SC Connecticut News

A recent study has identified a molecular difference in the brains of autistic individuals, marking the first time synaptic density has been measured in living people with autism. Using positron emission tomography (PET) scans, researchers discovered that autistic adults have fewer synapses than neurotypical individuals. The study, published in Molecular Psychiatry on October 4, found that a lower number of synapses correlates with more pronounced autistic features.

James McPartland, PhD, principal investigator and Harris Professor at the Yale Child Study Center, remarked on the significance of these findings: “As simple as our findings sound, this is something that has eluded our field for the past 80 years.” Adam Naples, PhD, assistant professor and co-investigator on the study added, “Synapses are the way neurons communicate. They’re the fundamental mechanism for how information moves around the brain and is computed.”

The research involved 12 autistic adults and 20 neurotypical adults who underwent both MRI and PET scans. A novel radiotracer called 11C‑UCB‑J was used to measure synaptic density. Results showed a 17% reduction in synaptic density across the brains of autistic participants compared to their neurotypical counterparts.

McPartland highlighted a major challenge in understanding autism: “Today’s diagnostic criteria [which predate this new study] involve descriptions of behavior that are broad and pretty vague.” He hopes that understanding the biological underpinnings of autism will lead to better-defined subgroups within the condition.

David Matuskey, MD, associate professor of radiology & biomedical imaging and first author of the study said: “This is the dream — to be able to give biologic confirmation to patients and their families.”

Future research will focus on nonradioactive methods for studying synapses directly and examining adolescent brains to track changes over time. The team also aims to explore connections between their findings and mental health outcomes such as depression or anxiety in autistic individuals. McPartland emphasized their ultimate goal: "to get information that can maximize quality-of-life for autistic people."