Studies shed light on autism effects and treatment

WASHINGTON (Reuters) - Two studies shed light on the possible effects of autism on the brain and point to potential treatments, researchers said on Monday.

One reports that oxytocin, which studies have found is important in human bonding, may help reduce debilitating symptoms in autistic adults. And a second found that fear-detecting areas of the brain are shrunken in people with autism.

The term autism describes a range of symptoms that can include very severe mental and behavioral effects, an inability to interact socially, and milder symptoms such as those seen in Asperger's syndrome. Severely autistic patients may bang their heads, repeat words or movements, or become obsessed with certain actions.

The U.S. Centers for Disease Control and Prevention published a survey in May indicating that up to 1 in every 175 children born in the United States develops an autism spectrum disorder of some kind.

The cause is unknown and treatments are limited.

Dr. Eric Hollander and Jennifer Bartz of the Mt. Sinai School of Medicine in New York conducted a study in which they administered Pitocin, a brand name for injectable oxytocin, to adults with autism. Pitocin is given to pregnant women to induce uterine contractions.

Hollander and Bartz tested the autism patients for their ability to identify emotions and to control repetitive behaviors.

Speaking to a meeting of the American College of Neuropsychopharmacology in Nashville, Tennessee, the researchers said they gave the volunteers either intravenous infusions of Pitocin or a saline solution.

They swapped the treatments two weeks later, then giving the volunteer patients questionnaires about mood and emotions.

The people given oxytocin on the first testing day developed and retained an ability to assess emotion, the researchers said. They also noted a rapid reduction of repetitive behaviors over the course of the oxytocin infusion, with no such reduction with the salt water.

"Studies with animals have found that oxytocin plays a role in a variety of behaviors, including parent-child and adult-to-adult pair bonding, social memory, social cognition, anxiety reduction and repetitive behaviors," Bartz said in a statement.

More study is needed, the researchers urged.

A second study found that the amygdala, an area of the brain that process and remember emotional reactions -- the brain's "fear hub," most likely becomes abnormally small in severely socially impaired males with autism.

Teens and young men who were slowest at distinguishing expressions had a smaller than normal amygdala, Richard Davidson, and colleagues at the University of Wisconsin found when they conducted magnetic resonance imaging studies of their brains.

They report that their findings suggest that social fear in autism may cause a hyperactive, abnormally enlarged amygdala, but the stress eventually kills off the cells in the structure and shrinks it.

Autistic patients with the smallest amygdalases took 40 percent longer than those with the largest fear hubs to recognize emotional facial expressions, they said.

Reporting in the Archives of General Psychiatry, they said they also found that seemingly unaffected siblings of people with autism have some of the same differences in amygdala volume.

"Finding many of the same differences, albeit more moderate, in well siblings helps to confirm that autism is likely the most severe expression of a broad spectrum of genetically influenced characteristics," Davidson said in a statement.