Tufts UniversityUniversity, Boston, Estados Unidos de América
The U.S. Census Bureau predicts that between 2005 and 2025, the number of U.S. individuals > 65 will increase by 50%. Currently, 686 million people (12%) are over 60 worldwide. By 2050, it is calculated that there will be nearly as many people aged > 60 as children under 15. Life expectancy in many countries at age 60 is now at least a third more than what it was in the mid-twentieth century. Of interest, the over-80 group is projected to be the fastest growing subset in this trend, which was 14 per cent in 2012, and is predicted to arrive at 20 per cent in 2050. This represents a major demographic shift with significant socio-economic impact. Scientific advances have greatly increased life span; at the same time, however, new and developing challenges such as sarcopenia, cardiovascular disease, obesity, diabetes, dementia, macular degeneration, cataracts, and infections and their associated costs associated are increasing, which is impacting the health and functional life span of older adults while it is diminishing their ability to contribute fully as members of their communities. Nevertheless, accumulating evidence indicates that poor health in late life is not inevitable. Contrary to the previously held belief that increased risk of diseases and disability with aging results from inevitable as well as genetically determined intrinsic aging processes, more recent studies show that many of the usual aging characteristics are caused by lifestyle and other modifiable factors and are not unavoidable consequences of aging. Thus, strategies to expand “health–span” or the number of years that older adults can enjoy “successful aging” will need to be developed. Key to developing such strategies is a universally accepted definition of “successful aging.” However, consensus on what factors constitute successful aging or what components are essential has not been reached. The National Institute of Aging, the White House Conference of Aging, and the World Health Organization have emphasized that healthy aging goes beyond absence of disease and disability. The widely quoted definition by Rowe and Kahn based on the MacArthur Research Network of Successful Aging describes successful aging as involving freedom from disability along with high cognitive, physical, and social functioning. Other definitions have included cognitive and emotional aging: for example, well-being, connectedness and adaptation. Centers for Disease Control and Prevention defined healthy aging as the “development and maintenance of optimal physical, mental and social well-being and function in older adults.” Health Canada has expanded the definition of “healthy aging” and described it as: a lifelong process of optimizing opportunities for improving and preserving health and physical, social and mental wellness, independence, quality of life and enhancing successful life-course transitions. Others have defined successful aging as the degree to which elderly individuals adapt to age-associated changes or view themselves as successfully aging or are morbidity-free until the latest time point before death. Young et al. proposed that successful aging is “A state wherein an individual is able to invoke adaptive psychological and social mechanisms to compensate for physiological limitations to achieve a sense of well-being, high self-assessed quality of life, and a sense of personal fulfillment even in the context of illness and disability.” Further they proposed to evaluate successful aging using three domains of the physiological (e.g., diseases, functional impairments), the psychological (e.g., emotional vitality, coping, resilience), and the social (e.g., spirituality and adaptation through social support mechanisms). While overlap exists among the different definitions of “healthy” or “successful” aging proposed to date, there is also debate as to which components are essential. Further, the debate continues as to whether successful aging should be defined by others (health professionals, researchers) or by the older adults themselves, or both. Current literature indicates that while there is some overlap between components of successful aging identified by older adults and others, there are also many factors that are considered important components of successful aging by older adults and not by others. Indeed, the percentage of healthy, successfully aging older adults will significantly vary depending on whether it is defined by older adults or others. Nevertheless, the common thread found among a majority of the definitions is high physical, cognitive and social function/engagement. While there is good consensus on how to assess physical and cognitive health, it is more difficult to objectively define social function/engagement. A close collaboration between biological, medical and social scientists would help to sharpen the objective tools needed to assess the key components of successful aging. Such collaboration would benefit by input from older adults themselves. Moreover, more research is required to better define early determinants/risk factors for the key components of successful aging.