Regression comparison for a 2X2 within sub

Hi there!

I'm searching for a way to perform a regression comparison for a 2X2 within subject design, where the 2 levels are time (Pre, Post) and condition (Drug, Placebo).

I tried doing regression for each condition like the following :

1-Drug condition:    Subject-effects[Between-subjects contrast]: [0 1] allsubject, BehaveDrug(compound of behavioral measurements delta between Post and Pre)
                               Conditions[Between-conditions contrast]: [-1 1] PreDrug, PostDrug

2-Placebo condition: Subject-effects[Between-subjects contrast]: [0 1] allsubject, BehavePlacebo(compound of behavioral measurements delta between Post and Pre)
                               Conditions[Between-conditions contrast]: [-1 1] PrePlacebo, PostPlacebo

I got a regression with significant r only in the Drug condition.

I would like to know if this is a valid way to say that the behavioral measurements correlate to the connectivity changes only in the Drug condition.

Is there a more elegant or correct way to perform this comparison between the two conditions using regression?

I really appreciate any help  :)

Libat