In a world where populations are ageing rapidly, understanding the ageing process has never been more crucial. Yet, society's most common approach to ageing—the reliance on chronological age—may be a limited measure of how we truly age.
Recent paper, On the Limits of Chronological Age, by Andrew J. Scott, challenges the conventional wisdom that chronological age is a reliable indicator of an individual's health, productivity, or economic potential. The study argues that chronological age is not an accurate reflection of physiological ageing, leading to misleading conclusions about the economic and social implications of ageing populations.
Primacy of Chronological Age
For centuries, chronological age has been the primary method by which societies measure ageing. It’s straightforward and universally understood: the number of years a person has lived since birth. This simple metric has been used in countless contexts, from determining retirement age to defining eligibility for pensions, healthcare benefits, and social security. Governments, policymakers, and researchers have long relied on chronological age as a proxy for biological ageing, assuming that as people grow older, their health deteriorates in a predictable way.
For example, the rising median age of populations in countries such as Japan and many parts of Europe has sparked debates about the economic challenges posed by ageing populations. As people live longer, retirement age has been extended, and healthcare systems are stretched to accommodate older individuals. But the study argues that this reliance on chronological age may be an oversimplification, as it doesn’t account for the considerable variation in how people age.
Issue with Chronological Age
Despite its ubiquity and convenience, chronological age has several significant drawbacks as a measure of ageing. The authors of the study point out three key reasons why chronological age is not a reliable measure: heterogeneity, malleability, and multidimensionality.
1. Heterogeneity: Ageing Differs Across People
One of the main criticisms of chronological age is the vast heterogeneity in how individuals experience ageing. People of the same chronological age can have drastically different levels of physiological and cognitive functioning. This variation is influenced by factors such as genetics, lifestyle, socioeconomic status, access to healthcare, and even environmental conditions. For instance, a 70-year-old in excellent health may still be active, sharp, and physically capable, while another 70-year-old may suffer from significant mobility issues, cognitive decline, or chronic health conditions.
Research shows that life expectancy and overall health outcomes can vary widely across different populations. In high-income countries, life expectancy has increased over the last century, but this has not been equally distributed across all groups. Individuals with higher education levels and better access to healthcare tend to live longer and healthier lives. Conversely, those with lower education or socioeconomic status may experience poorer health and shorter lifespans.
2. Malleability: The Rate of Ageing Can Change
The rate at which people age is not fixed. Advances in medicine, better access to healthcare, improvements in living standards, and healthier lifestyles can slow down the ageing process for certain populations. People in high-income countries, for example, are ageing more slowly than they did a few decades ago. Increased life expectancy and improved quality of life for older adults have resulted in many people living longer and remaining healthier into their later years. However, this malleability also means that aging processes can accelerate due to lifestyle factors like poor diet, smoking, or lack of exercise, and societal challenges such as rising obesity rates or drug use.
The paper demonstrates that chronological age fails to capture these shifts in the ageing process. As medical advancements continue to improve longevity and quality of life, chronological age is becoming an increasingly less useful measure of a person’s actual age in terms of health and productivity.
3. Multidimensionality: Ageing Affects Different Domains Differently
Ageing is not just a linear decline in physical health—it is a complex, multidimensional process. As we age, various aspects of our physiological and cognitive functions decline at different rates. For example, mobility may decline earlier than cognitive functions, and mental health may be more affected than physical health in some individuals. For others, the opposite may be true. Chronological age does not account for these differences, making it a poor measure of the overall ageing process.
The frailty index, which the paper uses as an alternative measure of ageing, provides a more nuanced understanding. It includes a variety of health conditions, from mobility issues to cognitive decline, and offers a comprehensive picture of a person’s ageing process. By using the frailty index, researchers can measure health deficits across different domains and track how individuals age in a more holistic manner.
Physiological Functioning as a Better Indicator
Given the limitations of chronological age, the study suggests a shift toward using physiological functioning as a measure of ageing. Physiological functioning refers to the physical and mental capabilities that enable people to live independently and perform daily activities. It encompasses mobility, cognition, strength, and the ability to perform activities of daily living, such as bathing, dressing, and cooking.
The frailty index is one of the most widely used measures of physiological functioning. It is a composite measure that tracks a person’s health deficits across multiple dimensions, such as physical mobility, cognitive function, and mental health. The frailty index has been shown to be predictive of mortality and is increasingly used in geriatric research to assess health outcomes. By focusing on physiological functioning, researchers can better capture the actual ageing process and its implications for individuals and society.
Why Physiological Functioning Matters
The importance of physiological functioning goes beyond just understanding how individuals age. It also has profound economic implications. As the study shows, physiological functioning is a better predictor of economic behavior and outcomes than chronological age. For example, labor force participation is closely linked to an individual’s health. A person in poor health may be less likely to work, while someone in better health may continue working well past traditional retirement age. Similarly, an individual’s ability to engage in nonmarket productive activities, like volunteering or helping others, is heavily influenced by their physiological functioning.
The paper’s analysis shows that chronological age is a weak predictor of labor force participation, life satisfaction, and healthcare spending. In contrast, the frailty index, which more accurately reflects a person’s physiological capabilities, is much more predictive of these economic behaviors. This finding has important implications for policy, particularly in areas like retirement age and healthcare costs.
Economic Implications of Relying on Chronological Age
The study also examines how the reliance on chronological age in economic models and policy-making can lead to suboptimal outcomes. Many policies, such as pension systems and retirement age regulations, are based on chronological age. However, the authors argue that these policies may not be suited to the diverse needs of an ageing population. As the population continues to age, it is essential to reconsider how we define and measure ageing.
For instance, pension systems often set retirement ages based on chronological age, assuming that people of a certain age will have the same capacity to work and contribute to society. However, this assumption ignores the heterogeneity in ageing and the fact that some people remain healthy and productive well into their 70s or beyond, while others may experience health problems much earlier.
The study suggests that policies should move toward a more personalized approach, one that takes into account an individual’s health and functional ability rather than simply their age. This approach could help ensure that people who are capable of continuing to work are not prematurely forced out of the workforce, while also providing better support for those who may need to retire earlier due to health issues.
Shift Toward Personalized Ageing Policies
The findings of this study suggest that society must move beyond chronological age as a catch-all measure of ageing. By focusing on physiological functioning, we can create policies that better address the individual needs of older adults. This shift could have significant benefits for both individuals and society. For instance, pension systems could be redesigned to offer more flexibility, allowing people to retire based on their health rather than a fixed age. Similarly, healthcare policies could be tailored to address the specific health needs of older adults, ensuring that resources are allocated efficiently.
Moreover, as people live longer and healthier lives, there are opportunities to tap into the economic potential of older populations. Many older adults remain productive well into their later years, contributing to society through both paid work and nonmarket activities like caregiving, volunteering, and mentoring. By focusing on physiological measures, we can better harness this potential and ensure that older adults continue to make valuable contributions to society.
Conclusion
In conclusion, On the Limits of Chronological Age provides compelling evidence that chronological age is an inadequate measure of ageing. It fails to account for the considerable variation in how individuals age, and it overlooks the fact that physiological functioning is a much more reliable indicator of health, productivity, and economic behavior. As the global population continues to age, it is crucial that we move toward a more personalized approach to ageing, one that considers not just the number of years a person has lived, but also their physical and cognitive health.
By shifting our focus from chronological age to physiological functioning, we can create policies that better support individuals as they age. This approach would enable societies to fully realize the benefits of increased longevity and ensure that older adults continue to thrive, both personally and economically. It’s time to rethink ageing and embrace a more accurate, nuanced understanding of what it truly means to grow older.
The study is published by Andrew J Scott.
