Dear experts,
I have read few articles on comparative studies between patients and healthy subjects structural changes in the gray matter regions of the brain. I have some questions regarding selection of control in comparative study.
In such studies a patient can be selected as study subject based on the diagnostic criteria. But on what basis a person can be selected as control? If you consider a person who has good health and without any psychiatric disorder as control, there are possibilities of significant variations in the gray matter regions among controls.
For example, a normal healthy control may not have any disorder but may have certain learned skills like drawing, singing, dancing etc. Those learned skills may cause changes in the gray matter regions of brain. Even it may show significant changes in the gray matter regions of the brain if you do intra-group comparison. When you compare those subjects with the patients, will it not give false positive effect?
Then, there may be variations in the brain size of each individuals though they are age, sex and handedness matched subjects of same ethnic group. This change in the size of the brain structure itself give significant differenc in the gray matter regions. How to eliminate such variations?
What is the ground reality in selecting normal subjects?
Your suggestion will help me to redefine my knowledge about comparative study in sMRI and will be very helpful for my future research work
Regards
Ramesh
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