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Introduction to Geriatrics


Richard G. Stefanacci

, DO, MGH, MBA, Thomas Jefferson University, Jefferson College of Population Health

Reviewed/Revised May 2022 | Modified Sep 2022

Geriatrics refers to medical care for older adults, an age group that is not easy to define precisely. Gerontology is the study of aging, including biologic, sociologic, and psychologic changes. “Older” is preferred over "elderly," but both terms are equally imprecise. It is important to avoid terms and attitudes that suggest bias against older people (ageism). Although there is no set age to define older age, > age 65 is often used because this is the age that determines eligibility for Medicare insurance in the US. However, some people with medical conditions require geriatrics expertise at a younger age. For example, the Program of All-Inclusive Care for the Elderly (PACE) Programs of All-Inclusive Care for the Elderly (PACE) The Programs of All-Inclusive Care for the Elderly (PACE) is designed for older people who meet criteria for nursing home admission but who wish to live at home as long as possible. The program... read more sets the age for eligibility beginning at 55 for people who meet the need for nursing home level of care.

Around the year 1900 in the US, people > 65 accounted for 4% of the population; now they account for > 16% (nearly 50 million, with a net gain of 10,000/day). In 2026, when post-World War II baby boomers begin to reach age 80, estimates suggest that > 20% of Americans (almost 80 million) will be > 65. Mean age of those > 65 is now a little more than 75, and the proportion of those > 85 is increasing most rapidly.

Life expectancy for men is an additional 17 years at age 65 and 10 years at age 75; for women, it is an additional 20 years at age 65 and 13 years at age 75. Overall, women live about 5 years longer than men in the US and 7 years longer worldwide. These differences in survival have changed little despite changes in women’s lifestyle (eg, increased smoking, increased stress) over the late 20th century and into the 21st.


Aging (ie, pure aging) refers to the inevitable, irreversible decline in organ function that occurs over time even in the absence of injury, illness, environmental risks, or poor lifestyle choices (eg, unhealthy diet, lack of exercise, substance abuse). Initially, the changes in organ function (see table Selected Physiologic Age-Related Changes Selected Physiologic Age-Related Changes Selected Physiologic Age-Related Changes ) do not affect baseline function; the first manifestations are a reduced capacity of each organ to maintain homeostasis under stress (eg, illness, injury). The cardiovascular, renal, and central nervous systems are usually the most vulnerable (the weakest links).

Diseases interact with pure aging effects to cause geriatric-specific complications (now referred to as geriatric syndromes), particularly in the weak-link systems—even when those organs are not the primary ones affected by a disease. Typical examples are delirium complicating pneumonia or urinary tract infections and the falls, dizziness, syncope, urinary incontinence, and weight loss that often accompany many minor illnesses in older adults. Aging organs are also more susceptible to injury; eg, intracranial hemorrhage is more common and is triggered by less clinically important injury in older adults.

The effects of aging must be taken into account during the diagnosis and treatment of older adults. Clinicians should not

  • Mistake pure aging for disease (eg, slow information retrieval is not dementia)

  • Mistake disease for pure aging (eg, ascribe debilitating arthritis, tremor, or dementia to old age)

  • Ignore the increased risk of adverse drug effects on weak-link systems stressed by illness

  • Forget that older adults often have multiple underlying disorders (eg, hypertension, diabetes, atherosclerosis) that accelerate the potential for harm

In addition, clinicians should be alert for diseases and problems that are much more common among older adults (eg, diastolic heart failure, Alzheimer disease, incontinence, atrial fibrillation). This approach enables clinicians to better understand and manage the complexity of the diseases that often coexist in older patients. Understanding the physical changes and geriatric-specific manifestations of disease that accompany advancing age is important to avoid the negative and prejudicial stereotypes about older adults that characterize ageism and can negatively impact patient care and quality of life.

Ageism refers to prejudice against people of older age. Similar to other forms of prejudice (eg, racial, ethnic), ageism is based on negative misconceptions and stereotypes and may be conscious or unconscious, overt or subtle. Unlike many other forms of prejudice, ageism is rarely intentionally malicious but nonetheless can cause emotional distress and has adverse practical consequences (eg, being encouraged to retire from work, not invited to participate in groups or committees). Healthcare providers effectuate age bias by not offering a treatment to an older adult based simply on their age rather than on factors such as expected life expectancy, quality of life, and patient preference.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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