My favorite articles are the ones that capture my initial interest and then lead me down a rabbit hole of other references and articles all relating to the first one. An article in the current Scientific American is a good example. Ultimately, "Ways to Extend Your Healthy Years, Not Just Your Life". [2]  covers no new ground. To extend life, perform preventive maintenance with regular medical checkups, "common-sense nutrition, sleep, exercise, and social connection." But the article touches on other topics along the way that are pretty interesting.

One is that U.S. life expectancy increases have not kept up with the rest of the world's wealthy nations. Americans die at higher rates across all demographics and ages. "The American health disadvantage begins at birth and extends across the life course, and it is particularly marked for American women and for regions in the US South and Midwest."[1] In fact, since 2014, U.S. life expectancy has begun to decrease. [8] The reasons for this range from national policy to individual choices. Interestingly, this decline is not part of the national political discourse.

Another is that the World Health Organization (WHO) maintains a dataset called Healthy Life Expectancy (HALE). [6] HALE is the number of years an individual is healthy and free from morbidity rather than a measure of overall longevity. The WHO defines it as the "average number of years that a person can expect to live in 'full health' by taking into account years lived in less than full health due to disease and/or injury."   Modern medicine has been successful at prolonging life but not necessarily extending HALE. In the United States, the average HALE at birth was 65.2 for men and 67 for women in 2019. By comparison, the life expectancy was 76.3 and 80.7, respectively. [9] This suggests that Americans spend the final decade of their lives in some state of morbidity. 

Today, we more fully understand the impact of lifestyle, particularly exercise, on the ratio of years lived without morbidity to total life span. In 1980, James Fries, professor of medicine at Stanford University School of Medicine, published "Aging, Natural Death, and the Compression of Morbidity" [3, 6) in the New England Journal of Medicine. In it, he proposed that the number of years spent with high morbidity could be compressed into a shorter period at the end of life by exercise. He writes: 

An important shift is occurring in the conceptualization of chronic disease and of aging. Premature organ dysfunction, whether of muscle, heart, lung, or joint, is beginning to be conceived as stemming from disuse of the faculty, not overuse. At the Standofr Arthritis Clinic, I tell patients to exercise and to 'use it or lose it'; 'Run, not rest' is the is the new advice of the cardiologist. The body, to an increasing degree, is now felt to rust out rather than to wear out. If loss of reserve function represents aging in some sense, then exercising an organ presents a strategy for modifying the aging process. [3]

Forty years later, the exercise prescription is generally acknowledged to improve HALE and life expectancy. 

There is overwhelming evidence in the scientific and medical literature that physical inactivity is a major public health problem with a wide array of harmful effects. Over 50% of health status can be attributed to unhealthy behaviors with smoking, diet, and physical inactivity as the main contributors. Exercise has been used in both the treatment and prevention of a variety of chronic conditions such as heart disease, pulmonary disease, diabetes, and obesity. While the negative effects of physical inactivity are widely known, there is a gap between what physicians tell their patients and exercise compliance. [4]

An unhealthy lifestyle (including tobacco use, excessive alcohol intake, poor sleep, and stress) underlies prevalent and costly chronic diseases (eg, heart disease and cancer) leading to premature morbidity and mortality. [4]

Research into the variability of the speed of the aging process has spawned the new field of geroscience. "Geroscience is essentially the study of mechanisms that make aging a major risk factor for common chronic conditions and diseases of aging." [5] Of course, genes play a large role in affecting life span and health span. However, 75% of this variability is due to environmental factors. [2] This includes lifestyle. Harvard researchers have identified five core factors that contribute to a longer, healthier life. In order of importance, they are a healthy diet, regular exercise, healthy weight, not smoking, and, surprisingly, moderate alcohol intake. [10] In particular, the requirements are adoption of the Mediterranean or DASH Diets, at least 30 minutes a day of moderate to vigorous activity,  a body mass index of 18.5-24.9, no history of smoking, and up to 1 drink daily for women, and up to 2 daily for men. Upon follow-up, the Harvard researchers found that those who adopted all five factors lived up to 14 years longer. Not only did they live a longer life they had healthier lives. The following table summarizes this variation.

 

Impact of the five factors on remaining years of life free of cardiovascular disease, diabetes, and cancer.
  Number of remaining
years free of morbidity

50 year old men who 
practice all  five factors

 31
50 year old men who 
practice none of the factors
 24
 50 year old women who 
practice all  five factors
 34
50 year old women who 
practice none of the factors
 24

 

This research suggests that lifestyle factors can play a significant role in the expected health span of individuals, offering as many as ten additional morbidity-free years. Ten extra years of health after the age of 50 represents a significant percentage of a senior's remaining years.


References:

1. Avendano M, Kawachi I. Why do Americans have shorter life expectancy and worse health than do people in other high-income countries? Annu Rev Public Health. 2014;35:307-25. doi: 10.1146/annurev-publhealth-032013-182411. Epub 2014 Jan 9. PMID: 24422560; PMCID: PMC4112220.  [1]

 2. Denworth, Lydia. Healthspan Can Matter More Than Life Span. Scientific American 329, 4, 83 (November 2023) doi:10.1038/scientificamerican1123-83.

3. Fries, James F. Aging, Natural Death, and the Compression of Morbidity. July 17, 1980. N Engl J Med 1980; 303:130-135 DOI: 10.1056/NEJM198007173030304.

4. Fries JF. The compression of morbidity. 1983. Milbank Q. 2005;83[6]:801-23. doi: 10.1111/j.1468-0009.2005.00401.x. PMID: 16279968; PMCID: PMC2690269.

5. Geroscience at Penn. (2023) Downloaded on November 02, 2023 from https://www.med.upenn.edu/aging/geroscience.html

 6. Healthy life expectancy (HALE) at birth (years). (2023) Downloaded on November 02, 2023 from https://www.who.int/data/gho/data/indicators/indicator-details/GHO/gho-ghe-hale-healthy-life-expectancy-at-birth

7. Healthy Longevity. (2023) Downloaded on November 02, 2023 from https://www.hsph.harvard.edu/nutritionsource/healthy-longevity/

 8. Lewis, Tanya. (2023) The U.S. Just Lost 26 Years’ Worth of Progress on Life Expectancy. Downloaded on November 02, 2023 from www.scientificamerican.com/article/the-u-s-just-lost-26-years-worth-of-progress-on-life-expectancy

 9. List of countries by life expectancy. (2023) Downloaded on November 02, 2023 from https://en.wikipedia.org/wiki/List_of_countries_by_life_expectancy

10. Healthy Longevity. (2023) Downloaded on November 02, 2023 from https://www.hsph.harvard.edu/nutritionsource/healthy-longevity/