Other react mostly to guns, but as a diver I can assure you that there is no automatic brain damage from 'diving deep underwater', whatever that layman term means. There are many folks in diving community with 10s of thousand of dives working cognitively as well as their peers. If you mean Nitrox for bigger depths, again that ain't true, Nitrox is actually better than regular compressed air re effects like nitrogen bubbles in your bloodstream.

If you screw up or your equipment fails and end up with decompression sickness thats another story, but its like saying paragliding breaks your legs.