Researchers at the University of Washington found that coronavirus lockdowns, such as school closures, canceled sports activities and stay-at-home orders, aged teenagers' brains up to four years earlier.
The new research, published Monday in the Proceedings of the National Academy of Sciences, adds further evidence to how disruptions to daily routines can contribute to behavioral problems, an increase in eating disorders, anxiety and depression in adolescent girls and boys.
Scientists at the university's Institute for Learning & Brain Sciences (I-LABS) began the study in 2018, using MRIs to see how the brain structure of 160 Seattle-area teenagers developed over time. The participants, a nearly equal number of boys and girls, ranged in age from 9 to 19 at the start of the study.
Lead researcher Patricia Kuhl, co-director of I-LABS, said that after the Covid lockdowns began in 2020, they were unable to do follow-up brain imaging studies until 2021. So they shifted the focus of the study to how the lockdowns had affected adolescent brain structure.
By measuring the thickness of the cerebral cortex, the outermost layer of tissue in the brain that controls higher brain functions such as reasoning and decision-making, they found that the brains of teenage boys had aged 1.4 years too early. The girls' brain scans showed accelerated aging of 4.2 years, the study found.
The cerebral cortex naturally thins as we age. Chronic stress can also cause similar changes in the brain. But in the three-year period between the first scan and the follow-up, there was much more thinning than the researchers expected.
"As we get older, the thinning of the cortex is associated with slower processing speed, with less flexible thinking, with all the things we associate with aging," Kuhl said. "All teenagers in general showed this accelerated aging."
In teenage girls, the aging was more pronounced. The scans showed that the thinning was widespread in the female brains, affecting 30 regions in both hemispheres and all lobes. In the male brains, the thinning was limited to just two regions, both in the occipital lobe, which affects distance and depth perception, face recognition and memory.
The greater influence on girls may be due to differences in the importance of social interaction for girls versus boys, Kuhl said. Boys often get together for sports and physical activity. Adolescent girls may rely on personal relationships for emotional support and self-identity.
"When girls and women are stressed, there's a natural response to come together and talk about it, and we release oxytocin and other neurotransmitters that make us feel better," said Dr. Ellen Rome, chief of the division of adolescent medicine at Cleveland Clinic Children's Hospital. Rome was not involved in the new study.
What does premature brain aging mean for the daily lives of young people who, due to pandemic restrictions, were often confined to their rooms, taking classes via Zoom or missing social contact?
Are there long-term risks of 'pandemic brain'?
The study doesn't prove that lockdowns caused the brain changes - mental health disorders were common in children before COVID. But it does suggest that the thinning of the cortex could be linked to increased anxiety, depression and other behavioral disorders, Kuhl said.
Another 2022 brain scan study from Stanford University showed similar changes in cortical thickness in teenage brains during Covid restrictions. The Stanford researchers compared the stress and disruption of the pandemic to childhood traumas such as violence, neglect and dysfunctional families.
The pandemic has been a traumatic time for everyone, Kuhl said. For young people - at a time in their lives when they are already experiencing intense changes in their emotional and behavioral development - the isolation has been even more damaging to their emotional health.
"The pandemic was of course dramatic and unexpected, but in a way also dramatic and catastrophic, not only for physical health, but also for mental health," she said.
Since 2021, several reports on youth mental health from the Centers for Disease Control and Prevention have revealed unprecedented levels of hopelessness and suicidal thoughts among teenage girls and boys. A CDC survey released in early August found a small improvement in teen mental health, though 53% of young high school women say they still feel persistent sadness.
There are periods in brain development when certain types of learning are most effective, says Dr. Jonathan Posner, a professor of psychiatry at Duke University School of Medicine. For example, it is much easier to learn language as a young child than as an adult.
"The teenage years are incredibly important for social development," said Posner, who was not part of the new study. "If you don't have those social interactions, there's just no opportunity to have that social learning."
The cortex cannot regrow and continues to shrink throughout life. It is not yet clear whether the prematurely aging "pandemic brains" of young people are at higher risk for conditions such as ADHD and depression, and possibly even diseases such as Alzheimer's and Parkinson's, Kuhl said.
Seattle mother Karin Zaugg Black, 54, watched the pandemic tear at her two children during more than a year of distance learning. Her daughter Delia, 14, was in seventh grade; Sam, 10, in fourth.
Delia especially felt the loss of social interaction.
"When she thinks back on that time, she definitely thought, 'Yeah, it was really hard. I felt like I had no friends, and that was really hard,'" Black said of her daughter's time during the pandemic.
"Their social skills are lagging behind. You know, they've lost the ability to navigate the social world with their peers," she said.
The good news is that Delia, now a senior in high school, has regained many of the social interaction skills she lost during the pandemic.
Experts say the loss need not be permanent, as long as young people's social interactions and connections have recovered since the pandemic.
"Fortunately, kids are very resilient and we can get them back out there and help them catch up," Posner said. "But we also don't want to tell ourselves that this was nothing. It had a significant impact on growth and development."
This article was originally published on NBCNews.com
