Adjusted HRs (95% CI) of all-cause dementia and its subtypes according to quartiles of the TBV-to-ICV ratio
| TBV/ICV (%) | No of subjects | No of events | HR (95% CI) | |
| Model 1† | Model 2‡ | |||
| All-cause dementia | ||||
| Q1 (71.54–76.81) | 289 | 51 | 3.60 (1.59 to 8.14)* | 3.36 (1.48–7.65)* |
| Q2 (76.82–78.43) | 290 | 33 | 2.41 (1.07 to 5.41)* | 2.31 (1.02–5.20)* |
| Q3 (78.44–79.80) | 290 | 21 | 2.28 (1.001 to 5.20)* | 2.10 (0.92–4.84) |
| Q4 (79.81–85.48) | 289 | 8 | 1.00 (Reference) | 1.00 (Reference) |
| P for trend=0.002 | P for trend=0.003 | |||
| Alzheimer’s disease | ||||
| Q1 (71.54–76.81) | 289 | 37 | 4.20 (1.53 to 11.53)* | 4.09 (1.48–11.31)* |
| Q2 (76.82–78.43) | 290 | 24 | 2.72 (0.996 to 7.41) | 2.66 (0.97–7.31) |
| Q3 (78.44–79.80) | 290 | 17 | 2.93 (1.07 to 8.02)* | 2.70 (0.98–7.50) |
| Q4 (79.81–85.48) | 289 | 5 | 1.00 (Reference) | 1.00 (Reference) |
| P for trend=0.01 | P for trend=0.01 | |||
| Vascular dementia | ||||
| Q1 (71.54–76.81) | 289 | 6 | 1.86 (0.31 to 11.34) | 1.54 (0.26–9.29) |
| Q2 (76.82–78.43) | 290 | 4 | 1.25 (0.21 to 7.34) | 1.16 (0.20–6.83) |
| Q3 (78.44–79.80) | 290 | 2 | 0.81 (0.11 to 5.81) | 0.72 (0.10–5.32) |
| Q4 (79.81–85.48) | 289 | 2 | 1.00 (Reference) | 1.00 (Reference) |
| P for trend=0.37 | P for trend=0.47 | |||
*P<0.05 vs Q4.
†Model 1: adjusted for age and sex.
‡Model 2: adjusted for age, sex, education status, systolic blood pressure, antihypertensive medication, diabetes mellitus, serum total cholesterol, body mass index, ECG abnormalities, cerebrovascular lesions on MRI, smoking habits, alcohol intake and regular exercise.
ICV, intracranial volume; TBV, total brain volume.