Kaiser Permanente and UCSF researchers find strong connection between which neighborhood a person lives in, how much education they have, and the length of their telomeres
By Janet Byron
A large new Kaiser Permanente study has identified links between a genetic marker of aging, how much education a person has, and the degree of socioeconomic deprivation in their neighborhood.
Genetics research suggests that longer telomeres — the “end caps” of DNA that keep strands of chromosomes from unraveling — mean more years of healthy life ahead.
Previous studies have shown links between shorter telomeres and an increased risk of cancer, diabetes, heart and autoimmune diseases, and dementia, not to mention cellular inflammation and psychological stress.
“The motivation for this work was to look at neighborhood socioeconomic status and try to understand if there were effects on the aging process that could be seen through associations with telomere length,” said lead author Stacey E. Alexeeff, PhD, a research scientist with the Kaiser Permanente Northern California Division of Research.
Analyzing 85,000 genetic samples
The study, “Telomere length and socioeconomic status at neighborhood and individual levels among 80,000 adults in the GERA cohort,” was published today in the journal Environmental Epidemiology. Researchers analyzed de-identified genetic data from 84,996 non-Hispanic white adults, all members of Kaiser Permanente Northern California in the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort.
GERA is part of the Kaiser Permanente Research Program on Genes, Environment and Health (RPGEH), a Northern California-based research program affiliated with the Kaiser Permanente Research Bank, to which Kaiser Permanente members voluntarily donated saliva samples. The Research Bank supports investigations into a variety of health conditions and diseases and includes de-identified biospecimens from more than 330,000 Kaiser Permanente members, as well as linked genetic, environmental, and health data.
Genetic samples collected between 2008 and 2011 from members of the GERA cohort were analyzed in the lab of study co-author Elizabeth Blackburn, PhD, a UC San Francisco scientist and one of three scientists awarded the 2009 Nobel Prize for Physiology or Medicine for work on how telomeres, and the enzyme telomerase, protect chromosomes.
Measuring neighborhood deprivation
Researchers used Kaiser Permanente’s electronic health records to abstract residential addresses for the specimens at the time they were collected and link them to census tracts across Northern California. A Neighborhood Deprivation Index was assigned to each individual who donated a specimen, based on census data from where they lived for income/poverty, education, employment, housing, and occupation. Because of the large number of samples, researchers were able to control for numerous factors that could also influence aging and telomere length, including smoking, weight, diet, and education.
“We found that telomere lengths increased with increasing levels of education, and that higher neighborhood deprivation was inversely associated with telomere length,” said senior author Stephen Van Den Eeden, Division of Research scientist, leader of the Environmental Exposures Core for RPGEH, and UCSF urology professor. “The upshot is that socioeconomic factors may be influencing the aging process by contributing to shorter telomere lengths.”
Blackburn explained that the enzyme telomerase actively protects chromosomes by helping to lengthen telomeres. “Healthy living habits appear to aid this process,” Blackburn said, “while living in an unhealthy place may be exposing people to factors that contribute to faster telomere loss, cell aging, and increased genetic damage.”
Largest study of socioeconomic status and telomeres
With fewer than 1,000 subjects each, previous studies looking at socioeconomic status and telomere length were much smaller than the current 85,000-person study; the next largest was a 2012 meta-analysis combining data from 14 smaller studies totaling about 8,300 people.
Co-author Cathy Schaefer, PhD, Division of Research scientist and RPGEH director, noted that this is the first GERA study to find an association between telomeres and socioeconomic factors. Future studies will look at an expanded range of risk factors that influence aging.
“By linking very large numbers of telomere measurements with years of our member health data, we will be able to take a clearer picture of what telomeres can reveal about the aging process,” Schaefer said.
In addition to Alexeeff, Van Den Eeden, Blackburn and Schaefer, co-authors of the study were Jun Shan, PhD, Dilrini K. Ranatunga, Eric Jorgenson, PhD, Lori C. Sakoda, PhD, and Charles P. Quesenberry, PhD, of Kaiser Permanente Division of Research; and Mark N. Kvale, PhD, Neil Risch, PhD, and Thomas J. Hoffman, PhD, of UCSF.