6.6%)

950 (19.9%)

6 (0.13%)

Women

 65–69

2080

18 (0.9%)

116 (5.6%)

0 (0.00%)

 70–74

1549

34 (2.2%)

159 (10.3%)

3 (0.19%)

 75–79

1282

71 (5.5%)

252 (19.7%)

0 (0.00%)

 80–84

872

141 (16.2%)

255 (29.2%)

1 (0.11%)

 85–89

533

196 (36.8%)

144 (27.0%)

2 (0.38%)

 ≥ 90

312

192 (61.5%)

58 (18.6%)

0 (0.00%)

Total

6628

652 (9.8%)

984 (14.9%)

6 (0.09%)

  1. MCI mild cognitive impairment
  2. aFor the calculation of prevalence, subjects with missing cognitive function data were assigned neither to the category of dementia nor the category of MCI
  3. bValues are shown as the number (percentage) of subjects with missing cognitive function data