These findings provide a small step toward specific noninvasive surrogates for pathologic brain development, structure, and function.
These investigators measured MRI T2 relaxation times in 60 children (age range, 2.0–4.5 years) with “idiopathic” autism. They compared the findings to those in 16 children with “idiopathic” nonautistic mental retardation who were matched to the autistic children by age and IQ (mean, 58) and in 10 age-matched typically developing children. Most participants were imaged during sedated sleep.
Compared to the typically developing children, those with developmental delay had prolonged mean T2 relaxation times in both cortical gray and white matter. Autistic children had prolonged relaxation times only in gray matter, and the delay was greater in the mental retardation group than in the autistic group.