The Neuropathology of Autism: a Review of the Current Literature

The neuropathology of autism is punctutated by a heterochronicity of brain development. There is overgrowth of the brain at early stages of childhood with a disproportionate increase in its white matter. Parcellation of the white matter has found an increase in its outer radiate matter (e.g. arcuate fibers) with reductions in its inner compartment (e.g., corpus callosum). These changes may be the result of supernumerary periventricular germinal cell divisions which manifests itself as migratory deficits and a minicolumnopathy. Other findings such as loss of Purkinje cells and evidence of neuroiflammation may be the result of agonal or preagonal changes. Findings suggest that in autism there is a bias in connectivity favoring short connections at the expense of longer ones. Postmortem neuropathological studies in autism are based on reports of a very small number of brains. Due to the broad age spectrum as well as clinical diversity of ASD, the pattern of neuropathological changes is incomplete and inconsistent. Running title: neuropathology