I ran a lot of MRIs for my PhD. I saw somewhere around 100-200 different brains. About 10% of them had abnormalities. Of all the technicians, scientists, and (non-clinical) doctors I spoke with, we all agreed this was a very high rate of discovery. All my friends graduated without seeing anything weird. My advisor liked to joke that I was cursed. Eventually I stopped inviting my friends to do my experiments because I didn't want to deal with the risk of them having an abnormality - thanks to some combination of HIPAA and medical liability laws, I wasn't allowed to say anything about it, even if asked point blank. I didn't like that very much.

I made one exception, as a friend of mine came in for a study and I saw a golf ball sized cyst in his sinus. He had it surgically removed and he told me he stopped snoring the next day. It felt good to make a difference for him.

But, I saw one brain similar to the one documented here. It belongs to one of my close friends. It was harrowing. Entire left hemisphere was malformed, the ventricles were way too big and the cortex was way too thin. But the right side of his brain was underdeveloped, maybe the size of a tennis ball.

The weirdest part, he is 100% normal. In fact, he competed at a high level of college athletics. Normal Cognition, normal motor function, great sense of humor, and a very caring person. Now he has a great job, wife and kid, and we hang out often. But I can't bring myself to say anything, and every time I see his son I wonder about his brain.