Fig. 1

Directed acyclic graph showing the conceptual causal mediation model of the associations between the apolipoprotein E gene ε4 allele (APOE-ε4) and cognitive abilities decomposed into a direct (blue line) and indirect pathway (red line). Confounder variables were age, sex, race, education, hypertension, diabetes, dyslipidemia, heart disease, body mass index, alcohol use, smoking, and physical activity