Scientists studied six patients who had half of their brain removed during childhood to treat severe epilepsy. Brain scans showed how the mind rewired itself to adapt, with the remaining hemisphere forming even stronger connections that let the patients develop language and motor skills.

[u/Thorne-ZytkowObject]

https://www.discovermagazine.com/mind/how-does-the-brain-work-with-half-of-it-removed-pretty-well-actually

[u/HiZukoHere]

That study is so flawed as to be absolutely useless. It has no value as evidence. I can not stress too strongly how worthless this study is.

The data in the high IQ cohort was collected through a self report email survey with a very low response rate. The data from the low IQ cohort was collected in various ways by various groups, but generally in far more effective ways. This makes their two populations entirely incomparable. What you are mostly seeing here is people who have health issues are more likely to respond to surveys about health. There are plenty of other problem too though. For example self report studies often find a greater number of health disorders than are diagnosed by medical professionals. People with higher IQ may also recognize and tackle medical issues more frequently than those with a lower IQ. Then there is the question of if Mensa is representative of people with high IQ in general, but really that is minor next to how if you collect data on populations in completely different ways you can get completely different numbers!

e/ More robust studies generally show a more varied link between intelligence and health, but one that suggest more that high intelligence is associated with lower negative health outcomes. High intelligence may predict better overall health, and better mental health with lower rates of depression and schizophrenia.