There is plasticity to aging. A range of options that narrow as we age about just how well we spend our final years; dementia and disease can be part of it, but we’re learning a lot more lately about how to live a healthy, long life.
Researchers in gerontology have defined something called health span vs life span. Life span is simply how long humans live, the current lifespan in the US is 78.7 years, but if you break lifespan down by state you’ll see a range from 81.3 (Hawaii) to 75 (Mississippi). Health span refers to the delayed onset of disease and/or dementia as a person ages. The triggers of disease and dementia definitely shorten lifespan, but they also curtail quality of life, or health span.
In fact, according to a landmark article in JAMA in 2006, among men with no risk factors at the age of 55, “the estimated probabilities of surviving to ages 75, 80, 85, and 90 years are 0.89, 0.79, 0.69, and 0.33, respectively. The corresponding probabilities for men with 6 or more risk factors are 0.47, 0.37, 0.22, and 0.06, respectively.”
Factors towards Longevity
The same study listed nine factors that contribute towards longevity … the study found the following risk factors would decrease lifespan if they were present at age 55.
- Overweight with a BMI above 25
- High glucose (>200 mg/dL)
- High triglycerides (> 150 mg/dL)
- Hypertension (> 140/90 mm Hg or medication use)
- Ever smoked during life
- High alcohol consumption (>3 drinks/day)
- Low education (< 12 years)
- Unmarried
This study has been supported over the years with other follow-up studies. A recent 2013 study looked at the characteristics of longevity and showed some diversity in results.
The University of Southern California researchers discovered that there is an ethnic difference with longevity. On average, when controlled for risk factors, people of African descent are about 10% less likely to survive to 90 compared with other groups.
- Widows are more likely to make it to 90
- Current smokers have a 30% smaller chance
- Former smokers have a 10% smaller chance
- Light drinkers are more likely to make it to 90
- Obesity and disability are factors that decrease longevity
Alleles and Longevity
Another area of research for longevity is genetics, in particular alleles. An allele is an alternate form of a gene that is located on a specific area of a specific chromosome. Researchers have been pinpointing alleles on island populations that have been associated with longevity, such as the population of Okinawa, Japan and Hawaii, U.S.A.
For example, on allele, the DRD4 7R, has been found in higher rates in people more than 90 years old and has been linked to increased lifespan in mouse studies. Another allele, FOX03A has been associated with longevity with centenarians in Germany.
As the longevity studies continue and big names such as Larry Page, Co-Founder of Google, get involved in the commercial side of aging well we should see a lot of new information in the next few years.
What do you think? As a physician do you check people in the 50s for risk factors for lifespan? Do you advise them to stay below a BMI of 25? We’ll be continuing the conversation inside Sermo, if you’re an M.D. or D.O. please join us.
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