The health impacts of stress are well documented in medical literature, with plenty of evidence that living in an underprivileged, crime-ridden neighborhood takes a considerable toll on health.

But the dramatic results of a study led by Mijung Park of the University of Pittsburgh, and published last month, in the journal PLOS One surprised even her.

The study, including researchers and data from the Netherlands, found that a person’s perception alone that he or she lives in a bad neighborhood is associated with shorter telomeres — the protective caps on chromosomes that diminish with age and more aggressively so from stress.

Compared with those who say they live in good quality neighborhoods, those in poor quality neighborhoods showed reduced telomere lengths equivalent to the addition of 12 biological years to their actual ages.

“The magnitude was very large — larger than anticipated, and I was very surprised, and also very intrigued by it,” said Ms. Park, who holds a Ph.D. and is assistant professor in health and community systems in Pitt’s School of Nursing. “It is controversial to conclude that telomere length predicts how long we live. The data are not complete.

”What we know so far is that telomere length, or relative telomere length, can be an indicator of biological stress a person is experiencing throughout life, and that is why telomere length may be associated with longevity.”

The study used telomere data collected from about 2,900 people involved in the Netherlands Study of Depression and Anxiety. Adjusting for known factors affecting telomere length, including depression, socioeconomic issues and lifestyle characteristics, among others, allowed the team to focus on the association between telomere length and whether the person considered his or her neighborhood to be of good, moderate or poor quality.

Telomeres are compounds that protect the ends of chromosomes, much like the plastic or metal tips (aglets) at the ends of shoelaces. They shrink every time the cell divides, making them a focus in studies on aging. Stress is known to accelerate their rate of shrinkage. 

Telomere length is measured in base pairs of DNA letters, with newborns having as many as 13,000 base pairs with an annual loss for healthy people of 14 to 15 pairs. When telomeres shrink to certain levels, scientists have found, the person begins facing ever higher risks of cancer, heart disease and other chronic diseases. But mysteries still prevail in telomere science, including whether their lengths are the cause or the effect of stress, health outcomes and aging.

Compared with people who said they live in good quality neighborhoods, those in neighborhoods described as moderate quality had a mean of 69 fewer base pairs, with those in neighborhoods described as poor quality having a mean of 174 fewer base pairs.

There’s already evidence “that living in disadvantaged neighborhoods has a direct unfavorable impact on mental and physical health.” “Evidence from numerous studies and meta-analyses confirms that individuals living in poor and underprivileged neighborhoods experience increased morbidity, disability and mortality,” the study introduction states.

It represents the first attempt to address whether living in a disadvantaged neighborhood has health impacts on a cellular level.

“We have established an association between perceived neighborhood quality and cellular aging over and above a range of individual attributes,” the study concludes. “Biological aging processes may be impacted by socioeconomic milieu.”

Beyond its value to telomere science, Ms. Park said, study results should help officials concerned with addressing economic and social disparities. 

“There are social and policy reasons why people are in disadvantaged circumstances, and policymakers may consider looking at this issue more carefully,” she said. “They can maybe think about an initiative to improve the quality of life in disadvantaged neighborhoods, and see if such initiatives would lead to better health outcomes.”

Belinda L. Needham, an epidemiologist at the University of Michigan School of Public Health referred to her previously published statements to denote the importance of the study: "Observing a link between neighborhood stressors and telomere length would suggest that the chronic stress associated with neighborhood conditions has measurable biological consequences with possible implications for a range of health outcomes."

David Templeton: dtempleton@post-gazette.com or 412-263-1578. 

First Published: July 7, 2015, 4:00 a.m.