Oculomotor abnormalities parallel cerebellar histopathology in autism

Objective: To investigate cerebellar function in autism by measuring visually guided saccades. Methods: A visually guided saccade task was performed by 46 high-functioning individuals with autism with and without delayed language acquisition, and 104 age and IQ matched healthy individuals. Results: Individuals with autism had increased variability in saccade accuracy, and only those without delayed language development showed a mild saccadic hypometria. Neither autistic group showed a disturbance in peak saccade velocity or latency. Conclusions: The observed saccadic abnormalities suggest a functional disturbance in the cerebellar vermis or its output through the fastigial nuclei, consistent with reported cerebellar histopathology in autism. The pattern of mild hypometria and variable saccade accuracy is consistent with chronic rather than acute effects of cerebellar vermis lesions reported in clinical and non-human primate studies, as might be expected in a neurodevelopmental disorder. The different patterns of oculomotor deficits in individuals with autism with and without delayed language development suggest that pathophysiology at the level of the cerebellum may differ depending on an individual's history of language development.