Sensitivity analyses demonstrated the relationship with lower brain volume was weaker when examined in night workers (n = 51) (rather than night or shift workers, n = 74) (−14.3 mL, 95% CI −29.0, 0.3; P = 0.05) but remained similar when adjusting for APOE ɛ4 carrier status (−21.2 mL, 95% CI −33.2, −9.3; P = 0.0005), Aβ PET Centiloids (−20.0 mL, 95% CI −32.3, −7.6; P = 0.002), childhood cognition (−19.9 mL, 95% CI −31.9, −7.8; P = 0.001) and after excluding those (n = 40, Supplementary Table 4) with significant brain disorders from the analysis (−18.1 mL, 95% CI −30.4, −5.8, P = 0.004). This evidence concerns the gene APOE and brain disorder.