Deepening the mystery of autism's origins, a Johns Hopkins Children's Center study has failed to link the typical autistic child's fixation on spinning objects and constant whirling around to long-suspected damage to the brain's control center for movement, balance and equilibrium.
Reporting in the December 2000 issue of the Journal of Autism and Developmental Disorders, the Hopkins team said test results of parts of the cerebellum in 13 autistic children were the same as in normal children without autism.
The cerebellum has long been the focus of autism research because of the relentless responses autistic children make to sensory stimulation, according to Melissa Goldberg, Ph.D., assistant professor of child and adolescent psychiatry at the Johns Hopkins Children's Center and the Kennedy Krieger Institute. "The stimulation we see autistic kids seeking out when they're spinning or putting things in front of their eyes would seem to be linked to the part of the brain known to control such things as our ability to stabilize our bodies and what we see and touch," she says. "But in this study we found this was not the case, at least not with the children with high-functioning autism."
Cautioning that their findings may not apply to all autistic children, Goldberg and her team added that they "still don't know what part of the brain is abnormal in autism."
In their study, the Hopkins researchers examined the eye movements of 13 high-functioning autistic children ages 7 to 17, after spinning them in a chair as they sat upright, tilting their heads forward just after the chair became still. If the cerebellum is functioning normally, the reflexive eye movements, which typically occur in the direction opposite to that in which the child spins, are diminished once the head is pitched forward. Researchers found the autistic children's eye reflexes diminished appropriately.
"This tells us that those parts of the cerebellum that govern our ability to restore balance operate normally in autistic children," Goldberg says. "Knowing what parts of the brain do not appear damaged in these children, we can move on to investigate other sources of the problem."
Dr. Goldberg and her colleagues plan to use brain imaging and other cognitive neuroscience research methods to investigate further how autistic brains operate and to corroborate their findings. In one study, for example, they are tracking infants at high risk of developing autism because they have a brother or sister with autism. The goal is to tease out genetic risk, and document the earliest indications of the onset of disorder, and to develop intervention strategies. This sibling study is led by colleague and co-author Rebecca Landa, Ph.D., an expert in child development and autism in the Division of Child and Adolescent Psychiatry at the Johns Hopkins Children's Center and director of the Kennedy Krieger Center for Autism.
Autism is a developmental disorder that affects an estimated one in 500 children in the United States., according to the Centers for Disease Control (CDC). Children with autism have trouble making social connections or responding properly to sights, sounds and touch.
The study was funded by the National Alliance for Autism Research. The eye reflex portion of the study was conducted in the laboratory of co-investigator David Zee, M.D., professor of neurology, otolaryngology and ophthalmology at the Johns Hopkins Medical Institutions.
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