Over the past two decades, the rate of violent crime in the U.S. and Europe has dropped dramatically. Despite increasingly sensational news stories about crime, we are in fact much less likely to become the victim of a violent crime today than we were in 1990. According to the New York Times, the city of New York had fewer murders last year than in any year since 1963, when reliable record keeping began. In 2013, there were 333 murders in the city, down from 417 in 2012 and a stunning 2,245 in 1991. Chicago, Los Angeles, and Philadelphia also had large declines in violent crime during this period, as did smaller cities across the country. In England, the 2013 murder rate was at a 33-year low, nearly 50% lower than its peak in 1995, according to a recent story in the Guardian. There is no question that the rate of violent crime is significantly lower than it was 20 years ago.

Many factors could be contributing to this change, including improvements in law enforcement, reductions in the use of crack cocaine and other drugs, economic changes, and the aging of the population. However, a study by economist Rick Nevin suggests that reductions in the crime rate can be attributed to diminishing levels of lead poisoning from exposure to leaded gasoline and lead paint—and there is a growing body of research that supports his theory.

“What makes Nevin’s work persuasive is that he has shown an identical, decades-long association between lead poisoning and crime rates in nine countries,” says the Washington Post’s Shankar Vedantam.

In a recent Forbes article, science writer Alex Knapp outlines reasons that Nevin’s theory deserves attention. First, the numbers correlate almost perfectly; when a lag time of 21 years is added (to account for early childhood lead exposure in adult offenders), levels of exposure to lead from gasoline and paint track extremely closely with the U.S. homicide rate (see the graph in Nevin’s 2013 update).

Second, the correlation holds true with no exceptions. “Every country studied has shown this same strong correlation between leaded gasoline and violent crime rates,” says Knapp. “Within the United States, you can see the data at the state level. Where lead concentrations declined quickly, crime declined quickly. Where it declined slowly, crime declined slowly. The data even holds true at the neighborhood level—high lead concentrations correlate so well that you can overlay maps of crime rates over maps of lead concentrations and get an almost perfect fit.”

Third, the connection between lead poisoning and brain damage is clear. “Not only does lead degrade cognitive abilities and lower intelligence, it also degrades a person’s ability to make decisions by damaging areas of the brain responsible for emotional regulation, impulse control, attention, verbal reasoning, and mental flexibility,” says Knapp.

Nevin’s conclusions have been criticized by some, including those who are wary of the implications of linking biology to criminal behavior. In a recent interview with BBC News Magazine, Roger Matthews, a professor of criminology at the University of Kent, said, “The things that push people into crime are very different kinds of phenomena, not in the nature of their brain tissue….There has been a long history of people trying to link biology to crime—that some people have their eyes too close together, or an extra chromosome, or whatever. This stuff gets disproved and disproved. But it keeps popping up.”

What do you think about the link between lead levels and crime? Are the correlations strong enough to imply causation? What are the social implications of high lead levels in the blood? PAR wants to hear from you, so leave a comment and join the conversation!

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Concussions are in the headlines once again as awareness grows about a possible link between concussions and the permanent brain damage associated with Alzheimer’s disease and dementia. The issue has far-reaching implications, including for one of the country’s most venerated institutions: the National Football League.

A major complaint filed last month against the NFL involving more than 2,400 former professional football players alleges that the NFL was not only aware of links between head injuries (such as concussions) and permanent brain injuries, but that they attempted to hide the information from players and the public. According to a June 30 AP report, “At issue is whether the NFL knew if there were links between football-related head trauma and permanent brain injuries and failed to take appropriate action.” Attorneys for retired players accuse the NFL of “negligence and intentional misconduct in its response to the headaches, dizziness, and dementia that their clients have reported.”

The league has denied the charges, stating, “The NFL has long made player safety a priority and continues to do so. Any allegation that the NFL sought to mislead players has no merit. It stands in contrast to the league’s many actions to better protect players and advance the science and medical understanding of the management and treatment of concussions” (Huffington Post, June 7).

According to a 2009 study commissioned by the NFL and conducted by the University of Michigan’s Institute for Social Research, former professional football players report being diagnosed with Alzheimer’s, dementia, and other mental impairments at many times the national average. Although the study was based on interviews and self-reporting rather than on independent diagnoses, the results suggest an alarming rate of memory-related problems.

Amid the swirl of headlines, allegations, and denials, one thing is clear: concussion is a brain injury that must be taken seriously by those who work with athletes at every level. With this goal in mind, PAR has been working closely with researchers at the Matthew Gfeller Sport-related Traumatic Brain Injury Research Center at the University of North Carolina, Chapel Hill, to develop tools that can help coaches, athletic trainers, and parents recognize the signs and symptoms of a concussion and respond appropriately. The Concussion Recognition & Response™ app (for parents and coaches) and the Concussion Assessment & Response™ app (for athletic trainers, team physicians, and other medical professionals) are the result of this collaboration.

Are attitudes toward concussion changing in your community? Is the recent media coverage helping to raise awareness about brain injuries? PAR wants to hear from you, so leave a comment and join the conversation!