Table 5 General characteristics, cognitive performance, serum B vitamin biomarkers and oxidative biomarkers of study populations for DNA methylation discovery and validation

Age

60.0 ± 2.4

61.4 ± 2.9

0.481

59.6 ± 3.0

59.6 ± 3.4

1.000

Gender (M/F)

3/4

2/3

1

40/62

40/28

0.041*

Education years

9.1 ± 3.3

10.8 ± 1.6

0.474

9 (9, 12)

11 (9, 15)

0.582

BMI (kg/m²)

26.0 ± 2.3

24.1 ± 2.4

0.386

24.2 ± 2.5

25.0 ± 2.7

0.134

Current smoker, n(%)

3 (42.9%)

2 (40.0%)

1

25 (24.5%)

25 (36.8%)

0.226

Current drinker, n(%)

1 (14.3%)

2 (40.0%)

0.572

19 (18.6%)

32 (47.1%)

< 0.001*

Diabetes, n(%)

3 (42.9%)

0 (0.0%)

0.407

20 (19.6%)

8 (11.8%)

0.375

Hypertension, n(%)

3 (42.9%)

2 (40.0%)

1

31 (31.4%)

22 (32.3%)

0.842

CHD, n(%)

2 (28.6%)

0 (0.0%)

0.416

5 (4.9%)

2 (2.9%)

0.691

MMSE

28.0 (24.0, 29.0)

28.0 (29.0, 29.0)

0.411

28.0 (27.0, 29.0)

28.5 (27.0, 30.0)

0.226

MoCA

20.3 ± 2.8

26.6 ± 0.9

0.005*

22.4 ± 3.0

26.1 ± 2.3

< 0.001*

AVLT-IR

13.3 ± 4.1

16.8 ± 2.8

0.323

15.3 ± 4.5

18.4 ± 4.7

< 0.001*

AVLT-SR

4.6 ± 3.6

6.4 ± 1.5

0.474

5.1 ± 2.7

6.4 ± 2.3

0.003*

AVLT-LR

3.9 ± 4.0

3.8 ± 2.7

0.96

4 (2, 7)

6 (3, 8)

0.007*

SDMT

30.4 ± 14.3

41.2 ± 8.6

0.336

33 (25, 40)

37 (31, 46)

0.015*

LMT

8.0 ± 3.6

16.2 ± 3.1

0.010*

10.0 (5.5, 13.0)

14.5 (10.0, 16.5)

< 0.001*

DSF

6.5 ± 1.0

8.8 ± 0.8

0.010*

7.2 ± 1.3

7.9 ± 1.5

0.008*

DSB

4.3 ± 1.0

4.8 ± 0.4

0.474

4 (3, 5)

4 (4, 5)

0.016*

Vitamin B₆ (mg/day)

1.9 (1.4, 2.0)

2.6 (1.5, 2.8)

0.596

2.2 (1.8, 2.6)

2.2 (1.7, 2.7)

0.720

Folate (μg/day)

311.6 (203.6, 496.4)

577.2 (239.4, 705.0)

0.596

307.5 (242.6, 442.7)

376.7 (271.8, 532.5)

0.019*

Vitamin B₁₂ (μg/day)

1.2 (0.3, 2.8)

3.2 (1.8, 3.9)

0.427

2.0 (1.3, 2.9)

2.0 (1.2, 3.1)

0.936

Vitamin B₆ (ng/L)

650.3 ± 125.0

542.3 ± 108.5

0.326

618.6 (531.2, 709.2)

596.5 (514.0, 645.9)

0.193

Folate (μg/L)

15.0 ± 5.6

30.2 ± 3.7

0.003*

17.4 (11.2, 22.8)

32.2 (28.0, 35.6)

< 0.001*

Vitamin B₁₂ (ng/L)

184.0 (113.0, 305.0)

284.0 (216.0, 333.5)

0.573

211.5 (174.8, 262.9)

198.5 (143.5, 256.3)

0.321

Hcy (μmol/L)

22.5 ± 2.9

9.8 ± 2.8

< 0.001*

21.1 (18.3, 23.4)

9.4 (6.7, 11.9)

< 0.001*

ROS (IU/ml)

1000.8 ± 345.3

779.1 ± 424.8

0.474

1043.8 (780.2, 1209.5)

728.0 (493.8, 964.8)

< 0.001*

MDA (mmol/L)

10.0 ± 1.7

7.0 ± 3.5

0.225

9.7 ± 2.8

8.1 ± 2.6

0.003*

8-OHdG (ng/L)

338.1 ± 112.2

185.2 ± 46.3

0.061

271.0 (201.1, 341.1)

151.2 (125.9, 176.7)

< 0.001*

8-iso-PGF2α (ng/L)

221.6 ± 59.1

118.2 ± 56.22

0.049*

188.0 (152.0, 279.6)

114.0 (90.3, 144.3)

< 0.001*