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For a creature foraging on the savannah 3 million years ago, a racing heart, flushed skin and a bad taste in the mouth — stress responses — were useful for avoiding predators.
A University of Iowa researcher and his colleagues have found that similar stressors occur in America's prisons, causing people who have been incarcerated to age faster.
"Thank God evolution gave us the tendency to be aroused and to flee," University of Iowa professor Mark Berg said. "We still possess that, and we use it occasionally. But if it happens too much, it's very, very unhealthy.
"That's what we think is happening in prison."
Spending time in jail or prison can speed up the aging process by an average of 11 months past someone's actual age, according to DNA research by Berg and his colleagues. Experiencing violence in prison accelerated the aging process by more than two years, according to the study published late last year in the Journal of Health and Social Behavior.
"Losing Years Doing Time: Incarceration Exposure and Accelerated Biological Aging among African American Adults" is based on data collected as part of a decades-long research study on Black families in the United States.
Berg said he was initially skeptical of prior research on the health impacts of incarceration, in part because it relied on self-reporting. But as someone who studies the social determinants of health in the UI Department of Sociology and Criminology, he said the "lights were flashing" to do his own analysis.
"To my great surprise, we found very durable effects among a sample of people who are only looking at their fourth decade of life who otherwise should be healthy," he said.
Nearly 8,000 people were in Iowa prisons as of September, according to data from the Department of Corrections. The majority were serving sentences of 10 years or more; about half were serving time for violent crimes.
No matter if someone believes the carceral system should be more or less intense, Berg said, the findings of his study and others like it should be used in policy-making decisions.
"And why is that?" he said. "Because these guys, basically, are leaving prison with an extended sentence."
Berg is director of the Crime and Justice Policy Research Program at UI's Public Policy Center. Ethan Rogers, a colleague at UI, along with Man-Kit Lei and Ronald Simons from the University of Georgia, also worked on the research.
How did the study work? Tracking 410 children into their adulthood
In 1996, about 800 families with children agreed to participate in a study, titled the "Family and Community Health Study," about the experiences of African Americans in the United States.
Children of those initial families, who are now middle-aged adults, make up the 410 people whose data were used in the study of aging and incarceration. About half of them had spent time incarcerated.
Berg says the data is "among the most extensively studied sample of adults in the United States." The availability of data on the same subjects over time — tracking the children since they were in elementary school — cleared the way for researchers to study the impacts of incarceration on age.
To do so, researchers used DNA analysis to assess whether those 410 adults are biologically "older" than their age on a calendar. They tested for methylation levels in DNA, which can take a toll on the essential biological process of gene expression and lead to accelerated aging.
Factors in the environment like lead, air quality, drinking water and disease have been linked to accelerating the aging process. So have physiological and psychosocial stressors, such as racial discrimination, Berg said.
He referenced not only violence, but also a lack of privacy and autonomy as main stressors that impact people who are incarcerated.
The research team made efforts to rule out other factors that could explain the accelerated aging, such as socioeconomic class, early childhood trauma and smoking. Researchers also ruled out factors that have the opposite effect on aging, like exercise.
"We controlled for all of that, and no dice," Berg said.
Berg said he hopes that, at a minimum, the research findings can help make prison less violent.
"If we can do anything, we can make the places safer for them, which we show would bring a pretty big net benefit to their health," he said.
This article originally appeared on Iowa City Press-Citizen: Prison time speeds up aging, according to Iowa study