APOE and vitamin B12 deficiency: Thus, we observed that for each year increase in the age of hypothyroidism onset, the adjusted odds of having a later age of AD onset increased by a factor of: 1.09 (95% CI: 1.05–1.12) after adjusting for history of vitamin B12 deficiency, 1.08 (1.05, 1.12) after adjusting for sex, 1.09 (1.05, 1.13) after adjusting for history of OSA, 1.10 (1.05, 1.14) after adjusting for BMI, 1.10 (1.06, 1.14) after adjusting for level of intellectual disability, and 1.09 (1.05, 1.14) after adjusting for APOE Ɛ4 status.