APOE and diabetes mellitus: Compared to the participants who only underwent the first MRI assessment, those who underwent a second MRI scan were more likely to be younger, white, have regular physical activity, have higher lung function and BMI, be an APOE ε4 non-carrier, and be diabetes- and hypertension-free (Supplementary Table 4, available at: http://links.lww.com/JS9/D766).