COVID-19 lockdowns are prematurely aging teen brains, study finds

During the COVID-19 pandemic, governments around the world have implemented restrictive measures, such as lockdowns and school closures, to limit the spread of the respiratory disease. It is well known that this disruption to daily routines and social activities has had a negative impact on adolescents’ mental health.

Adolescence, a period of transition between childhood and adulthood, is marked by dramatic changes in emotional, behavioral, and social development. It is also a time when a sense of personal identity, self-confidence, and self-control develop. The pandemic has reduced social interactions among adolescents and led to documented reports of anxiety, depression, and stress, particularly among girls.

New research from the University of Washington, published online September 9 in the Proceedings of the National Academy of Sciences, The researchers also found that the pandemic had also led to an unusual acceleration of brain maturation in adolescents. This maturation was more pronounced in girls. Measured in terms of the number of years of accelerated brain development, the average acceleration was 4.2 years in females and 1.4 years in males.

“We think of the COVID-19 pandemic as a health crisis,” said Patricia Kuhl, lead author and co-director of the UW Institute for Learning & Brain Sciences (I-LABS), “but we know it has produced other profound changes in our lives, especially for adolescents.”

Brain maturation is measured by the thickness of the cerebral cortex, the outer layer of brain tissue. The cerebral cortex naturally thins with age, even in adolescents. Chronic stress and adversity are known to accelerate the thinning of the cortex, which is associated with an increased risk of developing neuropsychiatric and behavioral disorders. Many of these disorders, such as anxiety and depression, often appear during adolescence, with females being at higher risk.

The UW research began in 2018 as a longitudinal study of 160 adolescents ages 9 to 17, with the initial goal of assessing changes in brain structure during typical adolescence.

The cohort was scheduled to return in 2020, but the pandemic delayed repeat testing until 2021. By then, the original intention of studying typical adolescent development was no longer viable.

“Once the pandemic was underway, we started thinking about brain measures that would allow us to estimate the effects of lockdown on the brain,” says Neva Corrigan, lead author and research scientist at I-LABS. “What did it mean for our teens to be home instead of in their social groups—not in school, not playing sports, not going out?”

Using the original 2018 data, the researchers created a model of expected cortical thinning during adolescence. They then re-examined the adolescent brains, more than 80% of whom returned for the second round of measurements. The adolescent brains showed a general effect of accelerated thinning throughout adolescence, but it was much more pronounced in females. The effects of cortical thinning in females were observed across the entire brain, in all lobes and both hemispheres. In males, the effects were only observed in the visual cortex.

Kuhl said the greater impact on women’s brains than men’s may be due to differences in the importance of social interaction between girls and boys. She added that teenage girls often rely more on relationships with other girls, prioritizing the ability to get together, talk to each other and share their feelings. Boys tend to get together for physical activity.

“Teens are really walking a tightrope, trying to rebuild their lives,” Kuhl said.

“They’re under a lot of pressure. Then a global pandemic hits and their usual ways of relieving stress disappear. Those ways of relieving stress are gone, but the criticism and social pressures remain because of social media. What the pandemic really seems to have done is isolate girls. All teenage girls have been isolated, but girls have suffered more. Their brains have been affected much more.”

It’s unlikely that the cerebral cortex will thicken again, Kuhl said, but the potential for healing could come in the form of a slower thinning over time, after normal social interactions and outings return. More research will be needed to see if that’s the case.

“It’s possible that there will be some recovery,” Kuhl said. “On the other hand, it’s also possible to imagine that brain maturation will remain accelerated in these adolescents.”

In older adults, measures of the brain’s cognitive functions, such as processing speed and ability to perform common tasks, are correlated with the degree of thinning of the cerebral cortex. This type of data is not yet available for adolescents, Kuhl said, but that may be where future research could go.

“The pandemic has served to test the fragility of the adolescent brain,” Kuhl said. “Our research introduces a new set of questions about what it means to accelerate the aging process of the brain. All the best research raises profound new questions, and I think that’s what we’ve done here.”

Ariel Rokem, a UW research associate professor of psychology and a data science researcher in the eScience Institute, is a co-author.