When the analysis was restricted to APOE ε4-positive Betula cohort participants , the study revealed that those in the third (> 17.0–26.0 μg/m3) and fourth (> 26.0 μg/m3) quartiles of NOX exposure had a 59% and 48% elevated risk, respectively, for incident dementia compared to the first quartile (4.8–9.0 μg/m3)54. Here, APOE is linked to dementia.