Table 4 Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident young-onset dementia across obesity categories defined by body mass index

All-cause dementia

< 18.5

22,568

96

179,912

0.53

1.40 (1.14‒1.73)

1.37 (1.12‒1.69)

1.39 (1.13‒1.71)

< 23

422,942

1,541

3,349,847

0.46

1 (Ref.)

1 (Ref.)

1 (Ref.)

< 25

240,476

1,196

1,851,544

0.65

1.11 (1.03‒1.20)

1.12 (1.04‒1.21)

1.08 (1.00‒1.17)

< 30

244,865

1,418

1,849,266

0.77

1.19 (1.11‒1.28)

1.20 (1.11‒1.28)

1.09 (1.01‒1.17)

≥ 30

33,685

244

254,514

0.96

1.54 (1.35‒1.77)

1.53 (1.34‒1.76)

1.26 (1.10‒1.45)

Alzheimer’s dementia

< 18.5

22,568

63

179,912

0.35

1.35 (1.05‒1.74)

1.31 (1.02‒1.69)

1.32 (1.02‒1.71)

< 23

422,942

1,063

3,349,847

0.32

1 (Ref.)

1 (Ref.)

1 (Ref.)

< 25

240,476

804

1,851,544

0.43

1.07 (0.98‒1.18)

1.08 (0.98‒1.18)

1.05 (0.96‒1.15)

< 30

244,865

954

1,849,266

0.52

1.15 (1.05‒1.25)

1.15 (1.05‒1.25)

1.07 (0.98‒1.17)

≥ 30

33,685

154

254,514

0.61

1.39 (1.18‒1.65)

1.38 (1.17‒1.64)

1.19 (1.00‒1.41)

Vascular dementia

< 18.5

22,568

12

179,912

0.07

1.05 (0.59‒1.88)

1.03 (0.58‒1.84)

1.07 (0.60‒1.92)

< 23

422,942

249

3,349,847

0.07

1 (Ref.)

1 (Ref.)

1 (Ref.)

< 25

240,476

232

1,851,544

0.13

1.40 (1.17‒1.67)

1.41 (1.17‒1.68)

1.30 (1.09‒1.56)

< 30

244,865

273

1,849,266

0.15

1.52 (1.28‒1.81)

1.52 (1.28‒1.81)

1.27 (1.06‒1.52)

≥ 30

33,685

57

254,514

0.22

2.38 (1.78‒3.17)

2.37 (1.77‒3.16)

1.65 (1.23‒2.22)