Too much alone time has a startling effect on the teenage brain
As teens spend less time with their friends in person, scientists are beginning to uncover how isolation may affect the developing “social brain." Here’s what we know—and when parents should be concerned.
For generations, adolescence has been defined as a time of social connection—hanging out with friends, dating, and developing bonds outside the family. These interactions aren’t just cultural rites of passage; they help shape how young brains learn to navigate emotions, relationships, and risk.
But that social landscape is changing. In recent years, teens have been spending less time together in person. According to a recent Organisation for Economic Co-operation and Development (OECD) report, daily face-to-face interactions with friends among children decreased from 53 percent in 2006 to 36 percent in 2022.
While some alone time is normal and even “healthy,” experts warn that too much of it may impact key aspects of teen brain development, with consequences that can extend into adulthood.
How the “social brain” takes shape during adolescence
Adolescence, the developmental period that begins with puberty and, in terms of brain maturation, can extend into the early thirties, is a time of profound physiological, biological, and psychological change. At the brain level, our teenage years are a time of rewiring, says Roselinde Kaiser, an associate professor of psychology and neuroscience at the University of Colorado, Boulder.
Starting in puberty, the brain builds new connections to allow faster, more efficient exchange of information between distant areas of the brain. This reconfiguration enables the development of new skills, including emotion regulation and risk and reward evaluation.
Some of the most pronounced changes occur within a network of brain regions that scientists call “the social brain,” which is physically located in areas such as the medial prefrontal cortex, the anterior cingulate cortex, and the amygdala.
(It's hard to reconnect with old friends. Science may have a solution.)
Last Chance - Save up to $20!
“The ‘social brain’ functions as a network that permits taking the perspective of others, interpreting the emotional expressions of our friends, and seeking out opportunities to bond,” says Adriana Galván, a professor of psychology and co-director of the Developmental Neuroscience Laboratory at the University of California, Los Angeles (UCLA). “It's why adolescents are experts at making new friends, energized by causes they are passionate about, and adept at the forefront of new ideas.”
Although development of the social brain begins in puberty, it requires some socialization to mature fully, Galván explains. “It’s a little bit like learning a language,” she says. “Our brains are framed to learn how to speak a language, but we become experts in a particular language because of the input we receive early in life.” In the same way, teens need some social interaction to fine-tune the neural systems that support social understanding and behavior.
As data indicate that teens, on average, experience less social connection than in previous generations, more scientists are trying to understand how this reduced socialization may impact brain development. “There is definitely a lot of interest on this subject,” says Livia Tomova, an assistant professor of psychology at Cardiff University who leads the Developing Social Minds Lab. “But it is a relatively new field,” she explains. “There is still very little data on this.”
What scientists know—and don’t—about isolation and the teenage brain
Much of what scientists currently know about social isolation and the brain comes from two main sources, Tomova explains: behavioral studies of adolescent humans and brain imaging studies in adolescent animals, such as mice.
At the behavioral level, most studies find that social isolation is associated with adverse outcomes like increased anxiety and greater vulnerability to addiction. In animal studies, researchers have found that isolation is associated with changes in the prefrontal cortex, an area involved in higher- and social cognition, Tomova explains.
Part of this lack of human data stems from the current pace of social change. To understand how reduced social interaction affects brain development, scientists rely on longitudinal studies that follow large groups of children over many years, says Kaiser.
(This generation is facing a host of completely unique health threats.)
Only recently has such data begun to emerge, largely through the Adolescent Brain Cognitive Development (ABCD) Study, the largest long-term study of teen brain development in the United States. Launched in 2016, the ABCD Study followed the development of nearly 12,000 teens across the U.S., tracking both biological data, such as brain scans, and behavioral information, such as socialization patterns or screen time.
“The ABCD data is finally allowing researchers to explore the relationship between kids' behaviors and brain development more fully,” says Caterina Stamoulis, an associate professor of pediatrics at Harvard Medical School and principal investigator of the Computational Neuroscience Laboratory at Boston Children’s Hospital.
Last October, Stamoulis published the most extensive study to date on the relationship between isolation and teen brain development, using advanced computational tools that can analyze brain networks through neuroimaging data.
Along with co-author Matthew Risner, a researcher at the Computational Neuroscience Lab at Harvard Medical School, she analyzed structural and functional MRI data from nearly 3,000 pre-teens aged 11 to 12, a time when social interaction outside the household becomes more prominent than in childhood.
To estimate levels of isolation, the researchers relied on parents’ reports of children’s social behavior. “As part of the ABCD study, parents were asked to report on how often their child preferred solitude versus socialization and whether they acted ‘withdrawn,’ as in ‘not getting involved with others,’ Stamoulis explains. “So we used data from those observations as a measure of isolation and social withdrawal.”
The results, published in Cerebral Cortex, indicate that the brain structure and the strength of brain circuits in teens who prefer solitude or were socially withdrawn differ from those who socialize more.
For example, the superior temporal gyrus, an area involved in social cognition, including the perception of motion, facial movements, and the understanding of other people’s mental states, was structurally and organizationally different in teens who had less frequent social interaction. The anterior cingulate cortex, an area that supports emotional processing, was also less developed in kids who socialized less.
“The fact that social isolation or withdrawal can impact the social brain was in line with our expectations,” Stamoulis says, adding that these impacts are also in line with studies on isolation and the brain conducted on adults. “But what we found out is that brain areas and networks associated with non-social skills were also affected.” Areas involved in attention and decision-making, such as the dorsal attention network and the parahippocampal gyrus, were less integrated with other brain structures in kids who experienced higher levels of isolation.
“We did not expect isolation to affect such an extensive array of brain networks,” Stamoulis says. Reasons for concern are primarily due to the profound impact that such changes can have on a developing brain.
Because adolescence is a period of heightened neural plasticity, she explains, changes that occur during this window may have more lasting effects. If not corrected, they can lead to the development of mental health issues like anxiety and depression that can last into adulthood. Though the study does not show that isolation directly causes these outcomes.
When isolation is a concern—and when it isn’t
But heightened sensitivity does not mean inevitability. Adolescence is a time of heightened neuroplasticity, meaning that early interventions, such as offering children more opportunities to socialize or, in some cases, seeking help from a therapist, are likely to offset the negative impacts that excessive isolation can have on the developing brain.
Of course, not all types of isolation are problematic, Stamoulis adds. “My suggestion is to learn the difference between ‘normal’ preference for solitude and too much isolation,” the researcher says. Yet, that difference can sometimes be hard to gauge, Kaiser notes.
“Each person has a different need for socialization,” she explains, “Some kids want a big diverse group while others get their social input in smaller groups or in different kinds of settings, and that’s OK too.” What matters most, Kaiser adds, is that adolescents have some form of meaningful interaction with peers.
Any response to social isolation should also account for individual differences, Galván notes. “The success of ‘reversing’ negative impacts depends on the nature of the social isolation, the individual’s developmental history, and current context,” she explains. “But in general, greater engagement in social interactions, establishing meaningful relationships, and genuine support from others can help mitigate any negative impacts of social isolation.”
(Read more on why this author thinks an endless ‘virtual life’ would be terrifying).
Whether virtual interaction can provide similar benefits remains an open question. “A lot of kids' social life takes place online,” Tomova says, “even for people who see each other in real life, they also interact virtually, so it’s becoming almost an extension of social life in a different realm.”
Just how much of this virtual hanging out can reap the same benefits of in-person connection is one of the questions that Tomova and her team at the Developing Social Minds Lab are currently exploring. “We want to understand what kinds of virtual interactions are beneficial and which kinds are not,” she explains. “So maybe we can teach young people how to use virtual interactions better.”
