Table 1 Baseline characteristics of the cohort with cut-off value 24 for MMSE scores, 1998–2018

Age (mean (SD))

88.35 (6.66)

86.96 (6.13)

89.34 (6.85)

< 0.001

Age group (%)

< 0.001

 80–90

5569 (59.91)

2632 (68.33)

2937 (53.96)

 90–100

2749 (29.58)

975 (25.31)

1774 (32.59)

 100 + 

977 (10.51)

245 ( 6.36)

732 (13.45)

Follow-up time (mean (SD))

5.45 (4.95)

7.16 (6.10)

4.23 (3.46)

< 0.001

Education (%)

< 0.001

 Illiteracy

5760 (61.97)

1992 (51.71)

3768 (69.23)

 Literacy

3535 (38.03)

1860 (48.29)

1675 (30.77)

Gender (%)

< 0.001

 Female

4663 (50.17)

1477 (38.34)

3186 (58.53)

 Male

4632 (49.83)

2375 (61.66)

2257 (41.47)

Marital status (%)

0.193

 No

106 ( 1.14)

51 ( 1.32)

55 ( 1.01)

 Yes

9189 (98.86)

3801 (98.68)

5388 (98.99)

Residence (%)

< 0.001

 Urban

4266 (45.90)

1865 (48.42)

2401 (44.11)

 Rural

5029 (54.10)

1987 (51.58)

3042 (55.89)

Smoke (%)

< 0.001

 No

5778 (62.16)

2127 (55.22)

3651 (67.08)

 Current

2155 (23.18)

1020 (26.48)

1135 (20.85)

 Former

1362 (14.65)

705 (18.30)

657 (12.07)

Drink (%)

< 0.001

 No

6171 (66.39)

2406 (62.46)

3765 (69.17)

 Current

2156 (23.20)

1002 (26.01)

1154 (21.20)

 Former

968 (10.41)

444 (11.53)

524 ( 9.63)

Exercise (%)

< 0.001

 No

5828 (62.70)

2216 (57.53)

3612 (66.36)

 Yes

3467 (37.30)

1636 (42.47)

1831 (33.64)

ADL disability (%)

< 0.001

 No

8026 (86.35)

3446 (89.46)

4580 (84.14)

 Yes

1269 (13.65)

406 (10.54)

863 (15.86)

BMI (mean (SD))

19.99 (4.24)

20.22 (4.24)

19.82 (4.23)

< 0.001

Hypertension (%)

0.01

 No

7805 (83.97)

3189 (82.79)

4616 (84.81)

 Yes

1490 (16.03)

663 (17.21)

827 (15.19)

Diabetes (%)

0.223

 No

9179 (98.75)

3797 (98.57)

5382 (98.88)

 Yes

116 ( 1.25)

55 ( 1.43)

61 ( 1.12)

Heart disease (%)

0.036

 No

8604 (92.57)

3539 (91.87)

5065 (93.06)

 Yes

691 ( 7.43)

313 ( 8.13)

378 ( 6.94)

Cerebrovascular disease (%)

0.621

 No

9004 (96.87)

3736 (96.99)

5268 (96.78)

 Yes

291 ( 3.13)

116 ( 3.01)

175 ( 3.22)

Respiratory disease (%)

0.016

 No

8235 (88.60)

3376 (87.64)

4859 (89.27)

 Yes

1060 (11.40)

476 (12.36)

584 (10.73)

Cancer (%)

0.818

 No

9271 (99.74)

3841 (99.71)

5430 (99.76)

 Yes

24 ( 0.26)

11 ( 0.29)

13 ( 0.24)

Comorbidity (%)

< 0.001

 No

6397 (68.82)

2552 (66.25)

3845 (70.64)

 Yes

2898 (31.18)

1300 (33.75)

1598 (29.36)

Housework or childcare (%)

> 0.999

 No

7078 (76.15)

2933 (76.14)

4145 (76.15)

 Yes

2217 (23.85)

919 (23.86)

1298 (23.85)

Main financial support (%)

< 0.001

 No

3248 (34.94)

1652 (42.89)

1596 (29.32)

 Yes

6047 (65.06)

2200 (57.11)

3847 (70.68)

Living or being visited (%)

0.31

 No

704 (7.57)

305 (7.92)

399 (7.33)

 Yes

8591 (92.43)

3547 (92.08)

5044 (92.67)

MMSE scores (mean (SD))

27.64 (1.88)

27.99 (1.78)

27.40 (1.91)

< 0.001