Parents, doctors, teachers, and researchers have long noticed that autism can look very different from one person to another. Some autistic children speak very little, while others develop advanced language skills.
Some are highly sensitive to sounds and textures, while others are less affected. This wide variation has led scientists to ask a fundamental question: Is autism really one condition, or could it actually be made up of several different biological conditions grouped under one name?
A major new study suggests that the answer may be more complicated than previously thought. Researchers have found evidence that autism may contain at least two distinct biological forms, each involving a different pattern of communication across the brain.
The study was carried out by an international team led by the Italian Institute of Technology, the Child Mind Institute in New York, and researchers from the University of Trento. Their work was published in Nature Neuroscience, one of the world’s leading neuroscience journals.
Scientists focused on brain connectivity, which describes how different brain regions communicate and coordinate with one another. Modern brain scans can measure these communication patterns while a person is resting quietly. Researchers believe these patterns may provide clues about the biological processes that shape brain development.
To search for hidden autism subgroups, the team analyzed brain scans from 940 autistic children and young adults and compared them with scans from more than 1,000 neurotypical individuals. They also examined 20 different mouse models that represented various autism-related biological changes.
The animal studies played a crucial role. By examining the brains, genes, and biological pathways in mice, researchers could identify what was happening at a cellular level. These findings then served as a guide when interpreting the human brain scans.
The researchers discovered two major patterns. One group of autistic individuals showed reduced communication between brain regions. In other words, certain parts of the brain were not exchanging information as strongly as expected. The second group showed the opposite pattern, with unusually strong communication between different brain areas.
The biological explanations also differed. Reduced connectivity was linked to pathways involving synapses, the structures that allow brain cells to send signals to each other. Increased connectivity was linked to immune-related biological systems. This finding suggests that different underlying mechanisms may contribute to autism in different people.
To confirm their results, the researchers tested the patterns across multiple independent datasets collected from many research centers around the world. The same two groups appeared again and again, providing strong evidence that the findings were reliable.
Gene expression analyses further supported the conclusions. Regions showing lower connectivity were associated with synaptic genes, while regions showing higher connectivity were associated with genes related to immune function. This close match between animal and human findings gave researchers greater confidence in their interpretation.
The study also found modest differences in behavior. Individuals with higher connectivity tended to score somewhat higher on standard measures of autism severity. However, the differences were not large enough to be easily identified through behavioral observation alone.
This highlights one of the study’s most important messages. Two people may appear similar clinically yet have very different biological mechanisms operating within their brains. Understanding these hidden differences could eventually lead to more personalized approaches to care.
In the future, researchers hope that brain-based markers may help identify which therapies are most likely to benefit specific individuals. This idea is often referred to as precision medicine, an approach that aims to match treatments to the underlying biology of each person.
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Source: Italian Institute of Technology.
