The Pandemic Disrupted Adolescent Brain Development

By Gary Stix

Before COVID, American teenagers’ psychological health was already in decline. The pandemic, with its sudden lockdowns, school closures and other jolts to normal life, made that downward slope steeper. The ensuing mental health crisis has given researchers a rare opportunity to gauge how an extraordinary event such as a public health catastrophe can physically affect the brains of teenagers.

Preliminary results for some of these studies are starting to be reported—and they are sobering. At the annual Society for Neuroscience conference in Washington, D.C., this week, Elizabeth Powell, a program officer at the National Institutes of Health, characterized the situation as a definitive disruption in normal adolescent brain development.

In one set of research results presented at the conference, Patricia Kuhl of the University of Washington reported a larger-than-normal thinning of the cerebral cortex in a group of 124 adolescents who had been tracked before the pandemic at ages nine to 17 and then again after the COVID lockdown period. “Our findings indicate that the teenage brain showed accelerated aging due to the pandemic lockdown,” she said at the conference.

Kuhl, a professor and co-director of the Institute of Learning & Brain Sciences at the University of Washington, and her team first took neuroimaging measurements of the participants’ brains in 2018. The researchers then compared the amount of brain thinning in 2021 with a computer model of what would usually be expected three years after the point at which the first measurements were made. The cortex normally gets thinner as an adolescent grows, but the model showed a sped-up pattern of thinning during the pandemic. The effect was much more noticeable in female adolescents in the 68 brain areas measured. “The magnitude of this shift in [female adolescents] is quite large,” Kuhl said. “A girl who visited the lab, on average, at age 11 and then returned to the lab for time two at age 14 showed the age of a 16-year-old.”

Kuhl and her team, who have yet to publish their findings, have more work to do, but the study supports the findings of similar research looking at the impact of the pandemic on brain development. Thinning of the cortex can be a sign of stress. It can affect neuroplasticity, the ability to learn new things; the researchers are still trying to determine whether plasticity was affected in the group study. Kuhl is looking at how cortical thinning may affect language, cognition and social and emotional well-being, and she and her team are also considering the impact of social media on teens.

Additionally, researchers are examining pandemic health effects from another perspective: How well were adolescent brains prepared to weather such an event? Adolescence is a time when brain circuits typically undergo substantive upheavals. “It is really important to understand the brain as a potential risk or protective factor that could have predisposed youth to mental health issues and/or may have amplified negative emotions and stress during the COVID-19 pandemic,” said Caterina Stamoulis, an associate professor at Harvard Medical School, describing unpublished research at the conference. “And it’s important to understand that so that we can develop better interventions for these youth.”

Stamoulis and her colleagues looked at neuroimaging data from 1,414 adolescents in the Adolescent Brain Cognitive Development Study, the largest ongoing U.S. study of brain development and child health. They examined the organization of brain networks and assessed the strength of connections in neural circuits and how efficiently those circuits processed information.

Less robust circuits in some brain networks foretold greater levels of reported sadness and other stresses among adolescents when these measurements were made in 2020 and 2021 (the two principal years of the pandemic) “We find that the organization of the developing—and vulnerable, therefore—brain circuits may have played a critical role in adolescent mental health, stress and emotional responses during the COVID-19 pandemic,” Stamoulis noted.