brain mapping disorders

An ever growing number of studies feature brain mapping to illustrate structural differences in the brain based on grouping those with and without a given disorder. Techniques such as structural magnetic resonance imaging (MRI) can aid in researchers understanding of differences in shape and volume of various brain regions. Group differences are often found, yet there is wide variability in the structure and volume within any group. One potential contribution is the current methods for defining disorder (see Problems with the DSM). Psychiatric/psychological disorders denote important functional differences between individuals, yet what technically counts as a disorder or not is flawed and often arbitrarily defined. For example, children may receive a diagnosis of ADHD if they meet criteria for 6 or more inattention OR hyperactive/impulsive symptoms. This means that one child could be diagnosed with ADHD who has 6 inattention and 0 hyperactive symptoms, whereas a child with 5 inattention and 5 hyperactive symptoms would not meet criteria. I hesitate to think that this is a perfect system. Yet, interestingly, there are MRI findings that differentiate ADHD from non-ADHD groups. Notably, any one child may not “fit” with their group, as these differences only appear at the group level.
I wonder, is it useful to use group data to make conclusions that may affect those at the individual level? And, perhaps the problems with our current psychological tools in honing in on the disorder are what causes the lack of consistency between groups in the MRI findings. Perhaps the use of biological measures to help to define the lines for what is and is not “disorder” will better aid in the identification and treatment of problems in functioning. An approach using differences in the brain that may be associated with specific functions or impairments in those functions to locate disease related endophenotypes is a promising future area of research.