It hasn't taken the impact of covid infections on these kids, even though it's well documented that covid can cause brain changes?
No they started a study pre covid to look at who kids brains developed in teenage years - got interrupted due to covid and noticed when they could get back to do research that part of the girls brains had matured faster than usual but boys also thinned faster but less fast than the girls.
Though it does look like another group in USA has found similar changes - they say this when quoting an expert commenting on this study later in article.
Essentially they've noticed this change in their study unexpectedly and need to do more research as to long term affects if any.
They speculated as to why girls were worse - teen girls and socialisation - but don't know what it means cognitively and they don't know if it will self correct by not aging as fast in next few years.
Also study was in USA - doesn't say anything about social economic status of kids - but employment security, housing security and access to medical care are all less secure than here and there was way more polarisation about mask wearing and everything - and not sure how they handle their schooling situation.
I doubt this group will be able to do more than speculate on causes - and other research work might have to be looked to for any answers if even possible.