Yeah, the pineal gland doesn’t seem to have anything to do with IQ or cognition in the first place. It deals with melatonin and sex hormones.

The internal secretions of the pineal gland are known to inhibit the development of the reproductive glands because when it is severely damaged in children, development of the sexual organs and the skeleton are accelerated.

Calcification rates vary widely by country and correlate with an increase in age, with calcification occurring in an estimated 40% of Americans by age seventeen.

https://en.wikipedia.org/wiki/Pineal_gland#Calcification

I’d like to see relevant factors beside cognition considered, like development.

Nothing more than conjecture so take it with a massive grain of salt brain sand, but if the gland not functioning leads to a speedup in the development of sexual organs, I’m curious if it could be one of the factors involved in the age of puberty declining. (https://pmc.ncbi.nlm.nih.gov/articles/PMC6378593/)

It’s good this study exists nonetheless. Nothing amiss from what I’ve read, so I trust the conclusions.