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Geriatrics stands at the intersection of three forces:

  1. Gerontology (both basic and applied)

  2. Chronic disease management, especially multimorbidities

  3. End-of-life care

Principles of gerontology can help explain insights of geriatric care. For example, the presentation of disease is often different in older persons because the response to stress is different. A hallmark of aging is a decreased ability to respond to stress. The body’s stress response is what typically generates the symptoms of an illness. Older people fail to respond as actively. Hence, they may not have spiking fevers or elevated white blood cell counts in the face of an infection. Heart disease may be silent.

Chronic disease management is difficult on its own. Age itself is the strongest risk factor for several chronic diseases such as heart disease, cancer, stroke, diabetes mellitus, and pneumonia (Miller, 2002). Management is much more difficult when an older patient suffers from multiple simultaneous diseases. Basic care guidelines may not work. Indeed, they may pose a threat (Boyd et al, 2005).

Much of the emphasis in care planning is directed at containing disease and maintaining function and identifying how to make the end of life meaningful (Gawande, 2014). Death is a part of old age. Geriatrics must address that reality and help patients and families deal with end of life, helping them make informed decisions that reflect their goals and preferences. But geriatrics cannot focus exclusively on end-of-life care. One compromise has been the evolution of palliative care (discussed in Chapter 18). To this triad, some might also add a role for advocating reasonable preventive actions (see Chapter 5).

This chapter describes the aging process, changes associated with normal aging, as well as hallmarks of aging at the cellular level. We then introduce the topic of frailty, and the concepts of resilience and homeostenosis. We posit the link between aging and multimorbidity. Next we describe geriatric syndromes and the atypical presentation of common clinical problems. Finally, we put it all together by describing clinical implications of the aging process.


Whereas most people think of age as a chronological phenomenon, gerontologists assess age based on the force of mortality—how much longer can an individual be expected to live. Aging is defined as the time-dependent sequential deterioration that occurs in most living beings, including weakness, increased susceptibility to disease and adverse environmental conditions, loss of mobility and agility, and age-related physiological changes (Goldsmith, 2006). At least in vitro, it is clear that the “aging clock” can be reset (Rando and Chang, 2012). Somatic cell nuclear transfer of the nucleus of a mature somatic cell into an enucleated oocyte can give rise to mature, fertile animals.

It is important to distinguish life expectancy from life span. The former ...

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