Even elders who are in relatively good health still experience changes as they age. This module describes these changes briefly by body system.
As we age, our metabolism slows and our lean body mass decreases; the proportion of the body that is made up of fat typically doubles between the ages of 25 and 75. Because of the slowing metabolism, the body is less able to tolerate changes in temperature.
Metabolism—the rate at which calories are burned—ultimately determines how easily weight is gained or lost. Metabolism is influenced by age, gender (men have a higher resting metabolic rate than women), heredity, and the proportion of lean muscle a person has (more lean muscle usually means a higher metabolic rate) (Steinbaum, 2017).
Each decade after age 30 there is a 2% decrease in metabolism, which makes it more difficult to maintain a desirable weight and body composition. To match this decreased energy metabolism, there must either be a 2% decrease in food intake or a 2% increase in energy expenditure (Morris, 2016).
Sarcopenia and osteoporosis are two of the most common musculoskeletal changes that occur with age. Osteoporosis is a disease of the bones that occurs when the body fails to form enough new bone, when too much old bone is reabsorbed by the body, or both. Bone mineral is lost and replaced throughout life, but loss begins to outstrip replacement around age 35. Women can lose up to 20% of their bone density in the first 5 to 7 years after menopause.
Half of all women and 1 in 4 men over the age of 50 will break a bone due to osteoporosis. Most will break a bone in the hip, spine, or wrist. If diagnosed early, the fractures associated with osteoporosis can often be prevented. Unfortunately, osteoporosis frequently remains undiagnosed until a fracture occurs (NIH, 2015; NOF, n.d.).
Many factors, including body structure, ancestry, diet, and lifestyle, as well as advanced age and prolonged use of certain medications can increase the risk for osteoporosis and fractures. The U.S. Preventive Services Task Force recommends that all women age 65 and older be screened for osteoporosis. There are several tests available for diagnosis and medications that may be effective for treatment (NIH, 2016).
Sarcopenia is the age-related decrease in muscle mass and is to muscles what osteoporosis is to bone. It is estimated that muscle mass declines 22% for women and 23% for men between the ages of 30 and 70, with a decline of muscle strength of up to 30%. As muscles lose strength, coordination and balance deteriorate and joint capsules tighten and lose flexibility. Lean muscle mass is lost and is replaced with adipose tissue (Winkler, 2016).
Sarcopenia is a major public health problem that affects about 25% of people younger than 70 years and 40% of those 80 years and older. Healthcare costs related to sarcopenia totaled about $18.5 billion in the United States in the year 2000 (NIH, 2011).
Regardless of a person’s level of activity, there is a decrease in muscle mass and muscle fiber size with age. By the age of 60, degenerative changes in weight-bearing joints are essentially a universal occurrence (Winkler, 2011). The consequences of muscle loss include decreased strength and endurance, loss of bone strength, increased fall and fracture risk, and a decreased ability to perform activities of daily living (ADLs). Men tend to have greater muscle mass than women, particularly in the upper body; however, rates of loss appear to be uniform between genders (NIH, 2011).
Resistance training is primary for the prevention, treatment, and even reversal of sarcopenia. It has been shown to influence hormone levels, the neuromuscular system, and protein synthesis. A program of progressive resistance training can have positive effects in as little as 2 weeks (WebMD, 2016).
Strengthening exercises are both safe and effective for women and men of all ages, including those who are not in perfect health. In fact, people with health concerns—including heart disease and arthritis—often benefit the most from an exercise program that includes lifting weights a few times each week.
[Much of the material in this section is taken from Medline Plus, 2014.]
The integumentary system, consisting of the skin, hair, and nails, has a variety of functions. It acts as a waterproof shield and insulates the body against extremes of temperature; it helps to regulate temperature, cushion and protect the deeper tissues, shield the body from sunlight and harmful chemicals, and excrete wastes. The skin contains sensory receptors to detect pain, sensation, pressure, and temperature and is involved in vitamin D synthesis.
Skin is the largest organ of the integumentary system and contains three primary layers: the epidermis, dermis, and hypodermis. The outermost layer, the epidermis, is a waterproof barrier and contains no blood vessels. The dermis lies just below the epidermis and contains connective tissue; nerve endings for touch and temperature; hair follicles, sweat glands, sebaceous glands; and lymphatic and blood vessels. The hypodermis lies below the dermis and connects it to underlying muscle and bone.
As we age, structures within the skin begin to atrophy and lose elasticity and turgor. A decrease in the number of nerve endings leads to decreased sensation. Melanocytes (pigment-producing cells) decrease, causing gray hair and making the skin more susceptible to sun damage.
As we age the epidermis begins to thin, reducing its protective function and allowing chemicals and pathogens easier access to the body. Adipose tissue also decreases with age, reducing the ability of the skin to cushion the body against trauma and to protect against environmental temperature change. Reduced collagen causes skin to tear more easily.
With a decrease in pigment-producing melanocytes, hair color fades and turns gray or white. Hair strands become smaller and many hair follicles stop producing hair altogether, causing hair thinning and baldness. Nails grow more slowly and may become yellowed and brittle.
Two temperature regulation issues can be especially critical for older adults: heat intolerance and hypothermia. Older adults adjust less well to sudden changes in temperature and are more prone to heat stress than younger people. They are more likely than younger people to have a chronic medical condition that changes normal body responses to heat, and more likely to be taking prescription medications that impair the body’s ability to regulate temperature or inhibit perspiration.
Heat stroke is the most serious heat-related illness in all ages. It occurs when we are no longer able to control body temperature. This creates a cascade in which body temperature rises rapidly, and the body loses its ability to sweat and thus the ability to cool. Body temperatures can rise to 106°F or higher within 10 to 15 minutes. Heat stroke can cause death or permanent disability if emergency treatment is not provided. Heat exhaustion is a milder form of heat-related illness that can develop after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids.
Hypothermia can also be a problem for older adults because of the body’s decreased ability to regulate and sense temperature. Certain medications older adults may be taking—such as antidepressants, antipsychotics, and sedatives—can also change the body’s ability to regulate temperature (Mayo Clinic, 2014).
Hypothermia is most likely at very cold temperatures, but it can occur even at cool temperatures (above 40°F) if a person becomes chilled from rain, sweat, or submersion in cold water. Hypothermia can be deadly if not treated quickly and it can happen anywhere. Older people can have a mild form of hypothermia if the temperature in their home is too cool.
Temperature regulation issues are a good case in point for the potentially complex interrelationship between age-related body changes, disease, injury, and treatments.
Diseases such as Parkinson’s, hypothyroidism, stroke, and arthritis may interfere with the body’s temperature regulation. Conditions that decrease sensation and movement—such as stroke, arthritis, and spinal cord injuries—can prevent a person from sensing changes in body temperature and can also prevent that person from moving to a warmer environment or obtaining blankets or warm clothing. Health problems such as diabetes that interferes with circulation, and some skin problems that cause the body to lose more heat than normal, can also contribute to hypothermia. In addition, some medications, including certain antidepressants, antipsychotics, narcotic pain medications, and sedatives can change the body’s ability to regulate its temperature (Mayo Clinic, 2014).
Age is the major risk factor for cardiovascular disease. Heart disease and stroke incidence rises steeply after age 65, accounting for more than 40% of all deaths among people age 65 to 74 and almost 60% at age 85 and above. Older adults are much more likely than younger people to suffer a heart attack or stroke, or to develop coronary disease and high blood pressure leading to heart failure. Cardiovascular disease is also a major cause of disability, limiting the activity and eroding the quality of life of millions of older people each year. The cost of these diseases to the nation is in the billions of dollars.
Age-related changes in heart muscle cells (myocytes) help explain alterations in the heart as a whole. There are fewer myocytes to do the work as we age and those that remain enlarge, compromising their ability to pump blood efficiently.
As the heart ages, it thickens and becomes less elastic, and it may become enlarged in size. The older heart is less able to relax completely between beats and its pumping chambers become stiffer. The heart is not able to pump as vigorously as it once did and is also less responsive to adrenaline. The older heart is less able to supply adequate blood and oxygen to muscles during exercise (Shea, n.d.).
The older heart is less able to accelerate to meet the body’s oxygen demands during pain, anxiety, fever, or hemorrhage. In addition, an older person may not exhibit the typical heart attack symptoms of chest pain and diaphoresis but instead may have only shortness of breath, anxiety, and confusion. Those with diabetes and long-standing angina are much less likely to exhibit typical symptoms of heart attack (Larsen, 2008–2009).
Atherosclerosis is the disease behind the disease. When atherosclerotic processes take hold in the arteries that supply blood to the heart, the condition becomes coronary artery disease (CAD). Atherosclerosis is a degenerative disorder that injures the inner walls of large arteries. In atherosclerosis, thick abnormal patches called plaques accumulate at scattered locations along the artery’s innermost layer. The plaques are disorganized masses filled with cholesterol, other lipids, and cells, all covered by a white fibrous coating (Mitchell & Schoen, 2009).
Atherosclerotic plaques narrow an artery and hinder blood flow. Further, the surface of a bulging atherosclerotic plaque sometimes tears, exposing material that stimulates clot formation. Clots and ruptured plaque material can then break away from the wall, be carried by the blood, and clog arteries downstream.
The events leading to CAD begin in childhood and can be addressed with diet and lifestyle changes. The risk of heart disease increases for men after age 45 and for women after age 55 (or after menopause). It is important to know the symptoms of heart attack and that these symptoms may be different in older adults and between men and women.
Coronary Artery Disease can take a chronic course called stable angina. It can also give rise to sudden cardiac emergencies called acute coronary syndromes. Acute coronary syndromes range from temporary episodes of significant ischemia (unstable angina) to permanent heart muscle damage (myocardial infarction) to sudden cardiac death.
Stroke is the number one cause of serious adult disability in the United States and it is devastating to the stroke patient and family. Stroke strikes all age groups, from fetuses still in the womb to centenarians. However, older people have a higher risk for stroke than the general population and the risk for stroke increases with age. For every decade after the age of 55, the risk of stroke doubles, and two-thirds of all strokes occur in people over 65 years old. People over 65 also have a seven-fold greater risk of dying from stroke than the general population, and the incidence of stroke is increasing proportionately with the increase in the elder population.
Age, and the diseases that occur more frequently with age, are major risk factors for stroke. The most important risk factors for stroke are hypertension, heart disease, diabetes, and cigarette smoking. Others include heavy alcohol consumption, high blood cholesterol levels, illicit drug use, and genetic or congenital conditions, particularly vascular abnormalities (NINDS, 2012).
Problems in the urinary system can be caused by aging, illness, or injury. With age, changes in the kidneys’ structure cause them to lose some of their ability to remove wastes from the blood. Further, the muscles in the ureters, bladder, and urethra tend to lose some of their strength. Older adults may have more urinary infections because the bladder muscles do not tighten enough to empty the bladder completely. A decrease in strength of muscles of the sphincters and the pelvis can also cause incontinence, the unwanted leakage of urine. Illness or injury can also prevent the kidneys from filtering the blood completely or block the passage of urine (NKUDIC, 2014).
With age, the number of nephrons (the filtering units of the kidneys) decreases and the kidneys are less able to filter waste from the blood. Blood vessels that supply the kidneys become stiffer, causing the kidneys to filter blood more slowly. The overall amount of kidney tissue also decreases and there is a reduced capacity for renal regeneration in the face of acute renal insults (Medline Plus, 2014a).
Because of age-related changes to the kidneys, older adults are more susceptible to the development of dehydration and drug toxicity due to reduced drug excretion. An important cause of renal toxicity is failure to adjust medication dosage to decreases in glomerular filtration rate, which measures how much blood passes through the tiny filters in the kidneys (glomeruli) each minute.
Changes in immune system function with aging can lead from an increased inflammatory response to renal injury and increased susceptibility to infection. Because the older person is less likely to develop a fever or an increase in white blood cells, kidney infections may go unnoticed and untreated, leading to sepsis and kidney injury.
In the older male, benign prostatic hypertrophy (BPH) can develop. The prostate gland, which surrounds the urethra, grows larger and may cause difficulty in urination. In addition, an infection or a tumor may cause problems passing urine. Men in their thirties and forties may begin to have urinary symptoms and need medical attention, but for others symptoms aren’t noticed until much later in life.
Urinary tract infections (UTIs) are the most common infection found in older adults. Most UTIs are not serious, but some infections can lead to serious problems, such as kidney infections. Recurrent or chronic kidney infections can cause permanent damage, including kidney scars, poor kidney function, high blood pressure, and other problems. Some acute kidney infections—infections that develop suddenly—can be life threatening, especially if the bacteria enter the bloodstream, a condition called septicemia (NKUDIC, 2012).
Symptoms of UTI vary by age, gender, and whether a catheter is present. While frequent and intense urge to urinate and a painful, burning feeling in the bladder or urethra during urination are typical in younger women, older people with UTIs are more likely to be tired, shaky, and weak, and to have muscle aches and abdominal pain. Urine may be cloudy, dark, or bloody or have a foul smell. If a person has a catheter, a fever that cannot be attributed to any other condition may be the only sign (NKUDIC, 2012).
Normally, UTIs do not cause fever if they are in the bladder. A fever may mean the infection has reached the kidneys or has penetrated the prostate. Other symptoms of a kidney infection include pain in the back or side below the ribs, nausea, and vomiting (NKUDIC, 2012).
Older adults are more susceptible to UTIs than younger adults for several reasons. They are generally more susceptible to infections and, if they are incontinent, to bacteria that can travel through the urethra to the bladder. Incomplete emptying of the bladder allows urine to stagnate, which is conducive to bacterial growth.
Bacteria may be introduced into the bladder on or around a urinary catheter. The Infectious Diseases Society of America recommends using catheters for the shortest time possible to reduce the risk of a UTI (NKUDIC, 2012).
Similar to other organ systems, aging of the pulmonary system is associated with structural changes leading to a progressive decline in function. Decreased collagen and elastin result in the loss of elastic recoil of the lungs. There is decreased diameter of small airways and a tendency to early closure, leading to air trapping and ventilation/perfusion mismatches.
With age, there is a decrease in the number of alveoli (the primary gas exchange units of the lungs) and lung capillaries, with a corresponding decrease in gas exchange.
Aging lungs become stiffer and less able to expand and contract. Vital capacity, muscle strength, and endurance decrease. The chest wall becomes more rigid and the diaphragm and other muscles of respiration become weaker. A decreased cough reflex and a reduction in the number of cilia that sweep mucous up and out of the lungs results in increased likelihood of infection (Medline Plus, 2014b).
[Material in this section is taken from Hormone Health Network, 2013.]
The endocrine system is made up of glands that secrete hormones that regulate the body’s growth, metabolism, and sexual development and function. With age, some hormones increase or decrease, some target organs become less receptive, and hormones may be broken down more slowly.
Despite these age-related changes, the endocrine system functions well in most older people. However, some changes do occur because of normal damage to cells during the aging process and genetically programmed cellular changes. These changes may alter:
Increasing age is thought to be related to the development of type II diabetes. Diabetes is a disorder that causes repeated episodes of inappropriately high concentrations of glucose in the bloodstream. This chronic hyperglycemia gradually produces tissue damage, notably to eyes, kidneys, nerves, heart, and blood vessels. With aging, the target cell response time becomes slower, especially in people who might be at risk for this disorder.
The signs and symptoms of endocrine system diseases affect many body systems. In elders they are frequently subtle and may be harder to detect than in younger people. At times, these signs are incorrectly linked with other causes, such as the changes of normal aging, other medical disorders or conditions, or drug therapy.
The aging process affects nearly every gland. For example, the hypothalamus is responsible for releasing hormones that stimulate the pituitary gland. During aging there is either impaired secretion of some hypothalamic hormones or impaired pituitary response. These changes appear to influence the endocrine system’s ability to respond to the body’s internal environment. As a result, the body cannot respond as well to internal and external stresses.
As we grow older, the prevalence of gastrointestinal problems increases. Gastroesophageal reflux disease, or GERD, occurs when the lower esophageal sphincter does not close properly and stomach contents leak back (reflux) into the esophagus. Heartburn that occurs more than twice a week may be considered GERD, and it can eventually lead to more serious health problems (Medline Plus, 2017).
Food intake may decrease in the older adult for several reasons. An older person’s ill-fitting dentures or tooth decay can make chewing difficult. Decreased saliva production causes dry mouth, which may increase tooth decay and even make swallowing more difficult. Taste becomes less acute, making food less appetizing.
Decreased intestinal motility and slower stomach emptying can lead to altered absorption of nutrients and medications. Decreased physical activity, decreased intestinal motility, and a lessened urge to defecate can lead to constipation.
Older adults regularly taking narcotic pain medications frequently experience constipation. Opioid pain medications slow movement of stool through the intestinal tract and the stool becomes hard and more difficult to expel. The usual treatments of fiber, fluids, and exercise are not sufficient. Stool softeners such as docusate and peristalsis-inducing medications such as senna and bisacodyl are the treatment of choice (Herndon et al., 2002).
Up to 40% of older adults experience some kind of gastrointestinal symptoms. In addition to GERD and constipation, these include diverticular disease, ulcers, polyps, and colon cancer. All of these are more prevalent in adults over age 60 (WebMD, 2016, 2016a).
[Material in the latter part of this section is taken from NIDCD, 2015.]
As the senses become less acute with age, less information can be gathered and processed about the world around us. The prevalence of sensory impairments is increasing as life expectancy increases. In order to maintain independent living, health, and quality of life for older adults it is important to minimize the impact of sensory impairments.
Sensory impairments are a substantial problem for older Americans. One out of 6 older Americans has impaired vision; 1 out of 4 has impaired hearing; 1 out of 4 has loss of feeling in the feet; and 3 out of 4 have abnormal postural balance testing (CDC, 2010).
Hearing loss is one of the most common conditions affecting older and elderly adults. One in 3 people between 65 and 74 has hearing loss and nearly half of those older than 75 have difficulty hearing, making it hard to understand and follow a doctor’s advice, respond to warnings, and hear doorbells and alarms. Hearing loss can also make it difficult to enjoy talking with friends and family (NIDCD, 2016).
In adults, visual impairment is associated with loss of personal independence and difficulty maintaining employment, often leading to the need for disability pensions, vocational and social services, and nursing home or assistive living placement. Older adults represent the vast majority of the visually impaired population. For older adults, visual problems have a negative impact on quality of life equivalent to that of life-threatening conditions such as heart disease and cancer (NEI, 1999).
Between the ages of 40 and 50, most people begin to have difficulty focusing their vision up close. This is a condition call presbyopia and it is a normal result of aging caused by a loss of elasticity of the lens. Presbyopia is easily corrected with glasses. The lens also thickens and discolors, making it more difficult to distinguish colors. Pupils decrease in size and more light is needed to see well.
There are certain diseases that are not a normal part of aging that can lead to vision loss. The leading causes of visual impairment are diseases that are common in elders: age-related macular degeneration (AMD), cataract, glaucoma, diabetic retinopathy, and optic nerve atrophy (NEI, 1999).
The largest single risk factor for cataract is age and it afflicts more than 50% of people over age 80. Glaucoma is a leading cause of irreversible blindness among African Americans and Hispanics. With the aging of the U.S. population, increased life expectancy, and higher incidence of glaucoma in older people, the population of those with the disease is expected to rise significantly (NEI, 2012).
More than two-thirds of those with visual impairment are over age 65. Although there are no gender differences in the prevalence of vision problems in older adults, there are more visually impaired women than men because, on average, women live longer than men. However, African Americans are twice as likely to be visually impaired than are whites of comparable socioeconomic status. As the older adult population grows, the number of people with visual impairment and other aging-related disabilities will increase (NEI, 1999).
As with vision and hearing, people gradually lose their ability to smell as they get older. Smell that declines with age is called presbyosmia and is not preventable. Roughly 1% to 2% of people in North America say that they have a smell disorder. Problems with smell are more common in men than women. In one study, nearly one-quarter of men ages 60 to 69 had a smell disorder, while about 11% of women in that age range reported a problem. Many people who have smell disorders also notice problems with their sense of taste (NIDCD, 2015).
Age is only one of the many reasons for problems with smell. Most people who develop a problem with smell have recently had an illness or injury. The most common causes are the common cold and chronic nasal or sinus infection.
Problems with the sense of smell can also be a sign of other serious health conditions. A smell disorder can be an early sign of Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, and (rarely) brain tumor. It can also accompany or be a sign of obesity, diabetes, hypertension, and malnutrition.
When smell is impaired, people often change their eating habits. Some may eat too little and lose weight while others may eat too much and gain weight. Food becomes less enjoyable and people may use too much salt or sugar to improve the taste, a practice that can worsen certain medical conditions such as high blood pressure, kidney disease, or diabetes. In severe cases, loss of smell can lead to depression.
It is important to identify and treat the underlying cause of a smell disorder. Certain antibiotics, some blood pressure pills, some cholesterol-lowering drugs, and some antifungal medications can cause problems with smell. The sense of smell usually returns to normal when the medicine is stopped.
Taste function decreases with aging to some degree and can be influenced by central tumors and lesions (eg, ischemic infarcts secondary to stroke). Taste can also be adversely affected by a number of medications. The most debilitating taste disorders are those in which a persistent, often chronic, bad taste is present, such as a bitter or salty taste. The causes of these taste disorders are poorly understood, although they usually appear later in life. In addition to dental and oral health considerations (eg, the presence of certain metals in oral appliances, purulent discharge from infected teeth or gums), viruses, physical damage to one or more taste nerves, and various medicines may be the cause. Among offending medicines are lipid reducing agents, antibiotics, antihypertensives, anxiolytics, and antidepressants.
Sleep needs change over a person’s lifetime. Children and adolescents need more sleep than adults. Older adults need about the same amount of sleep as younger adults—seven to nine hours of sleep per night. However, older adults may get less sleep than they need, often because they have trouble falling asleep. A study of adults over 65 found that 13% of men and 36% of women take more than 30 minutes to fall asleep.
There are many possible explanations for these changes. Older adults may produce and secrete less melatonin, the hormone that promotes sleep. They may also be more sensitive to—and may awaken because of—changes in their environment, such as noise. Older adults may also have other medical and psychiatric problems that can affect their nighttime sleep. Researchers have noted that people without major medical or psychiatric illnesses report better sleep.
Not sleeping well can lead to a number of problems. Older adults who have poor nighttime sleep are more likely to have depressed mood, attention and memory problems, excessive daytime sleepiness, more nighttime falls, and use more over-the-counter or prescription sleep aids. Poor sleep is also associated with a poorer quality of life.
Insomnia is the most common sleep complaint at any age. It affects almost half of adults 60 and older. Disorders that cause pain or discomfort during the night can interfere with sleep, as can conditions such as heart failure, lung disease, Parkinson’s disease, dementia, and depression. Medications can also adversely affect sleep.
As people age, their sleeping and waking patterns tend to change. Older adults usually become sleepier earlier in the evening and wake up earlier in the morning. If they don’t adjust their bedtimes to these changes, they may have difficulty falling and staying asleep.
Sleep apnea and snoring are two examples of sleep-disordered breathing—conditions that make it more difficult to breathe during sleep. When severe, these disorders may cause people to wake up often at night and be drowsy during the day.
Two movement disorders that can make it harder to sleep include restless legs syndrome, or RLS, and periodic limb movement disorder, or PLMD. Both of these conditions cause people to move their limbs when they sleep, leading to poor sleep and daytime drowsiness. Often, both conditions occur in the same person.