An expert is quoted in that Post piece makes this rather eye-popping assertion—not doubt exaggerating somewhat, but driving home the basic point: “All these kids that grew up in those houses, they all have ADHD.” Also, read this 2013 New York Review of Books piece by Helen Epstein, uncannily prescient today, with its emphasis on Baltimore.
But it’s not just about learning disorders. More recently, research has gone beyond that realm and has been starting to make more direct links between childhood lead poisoning and social dysfunction of the sort Gray exhibited, and even a tendency toward violence and crime.
Kevin Drum of Mother Jones has done a lot of interesting writing on this link in recent years. Research results even have people wondering, as this BBC article notes, whether removing the lead from “petrol” (car gasoline) has been the main reason crime has gone down in the last two decades. The BBC report notes that crime rose and rose across many advanced nations throughout the 20th century, until:
Then, about 20 years ago, the trend reversed—and all the broad measures of key crimes have been falling ever since.