An idea that has permeated gerontology for a century is that prolonged stress hastens the aging process. We're now at the exciting point where we have the knowledge and the tools to test that idea — and we're finding that it's true.
Using the groundbreaking work done by Nobel Prize-winning molecular biologist Elizabeth Blackburn as a foundation, Mark Haussmann has discovered a solid link between stress and the aging process. He has done so by examining telomeres, the protective caps found at the ends of DNA strands. Likening telomeres to aglets – the plastic sheaths at the ends of shoelaces – Haussmann says, "You know when aglets wear down, and then eventually come off? When this happens your shoelace falls apart. Telomeres are like aglets. They wear down with age and high stress levels, and the resulting DNA instability opens the door to cell death and disease. Long telomeres are linked to a long lifespan."
To test the relationship between telomeres, prenatal stress and longevity, Haussmann and his students injected chicken eggs with corticosterone, a stress hormone, or a control liquid. "Birds are ideal because after the mothers lay the eggs, the developing chick is no longer directly influenced by mom. In other words, we could dictate the stress levels experienced by the embryo," he says.
The team found that the chicks that received corticosterone during development were essentially pre-programmed toward overactive stress responses later in life. When confronted with a stressful situation one month after hatching, chicks that received embryonic corticosterone over-reacted to the stress by releasing high levels of their own stress hormones for a longer time than the control chicks. Furthermore, says Haussmann, the prenatally stressed chick's telomeres were drastically shortened. "We measured the telomeres of one-month-old chicks and saw shortening like you'd expect to see in a 5-year-old. That's the equivalent of measuring the telomeres of a six-month-old baby and seeing they had the cells of a 50-year-old."
Haussmann involves his students at every level of his research and makes sure they are well versed in the entire scientific process. "They're involved in it all, from working with the animals, to running the molecular assays, to co-authoring the manuscripts," he says. "And, it affects how we live our lives. When we see the results of a stressful lifestyle it definitely encourages us to manage our own stress levels better, and make sure we get to the gym and eat our vegetables."
Sometimes even Haussmann is surprised by how intimately our bodily systems are connected, but his evidence shows when you're always stressed you are, quite simply, prematurely aging. "An idea that has permeated gerontology for a century is that prolonged stress hastens the aging process," he says. "We're now at the exciting point where we have the knowledge and the tools to test that idea – and we're finding that it's true."
Posted October 2012
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