As researchers make new advances in our understanding of aging at the molecular level, there is new hope that we will one day be able to medically control the process. But while experts in the field agree that such a treatment remains far off, their discoveries confirm that there are steps we can take now to live longer, healthier lives.
A new Duke University study has added to the body of fascinating research showing that our life experiences can accelerate aging at the tiniest, chromosomal level. The study found that stress or violence experienced when we are young can lead to significant changes in our telomeres, the DNA sequences at the ends of our chromosomes. A statement from the Duke research team describes telomeres as "much like the plastic tips of shoelaces," in that they keep DNA from unraveling. Because telomeres shrink every time a cell divides, essentially putting a cap on the amount of time a cell can live, they are reliable markers of our true “biological age” — how old our bodies actually act, whatever our chronological age.
The Duke team studied data that tracked 1,100 sets of twins from childhood through young adulthood. DNA samples were taken at different ages, and the twins' mothers were interviewed about any negative psychological events the children had experienced, including physical violence, domestic abuse and bullying. The researchers found that kids who had been through at least two major stressors had significantly more telomere shrinkage than children who'd had fewer negative experiences.
This research, along with earlier studies conducted elsewhere, strongly suggests that psychological stress — particularly severe stress — can lead to premature aging. If this is true, then efforts to reduce stress, particularly early in life, might slow the process. "An ounce of prevention is worth a pound of cure," Terrie Moffitt, Duke professor of psychology and neuroscience, said in a statement released with the study. "Some of the billions of dollars spent on diseases of aging such as diabetes, heart disease and dementia might be better invested in protecting children from harm."
Can We Reverse the Aging Process?
If science could develop a treatment to slow or prevent telomere shrinkage, could we delay or stop the aging process? Dr. Ronald A. DePinho, president of the University of Texas M.D. Anderson Cancer Center, has done some groundbreaking work in this area. In one experiment, the results of which were published in 2010, he and his colleagues engineered mice in which the gene for telomerase, the enzyme which controls telomere length, could be activated or deactivated. When the gene was turned off, adult mice quickly and prematurely aged, roughly to the equivalent of 80-year-old humans. When the gene was switched back on, the researchers had expected that the mice's aging process would slow or stall. Instead, it actually reversed. "The reproductive function of the mice resumed so that they were fertile again," says DePinho, who was at Harvard Medical School at the time. "Their brain function improved, and their coats even became more youthful. This teaches us that tissues, even those in very severe states of degeneration, retain a remarkable capacity to renew themselves."
DePinho's experiments on mice were more of a "proof of concept" of how telomerase works than a blueprint for affecting its expression in humans. There are certainly other factors, genetic and environmental, which affect the way we age. As DePinho says, when it comes to methods of slowing the aging process, "we already have such agents: Exercise — just 15 minutes of vigorous every day increases life expectancy by three years, even longer if you do more; eating properly and not excessively — which can lead to obesity and a chronic state of inflammation; and not smoking, which results in massive cellular damage and aging.”
It’s also important to understand, when discussing possible means of slowing the aging process, that there’s a difference between life span and life expectancy. "Life span is fairly fixed in a species, although it may be increased by up to 50 percent with basic knowledge of aging," DePinho says. “Our own metabolism caps human life span at 110 to 120 years of age.”
Life expectancy — our odds of living healthier longer — is a different story. Our ability to overcome some of the health issues that most affect our lives, like obesity and cancer, can have a major impact on our life expectancy. "We have the opportunity to understand life and disease on such a fundamental level that we can change the human condition," DePinho says. "Cancer will be the first disease to fall to the axe of science, and we’ll continue to drive further toward the ultimate goal of existing — there is no greater drive of living organisms than to exist — but equally important is the goal of existing in a healthy state."
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