People With Autism May Have More Symmetrical Brains By Traci Pedersen



“A new study in the journal Nature Communications finds that people with autism have more symmetrical brains.

Research has shown that the left and right halves of our brains develop differently, as each hemisphere specializes in certain functions.

For example, in most people, the left hemisphere, which controls the right hand, is dominant for language.

However, natural brain asymmetry is sometimes affected in people with developmental or psychiatric disorders such as autism, a condition characterized by impaired social cognition, repetitive behavior and restricted interests.

“Previous studies have suggested that people with autism spectrum disorder are less likely to have the typical asymmetries for language dominance or hand preference,” said Ph.D. student Merel Postema.

“However, it has not been clear whether asymmetry of the brain’s anatomy is affected in autism, because different studies have reported different findings.”

To investigate this issue, scientists from the international ENIGMA consortium of brain researchers decided to do a large-scale study, based on brain scans that had been collected in different countries for more than 20 years.

The study is the largest ever conducted to investigate this issue, using brain scan data from 1,774 people with autism and 1,809 healthy controls.

The researchers found that the left and right cerebral hemispheres of the brain are indeed more similar in people with autism.

In other words, people with ASD had less brain asymmetry.

The reduced asymmetry was mostly found for cortical thickness, at various locations across the brain’s surface.

In the healthy brain, the thickness of the cerebral cortex (the thin layer of gray matter that covers the brain) differs between the left and right hemispheres.

Importantly, the anatomical differences did not depend on age, sex, IQ, the severity of symptoms, or medication use.

“The very small average differences in brain asymmetry between affected people and controls mean that changes of brain asymmetry will not be useful in terms of clinical prediction,” said study leader Dr. Clyde Francks, who also leads the Imaging Genomics research group at the Max Planck Institute, Nijmegen, The Netherlands.

“But the findings might inform our understanding of the neurobiology of autism spectrum disorder.”

Since most of the data came from children, the findings suggest that altered development of the brain’s left-right axis is involved in autism, affecting widespread brain regions with diverse functions.

For example, many of the affected brain regions overlap with the default mode network, a network of interconnected brain regions particularly active during passive rest and mind-wandering.

Future research may reveal how these findings relate specifically to autism spectrum disorders.”

Source: Max Planck Institute for Psycholinguistics

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