APOE and diabetes mellitus: Mediation analysis indicated that FW had a significant indirect effect (β = −0.0010, 95 % CI: −0.0034, −0.0001), accounting for 13.89 % of the relationship between IHD and ADNI-EF slope after adjusting for age, sex, education, right handedness, APOE ε4, hypertension, diabetes mellitus, hyperlipidemia, smoking, atrial fibrillation, and heart failure (Fig. 3).