The relationship between grey-matter and ASD and ADHD traits in typical adults.

We tested whether in 85 healthy adults (18-29 years) there is a relationship between grey-matter (GM) volume and autism and ADHD symptom severity. The structural MRI findings and autism and ADHD self-reports revealed that autism and ADHD symptom severity was correlated with GM volume in the left inferior frontal gyrus. Autism symptom-severity was correlated with the left posterior cingulate, ADHD with the right parietal lobe, right temporal frontal cortex, bilateral thalamus, and left hippocampus/amygdala complex. Symptom severity of both disorders form a continuum extending into the general population, but it seems to be an oversimplification to typify psychiatric disorders such as autism and ADHD solely as extremes of brain structure abnormalities.