A study on adolescent brain development that looked at children before and after lockdowns due to the pandemic of coronavirus in the United States discovered that the girls brain had grown old much faster than expected, something researchers attributed to social isolation.
The University of Washington study, published Monday in the Proceedings of the National Academy of Sciences, measured the cortical thinninga process that begins in late childhood or early adolescence, when the brain begins to prune redundant synapses and shrink its outer layer.
Thinning of the crust It’s not necessarily bad; some scientists attribute this to the fact that the brain is rewired as it matures, increasing its efficiency. But it is known that the process is accelerated in stressful situationsand accelerated weight loss is linked to depression and anxiety.
Scans taken in 2021, after lockdowns began to lift, showed that both boys and girls had experienced rapid cortical thinning during that period. But the effect was much more noticeable in girls, whose thinning had occurred on average 4.2 years earlier than expected; the thinning in the men’s brains had occurred 1.4 years earlier than expected.
“It’s a striking difference,” said Patricia Kuhl, director of the Institute for Learning and Brain Sciences at the University of Washington and one of the authors of the study. The results, she added, indicated that “a girl who came to the lab at age 11 and came back to the lab at age 14 now has a brain that is It looks like that of an 18 year old person”.
Researchers explained why they believe the Covid quarantine impacted women more than men. Photo: Xinhua
Kuhl attributed the change to the “social deprivation caused by the pandemic”which she suggested had affected teenage girls more because they rely more on social interaction – particularly talking about problems with friends – as a way of releasing stress.
The difference between the sexes “is as clear as night and day,” Kuhl said. “In girls, the effects were all over the brain: all lobes, both hemispheres.”
There has been abundant evidence of a deterioration of adolescent well-being during the pandemic, but the study brings something new to this debate: physical evidence.
The researchers described the finding as surprising but cautioned against assuming accelerated cortical thinning is a sign of damage.
Weight loss “is not necessarily indicative of a problem” and may be “a sign of maturational change,” said Ronald Dahl, director of the Institute of Human Development at the University of California, Berkeley, who was not involved in the study. “Accelerated weight loss is being interpreted as problematic and it could be, but it is a hasty conclusion.”
How they did the research
The researchers started with a cohort of 160 children and adolescents, aiming to characterize typical changes during adolescence. They took the first measurements in 2018, when the subjects were between the ages of 9 and 17. But pandemic lockdowns prevented them from collecting a second wave of data in 2020.
In 2021, all of the subjects were emerging from a period of prolonged stress, creating what Neva Corrigan, a research scientist and lead author on the study, described as “a natural experiment.” About 130 of the subjects returned for a second round of examinations. The team compared the post-pandemic results to a model that predicted typical brain development in adolescence.
Although several previous brain studies had found that pandemic stress accelerated cortical thinning, none had compared the changes in boys and girls.
“We were surprised by the significance of the effects we found,” Corrigan said. “The results were not subtle. These were not small changes that barely existed. It was a dramatic change after Covid.”
Accelerated cortical thinning occurred throughout the girls’ brains, 30 different regionsbut was most pronounced in the bilateral fusiform gyrus, which helps recognize faces and facial expressions; the left insula, which helps process emotions; and the superior temporal gyrus, which is critical for language comprehension. In contrast, accelerated cortical thinning was seen only in two brain regions of men, both of which are involved in visual processing.
The researchers said it was unclear whether the changes were permanent or whether, with the restoration of normal social interactions, the adolescents’ brain development would return to a typical rhythm.
“Let’s say that the whole life of that girl who goes back to being 14,” Kuhl said, “gets better as the pandemic recedes, her social life is restored and she’s back with her friends. Not all the stress has been eliminated, but at least she has that outlet.”
Bradley Peterson, a pediatric psychiatrist and brain researcher at Children’s Hospital Los Angeles who was not involved in the study, noted several limitations. The pre- and postpandemic brain data came from different subsets of the cohort, so the results do not reflect changes in cortical thickness in individual subjects but rather measurements from a single point in time.
“The authors repeatedly and wrongly refer to this correlation as a ‘pre-pandemic measure of change,’ which it is not,” he noted.
Furthermore, he said, the authors “offer no evidence” that the changes can be attributed to the social isolation of lockdown, rather than “any other of the numerous experiences” that occurred during that period, including a increased screen timeincreased use of social media, less physical activity, less time in the classroom, and more family stress.
And, like Dahl, he warned against viewing the changes as pathological. In otherwise healthy young people, thinning of the cortex is thought to “constitute adaptive remodeling of the brain according to the demands of experience.”
An acceleration of that process during confinement, if it occurred, “could actually constitute an adaptive response of nature in the brain that conferred greater emotional, cognitive and social resilience,” he said.
The New York Times. Especial
Translation: Elisa Carnelli
