Autism has long been viewed as a single condition with a wide range of symptoms and abilities. Some autistic people need significant daily support, while others live independently and may have exceptional strengths in certain areas.
For decades, scientists have known that autism is extremely diverse, but they have struggled to understand why. A new international study may help answer that question by providing evidence that autism may include at least two distinct biological subtypes that can be identified through patterns of brain activity.
The research was led by scientists at the Italian Institute of Technology in Rovereto, Italy, together with researchers at the Child Mind Institute in New York and the University of Trento. Their findings were published in the journal Nature Neuroscience.
Autism spectrum disorder affects millions of people worldwide. It is a neurodevelopmental condition that influences communication, social interaction, behavior, and sensory processing.
Although autism is diagnosed based on behavior and development, scientists have long suspected that different biological mechanisms may be responsible for similar outward symptoms.
To investigate this possibility, the research team used advanced brain imaging and animal studies. They examined how different parts of the brain communicate with each other, a concept known as brain connectivity.
Healthy brain function depends on different regions sharing information efficiently. Changes in these communication patterns may influence how people think, feel, learn, and interact with the world.
The researchers analyzed functional MRI scans from 940 children and young adults with autism. They compared these scans with data from more than 1,000 people without autism.
At the same time, they studied 20 different mouse models that carried autism-related biological changes. By combining the animal and human data, the scientists hoped to uncover biological patterns that could not be seen through behavior alone.
The study revealed two clear groups. One group showed lower-than-normal communication between brain regions. Scientists call this hypoconnectivity. The second group showed higher-than-normal communication between brain regions, known as hyperconnectivity.
The mouse studies helped explain what might be happening biologically. The hypoconnectivity pattern appeared to be linked to changes involving synapses, which are the tiny connections that allow brain cells to communicate with each other. The hyperconnectivity pattern appeared to be linked to immune-related processes in the brain and body.
The researchers then looked for the same signatures in human brain scans. Remarkably, they found matching patterns. Brain regions associated with reduced connectivity showed stronger links to genes involved in synaptic function, while highly connected regions were linked to immune-related genes.
One of the most important findings was that these patterns appeared repeatedly across many independent datasets collected at different research centers. This suggests the results were not due to chance and may represent real biological differences within the autism spectrum.
The study also found that the two groups showed somewhat different results on standard autism assessments. People in the hyperconnectivity group tended to have slightly higher autism severity scores. However, the researchers noted that current behavioral tests do not fully capture the biological differences revealed by brain imaging.
The findings could have important implications for future autism care. Today, autism is largely diagnosed and treated based on observable behavior. However, if different biological subtypes can be reliably identified, doctors may eventually be able to tailor interventions more precisely to each individual.
The researchers caution that these two groups likely represent only part of autism’s complexity. Autism is influenced by hundreds of genes and many environmental factors. As larger studies become available, additional subtypes may be discovered.
If you care about autism, please read studies about a new cause of autism, and cats may help decrease anxiety for kids with autism.
For more information about health, please see recent studies about vitamin D that may hold the clue to more autism, and results showing strange eating habits may signal autism.
Source: Italian Institute of Technology.
