Dear all, 
 I need to compare the common and specific differences in gray matter volume of three diseases. I did a meta-analysis to compare the differences in gray matter volume of the three diseases with the healthy group, but how to compare the common and specific differences in gray matter volume of the three diseases on the SDM software, we would be grateful if you could answer and explain our questions
 
best wishes 
 
Thanks!

Dear Wei Yu,

Imagine that you have two disorders. You should first create a variable in the SDM table called B which has a value of 0 for disorder A studies, and a value of 1 for disorder B studies. Then, to compare the two disorders, you must create a linear model with the variable B.

Hope this helps,

Joaquim

Dear Joaquim,
     Thank you very much for your answer. Do you mean to compare the three diseases in pairwise? SDM can show the brain regions with significant differences, but how can SDM be used to explore the common of these diseases? Thank you very much if you could answer this question. And we look forward to your reply.
     
   Thank you again.

Dear Wei Yu,

To obtain the common differences in gray matter of the diferent diseases you should perform a meta-analysis for each disease independetly and then run the multimodal analysis to get the overlap between them. 

Best,
Lydia