Reacción a "Pandemic related isolation accelerated the brain maturation in adolescents, especially in girls"

The authours should be congratulated on getting such an intricate sample together during such challenging circumstances of the pandemic. This is potentially an interesting proof of concept paper on how the brains of adolescents changed over the COVID lockdown but there are some key limitations to be aware of.

Firstly, the samples are quite small, so we need to be cautious not to generalise these findings to all adolescents.

Secondly, there is not a huge amount of information about these samples beyond the fact that they were collected at different times during the pandemic so we cannot assume it definitely is the lockdown which is the cause of these reported changes in the brain. For example, many other things may have happened during the pandemic period such as infection with covid or a number of infections. There are many factors that are not modelled or documented in this paper which could potentially explain these findings beyond the lockdowns themselves.

Thirdly, there is also an interesting choice of methods to completely split the different samples and use the normative modelling approach without looking at individual level trajectories (i.e not using the inherent strengths of the longitudinal sample, but instead taking a pre and post lockdown split ). We know from much of the work on normative changes in these trajectories that there is considerably individual level variation that may not be captured in a cross-sectional analyses. As is clear from general growth chart models (and also from the test-retest approach in this paper), normative models will allow some variation over time that is still in the normal range  (and also in this paper the validation seems to range quite widely between around 0.013 and 0.78 which would indicate that the normative scores estimated on the post lockdown sample from those models probably has a very broad uncertainty around it). It is hard to determine whether the observed difference between pre and post lockdown falls within such normal levels of individual variation over time (or in fact within the ‘reliability’ range of the normative model itself). Increased certainty about how generalisable the normative model is would help, but since this is based on a small sample its again hard to say how strong these effects really are. This is all purely based on the methodology.

The results need to be more firmly and generalisably established before we can conclude that adolescent brains changed beyond normal morphological changes during the pandemic. And even if these changes are established in further study, more work needs to be done to assess what factors during the pandemic are responsible for these changes, as there are many factors beyond lockdown which would also need to be considered and studied.