The ABCs of Autism

What Causes Autism?

Researchers are working harder than ever to pin down the source of this confusing condition, which was first described in 1943. Initially, experts pegged autism as a psychological condition and blamed poor parenting. But the current thinking is that autism is a disorder of the brain.

By studying the brains of older autistic patients, researchers have discovered an absence of certain nerve cells in different parts of the brain, including the prefrontal cortex, which assigns emotional states to others -- one to understand, say, the difference between a dog that's wagging its tail and one that's snarling. Another impaired area is the amygdala, which allows for emotional learning, such as recalling the meaning behind a facial expression.

Ultimately, autism deprives children of a brain that can easily pull pieces of information together into a unified whole. Instead of seeing the big picture, they see the world as little parts, says Dr. Powers.

That may be why autistic kids cling to these repetitive activities and rituals -- these provide them with a sense of predictability and structure, which is comforting, Dr. Powers explains.

Although researchers aren't sure just what causes the brain's wiring to go awry, studies suggest that autism's roots lie in a person's genes. In a recent study, Karin Nelson, MD, a child neurologist with the National Institutes of Health, and her colleagues compared blood drawn from newborns later diagnosed with autism with the blood of typical infants. The blood of the autistic babies contained vasoactive intestinal peptide, a protein molecule that affects brain development. Researchers are also looking into other possible genetic markers for autism, in hopes that high-risk babies might be identified and treated sooner with current therapies. Dr. Nelson hopes that such knowledge will also lead to the development of new therapies.

Congress recently mandated increased federal funding to examine autism, including the establishment of five research centers. So experts hope to have a clearer picture before long.

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