A new era has begun for human aging (Coscο, Howse & Brayne, 2017). Nowadays, people worldwide are living longer than before, and they are expected to pass their 60s (Beard & Cassels, 2016). The world is experiencing a rapid aging, namely a considerable increase in the older population. By 2050, the number of those over 60‐years old will nearly double. In real terms, in 2015, the population of older people was 900 million, and this is expected to increase to about 2 billion by 2050. According to the United Nations definition, when the population over 60‐years old surpasses 7% in a country, the country is considered aged (United Nations, 2019). This demographic transition toward aging invokes public action to find ways of improving health and maintaining well‐being throughout the life course (Beard & Cassels, 2016). Yet, living longer does not necessarily mean living healthier, as longevity (typically defined as reaching an age of ≥85 years) does not always entail experiencing better health (Beard & Cassels, 2016). In fact, scarce evidence exists that older people today are experiencing better health than their ancestors at the same age. Indeed, as human life expectancy is prolonged, age‐related diseases are common (Carmona, 2016), with three chronic disorders constituting the leading causes of death: ischemic heart disease, stroke, and chronic obstructive pulmonary disease (Beard & Cassels, 2016). Above all, living longer must be congruent with living well, and that is why adding health to years is the key factor for well‐being in later life (Beard & Cassels, 2016). Although 70 does not yet seem to be the new 60, undoubtedly, the extension of life span is extremely valuable, since it provides the chance to reconsider what older age might be and to rethink the endless prospects through which to spend these extra years fruitfully (Beard & Cassels, 2016). Older people can contribute to society in many ways and living these extra years in prosperity provides them with limitless opportunities. To illustrate this point, in high‐income countries, people over 60 are very likely to start looking for new career, continue lifelong learning, or a new hobby. Likewise, younger people, knowing that they will live more, might plan to live their lives differently (Green, 2013). However, if these additional years are dominated by decreased physical and mental capacities, they can ultimately lead to higher health and social costs (Goldman, 2016). Evidently, enabling people to age better and maintain better health, as well as to prolong good function and high levels of well‐being in the second half of life, are of major importance. This notion is highlighted by the fact that globally, public health agendas are investing in policies that promote healthy aging (Beard & Cassels, 2016). Nevertheless, there is clearly some difficulty in building a framework aimed at advancing quality aging while confusion as to the nature of the concept itself remains; reaching a consensus on the definition of healthy has proven to be a difficult task (Estebsari et al., 2020). Aging is the process of gradual physiological deterioration that all living beings experience with time (Carmona, 2016). At the biological level, aging results from the impact of an accumulated variety of molecular and cellular damage over time. This leads to a gradual decrease in physical and mental capacity, a growing risk of disease, and ultimately, death. This deterioration is the primary risk factor for major human pathologies including cancer, diabetes, cardiovascular disorders, and neurodegenerative diseases (Carmona, 2016). Nine hallmarks are generally considered responsible for this macromolecular damage: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient‐sensing, mitochondrial dysfunction, cellular senescence, stem‐cell exhaustion, and altered intercellular communication (López‐Otín et al., 2013) (Figure 7.1). FIGURE 7.1 The hallmarks of aging. The scheme enumerates the nine hallmarks: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient‐sensing, mitochondrial dysfunction, cellular senescence, stem‐cell exhaustion, and altered intercellular communication. Source: (López‐Otín et al., 2013 / with permission of Elsevier). FIGURE 7.2 Functional interconnections between the hallmarks of aging. The nine proposed hallmarks of aging are grouped into three categories. In the top, those hallmarks considered to be the primary causes of cellular damage. In the middle are those considered to be part of compensatory or antagonistic responses to the damage. These responses initially mitigate the damage, but eventually, if chronic or exacerbated, they become deleterious themselves. At the bottom are the integrative hallmarks that are the end result of the previous two groups of hallmarks and are ultimately responsible for the functional decline associated with aging. Source: (López‐Otín et al., 2013 / with permission of Elsevier). For example, molecular integrity of the genome, telomere length, epigenetic landscape stability, and protein homeostasis are all features linked to “youthful” states (Figure 7.2). Indeed, healthy aging refers to the prevention of this molecular and cellular decline to reach the longest lifespan (López‐Otín et al., 2013). A plethora of scientific evidence supports the claim that there is not a single cause of aging and that multiple mechanisms modulate the aging process (Wagner, Cameron‐Smith, Wessner & Franzke, 2016). Aging research has experienced remarkable progress over recent years. Specifically, the discovery that the rate of aging is controlled, at least to some extent, by genetic pathways and biochemical processes, was a scientific breakthrough (Wagner et al., 2016). The genome does not solely account for physiological traits or disease risk. Presumably, genetics have a low impact on the age of death (between 12% and 25%) (Passarino, de Rango & Montesanto, 2016). Although many longevity genes have been investigated, only two genes have been widely replicated, ApoE and FOX03A, as discussed in Chapter 8. In the longest‐living families, these variants have an impact on the age of death between 1% to 10% of a birth cohort. It is unclear, however, how these complex molecular signs interrelate with personal lifestyle and the diverse environments to which humans are exposed, especially considering that the dynamic interaction between a living being and its environment defines the rate and fate of aging (Carmona, 2016). Notably, beyond genetic variations and biological factors, aging is strongly associated with the physical and social environment (external factors: race/ethnicity, culture, religion, and security as well as social inequities and scientific/technological advances) as well as personal characteristics, such as sex, ethnicity, or socio‐economic status (Eaton et al., 2012) (Figure 7.3). The environments that people live in, combined with their personal characteristics, have long‐term effects on how they age. Environments have a strong impact on establishing healthy behaviors throughout life (Hernandez & Johnston, 2017), like a balanced diet (Black & Bowman, 2020), engaging in regular physical activity (Daskalopoulou et al., 2017), and refraining from tobacco use, habits that all contribute to reducing the risk of non‐communicable diseases and improving physical and mental capacity. FIGURE 7.3 Health determinants. Source: (Adapted from WHO, 2015). Furthermore, it is well accepted that environmental factors orchestrate epigenetic (which literally means “above the genes”, as discussed in Chapter 2) and gene transcription changes to affect health and aging process itself (Carmona, 2016). While genes have traditionally been a nonmodifiable factor, there is growing evidence linking epigenetic DNA modification through environmental exposures to a wide range of aging phenotypes (Eaton et al., 2012). The diversity seen in older adults is not random. Aging is an heterogenous and heterochronic process and is only loosely associated with a person’s age in years (Carmona, 2016). After all, there is no “typical” older person (Beard & Cassels, 2016). For instance, while some 70‐year‐olds enjoy extremely good health and functioning, others are frail and require significant help from others. Quality of life in older people has been variously conceptualized as “successful”, “active”, “productive”, “healthy”, and “positive” aging, among others (Estebsari et al., 2020). What do people need to age well? For most, the answer seems clear, since many people prioritize good health as an important goal in their lives and consider health and functioning in old age as a prerequisite for healthy aging (Reich et al., 2020). Notably, some might consider the term “healthy aging” an oxymoron, since the healthy usually implies optimal function and absence of disease yet aging is synonymous with co‐morbidities, physical or mental (Aronson, 2020). Conversely, many people worldwide experience high levels of well‐being despite their body’s decline. This “aging well‐being paradox” resembles the “disability paradox” in which people with severe physical disabilities rate their own well‐being rather positively, which is unexpected to outsiders. It is reasonable, however, that people adapt to their own disabilities (Rowe & Kahn, 1987). Therefore, maintaining good physical health might not be the only prerequisite for aging healthy. According to this scope, any critical analysis of the definitions of healthy aging should start with a clear understanding of the historical perspective on the concepts of aging (Urtamo, 2019a) (Table 7.1). Carl Jung’s work on aging during the 1920s and 1930s may be considered the most significant forerunner of modern gerontology, as he identified late life as a process of turning inward. One of the earliest definitions of successful aging found in the gerontology literature is that introduced by Robert Havighurst in 1961 (Neugarten, Havighurst & Tobin, 1961). According to this conceptualization, successful aging should promote maximum satisfaction and happiness with one’s present and past lives. This pioneering point of view was published in 1953, in a book titled Older People. This book was a milestone, it introduced a novel aspect of aging well, outside the medical domain, described through the eyes of older people themselves, the challenges people face daily, as they grow older. At the time, descriptions of old‐age problems were based on the perception of younger adults and there were two contrasting theories of aging well: activity theory and disengagement theory (Cumming, 1968). Activity theory stated that older adults are happiest when they stay active and maintain social interactions; gerontologists generally preferred this theory because it was assumed to capture the desire of aging individuals. Disengagement theory, on the other hand, stated that a person aging in success would want, over time, to disengage from an active life. Table 7.1 Historical preview of key concepts in successful/healthy aging. Source: (Adapted from Martin et al., 2015). Moreover, an innovative publication by Katz et al. in 1963 viewed successful aging as a process from the perspective of researchers or clinicians: to be “successful”, older persons should maintain their functioning within the bounds predetermined by researchers (Katz, 1963). Following this, the Index of Activities of Daily Living (ADL) (Instrumental ADL, IADL) was introduced as a systematic approach to measure physical performance in a population of older or chronically ill adults. This instrument was proposed as an objective guide to distinguish “usual” and “successful” aging within an older population, and it was used frequently in later studies on successful aging to make this distinction. Α multidimensional approach was introduced by Neugarten, which emphasized personality type as a predictor for successful aging, such as coping style, prior ability to adapt, and life expectations as well as income, health, social interactions, freedoms, and constraints (Neugarten, 1972). The successfully aging individuals not only play an active role in adapting to the biological and social changes with time, but also in creating patterns of life that will give them the greatest ego involvement and life satisfaction. The author also suggested that there might be differences in age norms even among older adults. She identified two major groups of aged adults: the “young‐old,” aged 55 to 75, and the “old‐old,” aged 75 or above. A few years later, Suzman and Riley added the “oldest ‐old” to the Neugarten framework (Suzman, 1985). Probably the most well‐known aging model was introduced by Rowe and Kahn in 1987, which advocated for a successful aging model for biomedical research purposes (Stowe & Cooney, 2015). Geriatrician John W. Rowe and social psychologist Robert L. Kahn argued that there is substantial heterogeneity among older persons and added an extra category to the traditional “normal aged” and “diseased aged” categories. “Normal” aging should be divided into two vastly different groups: a large group of people undergoing usual aging and a smaller group undergoing successful aging, differentiated from usual aging by the impact of extrinsic factors. For decades, studies on human aging believed that intrinsic factors such as genetics were the primary determinant of losses commonly seen in older people. The critical role of extrinsic factors such as diet, physical activity, and lifestyle in general was overlooked. It appeared that usual aging could be modified by personal, behavioral, and psychosocial parameters and that there was a causal relationship between extrinsic factors and the process of aging (Stowe & Cooney, 2015). The Rowe’s and Kahn’s biomedical model, which is arguably the best known and widely applied model (Estebsari et al., 2020), views “better than average” aging as a combination of three components: (i) being free of disease and disability, (ii) having high cognitive and physical abilities, and (iii) engaging with life (Figure 7.4). This model was a hallmark in gerontology and a major turning point in developing programs that view older adults as able, valuable social members. Nevertheless, this conceptualization has a relatively static nature since it emphasizes personal control over one’s later‐life outcomes and neglects developmental processes and the trajectories of continuity and change in function over time (Rowe & Kahn, 1987). In 2015, Rowe and Kahn suggested adding societal‐level principles to evaluations of successful aging: more opportunities for employment, voluntary work, and social activities; trust in older people, due to their knowledge and capacity for problem‐solving; and investment in training and education for older adults, rather than exclusion due to their chronological age (Stowe & Cooney, 2015). Moving beyond Rowe and Kahn’s model, psychosocial theories view aging as a lifelong process; the most well‐known model of this perspective is the one developed by Baltes and Baltes (Freund & Baltes, 1998
CHAPTER 7
Healthy Aging: Definitionand Scope
INTRODUCTION
OVERVIEW OF THE AGING PROCESS
BIOLOGY OF AGING
EARLY CONCEPTS OF HEALTHY AGING
Activity theory (1961)
Maintaining middle‐aged activities and attitudes into later adulthood
Cumming
Disengagement theory (1961)
Desire and ability of older people to disengage from active life to prepare themselves for death
Cumming
Successful aging (1961)
Conditions promoting a maximum of satisfaction and happiness
Havighurst
Successful aging (1963)
Having feelings of happiness and satisfaction with one’s present and past life
Havighurst
Index of activities of daily living (ADL)
(1963)
Systematic approach to measuring physical performance in a population of older or chronically ill persons
Katz
Aging successfully (1972)
Coping style, prior ability to adapt, and expectations of life as well as income, health, social interactions, freedoms, and constraints; coalescence of personality,
which plays into the enormous complexity of successful aging
Neugarten
Successful aging (1987; 1998)
Interplay between social engagement with life,
health, and functioning for a positive aging experience (low probability of disease and disease‐related disability)
Rowe
Selective optimization with compensation
(1990)
(i) Selective adaptation and transformation of internal and external resources. (ii) Optimization
and compensation. (iii) Maintaining function, maximizing gains, and minimizing losses
Baltes
Productive aging (1990)
Any activity by an older individual that contributes to producing goods or services, or develops the capacity to produce them
(whether or not the individual is paid for this activity)
Butler
Active aging (2002)
The process of optimizing opportunities for health, participation, and security to enhance quality of life as people
age
WHO
Healthy aging (2006)
Optimizing opportunities for good health, so that older people can take an active part in society and enjoy an independent and high quality of life
Swedish National Institute of Public Health
Cultural aspects of “good aging” (2007)
Cultures have different understandings and interactions to promote or detract from a good old age
Fry
Successful aging and diseases (2009)
Successful aging may coexist with diseases and functional limitations if compensatory psychological and/or social mechanisms are
used
Young
Healthy and active aging (2011)
The process of optimizing opportunities for health to enhance quality of life as people age and grow old
European Commission
Healthy aging (2015)
More than the absence of disease; it is the process of developing
and maintaining the functional ability that enables well‐being in older age
WHO
Active and healthy aging (2015)
An ability to perform daily activities, feeling happy, remaining free of cognitive or functional impairments, and free of major chronic diseases
Helsinki Businessmen Study cohort
THE CONCEPT OF SUCCESSFUL AGING
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