Wednesday, November 9, 2011

Autism tied too many brain cells


Study: Autistic Children Have More Brain Cells

There's growing evidence that the brains of autistic children are very different from the brains of other youngsters. Now a new study that found an excess of brain cells in children with autism comes closer to pinpointing the origins of the condition: in utero versus in toddlerhood.
In research reported in the Journal of the American Medical Association (JAMA), scientists at the University of California, San Diego, found that autistic children have about 67% more nerve cells in a part of the brain known as the prefrontal cortex than children without autism. The prefrontal cortex is involved in processing social skills, communication, cognitive functions and language — all areas in which autistic children often show abnormal development.
Lead researcher Eric Courchesne studied the brains of seven autistic boys between the ages of 2 and 16 after their death and compared his analysis to the brains of six unaffected boys who died at similar ages. The excess of neurons was a bit of a surprise since in most cases, deficits in social skills — like the ones autistic children typically have — are linked to less, not more, nerve tissue.
“When we think of the inability to handle complicated information, we usually think of too little in the way of connections or brain cells,” he says. “But this is just the opposite.”
Functionally, however, the autistic children may have been suffering from a dearth of proper nerve connections since the overabundance of neurons may have led to difficulty in their ability to connect and communicate with each other. That situation, says Courchesne, could "lead to pathways that slow down or prevent normal active interaction between different regions of the brain.”
Social interaction and communication, for example, require that nerves from distant portions of the brain link up. Think of too many nerves like an overgrown forest that could choke some of these critical neural bridges.
Equally significant is the fact that the excess of neurons in the prefrontal cortex aren't formed after birth, but during early development, in utero. That suggests that the changes responsible for autism are occurring much earlier than scientists had thought.
“Knowing that we have a specific type of defect that occurs very early in development really helps us to focus and sharpen the next steps in research to determine what caused the excess,” says Courchesne. And hopefully find new treatments that can help children and their families cope better with the symptoms of autism.

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