Researchers from the Institute of Psychiatry, King's College London have been using a sophisticated brain-imaging technique called voxel-based morphometry to compare the brains of people with autism/Asperger's syndrome and a healthy control group. They studied 39 people with Asperger's, 26 with autism and 33 healthy controls. The participants with autism/Asperger's had a significant reduction in grey matter in their medial temporal, fusiform and cerebellar regions and in their brainstem and cerebellar regions. The people with autism had more grey matter in their frontal and temporal lobe regions; something not found in the people with Asperger's.
Toal, F. ... [et al] - Clinical and anatomical heterogeneity in autistic spectrum disorder: a structural MRI study Psychological Medicine, July 2010, 40(7), 1171-1181