Hello Experts,

I am analyzing cortical thickness of two groups (APOE 4carries vs. noncarriers) in freesurfer with age as a co-variate.

I am uncertain about the statistical differences behind:

1)Does the correlation between thickness and age accounting for APOE, differ from 0?

    in contrast to:

2)Does the thickness-age correlation differ between 1 and 0?

I get significant results after FDR correction for the first but not for the second analysis. 

thank you for your help,

catherine