Adolescence is a period of social reorientation: a shift from a world centered on parents and family to one shaped by peers, schools, and broader networks. This expansion is critical for healthy development, but it also heightens susceptibility to social stressors. When those stressors lead young people to withdraw — choosing solitude more often than connection — the brain itself may be altered.
Using brain imaging and behavioral data, Caterina Stamoulis, PhD , and her team in the Division of Adolescent/Young Adult Medicine at Boston Children's Hospital have found that adolescents who are socially withdrawn or who frequently prefer solitude show measurable differences in brain structure and function. These results were published today in Cerebral Cortex.
Studying solitude at scale
In this study supported by the National Science Foundation, Stamoulis and her colleagues set out to identify the brain correlates of social withdrawal in adolescence — a risk that is particularly salient during this developmental period. To explore this, the team turned to the National Institutes of Health-funded Adolescent Brain Cognitive Development (ABCD) study : a cohort of 11,880 youth followed across 21 U.S. sites with deep neuroimaging, behavioral, and environmental measures. The team analyzed MRI and fMRI data from nearly 3,000 adolescents whose parents had reported on their children's social behaviors, including whether they tended to withdraw or preferred being alone.
"The ABCD study is unique because it's the only one that uses deep neuroimaging to measure both structural and functional brain activity," Stamoulis says. "It also samples the youth environment and measures social behavior, mental health, etc."
How withdrawal reshapes the adolescent brain
Stamoulis notes that while the findings themselves were not unexpected, the details offered important new insights. Adolescents who were socially withdrawn showed structural differences in regions of the brain supporting social and emotional processing, including the insula and anterior cingulate. Functionally, their brain networks also showed weaker connections, and greater fragility in circuits that support social behaviors, decision-making. These differences were not confined to a single region but spread across multiple networks supporting cognitive function across domains, amplifying their potential impact.
"We confirmed that social isolation affects not only brain areas supporting social function but other processes as well," Stamoulis explains. "Its association with widespread brain circuits suggests that social isolation may increase risk for mental health issues."
When solitude signals vulnerability: Guidance for clinicians
For clinicians, these findings carry several implications. Some solitude is normal, and even essential, during adolescence. But in the context of these brain changes, patterns of persistent withdrawal merit closer attention.
Clinicians are uniquely positioned to help families understand what's at stake. "It's powerful to educate families by showing them what is happening in their kids' brain," Stamoulis says.
By spotting withdrawal early and framing it in terms of measurable brain impact, clinicians can help families recognize risks sooner — opening the door to strategies that may protect mental health and foster resilience.
Tracking the impact of solitude over time
This project was only the first step in understanding how social withdrawal shapes the adolescent brain. Because the ABCD study is designed for follow-up imaging every two years, Stamoulis and her colleagues can now track how those patterns evolve as children develop.
"Now we can start to see a temporal trend in how the brain develops and compare it to those kids who don't have these preferences or behaviors," Stamoulis says.
The next phase of research will test whether persistent solitude leaves a lasting imprint, and how much early recognition and support can alter that path. By following these adolescents over time, Stamoulis and her colleagues hope to build a clearer picture of how social withdrawal shapes the brain — and, ultimately, how that knowledge can inform earlier, more effective interventions.
This study was supported by the National Science Foundation's Developmental Sciences and Collaborative Research in Computational Neuroscience programs.
