Fractional anisotropy distributions in 2- to 6-year-old children with autism

Background Increasing evidence suggests that autism is a disorder of distributed neural networks that may exhibit abnormal developmental trajecto- ries. Characterisation of white matter early in the developmental course of the disorder is critical to understanding these aberrant trajectories. Methods A cross-sectional study of 2 -t o6-year-old children with autism was conducted using diffusion tensor imaging combined with a novel statistical approach employing fractional anisotropy distribu- tions. Fifty-eight children aged 18-79 months were imaged: 33 were diagnosed with autism, 8 with general developmental delay, and 17 were typically developing. Fractional anisotropy values within global white matter, cortical lobes and the cerebel- lum were measured and transformed to random F distributions for each subject. Each distribution of values for a region was summarised by estimating d