Recently learned about Acquired savant syndrome. https://en.wikipedia.org/wiki/Jason_Padgett

After the attack, Padgett felt "off." He assumed it was an effect of the medication he was prescribed; but it was later found that, because of his traumatic brain injury, Padgett had signs of obsessive–compulsive disorder and post-traumatic stress disorder.^[5] He also began viewing the world through a figurative lens of mathematical shapes.

"Padgett is one of only 40 people in the world with “acquired savant syndrome,” a condition in which prodigious talents in math, art or music emerge in previously normal individuals following a brain injury or disease.

this makes it seem more likely to me that bio interventions for increases in IQ in adult humans is possible, though likely algernon's law holds and there's a cost.

h/t @Jesse Hoogland