introduction Recent studies have reported abnormal functional connectivity patterns in autism. This has led to the hypothesis that impaired integration of neural information and long distance disconnection underlies autism. However, little is known about the structural integrity of the white matter tracts that convey neural information.

methods Diffusion tensor imaging was performed on 12-18-year-old participants with high functioning autism, Asperger syndrome and typically developing children matched for age, iq, handedness, head circumference, and gender. Scans included the cerebrum, cerebellum and fractional anisotropy. Mean diffusivity measures were analyzed in a voxel based morphology manner.

results Participants with autism had lower fractional anisotropy in long distance white matter tracts including inferior and superior fronto- occipitial fasciculus and the inferior and superior longitudinal fasciculus bilaterally as well as the cerebello-pontine tract bilaterally. Fractional anisotropy in Asperger syndrome was intermediate between that of participants with autism and controls, but group differences were non-significant.

conclusion The findings suggest that there is a generalized reduction of structural integrity of long distance white matter tracts in autism that connect the frontal cortex to other systems. This may contribute to impaired integration of information and the clinical manifestations in autism.