[Freesurfer] Qdec covariates

Hi all, If i run a model in qdec that inludes 1 discrete and 1 continuous factor, does the output for the group contrast covary for the continuous variable? For example, if I want to compare two groups, and include group as my discrete factor and age as a continuous factor, will the output for the group contrast (Does the average thickness differ between grp1 and grp2?) covary for age? I've notice that running it without continuous factors leads to different results, so I just wanted to confirm this is the case.

Also, just wanted to check that group contrasts are run as level_1 - level_2, so that positive values (i.e., red-yellow) indicate level_1 > level_2.

Thanks for your help, Alex