Yet Another Study Shows How Lead Exposure Can Produce More Violent Crime

| Mon Jul. 15, 2013 11:12 AM EDT

The LA Times reports today on the latest study from the lab of Kent Kiehl, a neuroscientist who investigates the roots of violent and antisocial behavior:

It began with a casual question that neuroscientist Kent Kiehl posed to a postdoctoral fellow in his laboratory who had been conducting brain scans on New Mexico prison inmates. "I asked, 'Does ACC activity predict the risk of reoffending?'" Kiehl recalls, using the scientific shorthand for the anterior cingulate cortex, a brain structure associated with error processing.

The postdoctoral fellow, Eyal Aharoni, decided to find out. When he compared 96 inmates whose brains had been monitored while they performed a test that measures impulsiveness, he discovered a stark contrast: Those with low ACC activity were about twice as likely to commit crimes within four years of being released as those with high ACC activity.

Attentive readers will know why this caught my eye. The following passage comes from my story about the connection between lead and crime a few months ago. It's about a pair of MRI studies performed at the University of Cincinnati:

A second study found that high exposure to lead during childhood was linked to a permanent loss of gray matter in the prefrontal cortex—a part of the brain associated with aggression control as well as what psychologists call "executive functions": emotional regulation, impulse control, attention, verbal reasoning, and mental flexibility. One way to understand this, says Kim Cecil, another member of the Cincinnati team, is that lead affects precisely the areas of the brain "that make us most human."

Although I used "prefrontal cortex" as shorthand here, the precise part of the brain implicated in these studies was the anterior cingulate cortex. Cecil and his team found that lead exposure in children leads to a permanent loss of gray matter in the ACC, while Kiehl's team has discovered that low ACC activity increases the risk of recidivism. This linkage isn't surprising, given what we know about the functions of the ACC, but it's an unusually clear result that links ACC deterioration to criminal activity. Just thought I'd pass it along.