Scientists have identified two distinct biological forms of autism based on brain scans

A large international study has enabled researchers to take an important step toward understanding the nature of autism spectrum disorders (ASD). After analyzing numerous imaging results, the researchers concluded that autism is not a homogeneous condition but includes at least two distinct biological subtypes. Each is defined by its own unique pattern of interaction between different brain regions. 

To reach these conclusions, the experts conducted a large-scale analytical study. First, they examined the characteristics of functional brain connectivity in 20 different genetic mouse models. The authors then analyzed functional magnetic resonance imaging (fMRI) results from 940 children and young adults with confirmed autism. The data obtained were compared with scans of over 1,000 neurotypical individuals who made up the control group.

Thanks to this in-depth comparison, the researchers clearly identified two brain patterns that consistently recurred:

• The first subtype (hypo-connectivity): characterized by a significantly reduced level of interaction and information exchange between different neural centers. Researchers found that this form is directly linked to specific abnormalities in the synaptic pathways responsible for transmitting signals between neurons.

• The second subtype (hyperconnectivity): is characterized by excessive, heightened levels of interaction between brain regions. This variant was found to be closely linked to the functioning of the body’s immune systems.

Collectively, patients with these two subtypes accounted for about 25% of the total number of study participants diagnosed with ASD. In addition to differences in the architecture of connections, the groups demonstrated different clinical presentations on standard medical assessment scales. In particular, individuals in the hyperconnectivity group typically had slightly higher scores on measures of overall autism severity.

One of the study’s lead authors, Dr. Alessandro Gozzi of the Italian Institute of Technology (IIT), emphasized that for decades, medicine has grappled with the enormous variability of symptoms among patients; but now science has obtained irrefutable evidence of the existence of different fundamental biological processes underlying these manifestations. This discovery has the potential to completely transform the approach to diagnosis, allowing for the creation of individualized treatment and support programs. At the same time, the study authors note that the identified forms most likely reflect only part of a complex spectrum, and in the future, scientists hope to differentiate other subtypes of autism.