Body and Mind : Reading Doc (10) PDF

Body and Mind : I took my 1-year-old grandson to the playground. Another woman, watching her son, warned that the sandbox would soon be crowded because children from a nearby day-care center were coming. To my delight, she explained details of the center’s curriculum, staffing, scheduling, and tuit...

Body and Mind : I took my 1-year-old grandson to the playground. Another woman, watching her son, warned that the sandbox would soon be crowded because children from a nearby day-care center were coming. To my delight, she explained details of the center’s curriculum, staffing, scheduling, and tuition as if she assumed I was my grandson’s mother. Soon I realized that she was merely being polite, because a girl glanced at me and asked: “Is that your grandchild?” I nodded. “Where is the mother?” was her next question. Later came the final blow. As I opened the playground gate for a middle-aged man, he said, “Thank you, young lady.” That “young lady” was benevolent ageism: I realized that my pleasure at the first woman’s words was my own self-deceptive prejudice. Now we begin our study of the last phase of life, from age 65 or so until death. This chapter starts by exploring attitudes, evident in all three encounters. We then describe biosocial changes, and ways to mitigate them. Finally we consider four aspects of cognition: disease, decline, improvement, and wisdom. My playground reactions illustrate two of these four: I forgot the name of the recommended preschool, but I recognized ageism in me. New Understanding of Old Age Major changes have occurred in late adulthood for two reasons. First, science: We know more about causes and prevention of senescence. Second, the baby boom: The 1950s babies sparked the youth revolution of the 1960s. They now are creating an elder revolution. Demography Demographers are scientists who describe populations. They chronicled a demographic shift in the size of the age groups, called “the greatest demographic upheaval in human history” (Bloom, 2011, p. 562). Two hundred years ago, there were 20 times more children under age 15 than people over age 64. Now there are only three times as many. Worldwide, 9 percent of the population is 65 or older in 2020, a percent that is rising every year. The demographic shift is much larger in developed nations: Elders are 17 percent in the United States, 18 percent in Canada, 23 percent in Italy (United Nations, Department of Economic and Social Affairs, Population Division, 2019). Projections for Japan are that a third of the population might be over 65 in 2050. Demographers often depict the age structure of a population as a series of stacked bars, one bar for each age group, with the youngest at the bottom and the oldest at the top. Always, the shape was a demographic pyramid. Like a wedding cake, it was wide at the base, with each higher level narrower than the one below it (see Figure 14.1). The pyramid is becoming square, for many reasons (see Table 14.1). Demographers chart the average life expectancy, which is how long a typical person will live. Between 1950 and 2020, the average life expectancy in high-income nations became 16 years longer, from 65 to 81. In low-income nations, the average became 28 years longer, from 35 to 63 (United Nations, Department of Economic and Social Affairs, Population Division, 2019). Why? Less affluent nations added years because of fewer deaths early in life, thanks to clean water, immunization, nutrition, and newborn care. In more affluent nations, midlife deaths were also reduced, because of lifestyle (less smoking, more exercise) and medical (medication, surgery, early detection) advances. In the most developed nations, the ailments of old age have been pushed back a few years. Of course, improvement is not inevitable. Indeed, in the United States (not in other nations), beginning in 2014 and continuing for several years, drug overdoses and suicides in middle age slightly reduced average life expectancy (Case & Deaton, 2020). Then, in 2020 COVID deaths cut life expectancy by about 2 years. This varied by ethnicity, with the average Black American losing three years (see Figure 14.2). Nonetheless, for every ethnic group, the trends remain: U.S. residents who reach age 60 in good health usually live until their early 80s, about five years longer than was true in 1950. FIGURE 14.2 Death and Discrimination The pandemic increased deaths among older adults, not only from COVID but from other causes as well. The ethnic differences are thought to be job-related, as more people of color had jobs where social distancing and remote work were impossible. STATISTICS THAT FRIGHTEN Unfortunately, demographic data are sometimes reported in ways designed to alarm, suggesting that the demographic shift is a time bomb that will explode. For instance, some say that the United States had ten times as many people over age 85 in 2020 as in 1950. Or that more and more people have Alzheimer’s disease. Both true. Both alarming. Both misleading. THINK CRITICALLY: Why do many people contemplate aging with sorrow rather than joy? Consider numbers carefully. Yes, there are more old people alive. But the overall population has also grown. In 2020, only 2 percent of U.S. residents were aged 85 and older, a number that does not overwhelm the other 98 percent. The proportion of the population over age 85 is four times, not ten times, higher than it was. Because age is the main risk factor for Alzheimer’s disease, longer lives means more people with that disease. But in Europe and the United States, the rate of Alzheimer’s is decreasing, because health and education postpone brain disease, and more older people are college graduates (Matthews et al., 2013; Serrano-Pozo & Growdon, 2019; Sullivan et al., 2019). The leading British medical journal discussed “the time bomb that isn’t” (Spijker & MacInnes, 2013). The worst predictions, such as overwhelmed health care systems, are not based on analysis. One specific statistic makes the point: Older people spend fewer days, on average, in hospitals. That is the primary reason that the United States had about half as many hospital beds in 2018 as in 1980. The rate per thousand was 2.4 compared to 4.5 (National Center for Health Statistics, 2019). WHAT KIND OF OLD? To understand why this time bomb fizzled despite increasing numbers, the current cohort of baby boomers want to distinguish the young-old, the old-old, and the oldest-old. World’s Record for Centenarians Can you sprint 100 meters in less than 30 seconds? Almost until his death in 2019, this man, Hidekichi Miyazaki, could. Maybe you need more practice. Hidekichi had been running for 105 years! The young-old are the largest group (about 74 percent) of over 65s. They are healthy, active, and independent. This group is increasing, in part because serious impairment is decreasing. Most young-old adults live apart from their younger relatives. If their household is multigenerational, that usually means that their children or grandchildren need their help, not vice versa. The old-old (about 20 percent) suffer losses in body or mind. They need some assistance. Usually, they get help from other people over age 64 (often a spouse). Only the oldest-old (6 percent) are unable to care for themselves. In the United States, about 3 percent of the population over age 64 live in skilled nursing homes or hospitals. Another 3 percent live with family members who provide intensive care. Sometimes ages are assigned to these categories, with 65–75 young-old, 75–85 old-old, and 85+ oldest-old. However, age is a poor measure of dependency. For example, a detailed study in China of people categorized as oldest-old found that, even at age 100, only half said they were unable to care for themselves (Chen et al., 2020). Estimates of the prevalence of the oldest-old provides only approximate percentages: Variations in definition make it unclear when the old-old become the oldest-old. Estimates of how many people over age 65 need daily care vary from about 5 to 15 percent. Adults may disagree as to how dependent the oldest generations are. The overall picture is clear, however. Although many people eventually will depend on others for basic care, most people, most of the time, are competent and independent. For example, if a typical person is young-old from age 65–78, old-old from 78–80, becoming oldest-old at age 80 before dying at 81, only 6 percent of their older years fit the frightening, time-bomb stereotype. The social environment is crucial. Japanese gerontologists analyzed what would be needed if the typical Japanese person lived to 100 (Akiyama, 2020). To prevent or postpone dependence, they recommended better public transportation, accessible health care, improved social options, and flexible work opportunities. Then people could be young-old for decades. Ageism The stereotype that age determines a person is called ageism, which, like racism or sexism, ignores individuality. Sometimes ageism seems benevolent, but even so, it is a stereotype. Ageism flourishes everywhere. This includes nations that outsiders think are respectful of the old, such as in East Asia and sub-Saharan Africa (Chang et al., 2020). Opposing Perspectives Ageism and COVID-19 Ageism spread as COVID-19 spread (Previtali et al., 2020). In every nation, when ventilators and medicines were in short supply, some suggested that high-cost treatment should go to the young. Usually such suggestions were not written, but in the early days of the pandemic in Italy, a published guideline included the following: It might be needed to set an age limit for the admission to intensive care … to spare resources to those who have … the highest chance of survival and … more years of life saved. [quoted in Cesar & Proietti, 2020] Not only in Italy, but also in every nation, elders with COVID-19 were treated differently from the young. Personal protective equipment was scarce in nursing homes, where deaths were not lamented as much as “super spreader” events among younger adults, such as those who attended a large, maskless wedding of a young couple in Maine. One team of 20 Canadian gerontologists bemoaned the social tendency to be “careless about these lost lives because of ageist attitudes” (Fraser et al., 2020, p. 694). A year later, vaccine allocation followed an opposite policy. The very old were often first in line, ahead of those with serious health conditions. Was that ageism? Should healthy 75-year-olds be immunized before 50-year-olds with heart conditions? In one detailed example of mixed attitudes, social scientists analyzed hundreds of comments on Twitter when Texas Lieutenant Governor Dan Patrick opposed COVID-19 restrictions on businesses. He said that people over 70 should be willing to die to save the American dream. Most Texans expressed an opposing perspective. Of all the tweets regarding Patrick’s comments, only 5 percent were approving. The other 95 percent mentioned morals more often than politics. One wrote: “Imagine how morally bankrupt you have to be to be Dan Patrick”; another, “Dan Patrick thinks grandparents would be willing to die to protect the economy. This is morally repugnant” (Barrett et al., 2021, pp. e203, e202). Many younger people brought groceries to their older relatives and told them what kind of masks to wear. Nationwide, chain stores had special early hours for people over age 65. Such concern for elders is praiseworthy. However, even benevolent ageism is a stereotype. Consider vaccine allocation again. If it were done by risk category, then people of color should be ahead of White people, and men ahead of women. Would that be racism and sexism? Are age priorities different? BELIEVING THE STEREOTYPE Ageism is evident not only among younger people, or in social policies, but also in the aged themselves. It becomes a self-fulfilling prophecy, a prediction that comes true because people believe it: If younger adults treat older people as if they are frail and confused, that makes older people become more dependent. If urban designers consider only the average adult, the needs of elders will be ignored. If older adults themselves focus on what they have lost instead of what they have gained, they lose the joy of old age. Explaining Her Cancer Dr. Magnuson is a specialist in geriatric oncology, so she knows how to explain treatment options to Nancy Simpson. Older people are quite capable of making informed decisions, as long as their doctors do not oversimplify or use elderspeak. Examples of each of these are all around us. For the first, elderspeak is the way many people talk to the old. They might address older persons with “honey” or “dear,” use a nickname (“Billy,” not “Mr. White”), or talk slowly and loudly with simplified vocabulary. Ironically, elderspeak reduces communication (Kemper, 2015). Higher frequencies are harder to hear, stretching out words makes comprehension worse, shouting causes anxiety, and simplified vocabulary reduces the precision of language. Worse, if people talk to someone as if they are impaired, the person might believe that is the case. On the second, consider traffic control. Street crossings assume that people can walk quickly. Pedestrian bridges, longer “walk” signals, laws protecting crosswalks are scarce. The result: Older people stay home. On the third, many older people undercut other old people, and do not accept their own aging, which makes them shun others their age, maintain poor health habits, and ignore ailments that they should treat. For example, one study compared 1,877 adults, ages 30 to 95, in Germany, China, and the United States on eight aspects of aging. In every nation and domain, the elders felt that other people were old and impaired, but that their own abilities were more like a younger person (Hess et al., 2017). Consider the logic: If most people say they are younger than average, then “average” is not really average. Instead, it is a sign of ageism. In another study, 829 women, ages 40 to 75, were asked about how their health compared to the typical person their age. A sizable group said their health was excellent, many said their health was better than average, and very few said worse than average (Holahan et al., 2017). They did not treat health problems that they did not acknowledge. Most of those women were relatively inactive — despite evidence that activity improves blood pressure, digestion, and almost every other aspect of health. Did ageism undermine health? The Facts This is not to deny that illness and disability increase with chronological age. Let us look at two examples — sleep and exercise — to distinguish fact from prejudice. SLEEP Sleep changes with age. Restless legs, muscle pain, breathing difficulties, and snoring all make eight solid hours of sleep less common. That can impair physical and mental health (D. Patel et al., 2018). But wait. Only babies should “sleep like a baby.” The circadian rhythm that shifts at adolescence shifts in the other direction in late adulthood, making many elders sleepy in the early evening and up before dawn. That is normal, as is interrupted sleep and napping (Gulia & Kumar, 2018, p. 161). Insomnia, according to DSM-5, is being distressed with sleep. It is the distress, not the lack of sleep, that is the problem. Distress can lead to self-medication, such as drinking alcohol at bedtime. That increases nighttime falls, disturbs dreams, and causes early waking. In other words, because usual, age-related changes cause distress, that causes insomnia, which causes late-night drinking, which causes real sleep disturbances. Doctors may make the same mistake. If a patient complains, they might prescribe drugs that are commonly used to manage insomnia, such as benzodiazepines and non-benzodiazepines, [which] can lead to several residual side-effects like drug dependence, tolerance, rebound insomnia, muscle relaxation, hallucinations, depression, and amnesia. [Gulia & Kumar, 2018] LESS EXERCISE OR MORE? Many people have sought the secret sauce, the fountain of youth, the magic bullet that will slow, stop, or even reverse the effects of senescence. Few realize that it has already been found. Thousands of scientists, studying every disease of aging, have found something that helps every condition — exercise. Exercise reduces blood pressure, strengthens the heart and lungs, promotes digestion, and makes depression, diabetes, osteoporosis, strokes, arthritis, and several cancers less likely. Yet ageism in everyone works against movement, which explains why older adults exercise much less than younger ones. (See Figure 14.3.) FIGURE 14.3 Worse and Worse As people grow older, they should exercise more, because exercise is the best defense against all ailments of age. Unfortunately, the opposite is true: Twice as many of the oldest do not exercise compared to the youngest. These data are from the United States, where the standards for aerobic exercise and weight-bearing exercise are defined by minutes spent per week. Elders could meet the standards even if they walk more slowly, but most of them simply stop. Blame ageism in the young, who say “Sit down, I will bring your coffee, or sweater, or newspaper to you” (Franco et al., 2015). Blame ageism in the athletic center, or neighborhood, or community group that sponsors: dancing that assumes a balanced sex ratio; yoga, aerobics, and so on paced for young adults; pickup basketball games that are rough and rapid; spandex workout clothes designed for younger bodies; and bikes designed for speed, not stability. Blame the media. Whenever an older person is robbed, raped, or assaulted, sensational headlines appear. In fact, ten times as many young adults as older ones are victims of street crime. To protect them, should we insist that our young adult relatives never leave home alone? That question makes it obvious why telling older adults to stay home is ageist. And finally blame the elders themselves, who avoid a daily walk, a weekend hike, or, if warranted, shoes designed for stability and equipment that increases safe walking, such as a cane, a walker. They choose to stay home, harming their circulation, digestion, and muscles. Fear overcomes the facts. Theories and Systems: Theories and Systems Scientists try to understand the broader and deeper aspects of the developmental process, the systems and pervasive causes of senescence. That is the topic now. Accordingly, we consider theories of how and why senescence occurs, and how the various systems identified in Chapter 1 interact to affect the life of every single aging individual. Theories of Aging To separate fact from fear, we need to understand why senescence occurs. Theories are clustered into three general groups: one begins with organs, one with genes, and one with cells. NO MORE ORGAN RESERVE The oldest, most general theory of aging is known as wear-and-tear, that the body wears out after years of use. Organ reserve is used up, because of time and overuse. Inclement weather, harmful food, pollution, radiation, and social stress wear down the body. Thus, too much sun causes skin cancer, too much animal fat clogs arteries, too much pollution causes cancer, too many blows to the head harms the brain. Note that social stress is listed here. Adverse childhood experiences, described in Chapter 6, can start a cascade of wear that ends with premature death (Asmundson & Afifi, 2020). Thus, wear and tear is not only about biology: This theory recognizes the “structural and cultural conditions” that “accelerate biological decline” (Simons et al., 2020). A lifetime of dealing with discrimination and microaggressions takes a toll on the body, a phenomenon called weathering as allostatic load increases. Weathering may explain ethnic and gender differences in death rates (more people of color, more men). Many COVID deaths were blamed on “preexisting conditions,” but those conditions themselves may result from a lifetime of wear, resulting in hypertension and obesity and so on (Wakeel & Njoku, 2021). Find the Joy Most elders are happier than when they were younger. They appreciate nature, other people, and life itself, and are less often dependent on food, drugs, or possessions. Can people reduce wear and tear? One intriguing example is digestion: If people eat 1,800 calories a day instead of the usual 3,000, would that slow all aging processes? That question led to experiments in calorie restriction, limiting the quantity of food consumed. That reduces wear and tear, and sometimes doubles the life span in many species, from fruit flies to monkeys (Dorling et al., 2020). Regarding humans, thousands of members of the Calorie Restriction Society voluntarily undereat. They give up things that others cherish, not just cake and hot dogs but also a strong sex drive and high energy. As a result, they have lower blood pressure, fewer strokes, less cancer, and almost no diabetes. They wear down their bodies much more slowly (Dorling et al., 2020). Similar results were reported from Cuba. Because the United States led an embargo, Cuba experienced food and gas shortages from 1991 to 1995. People walked more, ate homegrown fruits and vegetables, and lost weight. They had much less heart disease and diabetes, and they lived longer (Franco et al., 2013). But once more food was available, Cubans ate more, gained weight, and died earlier. THINK CRITICALLY: Do people want the comforts of daily life — driving and eating — more than longer lives? Researchers seek the benefits of calorie restriction that most people will accept. There is no particular pill or food that achieves this, but intermittent fasting may do so. Millions of people have been able to periodically eat almost nothing, but eat normally most of the time (Fontana & Partridge, 2015; Tinsley & Horne, 2018). (Of course, adults should consult with their doctor before undertaking this or any weight loss method.) Several versions of intermittent fasting have been tried: Fasting for two of the seven days per week, or every other day, or not eating at all for 14 to 20 hours each day. Intermittent fasting results in lower blood pressure, less obesity, and better metabolism, not only because the digestive system is less active but also because other physiological responses are more active, to protect against temporary starvation (Mani et al., 2018). That suggests that a simple version of wear and tear is inadequate. Some organs of the body wear down, but others benefit from use. Running improves hearts and lungs; tai chi improves balance; weight-training increases muscle mass; sexual activity stimulates the sexual-reproductive system; mental challenge keeps the brain healthy. A surprising study of 55- to 79-year-olds who bicycled over 100 miles per week (they enjoyed the exercise and the views!) found very little age-based deterioration of the muscles. Indeed, on most measures those older bikers had much stronger legs than the average 30-year-old (Pollock et al., 2018). IT’S ALL GENETIC A second cluster of theories focuses on genes, both genes of the entire species and genes that vary from one person to another. You already read about the average life span. In addition, every species has a maximum life span, the oldest age that members of that species can attain. The maximum life span set by genes: rats, 4 years; rabbits, 13; tigers, 26; house cats, 30; brown bats, 34; brown bears, 37; chimpanzees, 55; Indian elephants, 70; finback whales, 80; humans, 122; lake sturgeon, 150; giant tortoises, 180. Genes affect the entire aging process for every creature, from how long the fetus stays in the womb to when, where, and whether hair on the head grows, greys or disappears. Because of the genes of the human species, few people live to 100 and no one has proven to live longer than a French woman named Jeanne Calment, who died in 1997 at the age of 122. Some contend that she was only about 100, because the daughter of the real Jeanne Calment took her identity in middle age to avoid paying some taxes. Most gerontologists accept her claim to 122. Other people have lived to 121, so 122 seems possible (Robine et al., 2019). Touch Your Toes? This woman could even put both feet behind her neck. Although everyone loses some flexibility with age, daily practice is crucial. Tao Porchon-Lynch taught yoga for a half-century. At age 99, shown here, she could balance on one leg in tree pose, stretch her hamstrings in downward dog, and then relieve any remaining stress in cobra pose. She died at age 101 in February 2020, peacefully and without pain. Certainly, Calment lived far longer than most. Her genes included some that are uncommon in the general population but common in centenarians. There are a dozen or more longevity genes, some rare and some more common. If a person happens to inherit many of them, and to have a healthy life, they might live past 100 (Nygaard et al., 2019). Like wear and tear, this theory explains some aspects of aging, but not all. Children born with the genetic disease called Hutchinson-Gilford syndrome (also called progeria) stop growing at about age 5 and begin to look old, with wrinkled skin and balding heads. They die in their teens of genetic conditions more common in people five times their age. Other genes program a long and healthy life. People who reach age 100 usually have alleles that other people do not (Govindaraju et al., 2015; Nygaard et al., 2019). THINK CRITICALLY: For the benefit of the species as a whole, why would genes promote aging? Alleles of the ApoE gene prove the importance of genetic variations (Y-W. Huang et al., 2017). Most people have the third allele (ApoE3), which does not seem to affect health. However, about 20 percent of the population have the second allele (ApoE2). In one study, ApoE2 was found in 15 percent of men in their 70s and 29 percent of men from the same population in their 90s. Obviously, Apoe2 is protective (Le Couteur et al., 2020). Another allele of the same gene, ApoE4, increases the risk of Alzheimer’s, especially if a person inherits that gene from both parents. ApoE4 also correlates with heart disease, stroke, and — if a person is HIV-positive — AIDS. Many other genes (ABCA7, Cr1m, SORL1, TREM2) increase the risk of Alzheimer’s. However, no single gene or combination of genes and alleles necessarily results in late onset Alzheimer’s. Thus, connecting variations in human senescence directly to one or more genes seems impossible. As you remember, humans have thousands of genes, often with many alleles, and always interacting in hundreds of ways. A View From Science Diabetes and Aging One type of diabetes is called childhood-onset, or type 1, because it begins early in life. That type is heavily influenced by genes, although environmental factors are relevant as well (Redondo & Concannon, 2020). But most diabetes is adult-onset, type 2. The rate increases with age, such that only 5 percent of U.S. adults aged 20–44 has it, but 29 percent of those over age 65 do (National Center for Health Statistics, 2019). Type 2 is partly related to genes, but not genes alone. Genome-wide association studies (called GWAS), which examine the entire genome, have found more than 100 genes that increase the risk of diabetes, each by a small amount (Visscher et al., 2017). Those genes appear in someone of any ethnicity, but some groups have more of particular ones, and ethnic differences in diabetes include the following. In China, Han people have higher rates of diabetes than other Chinese people (Hsu et al., 2015; L. Wang et al., 2017). In the United States, African Americans are particularly likely to develop diabetes (Layton et al., 2018). Among White residents of the United States, Hispanic people have higher rates than non-Hispanic people, with variations depending on national origin (Baquero & Parra-Medina, 2020). But these ethnic generalities fall short of understanding the genetics of diabetes. No doubt genetic variants and alleles affect the risk, but ethnicity does not reveal a person’s genes. Especially in people whose ancestors lived in Africa, genetic diversity is vast among people who, superficially, seem to be similar (Pennisi, 2021). To best predict and treat diabetes, genetic variants and combinations, as well as diet and microbiome, need to be considered. This is true for every condition: Precise prescriptions for disease, health, and senescence must be tailored for each individual (Bumpus, 2021). As a theory of aging, looking at genes makes sense. But research on the genes of diabetes reveals the problems with genetic theories of aging, especially when age is a factor. Focusing on genes may distract us from considering other causes of senescence, disease, and death. Diabetes is strongly influenced by nongenetic factors. African Americans who live in areas with high residential segregation are more likely to develop diabetes — and the reasons are not genetic (Bancks et al., 2017). Similarly, the rate for people in the lowest quintile of income is almost double the rate in the highest quintile (19 and 11 percent), a particularly troubling statistic since far more children than older adults live in poverty, so that should skew the statistic in the opposite way. Economic policies and practices, which affect diet and exercise, affect both incidence and treatment of diabetes more than genes. Genes alone rarely cause the diseases and disabilities of old age until age 90 or so. A few dominant genes make some serious problems almost inevitable (as for progeria and early-onset Alzheimer’s), but for most of us, the pace of senescence depends much more on how and where we live our lives than on our genes. AGING CELLS The third cluster of theories examines cellular aging, focusing on molecules and cells (Khosla et al., 2020; Rattan & Hayflick, 2016). Remember, cells duplicate many times over the life span. Minor errors — repetitions and deletions of triplets — in copying accumulate. Early in life, the immune system repairs such errors, but eventually the immune system itself becomes less adept. In general, when the organism can no longer repair cellular errors, senescence occurs. This process is first apparent in the skin, an organ that replaces itself often, particularly if damage occurs (such as peeling skin with sunburn). With senescence, scrapes take a little longer to heal, scarring becomes more obvious. Cellular aging also occurs inside the body; the aging immune system is increasingly unable to control abnormal cells. Cellular aging, with some cells out of control, is a major cause of all forms of cancer (Beck et al., 2020). Before age 40, biological mechanisms keep cancer cells from reproducing and metastasizing. However, once childbearing years are over, cancer cells duplicate unchecked. The results are apparent from many statistics. For instance, in the United States in 2017, only 2 percent of those aged 25 to 44 had ever had cancer. Then rates began to increase. By age 74 and older, rates were 23 percent (National Center for Health Statistics, 2019). Old Caterpillars? No, these are young chromosomes, stained to show the glowing white telomeres at the ends. There are dozens of cellular changes over time, from the mitochondria to the stem cells (Sameri et al., 2020; Wan & Finkel, 2020). One particular aspect of cell aging focuses on telomeres, the material at the end of each chromosome that becomes shorter over time. Telomeres are longer in children (except those with progeria) and shorter in old adults. Eventually, after many cell divisions over a life span, the telomere is too short, and duplication is impossible. Aging is evident, and, when many cells can no longer replicate, the maximum life span of that person (or mouse, or any other mammal) has been reached and death occurs. The more stress a person experiences, from childhood on, the shorter their telomeres become. In late adulthood, telomere length predicts death (Yegorov et al., 2020). Not surprising, then, telomere length is about the same in newborns of all genders and ethnic groups, but by late adulthood telomeres are typically longer in women than in men and longer in White people than in Black people. IT’S ALL GENETIC A second cluster of theories focuses on genes, both genes of the entire species and genes that vary from one person to another. You already read about the average life span. In addition, every species has a maximum life span, the oldest age that members of that species can attain. The maximum life span set by genes: rats, 4 years; rabbits, 13; tigers, 26; house cats, 30; brown bats, 34; brown bears, 37; chimpanzees, 55; Indian elephants, 70; finback whales, 80; humans, 122; lake sturgeon, 150; giant tortoises, 180. Genes affect the entire aging process for every creature, from how long the fetus stays in the womb to when, where, and whether hair on the head grows, greys or disappears. Because of the genes of the human species, few people live to 100 and no one has proven to live longer than a French woman named Jeanne Calment, who died in 1997 at the age of 122. Some contend that she was only about 100, because the daughter of the real Jeanne Calment took her identity in middle age to avoid paying some taxes. Most gerontologists accept her claim to 122. Other people have lived to 121, so 122 seems possible (Robine et al., 2019). Touch Your Toes? This woman could even put both feet behind her neck. Although everyone loses some flexibility with age, daily practice is crucial. Tao Porchon-Lynch taught yoga for a half-century. At age 99, shown here, she could balance on one leg in tree pose, stretch her hamstrings in downward dog, and then relieve any remaining stress in cobra pose. She died at age 101 in February 2020, peacefully and without pain. Certainly, Calment lived far longer than most. Her genes included some that are uncommon in the general population but common in centenarians. There are a dozen or more longevity genes, some rare and some more common. If a person happens to inherit many of them, and to have a healthy life, they might live past 100 (Nygaard et al., 2019). Like wear and tear, this theory explains some aspects of aging, but not all. Children born with the genetic disease called Hutchinson-Gilford syndrome (also called progeria) stop growing at about age 5 and begin to look old, with wrinkled skin and balding heads. They die in their teens of genetic conditions more common in people five times their age. Other genes program a long and healthy life. People who reach age 100 usually have alleles that other people do not (Govindaraju et al., 2015; Nygaard et al., 2019). THINK CRITICALLY: For the benefit of the species as a whole, why would genes promote aging? Alleles of the ApoE gene prove the importance of genetic variations (Y-W. Huang et al., 2017). Most people have the third allele (ApoE3), which does not seem to affect health. However, about 20 percent of the population have the second allele (ApoE2). In one study, ApoE2 was found in 15 percent of men in their 70s and 29 percent of men from the same population in their 90s. Obviously, Apoe2 is protective (Le Couteur et al., 2020). Another allele of the same gene, ApoE4, increases the risk of Alzheimer’s, especially if a person inherits that gene from both parents. ApoE4 also correlates with heart disease, stroke, and — if a person is HIV-positive — AIDS. Many other genes (ABCA7, Cr1m, SORL1, TREM2) increase the risk of Alzheimer’s. However, no single gene or combination of genes and alleles necessarily results in late onset Alzheimer’s. Thus, connecting variations in human senescence directly to one or more genes seems impossible. As you remember, humans have thousands of genes, often with many alleles, and always interacting in hundreds of ways. A View From Science Diabetes and Aging One type of diabetes is called childhood-onset, or type 1, because it begins early in life. That type is heavily influenced by genes, although environmental factors are relevant as well (Redondo & Concannon, 2020). But most diabetes is adult-onset, type 2. The rate increases with age, such that only 5 percent of U.S. adults aged 20–44 has it, but 29 percent of those over age 65 do (National Center for Health Statistics, 2019). Type 2 is partly related to genes, but not genes alone. Genome-wide association studies (called GWAS), which examine the entire genome, have found more than 100 genes that increase the risk of diabetes, each by a small amount (Visscher et al., 2017). Those genes appear in someone of any ethnicity, but some groups have more of particular ones, and ethnic differences in diabetes include the following. In China, Han people have higher rates of diabetes than other Chinese people (Hsu et al., 2015; L. Wang et al., 2017). In the United States, African Americans are particularly likely to develop diabetes (Layton et al., 2018). Among White residents of the United States, Hispanic people have higher rates than non-Hispanic people, with variations depending on national origin (Baquero & Parra-Medina, 2020). But these ethnic generalities fall short of understanding the genetics of diabetes. No doubt genetic variants and alleles affect the risk, but ethnicity does not reveal a person’s genes. Especially in people whose ancestors lived in Africa, genetic diversity is vast among people who, superficially, seem to be similar (Pennisi, 2021). To best predict and treat diabetes, genetic variants and combinations, as well as diet and microbiome, need to be considered. This is true for every condition: Precise prescriptions for disease, health, and senescence must be tailored for each individual (Bumpus, 2021). As a theory of aging, looking at genes makes sense. But research on the genes of diabetes reveals the problems with genetic theories of aging, especially when age is a factor. Focusing on genes may distract us from considering other causes of senescence, disease, and death. Diabetes is strongly influenced by nongenetic factors. African Americans who live in areas with high residential segregation are more likely to develop diabetes — and the reasons are not genetic (Bancks et al., 2017). Similarly, the rate for people in the lowest quintile of income is almost double the rate in the highest quintile (19 and 11 percent), a particularly troubling statistic since far more children than older adults live in poverty, so that should skew the statistic in the opposite way. Economic policies and practices, which affect diet and exercise, affect both incidence and treatment of diabetes more than genes. Genes alone rarely cause the diseases and disabilities of old age until age 90 or so. A few dominant genes make some serious problems almost inevitable (as for progeria and early-onset Alzheimer’s), but for most of us, the pace of senescence depends much more on how and where we live our lives than on our genes. AGING CELLS The third cluster of theories examines cellular aging, focusing on molecules and cells (Khosla et al., 2020; Rattan & Hayflick, 2016). Remember, cells duplicate many times over the life span. Minor errors — repetitions and deletions of triplets — in copying accumulate. Early in life, the immune system repairs such errors, but eventually the immune system itself becomes less adept. In general, when the organism can no longer repair cellular errors, senescence occurs. This process is first apparent in the skin, an organ that replaces itself often, particularly if damage occurs (such as peeling skin with sunburn). With senescence, scrapes take a little longer to heal, scarring becomes more obvious. Cellular aging also occurs inside the body; the aging immune system is increasingly unable to control abnormal cells. Cellular aging, with some cells out of control, is a major cause of all forms of cancer (Beck et al., 2020). Before age 40, biological mechanisms keep cancer cells from reproducing and metastasizing. However, once childbearing years are over, cancer cells duplicate unchecked. The results are apparent from many statistics. For instance, in the United States in 2017, only 2 percent of those aged 25 to 44 had ever had cancer. Then rates began to increase. By age 74 and older, rates were 23 percent (National Center for Health Statistics, 2019). Old Caterpillars? No, these are young chromosomes, stained to show the glowing white telomeres at the ends. There are dozens of cellular changes over time, from the mitochondria to the stem cells (Sameri et al., 2020; Wan & Finkel, 2020). One particular aspect of cell aging focuses on telomeres, the material at the end of each chromosome that becomes shorter over time. Telomeres are longer in children (except those with progeria) and shorter in old adults. Eventually, after many cell divisions over a life span, the telomere is too short, and duplication is impossible. Aging is evident, and, when many cells can no longer replicate, the maximum life span of that person (or mouse, or any other mammal) has been reached and death occurs. The more stress a person experiences, from childhood on, the shorter their telomeres become. In late adulthood, telomere length predicts death (Yegorov et al., 2020). Not surprising, then, telomere length is about the same in newborns of all genders and ethnic groups, but by late adulthood telomeres are typically longer in women than in men and longer in White people than in Black people. Cellular-aging theorists believe that weathering chips away at telomeres, and that this is one reason for variations in longevity. Women outlive men, and European Americans outlive African Americans, at least until age 80. Those who live to age 100 or more tend, by temperament, to be less troubled by stress, and that protects their cells. Systems of Aging As you have doubtless noticed, these three clusters of theories overlap. Weathering and genes affect cells, and vice versa. However, they share one limitation: All three emphasize details of the biology of aging. We need to look beyond that to consider the systems that sustain human development. Selective optimization with compensation (explained in Chapter 12) involves social contexts and human decisions, which becomes increasingly important on many levels — the biosystem, microsystem, macrosystem, and exosystem. To illustrate, we now explain the senses, sexual intercourse, driving, and technology, noting how they are part of systems. BIOSYSTEM COMPENSATION: THE SENSES As already explained in Chapter 12, every sense becomes slower and less sharp with each passing decade. That continues in late adulthood. For instance, only 10 percent of people of over age 65 see well without glasses, and everyone loses some hearing, especially men. Indeed, 16 percent of U.S. men over age 75 are virtually deaf (National Center for Health Statistics, 2017). Beyond that, here we emphasize that all the senses are interconnected with each person’s body and brain, because each person is a biosystem. Each sense affects all the others, with sensory losses increasing depression and cognitive loss (Hajek & König, 2020). IT’S ALL GENETIC A second cluster of theories focuses on genes, both genes of the entire species and genes that vary from one person to another. You already read about the average life span. In addition, every species has a maximum life span, the oldest age that members of that species can attain. The maximum life span set by genes: rats, 4 years; rabbits, 13; tigers, 26; house cats, 30; brown bats, 34; brown bears, 37; chimpanzees, 55; Indian elephants, 70; finback whales, 80; humans, 122; lake sturgeon, 150; giant tortoises, 180. Genes affect the entire aging process for every creature, from how long the fetus stays in the womb to when, where, and whether hair on the head grows, greys or disappears. Because of the genes of the human species, few people live to 100 and no one has proven to live longer than a French woman named Jeanne Calment, who died in 1997 at the age of 122. Some contend that she was only about 100, because the daughter of the real Jeanne Calment took her identity in middle age to avoid paying some taxes. Most gerontologists accept her claim to 122. Other people have lived to 121, so 122 seems possible (Robine et al., 2019). Touch Your Toes? This woman could even put both feet behind her neck. Although everyone loses some flexibility with age, daily practice is crucial. Tao Porchon-Lynch taught yoga for a half-century. At age 99, shown here, she could balance on one leg in tree pose, stretch her hamstrings in downward dog, and then relieve any remaining stress in cobra pose. She died at age 101 in February 2020, peacefully and without pain. Certainly, Calment lived far longer than most. Her genes included some that are uncommon in the general population but common in centenarians. There are a dozen or more longevity genes, some rare and some more common. If a person happens to inherit many of them, and to have a healthy life, they might live past 100 (Nygaard et al., 2019). Like wear and tear, this theory explains some aspects of aging, but not all. Children born with the genetic disease called Hutchinson-Gilford syndrome (also called progeria) stop growing at about age 5 and begin to look old, with wrinkled skin and balding heads. They die in their teens of genetic conditions more common in people five times their age. Other genes program a long and healthy life. People who reach age 100 usually have alleles that other people do not (Govindaraju et al., 2015; Nygaard et al., 2019). THINK CRITICALLY: For the benefit of the species as a whole, why would genes promote aging? Alleles of the ApoE gene prove the importance of genetic variations (Y-W. Huang et al., 2017). Most people have the third allele (ApoE3), which does not seem to affect health. However, about 20 percent of the population have the second allele (ApoE2). In one study, ApoE2 was found in 15 percent of men in their 70s and 29 percent of men from the same population in their 90s. Obviously, Apoe2 is protective (Le Couteur et al., 2020). Another allele of the same gene, ApoE4, increases the risk of Alzheimer’s, especially if a person inherits that gene from both parents. ApoE4 also correlates with heart disease, stroke, and — if a person is HIV-positive — AIDS. Many other genes (ABCA7, Cr1m, SORL1, TREM2) increase the risk of Alzheimer’s. However, no single gene or combination of genes and alleles necessarily results in late onset Alzheimer’s. Thus, connecting variations in human senescence directly to one or more genes seems impossible. As you remember, humans have thousands of genes, often with many alleles, and always interacting in hundreds of ways. A View From Science Diabetes and Aging One type of diabetes is called childhood-onset, or type 1, because it begins early in life. That type is heavily influenced by genes, although environmental factors are relevant as well (Redondo & Concannon, 2020). But most diabetes is adult-onset, type 2. The rate increases with age, such that only 5 percent of U.S. adults aged 20–44 has it, but 29 percent of those over age 65 do (National Center for Health Statistics, 2019). Type 2 is partly related to genes, but not genes alone. Genome-wide association studies (called GWAS), which examine the entire genome, have found more than 100 genes that increase the risk of diabetes, each by a small amount (Visscher et al., 2017). Those genes appear in someone of any ethnicity, but some groups have more of particular ones, and ethnic differences in diabetes include the following. In China, Han people have higher rates of diabetes than other Chinese people (Hsu et al., 2015; L. Wang et al., 2017). In the United States, African Americans are particularly likely to develop diabetes (Layton et al., 2018). Among White residents of the United States, Hispanic people have higher rates than non-Hispanic people, with variations depending on national origin (Baquero & Parra-Medina, 2020). But these ethnic generalities fall short of understanding the genetics of diabetes. No doubt genetic variants and alleles affect the risk, but ethnicity does not reveal a person’s genes. Especially in people whose ancestors lived in Africa, genetic diversity is vast among people who, superficially, seem to be similar (Pennisi, 2021). To best predict and treat diabetes, genetic variants and combinations, as well as diet and microbiome, need to be considered. This is true for every condition: Precise prescriptions for disease, health, and senescence must be tailored for each individual (Bumpus, 2021). As a theory of aging, looking at genes makes sense. But research on the genes of diabetes reveals the problems with genetic theories of aging, especially when age is a factor. Focusing on genes may distract us from considering other causes of senescence, disease, and death. Diabetes is strongly influenced by nongenetic factors. African Americans who live in areas with high residential segregation are more likely to develop diabetes — and the reasons are not genetic (Bancks et al., 2017). Similarly, the rate for people in the lowest quintile of income is almost double the rate in the highest quintile (19 and 11 percent), a particularly troubling statistic since far more children than older adults live in poverty, so that should skew the statistic in the opposite way. Economic policies and practices, which affect diet and exercise, affect both incidence and treatment of diabetes more than genes. Genes alone rarely cause the diseases and disabilities of old age until age 90 or so. A few dominant genes make some serious problems almost inevitable (as for progeria and early-onset Alzheimer’s), but for most of us, the pace of senescence depends much more on how and where we live our lives than on our genes. AGING CELLS The third cluster of theories examines cellular aging, focusing on molecules and cells (Khosla et al., 2020; Rattan & Hayflick, 2016). Remember, cells duplicate many times over the life span. Minor errors — repetitions and deletions of triplets — in copying accumulate. Early in life, the immune system repairs such errors, but eventually the immune system itself becomes less adept. In general, when the organism can no longer repair cellular errors, senescence occurs. This process is first apparent in the skin, an organ that replaces itself often, particularly if damage occurs (such as peeling skin with sunburn). With senescence, scrapes take a little longer to heal, scarring becomes more obvious. Cellular aging also occurs inside the body; the aging immune system is increasingly unable to control abnormal cells. Cellular aging, with some cells out of control, is a major cause of all forms of cancer (Beck et al., 2020). Before age 40, biological mechanisms keep cancer cells from reproducing and metastasizing. However, once childbearing years are over, cancer cells duplicate unchecked. The results are apparent from many statistics. For instance, in the United States in 2017, only 2 percent of those aged 25 to 44 had ever had cancer. Then rates began to increase. By age 74 and older, rates were 23 percent (National Center for Health Statistics, 2019). Old Caterpillars? No, these are young chromosomes, stained to show the glowing white telomeres at the ends. There are dozens of cellular changes over time, from the mitochondria to the stem cells (Sameri et al., 2020; Wan & Finkel, 2020). One particular aspect of cell aging focuses on telomeres, the material at the end of each chromosome that becomes shorter over time. Telomeres are longer in children (except those with progeria) and shorter in old adults. Eventually, after many cell divisions over a life span, the telomere is too short, and duplication is impossible. Aging is evident, and, when many cells can no longer replicate, the maximum life span of that person (or mouse, or any other mammal) has been reached and death occurs. The more stress a person experiences, from childhood on, the shorter their telomeres become. In late adulthood, telomere length predicts death (Yegorov et al., 2020). Not surprising, then, telomere length is about the same in newborns of all genders and ethnic groups, but by late adulthood telomeres are typically longer in women than in men and longer in White people than in Black people. In that study, the researchers expected cultural differences between adults in nations with different cultural norms about sex (Norway, Denmark, Belgium, and Portugal). Instead they found similar rates in the various nations but differences from one couple to another. Health concerns were relevant in every nation, but attitude was even more important. If a person thought sex was important for overall well-being, usually they were sexually active, no matter what their nationality or age (N. Fischer et al., 2018). Most older people reject the idea that sex means intercourse and orgasm, in part because that indicates individual pleasure, not the microsystem. Relationships are crucial. This was one conclusion from a study of more than 7,000 older adults in England (Tetley et al., 2018). A man in his 80s, when asked about intercourse, replied: Now too old but my wife and I sleep in the same bed, and kiss and cuddle each other before settling down to sleep. We enjoy each other’s company. And a woman said: The act of sex does not make you “happy” but having a loving partner does. This explains how older people adapt, sexually, to divorce or widowhood. Since the sex drive varies from person to person, some elders prefer to stay single and alone, some no longer seek intercourse, some cohabit, some begin LAT (living apart together) with a new partner, and some remarry. Each older person selects whether and how to be sexual, by finding the microsystem that works for them. This was evident in a detailed study of several couples in the United States (see A Case to Study). A Case To Study Should Older Couples Have More Sex? Sexual needs and interactions vary extremely from one person to another, so no single case illustrates general trends. Further, questionnaires and physiological measures designed for young bodies may be inappropriate for the aged. Accordingly, two researchers studied elders’ sexuality using a method called grounded theory. They found 34 people (17 couples, aged 50 to 86, married an average of 34 years), interviewing each privately and extensively. They read and reread all of the transcripts, tallying responses and topics by age and gender (that was the grounded part). Then they analyzed common topics, interpreting trends (that was theory). They concluded that sexual activity is more a social construction than a biological event (Lodge & Umberson, 2012). All of their cases said that intercourse was less frequent with age, including four couples for whom intercourse stopped completely because of the husband’s health. Nonetheless, more respondents said that their sex life had improved than said it deteriorated (44 percent compared to 30 percent). Surprisingly, those 30 percent were more likely to be middle-aged than older. Some midlife men were troubled by difficulty maintaining an erection, and many women worried that they were not sexy. One woman said: All of a sudden, we didn’t have sex after I got skinny. And I couldn’t figure that out. I look really good now and we’re not having sex. It turns out that he was going through a major physical thing at that point and just had lost his sex drive.… I went through years thinking it was my fault. [Irene, quoted in Lodge & Umberson, 2012, p. 435] The authors theorize that “images of masculine sexuality are premised on high, almost uncontrollable levels of penis-driven sexual desire” (Lodge & Umberson, 2012, p. 430), while the cultural ideals of feminine sexuality emphasize women’s passivity and yet “implore women to be both desirable and receptive to men’s sexual desires and impulses,” deeming “older women and their bodies unattractive” (Lodge & Umberson, 2012, p. 430). Thus, when middle-aged adults first realize that aging has changed them, they are distressed. By late adulthood they realize that the young idea of good sex (frequent intercourse) is irrelevant. Instead, they compensate for physical changes by optimizing their relationship in other ways. As one man over age 70 said: I think the intimacy is a lot stronger.… more often now we do things like holding hands and wanting to be close to each other or touch each other. It’s probably more important now than sex is. [Jim, quoted in Lodge & Umberson, 2012, p. 438] An older woman said her marriage improved because: We have more opportunities and more motivation. [Sex] was wonderful. It got thwarted, with … the medication he is on. And he hasn’t been functional since. The doctors just said that it is going to be this way, so we have learned to accept that. But we have also learned long before that there are more ways than one to share your love. [Helen, quoted in Lodge & Umberson, 2012, p. 437] The next cohort of older adults may have other attitudes; the male/female and midlife/older differences evident with these 17 couples may not apply. These cases do suggest, however, that selective optimization with compensation is possible. That makes many older drivers ignore their own losses. Per mile driven, compared to younger drivers, those over age 80 have more accidents, hit more pedestrians (whom they did not see), and are more likely to be fatally injured themselves in motor vehicle crashes. The macrosystem needs to set standards, although often it does not. This was evident in 2019 in England, as reported by one physician: On 17 January the Duke of Edinburgh was driving his Land Rover when it was in a collision with another car. One of three passengers in the other car was injured, and the duke’s car flipped over. The duke, 97, was reportedly left bruised and bewildered. Two days later he was seen driving another Land Rover with no seatbelt and was spoken to by police. [Oliver, 2019] But the United States has the same problem: deference for older drivers. Many jurisdictions renew licenses by mail, even for 80-year-old drivers. Because news accounts rarely emphasize the systems that cause a problem, if an older driver crashes, that person is blamed, not the Department of Motor Vehicles. Instead, the macrosystem could require retesting, via simulation with a computer and video screen. That would allow some older drivers to renew their licenses and some not, with many realizing that they are less capable than they thought. Moreover, older drivers could be required to attend a driver’s education class, as is done for new drivers. For example, they need to learn how to use GPS devices, not rely on memory or paper instructions, which makes accidents more likely (Thomas et al., 2018). The macrosystem could provide other ways to reduce accidents. Free and efficient public transportation, well-maintained sidewalks, and large print signs would save lives. Ironically, the pedestrians most likely to be killed are under age 10 or over age 70, yet communities rarely design cars, streets, or highways with their safety in mind. Visualizing Development ELDERS BEHIND THE WHEEL Older people often reduce or change their driving habits in order to compensate for their slowing reaction time, avoiding nighttime, bad weather, and long distances. Many states have initiated restrictions, including requiring older drivers to renew their licenses in person, to make sure they stay safe. Consequently, their crash rate is low overall, but not when measured by the rate per miles driven. EXOSYSTEM: TECHNOLOGY AND NATIONAL POLICY Every one of the three examples just cited relates to the exosystem in addition to the systems noted for each one. National and cultural norms affect whether old individuals thrive or not. In sexuality, for instance, many hospitals and nursing homes separate men and women, even if the two are married to each other. On driving, variations in laws and licensing vary markedly state by state, with some considering the needs of older people and some not. Disability advocates want the exosystem to incorporate universal design. The idea is that environments and equipment should be designed to be used by everyone, old or young, able-bodied and sensory-acute or not. Looped In? This sign indicates that a hearing loop is installed in this New York City subway booth, enabling most people with hearing aids and cochlear implants to receive important messages and to communicate with transit personnel. Frequent riders of public transit, however, complain that the public address system malfunctions, the elevators are often broken, and the signs do not always reflect reality. Here we use the example of universal design to accommodate sensory loss, in part because impaired vision, audition, and so on are too easily considered personal problems, not exosystem ones. Since 1980, many aspects of the exosystem have helped people with sensory limitations. Forty years ago there were no inexpensive eyeglasses at drugstores, no smoke alarms in homes, no volume controls and headphones, no halogen streetlights. All these are now accepted within the culture, making it easier for people to function well despite sensory loss. However, much more could be done. Quality dental and medical care, canes and service dogs, large-screen computers and much more are free in some nations, but available only to the very rich in others. Several eye diseases (cataracts, glaucoma, and macular degeneration — see Table 14.2) increase with age. If discovered early, blindness can be prevented, yet prevention is not a priority of the U.S. health exosystem. Hearing aids, with the expertise required for individual adjustment, cost thousands of dollars. TABLE 14.2 Common Vision Impairments Among Older Adults Cataracts. As early as age 50, about 10 percent of adults have cataracts, a thickening of the lens, causing vision to become cloudy, opaque, and distorted. By age 70, 30 percent do. Cataracts can be removed in outpatient surgery and replaced with an artificial lens. Glaucoma. About 1 percent of those in their 70s and 10 percent in their 90s have glaucoma, a buildup of fluid within the eye that damages the optic nerve. The early stages have no symptoms, but the later stages cause blindness, which can be prevented if an ophthalmologist or optometrist treats glaucoma before it becomes serious. African Americans and people with diabetes may develop glaucoma as early as age 40. Macular degeneration. About 4 percent of those in their 60s and about 12 percent over age 80 have a deterioration of the retina, called macular degeneration. An early warning occurs when vision is spotty (e.g., some letters missing when reading). Again, early treatment — in this case, medication — can restore some vision, but without treatment, macular degeneration is progressive, causing blindness about five years after it starts. Many disabilities would disappear with universal design. Instead, just about everything, from houses to shoes, is fashioned for young adults with no impairments.