“That which doesn’t kill me makes me stronger,” Friedrich Nietzsche famously wrote. But the truth is likely to be the reverse: If an ordeal doesn’t break you, it is probably because you were stronger in the first place.
So says a paper just published in the journal Proceedings of the National Academy of Sciences by Greg Miller, a psychology professor at Northwestern University’s Institute for Policy Research, and his colleagues. By looking at the health of teenagers living in Chicago’s rougher neighborhoods, they explored why some young people are more resilient than others. Why is it that we don’t all react to adversity the same way?
The team already knew when they started that proximity to crime can damage the health of young people. On the night after a violent crime, for example, local teens’ sleep patterns are often disrupted and their cortisol levels spike, according to a study published in 2017. Even if they don’t witness it directly, many teens’ awareness of a local homicide or assault leaves a distinct biological signature in the form of an elevated heart rate and altered behavior.
These clues show that fear is literally getting under the skins of young people, engendering long-term cardiovascular risks. “Kids who live where there is violent crime have more health issues than [those] in higher income neighborhoods. But it’s not just about income. Violence per se is related to higher blood pressure, blood sugar, more obesity and all the precursors of diabetes and heart disease,” Prof. Miller told me.
Yet some children who live in the same areas seem to be shielded from crime’s corrosive effects. To find out what protects them, researchers recruited a diverse group of 218 eighth-graders in Chicago. The researchers tracked the incidence of crime in each teenager’s neighborhood by using data from local police departments. On average, the adolescents in the study lived in areas where the murder rate is 142% higher than elsewhere in the U.S.
The researchers brought the teens into the lab for two testing sessions. First, their weight, blood pressure, abdominal fat, blood insulin and glucose levels were measured—all of which can be signs of cardiovascular risk. The second time, the young people underwent brain imaging, with fMRIs to assess the strength and efficiency of certain resting state neural networks. The goal was to check for any differences between the brains of the children with cardiovascular risk factors and those of the hardier ones. Could the more resilient participants be identified by their brain scans alone?
Indeed they could. The study found that young people with a stronger, more efficient central executive network (CEN)—the brain areas that govern the regulation of emotion, and the vigilance that accompanies fear—were also the ones who demonstrated fewer cardiovascular risk factors. “We used statistical measures to rule out the effect of the family’s income, their area’s level of pollution or segregation, or the availability of fresh food,” Prof. Miller told me. “The kids with low CEN connectivity had worse cardiovascular health.”
What this means is that participants whose brains allowed them to suppress intrusive, unpleasant thoughts and to reappraise threatening events were also physically more resilient. They were thinner, with lower biological measures of stress, and their hearts were stronger.
This was an observational study, so we can’t say for certain that a teenager’s brain architecture is what’s keeping their damaging physical reactions to violence in check. Perhaps some kids are just born resilient. Their more measured cognitive response to life’s risks comes packaged with the signs of robust cardiovascular health. I wouldn’t say that these kids have all the luck, but they do seem biologically equipped to face stress with equanimity. And that’s a good start.