It's an interesting study, but weirdly framed IMO.
For some reason, throughout the study itself and in the article, the effects they've observed are attributed entirely to 'Covid lockdowns'. But there doesn't appear to actually be any of the necessary work there (e.g. maybe a comparison to a similar demographic in a region that had significantly weaker or shorter lockdown measures showing a diminished effect?) to establish or support that. On the contrary, the group isn't diverse at all in that regard ("All study participants were selected from adolescents living in the same community, using identical exclusion criteria; all study participants experienced similar pandemic lockdown timelines").
And in the discussion section, they do actually partially acknowledge that limitation, and a bunch of others:
"First, the size of the sample measured here is small relative to several ongoing large-scale multisite studies of adolescent brain development, some of which collected data both before and after the pandemic. Future work should focus on replicating the effects of sex reported here on these larger cohorts using data collected before and after the pandemic. Second, it would be beneficial to have behavioral data that would allow characterization of specific lockdown-related stressors that might be correlated with brain structural findings. The current study did not collect such behavioral measures, nor did we collect data on families’ job security, financial insecurity, and/or food insecurity, which might also be associated with structural brain changes. Data on exercise, sleep, or diet, which have been reported to have been greatly affected by the pandemic lockdowns, would also be valuable. Third, it is not clear whether the effects observed in this study are specific to the age range of our sample. Our post-COVID-19 lockdown test sample consisted of children ranging from 12 to 16 y of age. It is unclear whether our findings extend to younger children or to young adults. And finally, we do not know whether contraction of the COVID-19 virus itself may have contributed to these findings, though in the community from which our study sample was derived, COVID-19 prevalence was widespread, and we have found no reports of a sex disparity in contraction of the virus."
So, basically, they have an entire study that asserts the cause of their measured effects to "Covid lockdowns", and then, in the limitations section, they essentially say, "Although we didn't look at that many people, and we didn't look at their actual behaviour changes during the pandemic. And you know, it might have been down to family circumstances like financial insecurity, or disruption to exercise, sleep, or diet, which we also didn't look at. And there was also the whole virus thing itself, since contracting that might have contributed but we also don't know about that." There's also a flaw there; they assert that there's no "reports of a sex disparity in
contraction of the virus", but that disregards the possibility of a sex disparity in the
effects of contracting the virus.
And they also don't seem to consider at all the general effects in terms of stress of just living through a pandemic in itself. Like, millions of people dying, including quite possibly family members, it was a pretty stressful time. Could be a factor? Seems to be a glaring omission.
So the conclusion, that "lockdowns did it", seems flawed to me. The implication is that if they'd lived through a pandemic, but no measures had been taken whatsoever, there'd have been fine in this regard, even with the significantly greater sickness and death that would have come from that. Which, to me, seems like a bit of a stretch.