Aging is a biological phenomenon that belongs to all living species, especially the complex ones. If before the goal was to slow down aging until it was stopped, be it with the philosopher’s stone or with the biochemical knowledge achieved so far, Anti-Aging medicine has revolutionized the concept of “aging well and in health”. But what if, in addition to biological factors, social and environmental factors also contribute to the quality of collective ageing? Three new articles, published together a few years ago in the specialized journal Aging Research Reviews, have underlined how behavioral and social factors are intrinsic to aging. This means that they are causal factors of biological aging. Indeed, the influence of behavioral and social factors on the rate at which people age is large and significant.
However, geroscience — the study of how to slow biological aging to extend health span and longevity — has not traditionally incorporated behavioral or social science research. These papers are by three pioneers in aging research and members of the National Academy of Medicine who study different aspects of the intersection of biology and social factors in shaping healthy aging across the life course. The exciting biological discoveries about the rate of aging in non-human species are sometimes not applicable or lost when we apply them to humans. Including behavioral and social research can support the translation of geroscience findings from animal models.
Terrie Moffitt, a Nannerl O. Keohane University professor of Psychology and Neuroscience at Duke University, elaborated: “The transition from slowing the fundamental aging processes in laboratory animals to slowing aging in humans will not be as simple as prescribe a pill and watch it operate. Compared to aging in laboratory animals, human aging has many social behaviors in addition to cellular origins and influences. These influences include potential intervention targets that are uniquely human, and thus are not easily investigated in animal research. Many of these human factors have a large impact on health and mortality: early childhood stress and adversity, psychiatric history, personality traits, intelligence, loneliness and social connectedness, and life purpose are linked to a variety of health outcomes in later life. These important factors must be taken into account to obtain a meaningful prediction of human biological aging.”
Geroscience can be augmented through collaboration with behavioral and social sciences to accomplish translation from animal models to humans and improve the design of clinical trials of anti-aging therapies. It is imperative that advances in geroscience are delivered to everyone, not just the well-heeled, because people who have low education, low incomes, negative early childhood experiences, and biases are the people who age the fastest and die youngest. The hallmarks of social aging can be strongly predictive of age-related health outcomes, in many cases even more so than biological factors. While the field of aging commonly discusses the biological characteristics of aging, we do not tend to include the social and behavioral factors that lead to premature aging. We have called the five main factors below “the social hallmarks of aging” and have argued that these should not be ignored in any sample of humans and that the concepts should be incorporated into non-human studies where possible.”
Dr. Moffit examined data collected in 2016 from the Health and Retirement Study, a large nationally representative study of Americans over the age of 56 that incorporates both social factor surveys and biological measurements, including a blood sample for analysis genetics. For the study, she focused on five social hallmarks for poor health outcomes:
- low lifetime socioeconomic status, including lower educational attainment
- adversity in childhood and adulthood, including trauma and other hardships
- be a member of a minority group
- adverse health behaviours, including smoking, obesity and alcohol problems
- adverse psychological states, such as depression, negative outlook and chronic stress.
The presence of these five factors was strongly associated with older adults having difficulties with activities of daily living, cognitive problems, and multimorbidity (with five or more diseases). Even when controlling for biological measures — including blood pressure, genetic risk factors, mitochondrial DNA copy number, and more — social differences, as well as demographic factors such as age and gender, explained most of the differences in aging outcomes among study subjects, she said. However, biological and social factors are not completely independent of each other, which is why scientists argue for the further incorporation of social and behavioral factors into the biology of aging.
Variability in human aging is strongly related to the social determinants of aging; and remains so when extended biology is introduced as mediating factors. This means that the social variability in the aging process is only partially explained by the biological measurements currently performed by researchers. The hypothesis is that if the basic biological mechanisms of aging could be fully grasped, they would explain even more strongly the social variability in the aging process, since social factors must “get under the skin” through biology.
Elissa Epel, professor and vice chair of the Department of Psychiatry and Behavioral Sciences at UC San Francisco, detailed how stress and resilience research must incorporate psychosocial factors to understand how different types of stress affect aging: Not all types of stress are created equal and in fact some are healthy. The social characteristics of aging may influence the rate of aging in part through toxic responses to stress, she said. While acute responses to minor or moderate stressors, including infection or injury, are critical for survival, chronic exposure to high amounts of stress, including long-term psychological stressors such as abuse, can prove toxic and lead to poor health outcomes. Brief, intermittent, low-dose stressors can lead to positive biological responses, improving resistance to injury, which is called hormesis.
For example, physiological hormonal stresses include short-term exposure to cold, heat, exercise, or hypoxia. Hormetic stress activates cell repair and rejuvenation mechanisms. Conversely, a high dose of chronic exposure can override these mechanisms, resulting in harm or death. Therefore, toxic stress can accelerate biological aging processes, while hormetic stress can slow down aging. However, the types, timing, and frequency of hormetic stress need to be better delineated to be useful for human aging research and interventions. Stress resilience, an umbrella term that includes hormetic stress, can be measured through cellular, physiological, and psychosocial functioning.
Developing a deeper understanding of stress resilience will lead to more targeted innovative interventions. Stress resilience can also include social interventions that protect against the malleable social characteristics of aging, including safe neighborhoods to reduce trauma and violence, and social support programs to combat loneliness and depression. Geroscience is now more important than ever, both to our aging global demographics but also to the health challenges we face in the future, and stress resilience is a particularly hot topic right now. In our new era, we have soaring extreme temperatures, fires and small particle pollution, and new zoonotic viruses to contend with intermittently.”
Reducing social inequalities, improving resilience to stress, and strengthening immune function have therefore become key public health goals. In summary, the three articles together point to a promising decade ahead for aging research, unveiling how humans, as complex social mammals, age together in response to social conditions and behavioral factors that are in part malleable.
- Edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
Scientific references
Choi YJ et al. Public Health Nutr. 2021 Feb 9:1-31.
Heid AR et al. Gerontologist. 2021; 61(1):48-58.
Crimmins EM. Ageing Res Rev. 2020; 63:101136
Epel ES. Ageing Res Rev. 2020 Nov; 63:101167.