Abstract

Cerebellar histopathological abnormalities have been well documented in autism, although findings of structural differences, as determined by magnetic resonance imaging, have been less consistent. This report explores specific cerebellar vermal structures and their relation with severity of symptoms and cognitive functioning in young children with autism spectrum disorder (ASD). Children with ASD aged 3 to 4 years were compared with typically developing children (TD) matched to the ASD children on chronological age, and children with developmental delay (DD) matched to the ASD children on both chronological and mental age. Volumes of the cerebellum and midsagittal vermal areas were measured from 3-D T1-weighted magnetic resonance images. Children with ASD had reduced total vermis volumes compared with children with TD after controlling for age, sex, and overall cerebral volume or cerebellum volume. In particular, the vermis lobe VI-VII area was reduced in children ASD compared with TD children. Children with DD had smaller total vermis areas compared with children with ASD and TD. Within the ASD group, cerebellar measurements were not correlated with symptom severity, or verbal, non-verbal or full scale IQ. Within the DD group, larger cerebellar measurements were correlated with fewer impairments. The specific relation between altered cerebellar structure and symptom expression in autism remains unclear.