10.5% of babies in the US are going to be born prematurely, and they're going to have cognitive flexibility, reading, & verbal skills that are half a standard deviation below average, quantitative skills that are three-quarters of a standard deviation down, and working memory that's more than a third of a standard deviation down.
We can basically isolate & identify a major vector of cognitive inequality from the delivery ward.
What do you figure is the overlap between the 10.5% of the population that's born prematurely and the 8.5% of the population that gets TBI? It can't be 0 or 100% .
I ask because there's got to be some portion of the developed-world population (somewhere between a tenth and a fifth) that's going to be set for lifetime of sub-optimal cognition just due to these two factors.
Through an odd coincidence, a similar proportion of the population in developed countries also experience Traumatic Brain Injuries.
96% of people with brain injuries have substance use problems.
People with brain injuries are 19x more likely to go to prison. Of US prisoners, some proportion between half and four-fifths have brain injuries.
<https://www.economist.com/leaders/2021/03/27/a-huge-share-of-prisoners-have-brain-injuries-they-need-more-help>
<https://www.economist.com/international/2021/03/27/brain-injuries-are-startlingly-common-among-those-who-have-committed-crimes>