Teens' brains aged faster during the first year of the pandemic, study says, and stress may be to blame

The brains of U.S. teens have physically changed during the COVID-19 pandemic, aging faster than normal, a new study says.

The young study participants also reported more severe symptoms of anxiety, depression and what scientists call internalized problems -- meaning feelings of sadness, low self-esteem and fear and trouble regulating their emotions -- after the first year of the pandemic.

Dozens of studies have found that teens' and adolescents' mental health has suffered during the pandemic. They have been taken out of school, away from their friends and familiar support structures, and had to live with the uncertainty and fear that came with the coronavirus. Many parents lost jobs. Millions of children lost parents and grandparents to COVID-19.

The study, published Thursday in the journal Biological Psychiatry: Global Open Science, is one of the first to look at the physical changes in the brain brought by that the stress and anxiety.

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The research comes out of a larger study in which scientists were trying to understand the gender differences in depression among adolescents.

Eight years ago, they set out with a plan to take MRI scans of 220 children ages 9 to 13 every two years. The team had completed two sets of scans when the pandemic interrupted their research, and they weren't able to start scanning again until the end of 2020.

When their research was interrupted, the team decided it would be interesting to study the effects that this stressful event was having on kids' developing brains. The pre-pandemic scans would help them make this comparison.

The researchers matched children in the same demographics -- including gender, age, exposure to stress and socioeconomic status.

To find the average brain age, they put the MRI scans through a model that pools data from other scans.

The researchers compared the MRI scans of 128 children. Half the scans were taken before the pandemic and the other half at the end of 2020.

They found that the children who had lived through the first year of the pandemic had brain ages that were older than their chronological age.

The brains that had gone through the beginning of the pandemic had growth in the area that can help regulate fear and stress, called the amygdala, and in the hippocampus, the area of the brain that can controls access to memories. Tissues had thinned in the part of the brain that controls executive functioning, the cortex.

A child's brain changes naturally over time, but research has found that these physical changes can speed up when a person goes through significant adversity in childhood.

Studies have shown that people who are exposed to violence, neglect, poverty and family problems early in life have faster brain aging and can have problems with their mental health later on.

Ian Gotlib, lead author of the new study, said the research team had expected to find the problems with anxiety, depression and internalized problems. "The pandemic has not been kind to adolescent mental health," said Gotlib, a psychology professor at Stanford University.

But they weren't exactly sure what they would find with the MRI scans.

"It's always interesting to do research like this when you're not really sure what's going to happen," Gotlib said. "These effects were interesting and happened pretty quickly.

"This was just a one-year shutdown, so we didn't know that the effects on the brain would be this pronounced after that short a period of stress," he added. "It tracks with the mental health difficulties that we're seeing."

What isn't clear, he said, is whether the brain changes will have an impact later in life. The research team plans to scan the same kids later to track their brain development. There is a chance that their brain changes could have just been an immediate response to a stressor that will normalize over time, he said.

The team also plans to look at the 10 children in the study who had COVID-19 to see whether there is a different effect. The physical differences seem to be "a little more pronounced" in the children who had COVID, Gotlib said.

Dr. Max Wiznitzer, diversion chief of pediatric neurology at UH Rainbow Babies & Children's Hospital, said the changes in the brain were interesting, but what's important is whether the mental health problems persist.

"The anatomy is not important. It's the functionality that's important," said Wiznitzer, who wasn't involved in the research. "The clinical consequence here is the functional impact, the mental health condition clinically and how it's functioning and how you deal with it."

With appropriate mental health interventions, problems like anxiety or depression can be managed. "The brain has that capacity for reorganization -- or call it improvement, if you will," Wiznitzer added.

Gotlib hopes parents and guardians keep in mind that although lockdowns and school closures may be over, the mental health consequences may be lingering.

"Be sure that your adolescent or your teen is getting any help that he or she, that they, might need if they're experiencing symptoms of depression, anxiety" or being withdrawn.