Table 2

HRs and 95% CIs of all-cause dementia and its subtypes according to serum total homocysteine levels

Serum total homocysteine levels (µmol/L)No. of eventsPerson-yearsCrude incidence rate, /103 person-yearsHR (95% CI)
Age-adjusted and sex-adjustedP valueMultivariable-adjusted*P value
All-cause dementia
 Quintile 1 (≤6.4)54309217.51.00 (reference)1.00 (reference)
 Quintile 2 (6.5–7.6)55273620.11.09 (0.75 to 1.59)0.641.13 (0.77 to 1.66)0.53
 Quintile 3 (7.7–9.0)68303522.41.15 (0.80 to 1.65)0.461.25 (0.85 to 1.82)0.25
 Quintile 4 (9.1–11.4)80262030.51.31 (0.91 to 1.87)0.151.38 (0.93 to 2.03)0.11
 Quintile 5 (≥11.5)115210954.52.14 (1.49 to 3.07)<0.0012.28 (1.51 to 3.43)<0.001
 P value for trend†<0.001<0.001
Alzheimer's disease
 Quintile 1 (≤6.4)40309212.91.00 (reference)1.00 (reference)
 Quintile 2 (6.5–7.6)39273614.21.07 (0.68 to 1.66)0.771.13 (0.72 to 1.78)0.59
 Quintile 3 (7.7–9.0)46303515.11.09 (0.71 to 1.69)0.681.12 (0.71 to 1.76)0.62
 Quintile 4 (9.1–11.4)53262020.21.20 (0.78 to 1.85)0.401.28 (0.80 to 2.04)0.31
 Quintile 5 (≥11.5)69210932.71.83 (1.18 to 2.82)0.0071.96 (1.19 to 3.24)0.008
 P value for trend†0.0020.003
Vascular dementia
 Quintile 1 (≤6.4)1430924.51.00 (reference)1.00 (reference)
 Quintile 2 (6.5–7.6)927363.30.67 (0.29 to 1.56)0.350.64 (0.27 to 1.52)0.31
 Quintile 3 (7.7–9.0)1730355.61.05 (0.51 to 2.17)0.891.37 (0.64 to 2.94)0.42
 Quintile 4 (9.1–11.4)1926207.21.17 (0.56 to 2.41)0.671.21 (0.56 to 2.63)0.63
 Quintile 5 (≥11.5)39210918.52.67 (1.34 to 5.33)0.0052.51 (1.14 to 5.51)0.02
 P value for trend†<0.0010.001
  • *Adjusted for age, sex, education, hypertension, diabetes, serum total cholesterol, body mass index, estimated glomerular filtration rate, history of stroke, current smoking, current drinking, regular exercise, serum albumin, serum folate and serum vitamin B12 levels (log-transformed).

  • †Trend tests were conducted by treating the quintiles as a continuous variable and assigning the midpoint concentration for each quintile.