How much does genetics affect the aging process? – Mayo Clinic Press

After spotting someone who has aged gracefully or perhaps looks and acts decades younger than their age, you may have heard someone comment, “Those are good genes.”

Genetics influence the aging process, says Robert J. Pignolo, MD, Ph.D., past chairman of the Division of Geriatrics and Gerontology at the Mayo Clinic and the Robert and Arlene Kogod Professor of Geriatrics. But genes are thought to account for no more than about 20% of lifespan.

“The contribution of genetics is much lower than some would think,” says Dr. Pignolo.

The other 80% of factors affecting aging include external influences such as:

• Way of life. Diet, activity levels, stress levels, smoking and alcohol use can all play a role.
• The environment. Access to health care, access to healthy foods, and exposure to air pollution, chemicals, and toxins can all affect aging.
• Life circumstances. Social support, socioeconomic status, and education levels can affect how long and how well people live.

These factors interact with your genes to affect your life and health. So while your lifestyle and environment weigh more heavily in determining your lifespan, your genes are still an important piece of the puzzle.

Dr. Pignolo points to four lines of evidence that genetics influence longevity: twin studies, gender differences in longevity, animal longevity, and accelerated aging disorders.

Twin studies

According to Dr. Pignolo, researchers have found that identical twins who have a much closer genetic makeup than fraternal twins typically experience more similar life spans than fraternal twins.

Then there is general evidence that individuals with long-lived parents and grandparents also often live long lives. You may have observed this anecdotally, but it is backed up by data.

“If you had the choice, you’d choose long-lived parents instead of rolling the dice,” says Dr. Pignolo.

Interestingly, people with longer-lived ancestors also tend to stay healthy longer. According to the National Library of Medicine, 70-year-olds with long-lived parents are less likely to have age-related diseases than other people their age.

Differences in life expectancy by sex

Women who usually have two X chromosomes, as opposed to X and Y chromosomes in men, generally have longer life spans. It is not entirely clear why this difference in life expectancy exists between the sexes. There are probably many reasons for this disparity, including an important genetic component, says Dr. Pignolo. Contributing factors may include:

• Evolutionarily, women had to live long enough to reproduce and give birth.
• Women are generally smaller than men, and smaller organisms may live longer because of reduced levels of IGF-1, a mediator of growth hormone effects.

Lifespan of animals

Dr. Pignolo further points to genetic influences on the species. For example, a mouse will never be able to live as long as a human can live. This fact has nothing to do with what mice versus humans experience, but is a genetic determinant.

Accelerated aging syndromes

Some syndromes, known as progeroid syndromes, result in accelerated aging. These rare genetic disorders “mimic physiological aging, such as hair loss, short stature, skin tightening, cardiovascular disease and osteoporosis. Consequently, they constitute an important source of information for understanding the molecular mechanisms involved in normal aging,” a 2016 review of Disease Patterns and Mechanisms details. Individuals with these conditions, such as Hutchinson-Gilford progeria syndrome, usually die young.

The study of genetics and aging

There is still much to learn about the interplay between aging and genetics. Some research aims to identify which genes influence longevity. Other research looks at those who live a long time and tries to understand how genetics and environment contributed to that longevity.

“Sometimes it’s hard to tease out the contributions of longevity to environmental influences,” says Dr. Pignolo.

Dr. Pignolo believes researchers have several choices to take this research forward: using model organisms, studying long-lived cohorts, studying centenarians, and using biomarkers.

Model organisms

One way to study aging is to experiment on model organisms such as mice with short lifespans to see if researchers can increase those lifespans through behavior or genetic modification.

Study of longevity cohorts

Some researchers focus on studying long-lived populations in an attempt to determine what factors led to their longevity. Prime candidates for this type of research are so-called blue zone geographic areas where people often live longer than the norm.

Researchers sometimes attribute longer lifespans in blue zones to environmental or mundane factors. But it’s likely that genetics are also at play. Dr. Pignolo points to Okinawa, Japan, an area known for producing impressive longevity. Lifestyle may contribute to this longevity with some researchers pointing to low calorie diets among this population. But long-lived individuals in this group were also more likely to have long-lived siblings.

The study of centenarians

When someone lives to be 100 years old or more, they receive the impressive title of “centenarian.” It is natural to wonder what led to such a long life.

Researchers take that curiosity to the next level. They study centenarians and other people who were born at the same time (known as the birth cohort) but died earlier. Researchers can then look for genes that are different between these two groups.

An example: There is a group of men who live an average of 10 years longer than others in their birth cohort. It turns out that the longest-lived group has a deletion in a particular gene, implying that the gene contributes significantly to aging.

Surrogate biomarkers

Studying aging and longevity in humans can take a long time because you don’t know someone’s lifespan until they die.

A possible method to obtain faster and more tangible results is the use of surrogate biomarkers, says Dr. Pignolo. A surrogate biomarker is a measurement that is used instead of stronger indicators, such as life expectancy, to get faster results, although they may not always be as accurate.

This difference may be particularly useful when looking at longevity, as studies using these biomarkers may not need to wait a lifetime to get results on how particular inventions work, says Dr. Pignolo.

An example of a surrogate biomarker of aging is grip strength, as this decreases with age. In theory, tracking grip strength could provide feedback on whether a particular intervention aimed at slowing aging was working.

Biomarkers may also be able to provide individuals with valuable information about their life expectancy. A biomarker could help “on a very practical level,” says Dr. Pignolo, because it can help determine “what kind of medical care and treatment, including examinations, you may receive.”

For example, cancer screening recommendations are based on life expectancy, he says. So if a biomarker indicates that your life expectancy may be longer than average, some screening may be helpful, even if the guidelines do not recommend continued screening.

Beyond Genes: Steps to a Longer Life

Remember: Although genes are important, they do not dictate your lifespan. The basics of healthy living, such as diet, exercise and preventive health care can extend your life.

And aging research shows that longevity can be possible through pathways such as increased resilience, living with purpose and creating strong social support networks.

“I think it’s important to note that if you don’t have genetic markers associated with longevity, that doesn’t preclude you from living a long life,” says Dr. Pignolo.