The exact causes of autism are unknown, but it is believed that both genetic and environmental factors play a role in its development. Multiple studies have shown structural and functional abnormalities in the brains of autistic people. Experiments have been conducted to determine if the degree of brain abnormality yields any correlation to the severity of autism. One study done by Elia et al. (2000) used magnetic resonance imaging (MRI) on the midsagittal area of the cerebrum, midbrain, cerebellar vermis, corpus callosum, and vermal lobules VI and VII to measure brain abnormalities in children with<unk> . The results suggested that the midbrain structures correlate with certain developmental behavioral aspects such as motivation, mnemonic, and learning processes, though there is more research needed to confirm this. Furthermore, many developmental processes may contribute to several types of brain abnormalities in autism; therefore, determining the link between such abnormalities and severity of autism proves difficult.
Low-functioning autism
High-functioning autism
Nonverbal autism
Autism spectrum
Multiple complex developmental disorder
Conduct disorder
Selective mutism
Pervasive developmental disorder