THE NEUROBIOLOGY AND GENETICS OF INFANTILE-AUTISM

This chapter discusses neurobiological studies and reviews the diseases associated with autism. Genetic research becomes a major focus in studying the etiology of autism and a number of neurological disorders considered to be responsible for specific cases of autism are discusses in the chapter. Neuropathological studies appear to have identified common abnormalities in the cerebellum and limbic system of at least five autistic subjects. These subjects, with variable levels of mental retardation, demonstrated marked Purkinje cell loss in the cerebellar hemispheres, together with retained fetal neuronal circuitry in cerebellar nuclei and increased neuronal packing in specific regions of the limbic system, amygdala, and hippocampus. The architecture of the cerebral cortex was not affected. Positron emission tomography (PET) and nuclear magnetic resonance (NMR) studies of autism are at a preliminary stage, but these methodologies allow insight into the functioning of the brain, rather than simply brain anatomy. Recent PET studies indicating decreased association between paired regions of the brains of autistic subjects are of interest, particularly if they can be confirmed and refined by additional studies. Neurophysiological studies also offer insight into brain function, but are subject to numerous methodological criticisms. The disturbances in brain development associated with autism can be produced in a number of ways and at different times during development of the nervous system. © 1993, Academic Press Inc. All rights reserved.