COVID-19 | Concerns for the teenage brain

The pandemic has prematurely aged the brains of adolescents, suggests an American study. Its methodology is controversial, but it nevertheless adds to other studies that have shown that adversity experienced before adulthood causes premature maturation of the brain.

The study

The original goal of Ian Gotlib, the Stanford University psychologist who published his findings in December in the journal Biological Psychiatry, was to observe adolescent brain maturation in several hundred adolescents. “We had them brain scanned every two years. But in the middle of the third period of scans, the pandemic hit. We had to interrupt the program. When we resumed it, we completed the third period of scans for 163 teenagers who had not had theirs before the pandemic. We decided to compare their brain images with images of teenagers of the same age, before the pandemic. This is where we saw that the brains of adolescents who lived through the pandemic had experienced premature maturation. For example, their hippocampus, a brain region important for memory, had grown faster than normal.

The critics

Sylvain Baillet is a neuroimaging specialist at the Montreal Neurological Institute. For him, Mr. Gotlib’s study has several shortcomings. “These are not the same participants who were tested pre and post-COVID, says Mr. Baillet. The diversity across the population is large and the reported effects are too small to be certain of their biological significance. »

To have enough statistical impact, the researchers compared the brains of two groups of adolescents in their analysis. On the one hand, teenagers who had the post-COVID scan. On the other, teenagers who did not have it. The pre-COVID examination analyzed for the latter must have been done when they were the same age as those in the first group when they were tested post-COVID. Marie-France Marin, a stress biologist at UQAM, is less categorical, but also critical.

“The methodology is not bad, but you have to take it with a big grain of salt, before parents get worried,” says Ms.^me Marine. She also points out that the medical imaging device was replaced during the pandemic. “Normally, it can happen during research, but here, we are comparing two groups and two machines. »

Gustavo Turecki, a psychiatrist at McGill University’s Douglas Institute who worked with Mr. Gotlib’s cohort of adolescents a few years before the pandemic, points out that it is very difficult to demonstrate longitudinally, following the same people for several years, that certain traumas affect the development of the brain.

“You see it in multiple cross-sectional studies, point-in-time photos, and usually with bigger trauma, like placement, for example,” says Dr.^r Turecki. It is important to acquire this knowledge to better help children and adolescents in their development. »

Evolution

Why do adolescent brains mature faster in the face of adversity? “We think it’s an evolutionary legacy,” says Dr.^r Turecki. When life is more difficult, puberty must arrive more quickly, and the individual must become independent more quickly, in order to have a chance to reproduce before dying. But there is a cost to this faster maturation. The brain does not develop optimally. In particular, there is a hypervigilance towards potential threats. » M^me Marin confirms that this hypothesis is considered valid by many researchers.

brain age

The concept of brain age was initially developed for the elderly, to associate certain factors with a more or less hasty cognitive decline. “It is a measure that is not unanimous, even among the elderly, says Mr. Baillet. Its biological validity is not established, particularly for groups for which little use is made of the concept of brain age, such as adolescents. Dr. Gotlib argues that he limits himself to describing the maturation of certain regions of the brain during adolescence. “I used the term brain age, but that’s not to say that you can tell by looking at a specific teenager’s brain how old they should be. »

adversity

Other studies have shown that adversity affects brain maturation. M^me Marin mentions in particular the work of Megan Gunnar at the University of Minnesota and Sonia Lupien at the University of Montreal. In 2015 in the magazine Neuroimagingfor example, M^me Gunnar had demonstrated that in children placed in an orphanage and then adopted, the length of stay in an orphanage was linked to changes in the structure of the brain. M^me Lupien, a stress specialist, had shown in 2011 in the journal PNAS that children whose mothers suffered from severe depression had a larger amygdala and were “hypervigilant” in the face of threats. This is the region of the brain responsible for managing emotions. “The brain also responds on the positive side,” says Ms.^me Marine. Michael Meaney has shown that a rich and stimulating environment has a beneficial effect on the brain. »