How much does genetics affect lifespan

When the genes take over

How old we get depends three-quarters on our lifestyle and one-fourth on our genes - this is an important finding in modern gerontology. Scientists from the Boston University School of Medicine are now reporting in the Journal of Gerontology: Biological Sciences that the proportions are apparently reversed in very old age and that genetics become the decisive factor.

Siblings of 90-year-olds only rarely live to be the same age, as the study shows: Compared to other people in their birth cohort, their chances are only 1.7 times greater. But then the genes gradually take over the command: If a sibling is 95 years old, the others are 3.5 times more likely to reach the same age; for 100-year-olds the chance is even nine times higher. And when a person is 105 years old, write the researchers working with biostatistician Paola Sebastiani, then there is a 35 times higher probability that his brothers and sisters will live just as long. The authors of the study conclude that this is how old they are, but only very few people live.

"Our results support the idea that genetic makeup plays an increasingly important role in very old age," says the last author of the study, Thomas Perls, in an interview with the research information service MedicalResearch.com. "We also suspect that the gene combinations that promote survival up to the age of 95 differ significantly from those that make some people 105 years old."

Similar disease patterns in very old age

From this old age on, 75 percent of survival has to do with the individual gene profile and only 25 percent with the way of life, believes the renowned physician. His assumption coincides with the observation that people become more and more similar in their diseases once they have reached the age of 105 years. In addition, the typical age-related illnesses often set in at the same time. It is known from 110-year-olds, so-called supercentenarians, that many of them were healthy up to the age of 105 and that serious illnesses only accumulated in the last years of life.

The Boston study was made possible by the New England Centenarian Study, founded by Thomas Perls and, with 1,500 participants, the world's largest registry of centenarians and their families. For the current study, the researchers analyzed more than 1,900 sibling relationships of the very old.

In addition to the concrete results, the Boston researchers hope to be able to contribute to a more precise definition of important technical terms with their study. Currently, the terms aging, life span and exceptional longevity are often used with different meanings. According to the new findings, the general statement that around 25 percent of longevity and lifespan are genetically determined can no longer be maintained. The statement is based on studies that were carried out on Scandinavian twins around thirty years ago: the oldest of them were in their late eighties.

How healthy behavior increases life expectancy

Up to this age, life expectancy can be increased in an impressive way through a healthy lifestyle, says Thomas Perls. This is clear from the example of the Seventh-day Adventists, a Protestant free church whose members eat a vegetarian diet, regularly play sports and avoid alcohol and tobacco. Their average life expectancy is 88 years, almost eight years above the value applicable in many countries.

In view of the apparently decisive influence of genetic factors beyond an age of 105 years, the authors of the new study advocate focusing the search for longevity genes on this age group.

 

From Lilo Berg

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Additional information:

Paola Sebastiani et.al., Increasing Sibling Relative Risk of Survival to Older and Older Ages and the Importance of Precise Definitions of "Aging", "Life Span" and "Longevity", J Gerontol A Biol Sci Med Sci, 2015 DOI: 10.1093 / gerona / glv020

MedicalResearch.com Interview with: Thomas Perls, MD, MPH Professor (2015): Living Past 100 May Be In Our Genes.

 

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