Adding FA index as a co-variate

Dear All,

Using Task-based gPPI (Seed-to-Voxel) in CONN, I am working on a combined DTI-fMRI study for two groups (YOUNG and OLD). My main interest is to see how ageing (as indexed by FA) could account for the connectivity changes in those selected seed regions. In doing so, YOUNG_FA>OLD_FA as in between subject contrasts, TASK1> TASK2 as in between condition contrasts, and one seed at a time as in between source contrasts was performed at the 2nd level analysis. Would this design give me the accounted variation of ageing to the FC of the selected seed region related to TASK1?

Thank you for your insight.