Table 2.
Associations between categories of 10 year mean residential exposure to road traffic and railway noise at the most (Ldenmax) and least (Ldenmin) exposed façades of buildings and risk of all cause dementia and different dementia subtypes
| Noise exposure (10 year) by category | All cause dementia | Alzheimer’s disease | Vascular dementia | Parkinson’s disease dementia | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No of cases | Hazard ratio (95% CI)* | No of cases | Hazard ratio (95% CI)* | No of cases | Hazard ratio (95% CI)* | No of cases | Hazard ratio (95% CI)* | ||||
| Road | |||||||||||
| Ldenmax (dB): | |||||||||||
| <45 (reference) | 9718 | 1 | 2799 | 1 | 827 | 1 | 242 | 1 | |||
| 45-50 | 13 500 | 1.09 (1.06 to 1.12) | 4081 | 1.10 (1.04 to 1.15) | 1090 | 1.03 (0.94 to 1.13) | 287 | 0.94 (0.79 to 1.12) | |||
| 50-55 | 21 738 | 1.16 (1.13 to 1.19) | 6798 | 1.19 (1.14 to 1.25) | 1754 | 1.10 (1.01 to 1.20) | 463 | 1.03 (0.88 to 1.21) | |||
| 55-60 | 24 533 | 1.17 (1.14 to 1.20) | 7427 | 1.17 (1.12 to 1.22) | 2084 | 1.17 (1.08 to 1.27) | 519 | 1.07 (0.92 to 1.25) | |||
| 60-65 | 21 196 | 1.16 (1.13 to 1.19) | 6242 | 1.14 (1.09 to 1.19) | 1802 | 1.18 (1.08 to 1.28) | 443 | 1.10 (0.94 to 1.29) | |||
| ≥65 | 12 815 | 1.16 (1.13 to 1.19) | 3872 | 1.16 (1.11 to 1.22) | 1107 | 1.19 (1.09 to 1.31) | 238 | 1.04 (0.87 to 1.25) | |||
| Ldenmin (dB) | |||||||||||
| <40 (reference) | 18 136 | 1 | 4902 | 1 | 1475 | 1 | 394 | 1 | |||
| 40-45 | 30 306 | 1.12 (1.10 to 1.14) | 8608 | 1.10 (1.06 to 1.14) | 2621 | 1.19 (1.12 to 1.27) | 619 | 1.10 (0.96 to 1.25) | |||
| 45-50 | 27 261 | 1.18 (1.16 to 1.20) | 8403 | 1.22 (1.17 to 1.26) | 2239 | 1.20 (1.12 to 1.28) | 580 | 1.18 (1.03 to 1.35) | |||
| 50-55 | 18 005 | 1.21 (1.19 to 1.24) | 5985 | 1.30 (1.25 to 1.36) | 1567 | 1.31 (1.21 to 1.41) | 402 | 1.26 (1.08 to 1.46) | |||
| ≥55 | 9792 | 1.18 (1.15 to 1.21) | 3321 | 1.27 (1.22 to 1.34) | 762 | 1.14 (1.04 to 1.25) | 197 | 1.16 (0.96 to 1.39) | |||
| Railway | |||||||||||
| Ldenmax (dB): | |||||||||||
| <40 (reference) | 75 690 | 1 | 22819 | 1 | 6409 | 1 | 1603 | 1 | |||
| 40-45 | 4441 | 1.09 (1.06 to 1.12) | 1287 | 1.02 (0.96 to 1.08) | 387 | 1.14 (1.03 to 1.26) | 117 | 1.43 (1.18 to 1.72) | |||
| 45-50 | 5844 | 1.11 (1.08 to 1.14) | 1737 | 1.06 (1.01 to 1.12) | 488 | 1.10 (1.00 to 1.20) | 122 | 1.17 (0.97 to 1.41) | |||
| 50-55 | 8040 | 1.19 (1.16 to 1.22) | 2491 | 1.20 (1.15 to 1.26) | 656 | 1.13 (1.04 to 1.23) | 149 | 1.16 (0.98 to 1.38) | |||
| 55-60 | 5577 | 1.19 (1.16 to 1.23) | 1695 | 1.20 (1.15 to 1.27) | 403 | 0.99 (0.90 to 1.10) | 134 | 1.49 (1.25 to 1.78) | |||
| ≥60 | 3908 | 1.16 (1.12 to 1.20) | 1190 | 1.16 (1.10 to 1.23) | 321 | 1.09 (0.97 to 1.22) | 67 | 1.07 (0.84 to 1.37) | |||
| Ldenmin (dB): | |||||||||||
| <40 (reference) | 86 286 | 1 | 25808 | 1 | 7309 | 1 | 1845 | 1 | |||
| 40-45 | 6049 | 1.12 (1.09 to 1.15) | 1866 | 1.12 (1.06 to 1.17) | 505 | 1.10 (1.00 to 1.20) | 149 | 1.39 (1.17 to 1.64) | |||
| 45-50 | 6302 | 1.17 (1.14 to 1.20) | 1973 | 1.20 (1.15 to 1.26) | 467 | 1.01 (0.92 to 1.11) | 102 | 0.98 (0.80 to 1.20) | |||
| ≥50 | 4863 | 1.16 (1.12 to 1.19) | 1572 | 1.24 (1.17 to 1.30) | 383 | 1.03 (0.93 to 1.14) | 96 | 1.19 (0.96 to 1.47) | |||
Model 2 adjusted for age (by design), sex, calendar year, civil status, income, region of origin, occupational status, proportion of high quality green space, and a number of area level socioeconomic variables: percentage population with low income, only basic education, unemployment, manual labour occupation, single parent, and a criminal record, as well as mutual adjustment for road traffic and railway noise. All covariates, apart from sex and region of origin, were included in the model as time varying variables.