Fig. 2. Differential effects of CBF, CT, and APOE on baseline memory and memory change.

Three-way interaction plots with simple slopes (mean ±1SD) showing that the combination of higher CBF and lower CT among ε4 carriers is associated with worse memory performance at baseline, but with greater memory stability over time. In contrast, the combination of lower CBF and lower CT at baseline among ε4 carriers is associated with greater memory decline over time. These differential findings suggest that compensatory increases in CBF at baseline among ε4 carriers with lower cortical reserve (although associated with worse baseline memory) are supportive of memory function over time, whereas relative reductions in CBF among this same group are associated with memory decline, likely reflecting an absence or breakdown of cerebrovascular compensatory mechanisms. Note: EC= Entorhinal cortex; APOE= Apolipoprotein E gene; CBF= Cerebral blood flow; CT= Cortical thickness; std= Z-score standardization; SD= standard deviation; t= t-statistic; p= p-value; n.s.= not significant; +Denotes marginal simple slope significance at p<0.10; **Denotes simple slope significance at p<0.01