In a new study, researchers have shown that the brains of young men with autism have low levels of a protein that appears to play a role in inflammation and metabolism.
The research was conducted by a team at Massachusetts General Hospital (MGH).
This surprising discovery provides an important new insight into the possible origins of autism, which affects one in 59 children.
Autism is a developmental disorder that emerges in early childhood and is characterized by difficulty communicating and interacting with others.
While the cause is unknown, growing evidence has linked autism to inflammation of brain tissue, or neuroinflammation.
One sign of neuroinflammation is elevated levels of a substance called translocator protein (TSPO), which can be measured and located in the brain using positron-emission tomography (PET) and anatomical magnetic resonance imaging (MRI).
In the study, the team scanned the brains of 15 young adult males (average age, 24) with autism. The group included both high- and low-functioning subjects with varying degrees of intellectual abilities.
For comparison, the team scanned the brains of 18 healthy control subjects who were similar in age.
The scans showed that the brains of males with autism had lower levels of TSPO than those of healthy people.
In fact, men with the most severe symptoms of autism tended to have the lowest expression of TSPO. When the tests were repeated several months later, the pattern persisted.
The brain regions found to have low expression of TSPO have previously been linked to autism in earlier studies, and are believed to govern social and cognitive capacities such as processing of emotions, interpreting facial expressions, empathy, and relating to others.
To understand this unexpected finding, the team notes that TSPO does more than serve as a marker of inflammation.
It has multiple complex roles, and some actually promote brain health.
For example, adequate TSPO is necessary for the normal functioning of mitochondria, which are the “powerhouses” in cells that produce energy. Earlier research has linked malfunctioning mitochondria in brain cells to autism.
One author of the study is Nicole Zurcher, Ph.D., an investigator in MGH’s Athinoula A. Martinos Center for Biomedical Imaging.
The study is published in the journal Molecular Psychiatry.
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