How Stress Accelerates Aging
In a study published in the May 2008 issue of Brain, Behavior and Immunity, scientists from the University of California, Los Angeles explain the relationship between emotional stress and shortening of telomeres – markers of biological aging.
Telomeres are caps at the ends of chromosomes (the genetic material of a cell) that ensure their stability. Each time a cell divides, the telomere length decreases. Chronic stress also contributes to the shortening of telomeres. Shortened telomeres in white blood cells – lymphocytes – have previously been associated with HIV, osteoporosis, cardiovascular diseases and premature aging. An intracellular enzyme inside the cell, known as telomerase, helps prevent telomere shortening and supports the ability of cells to divide.
In the current study, Rita Effros, Professor of pathology and laboratory medicine at the David Geffen School of Medicine at the University of Los Angeles, California (UCLA School of Medicine), and her colleagues studied lymphocytes from healthy donors - men and women aged 25 to 55 years. The cells were exposed to different concentrations of cortisol, a hormone produced by the body under stress, or dimethyl sulfoxide (control group).
After three days, the cultures of cells exposed to cortisol contained fewer cells than the cultures of the control group. While cortisol concentrations, which can usually be detected in the human body, did not affect telomerase activity in any way, cortisol concentrations present in the body during stress reduced telomerase activity by 50% compared to the control group.
This discovery explains how stress reduces telomerase levels and thereby accelerates cell aging by increasing cortisol production. "Under stress, the body stimulates the production of cortisol to support the fight-or-flight response," Dr. Effros explained. "If the hormone content in the blood remains elevated for a long period of time, then this leads to the deterioration of the immune system. We are currently testing medical ways to increase telomerase levels to help the immune system reflect the effects of cortisol. If our efforts are successful, then one day there will be pills that strengthen the immune system and are able to withstand chronic emotional stress."