The pandemic’s impact on teenagers was significant, with numerous studies documenting the mental health challenges, social disruptions, and more that they faced.
A recent study now suggests that these experiences caused some adolescents’ brains to age faster than they normally would—on average, 4.2 years faster in girls and 1.4 years faster in boys, according to findings.
This study is the first to provide details on aging differences between sexes, adding to previous research on the pandemic and its effects on accelerated brain aging in adolescents.
“The findings are an important wake-up call about the fragility of the teenage brain,” said Dr. Patricia K. Kuhl, senior author of the study and the Bezos Family Foundation Endowed Chair in Early Childhood Learning.
Kuhl, who is also co-director of the Institute for Learning and Brain Sciences at the University of Washington, emphasized that teens need more support now than ever before.
Adolescence is a critical period for socioemotional development, accompanied by significant changes in brain structure and function. The cerebral cortex, which thickens during childhood, gradually thins during adolescence and continues to do so throughout life.
Originally, the researchers planned to track typical brain development in adolescents by conducting MRI scans in 2018 and following up with another scan in 2020.
However, the pandemic delayed the second MRI for three to four years. By that time, the 130 participants, all from Washington state, were between the ages of 12 and 20.
The study excluded adolescents with developmental or psychiatric disorders or those taking psychotropic medications.
Using the pre-pandemic MRI data, the researchers created a “normative model” to predict how 68 regions of the brain would typically develop during adolescence.
This allowed them to compare the post-pandemic MRI data and determine whether it deviated from expectations. The normative model is similar to growth charts used in pediatric offices to track height and weight in children.
It has also been employed by other researchers to study the effects of factors such as socioeconomic disadvantage, autism, depression, ADHD, and traumatic stress.
The study found accelerated cortical thinning in the post-pandemic brains of teens—affecting 30 brain regions in both hemispheres and all lobes for girls, and only two regions for boys. This thinning occurred in 43% of the studied brain regions for girls and 6% for boys.
Dr. Max Wiznitzer, a professor of pediatrics and neurology at Case Western Reserve University School of Medicine, noted that while the study “is not a major revelation,” it adds to our understanding of the topic. Wiznitzer was not involved in the research.
However, the study has limitations. Dr. Kuhl, as senior author, was also an editor of the study, meaning she had some say in choosing peer reviewers.
Additionally, because everyone was affected by the pandemic, there was no control group, so the researchers had to rely on normative modeling.
While not as accurate as true controls, Wiznitzer said this was likely the best option under the circumstances.
The study also lacked data on the participants’ family backgrounds, such as job stability, financial security, or food access, as well as information on their exercise, sleep, or dietary habits.
It is also unclear whether some participants having contracted Covid-19 could have influenced the results.
Dr. Ian Gotlib, director of the Stanford Neurodevelopment, Affect, and Psychopathology Laboratory at Stanford University, pointed out that the sample size may not be large enough to reliably demonstrate sex differences in brain aging.
While Gotlib’s own study on the subject showed a similar trend, the sex differences in his research were not statistically significant.
Experts noted that teen brains undergo significant transitions, with the most accelerated thinning among girls occurring in regions linked to social cognition, such as processing faces, emotions, and social experiences, as well as empathy, compassion, and language comprehension. In boys, the affected regions are associated with processing visual objects and faces.
The study’s authors suggest the “stress acceleration hypothesis” may explain the findings.
This theory posits that high-stress environments can cause the brain to mature earlier to protect emotional circuits and regions responsible for learning and memory, potentially mitigating the impact of adversity on structural development.
Research has also shown correlations between stress, cortisol levels, and cortical thinning, particularly in the frontal lobe.
The sex differences observed in the study may reflect varying effects of stress on boys and girls, based on their unique developmental priorities.
However, it remains unknown whether these effects on the brain are permanent. “The brain does not recover and get thicker, we know that,” Kuhl said, but added that if teens’ brains thin more slowly as life returns to normal, it may indicate some recovery. This could be a focus of future research.
Ensuring that teenagers receive the mental health support they need is crucial, emphasized Gotlib.
He recommended encouraging in-person social interactions, limiting social media use, and being vigilant for changes in behavior that may signal a decline in mental health, so interventions can be made early.
While the pandemic has largely ended, its effects on adolescents persist. “A total return to ‘normal’ may never occur,” Kuhl said. These findings highlight the importance of investing in science that prepares us for future pandemics and strengthens prevention efforts.
