Biological theories of aging
This is a biological theory of aging which proposes that aging is due to damage caused by molecules that accumulate in the body, such as oxygen species.
Free radical theory of aging
According to the fundamental cause theory, what is the primary reason for persistent health inequalities?
Unequal distribution of socioeconomic resources
This theory examines how individuals' behavior is influenced by social roles they occupy, such as being a parent, employee, or student.
Role theory
These two types of aging, distinguished by when extrinsic factors (e.g. sun exposure, chronic disease, hydration, social exposure, mental challenge) heighten the physiological effects of aging alone, and when extrinsic factors have either neutral or even positive effects, were postulated by researchers John Rowe and Robert Kahn in their 1987 article. One type of aging is usually measured as an average of a health outcome in a group, whereas the other type of aging is a measurement of whether those who are in top quartile or not show decline; this is a way to disaggregate what is normal to aging and what is due to illness or other external factors.
“Usual” aging and “successful” aging.
O’Rand uses these three terms to describe aging because it occurs continuously across the lifespan, continuously integrates diverse factors from across levels of observation (e.g. from the molecular to the social to the global), and is never fully and directly observable as an ongoing generative process.
Long, broad, and deep
This class of biological theories of aging posit that aging is due to the accumulation of “insults” from the environment which eventually reach a level that is not compatible with life (include somatic mutation theory, and error catastrophe theory).
Stochastic theories of aging
This theory of aging holds that earlier status and achievement in life have a persistent influence on later status and achievement in life, not just as a result of individual motivation and capacity, but as the outcome of institutional processes bearing on individual lives. For instance, an example of this theory is when educational institutions select and sort students in ways that have a lifelong consequence on average within a cohort, which leads to inequalities in later years based on factors associated with the education system, which may go unobserved. This theory discusses how small initial inequalities accumulate over time and lead to significant health, wealth, and social disparities.
Cumulative advantage/disadvantage (CAD) theory
This theory suggests that older adults adjust their goals by focusing on emotionally meaningful relationships and experiences as they perceive time as more limited.
Socioemotional selectivity theory
Three components comprise this model of successful aging: low risk of disease and disease-related disability, maintenance of high mental and physical function, and continued engagement with life. This model was developed by Rowe and Kahn and faced heavy criticism, resulting in a 2015 editorial from the researchers that acknowledged the complaints and provided recommendations for future work.
The MacArthur model of successful aging.
Ferrucci invokes this Greek and Roman philosophy in his discussion of resilience, in the context of aging. Conceptually, this is the ability to be resilient in the face of setbacks and disasters. Ferrucci uses this concept as a metaphor for biological resilience and posits that its impact can be measured via biomarkers as a potential breakthrough in gerontology.
Stoicism
This theory proposes that the biological mechanisms that drive aging are the root cause of the phenotypic transformations typical of aging as well as their functional consequences (e.g. loss of mobility and cognition). This theory has major implications for extending the “health span” to match modern humanity’s lengthened lifespan.
The geroscience hypothesis of aging
Rowe and Kahn urge aging scholars to adopt this type of societal perspective, in a shift from our current preoccupation with education in youth, work in midlife, and “leisure” in later life. This perspective redistributes life’s major activities across the whole lifespan, requires adaptation to changes in longevity, and recognizes that change introduced at one stage of the life course may alter the needs and opportunities at other stages. This theory proposes that earlier life experiences affect individual perception of aging.
Life course perspective theory
According to this theory, older adults compensate for age-related declines by optimizing their existing strengths and finding new ways to maintain function.
Selective optimization with compensation theory
Name Rowe and Kahn’s theory of the potential upside of aging in society, that older people actually have much to offer to the workforce.
The “longevity dividend”
The field of gerontology in the US was founded and defined following the Second World War by this organization, comprising many American scientists specializing in biology, psychology, and human development.
The Gerontological Society of America
This biological theory emphasizes the role of resilience mechanisms in aging, positing that interventions enhancing these mechanisms may delay aging and prevent late-life pathologies.
The resilience theory of aging
This theory focuses on how economic factors, such as the profit made by businesses like the anti-aging industry (this example could link to last week’s reading on the role of social media and the anti-aging industry), affect how aging is experienced by older adults.
Political economy of aging
In her 2009 article, Levy drew on empirical evidence to propose this psychosocial theory of aging, arguing that older people can internalize both harmful and positive societal beliefs about them, which can exert influence on their functioning on psychological, behavioral, and physiological levels.
Stereotype embodiment
Acknowledging in 1987 that a “revolutionary increase” in lifespan has already occurred, Rowe and Kahn subsequently define this as the next gerontological goal for researchers, practitioners, and for older men and women themselves.
A corresponding increase in “health span”, or the maintenance of full function as nearly as possible to the end of life
This physiological process has been identified as a commonality among all major chronic diseases, causing Ferruci et al. to call it a “hallmark of aging”. They also point out that the ideal situation of regulating this process in a manner that preserves its benefits while preventing its harmful effects has not yet been achieved.
Inflammation
This biological theory of aging, which is considered an evolutionary theory, proposes that genes beneficial in early life might be selected for, even if they have harmful effects later in life, contributing to aging.
Antagonistic pleiotropy theory
This idea explains the process of influencing others by altering the perceived outcomes of their actions.
Consequential manipulation
In stereotype embodiment theory, Levy identifies these three mechanisms through which age stereotypes affect physical and cognitive health.
1. Internalization of stereotypes
2. Unconscious activation
3. Stereotype salience influencing health behaviors
Rowe and Kahn motivate their 1987 distinction between usual and successful aging by pointing out that aging research until then had neglected this crucial attribute within age groups. They explain that this aspect of a population appears to increase with age.
Heterogeneity within age groups
In what Ferruci et al. call the “ideal implementation” of geroscience, their evaluation of aging would test these measures of biological or physiological processes, providing tailored assessments and interventions that could result in longer and healthier lives. But they point out that such indicators already exist and finding a unified one for aging is difficult. Debate exists on whether measuring frailty using these measures is of clinical value, given the its nebulous definitions and the lack of a relevant clinical outcome.
Biomarker tests