Table 2 Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident young-onset dementia across abdominal obesity categories defined by waist circumference

All-cause dementia

< 75

413,249

1,320

3,306,210

0.40

1 (Ref.)

1 (Ref.)

1 (Ref.)

< 85

398,540

2,048

3,053,504

0.67

1.19 (1.11‒1.27)

1.19 (1.11‒1.28)

1.13 (1.05‒1.21)

< 95

129,472

905

955,556

0.95

1.41 (1.30‒1.54)

1.41 (1.29‒1.53)

1.24 (1.14‒1.36)

≥ 95

23,275

222

169,816

1.31

1.92 (1.67‒2.22)

1.90 (1.65‒2.19)

1.55 (1.34‒1.79)

P for trend < 0.0001

P for trend < 0.0001

P for trend < 0.0001

Per 1 cm increase in waist circumference

1.043 (1.040–1.046)

1.019 (1.015–1.022)

1.012 (1.008–1.016)

Alzheimer’s disease

< 75

413,249

922

3,306,210

0.28

1 (Ref.)

1 (Ref.)

1 (Ref.)

< 85

398,540

1,353

3,053,504

0.44

1.10 (1.01‒1.20)

1.11 (1.02‒1.20)

1.06 (0.98‒1.16)

< 95

129,472

616

955,556

0.64

1.34 (1.21‒1.49)

1.34 (1.21‒1.48)

1.21 (1.09‒1.35)

≥ 95

23,275

147

169,816

0.87

1.78 (1.49‒2.12)

1.76 (1.47‒2.09)

1.49 (1.25‒1.78)

P for trend < 0.0001

P for trend < 0.0001

P for trend < 0.0001

Per 1 cm increase in waist circumference

1.042 (1.037–1.046)

1.016 (1.011–1.020)

1.010 (1.006–1.015)

Vascular dementia

< 75

413,249

202

3,306,210

0.06

1 (Ref.)

1 (Ref.)

1 (Ref.)

< 85

398,540

405

3,053,504

0.13

1.66 (1.40‒1.97)

1.66 (1.40‒1.97)

1.50 (1.26‒1.78)

< 95

129,472

174

955,556

0.18

1.99 (1.62‒2.44)

1.99 (1.62‒2.45)

1.58 (1.28‒1.95)

≥ 95

23,275

42

169,816

0.25

2.68 (1.92‒3.75)

2.66 (1.90‒3.72)

1.83 (1.30‒2.57)

P for trend < 0.0001

P for trend < 0.0001

P for trend < 0.0001

Per 1 cm increase in waist circumference

1.054 (1.046–1.061)

1.036 (1.028–1.044)

1.024 (1.015–1.032)