Makes me wonder if professional divers are statistically more intelligent than average, as they will experience hypoxia as part of the job.
It probably wouldn't be significant as executive function and overall intelligence can change independently.
Professionals at anything, let alone an elite performance sport like this, are almost certainly statistically more intelligent than average.
s/professional divers/free-divers/
They shouldn't experience hypoxia. That's what the air supply is for.