Assessing Recent Changes in the Pace of Secondary Aging

Biological age, as opposed to chronological age, is driven by the intrinsic processes of primary aging, the accumulation of molecular damage outlined in the SENS rejuvenation research proposals, but also by the influence of the environment, secondary aging. The important contributions to secondary aging are excess visceral fat tissue as a consequence of diet, burden of infectious disease, lack of exercise, and smoking, acting through a range of mechanisms that overlap with the intrinsic processes of primary aging. There are others, but their effects are smaller and it is harder to see them in the data in comparison to the points above.

In the paper here, researchers make an effort to map recent changes in secondary aging, picking combinations of metrics from past data that might offer insight into the biological age of patients. I would say that there is little reason to expect primary aging to have altered significantly in the past few decades, given the landscape of medical technology, but it is certainly up for debate as to whether medications that control blood pressure and cholesterol levels might have some effect. They have certainly become more prevalent and effective over the time covered by the study data.

Overall this is an interesting exercise, but of little relevance to the future of aging. Gains from here on out will increasingly arise from the development of rejuvenation therapies that can repair the damage of primary aging, rather than from lifestyle improvements such as reduction in smoking or obesity. Greater potential gains in health and life span might be achieved through addressing primary aging; the scope of increased longevity through better lifestyle choices is far more limited. Our remaining healthy life span will be determined ever more by progress in rejuvenation biotechnology as time passes.

A new study suggests that at least part of the gains in life expectancy over recent decades may be due to a change in the rate of biological aging, rather than simply keeping ailing people alive. "This is the first evidence we have of delayed aging among a national sample of Americans. A deceleration of the human aging process, whether accomplished through environment or biomedical intervention, would push the timing of aging-related disease and disability incidence closer to the end of life. Life extension without changing the aging rate will have detrimental implications. Medical care costs will rise, as people spend a higher proportion of their lives with disease and disability. However, lifespan extension accomplished through a deceleration of the aging process will lead to lower healthcare expenditures, higher productivity, and greater well-being."

Using data from the National Health and Nutrition Examination Survey (NHANES) III (1988-19994) and NHANES IV (2007-2010), the researchers examined how biological age, relative to chronological age, changed in the U.S. while considering the contributions of health behaviors. Biological age was calculated using several indicators for metabolism, inflammation, and organ function, including levels of hemoglobin, total cholesterol, creatinine, alkaline phosphatase, albumin, and C-reactive protein in blood as well as blood pressure and breath capacity data.

While all age groups experienced some decrease in biological age, the results suggest that not all people may be faring the same. Older adults experienced the greatest decreases in biological age, and men experienced greater declines in biological age than females; these differences were partially explained by changes in smoking, obesity, and medication use. Slowing the pace of aging, along with increasing life expectancy, has important social and economic implications. The study suggests that modifying health behaviors and using prescription medications does indeed have significant impact on the health of the population.


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