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Scientists say they have discovered an important indicator of human lifespan.
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Data suggests that genetics may be the biggest influence on lifespan.
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Experts stress that a healthy lifestyle remains important.
Lifestyle factors play a big role in living a long and healthy life, but scientists say new research may have found an important indicator of how long you’ll live.
The research is published in the journal science, The researchers analyzed lifespan and genetics in groups of identical and fraternal twins in Denmark, Sweden and the United States, then compared how well these factors matched across groups of twins.
Because older records don’t specify why people died, researchers must estimate which deaths were caused by external factors, such as accidents or illness, and separate them from natural, internal causes. The researchers found that mortality rates remained stable between the ages of 20 and 40 and then increased rapidly with age. What’s more, deaths caused by external factors increase with age, but more slowly than deaths caused by internal factors such as aging or genetics.
After analyzing the data, the researchers found that genes may determine up to 55% of lifespan, more than double previous estimates. Researchers say the rest of your life can result from environmental influences such as lifestyle and medical care, as well as random changes and modifications in your genes.
The researchers discovered this by accident while modifying a mathematical model, said lead author and researcher Ben Shenhar, a researcher in the physics of aging at the Weizmann Institute of Science in Rehovot, Israel.
Meet the experts: Leonard E. Egede, MD, chair, Department of Medicine, Jacobs School of Medicine and Biomedicine, University at Buffalo; Ben Shenhar, lead study author and researcher in the physics of aging at the Weizmann Institute of Science, Rehovot, Israel; Janet O’Mahony, MD, internist, Mercy Medical Center, Baltimore, MD; Leigh Frame, PhD, executive director, Office of Integrative Medicine and Wellness, George Washington University
These findings may sound like bad news for those looking for possible ways to help extend their lives, but experts say that’s not the case. Here’s why.
Why are genes so important?
There are several reasons for this. “A big part of it is disease risk,” Schenhar said. “We analyzed the heritability of death from cancer, cardiovascular disease and dementia. Death from dementia was most heritable, followed by cardiovascular disease and then cancer.”
Twin studies show that about half of the variation in nearly all human traits, including personality traits, is due to genetics, Schenhar said. “In this sense, lifespan is not an outlier – rather, it falls within the range of genetic influences that we already know about,” he said.
But Schenhar points out that one or two genes don’t tell the whole story. “Lifespan…is influenced by hundreds or even thousands of genes, not just a few,” he said.
Genes don’t tell the whole story, either, said Dr. Leigh Frame, executive director of the Office of Integrative Medicine and Wellness at George Washington University. “Genes don’t work in isolation,” she said. “They set out a range of possibilities rather than fixed outcomes, influencing individual responses to environmental exposures, lifestyle and aging itself.”
Leonard E. Egede, MD, chair of the Department of Medicine at the Jacobs School of Medicine and Biomedicine at the University at Buffalo, noted that the study is not perfect: It used the Scandinavian Twin Registry, which means the findings may not generalize to other populations.
What does this mean for lifestyle factors?
It’s easy to think this study shows that the time you spend eating healthy and going to the gym isn’t that important. Experts say that’s not the case. “Longevity is a combination of genetics, lifestyle and environmental factors,” Dr. Egged said.
Additionally, even though lifespan is about 50 percent determined by genetic factors, another 50 percent is determined by other factors, Shenhar said. “That’s where all the usual problems come from — exercise, diet, social relationships, environment, etc.,” he said.
Dr. Egged agrees. “Poor lifestyle remains an important driver of morbidity and mortality,” he said. “Healthy eating, moderate exercise, stress management and not smoking are key lifestyle changes that should still be encouraged.”
Schenhar says following a healthy lifestyle may become more important as you age. “For example, at age 30, there’s not much difference in mortality between people who drink, smoke and live a debauched life and those who live well,” he said. “The opposite is true for 80-year-olds. As we age, our environment and lifestyle become increasingly important to our health and survival.”
Janet O’Mahony, an internist at Mercy Medical Center in Baltimore, Maryland, says it’s also important to see your doctor regularly to learn about any health conditions you may have, whether due to genetics or lifestyle. “Access to quality primary care [may] Diagnosing and treating high blood pressure, diabetes, obesity and high cholesterol,” she said. “Getting cancer screening tests like mammograms and colonoscopies is also thought to save lives. “
While genes set the stage, lifestyle factors also play a role in your health outcomes. “Even if genetics contribute a lot to lifespan—up to half, according to this study—lifestyle factors still exist extremely importantEspecially for healthspan, which means a lifespan of physical and cognitive health, Frame said. In fact, lifestyle choices can either amplify genetic vulnerabilities or help buffer them. While healthy behaviors may not completely override genetic factors, they strongly influence how well people age and how long they live free from disease and disability. “
bottom line
Shenhar stresses that you shouldn’t give up on healthy lifestyle choices based on these findings. “This message should be 100 percent not genetically deterministic,” he said. “I don’t think it has any direct impact on the decision-making level of personal lifestyle.”
But Schenhar said the study shows that we still have a lot to learn about the genetics of aging. “For example, if we can understand what the biological pathways are behind the favorable genetic profile that allows 20 percent of centenarians to live to 100 without any serious disease, then this will hopefully better guide and drive research into longevity drugs and interventions in the future,” he said.
Until then, Dr. Egged recommends sticking to lifestyle choices that have been shown to help maintain health. “You can’t control your genes, but you can change your lifestyle,” he said. “Focus on lifestyle changes.”
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