Dear all,

I am planning to run *separate* VBM regression analysis with gray matter
volume in two very different populations (young and elderly subjects).
Depending on results, I may be interested in comparing regression slopes
between the two groups. My question is: should I run Dartel with all
subjects of the two population, although most of the analysis (sex
differences, correlations with performance, etc)  will be performed in each
sample separately? I am not sure if combining the two samples in the same
Dartel template may affect structural brain changes obtained within each
separate group, especially when groups are so different (young vs. elderly).

Looking forward to your comments.

Many thanks in in advance.

Best regards,