Physical and Cognitive Development in Middle Adulthood

By Santrock, J.W.

Edited by Paul Ducham


Many of today’s 50-year-olds are in better shape, more alert, and more productive than their 40-year-old counterparts from a generation or two earlier. As more people lead healthier lifestyles and medical discoveries help to stave off the aging process, the boundaries of middle age are being pushed upward. It looks like middle age is starting later and lasting longer for increasing numbers of active, healthy, and productive people. A current saying is “60 is the new 40,” implying that many 60-year-olds today are living a life that is as active, productive, and healthy as earlier generations did in their forties.
Questions such as, “To which age group do you belong?” and “How old do you feel?” reflect the concept of age identity. A consistent finding is that as adults become older their age identity is younger than their chronological age (Setterson & Trauten, 2009; Westerhof, 2009). One study found that almost half of the individuals 65 to 69 years of age considered themselves middle-aged (National Council on Aging, 2000), and another study found a similar pattern: Half of the 60- to 75-year-olds viewed themselves as being middle-aged (Lachman, Maier, & Budner, 2000). Also, some individuals consider the upper boundary of midlife as the age at which they make the transition from work to retirement.
When Carl Jung studied midlife transitions early in the twentieth century, he referred to midlife as the aft ernoon of life (Jung, 1933). Midlife serves as an important preparation for late adulthood, “the evening of life” (Lachman, 2004, p. 306). But “midlife” came much earlier in Jung’s time. In 1900 the average life expectancy was only 47 years of age; only 3 percent of the population lived past 65. Today, the average life expectancy is 78, and 12 percent of the U.S. population is older than 65. As a much greater percentage of the population lives to an older age, the midpoint of life and what constitutes middle age or middle adulthood are getting harder to pin down (Cohen, 2012).
In a recent book, In Our Prime: The Invention of Middle Age, Patricia Cohen (2012) describes how middle age wasn’t thought of as a separate developmental period until the mid-1800s and the term midlife wasn’t in a dictionary until 1895. In Cohen’s analysis, advances in health and more people living to older ages especially fueled the emergence of thinking about middle age. People today take longer to grow up and longer to die than in past centuries.
Compared with previous decades and centuries, an increasing percentage of the population is made up of middle-aged and older adults. In the past, the age structure of the population could be represented by a pyramid, with the largest percentage of the population in the childhood years. Today, the percentages of people at different ages in the life span are more similar, creating what is called the “rectangularization” of the age distribution (a vertical rectangle) (Himes, 2009). The rectangularization has been created by health advances that promote longevity, low fertility rates, and the aging of the baby-boom cohort (Moen, 2007).
The portrait of midlife described so far here suggests that for too long the negative aspects of this developmental period have been overdrawn. However, it is important not to go too far in describing midlife positively. Many physical aspects decline in middle adulthood, and increased rates of health problems such as obesity need to be considered in taking a balanced approach to this age period.


Although the age boundaries are not set in stone, we will consider middle adulthood to be the developmental period that begins at approximately 40 to 45 years of age and extends to about 60 to 65 years of age. For many people, middle adulthood is a time of declining physical skills and expanding responsibility; a period in which people become more conscious of the young-old polarity and the shrinking amount of time left in life; a point when individuals seek to transmit something meaningful to the next generation; and a time when people reach and maintain satisfaction in their careers. In sum, middle adulthood involves “balancing work and relationship responsibilities in the midst of the physical and psychological changes associated with aging” (Lachman, 2004, p. 305).
In midlife, as in other age periods, individuals make choices—selecting what to do, deciding how to invest time and resources, and evaluating what aspects of their lives they need to change. In midlife, “a serious accident, loss, or illness” may be a “wake-up call” and produce “a major restructuring of time and a reassessment” of life’s priorities (Lachman, 2004, p. 310). And with an absence of seniority protections, many middle-aged adults experience unexpected job loss and/or are strongly encouraged to take early retirement packages (Sweet, Moen, & Meiksins, 2007).
The concept of gains (growth) and losses (decline) is an important one in life-span development. Middle adulthood is the age period in which gains and losses as well as biological and sociocultural factors balance each other (Baltes, Lindenberger, & Staudinger, 2006). Although biological functioning declines in middle adulthood, sociocultural supports such as education, career, and relationships may peak in middle adulthood (Willis & Schaie, 2005). Thus, middle adulthood may be a unique developmental period in which growth and loss balance each other for many individuals.
Individuals have not only a chronological age but also biological, psychological, and social ages. Some experts conclude that compared with earlier and later periods, middle age is influenced more heavily by sociocultural factors (Willis & Martin, 2005).
For many healthy adults, middle age is lasting longer than it did in the past. Indeed, an increasing number of experts on middle adulthood describe the age period of 55 to 65 as late midlife (Deeg, 2005). Compared with earlier midlife, late midlife is more likely to be characterized by “the death of a parent, the last child leaving the parental home, becoming a grandparent, the preparation for retirement, and in most cases actual retirement. Many people in this age range experience their first confrontation with health problems” (Deeg, 2005, p. 211). Overall, then, although gains and losses may balance each other in early midlife, losses may begin to outnumber gains for many individuals in late midlife (Baltes, Lindenberger, & Staudinger, 2006).
Keep in mind, though, that midlife is characterized by individual variations (Ailshire & Burgard, 2012; Wallin & others, 2012). As life-span expert Gilbert Brim (1992) commented, middle adulthood is full of changes, twists, and turns; the path is not fixed. People move in and out of states of success and failure.


The most visible signs of physical changes in middle adulthood involve physical appearance. The first outwardly noticeable signs of aging usually are apparent by the forties or fifties. The skin begins to wrinkle and sag because of a loss of fat and collagen in underlying tissues (Stone & others, 2011). Small, localized areas of pigmentation in the skin produce age spots, especially in areas that are exposed to sunlight, such as the hands and face. Hair becomes thinner and grayer due to a lower replacement rate and a decline in melanin production. Fingernails and toenails develop ridges and become thicker and more brittle.
Since a youthful appearance is stressed in many cultures, individuals whose hair is graying, whose skin is wrinkling, whose body is sagging, and whose teeth are yellowing strive to make themselves look younger. Undergoing cosmetic surgery, dyeing hair, purchasing wigs, enrolling in weight reduction programs, participating in exercise regimens, and taking heavy doses of vitamins are common in middle age. Baby boomers have shown a strong interest in plastic surgery and Botox, which may reflect their desire to slow down the aging process (Brun & Brock-Utne, 2012).


Individuals lose height in middle age, and many gain weight (Onwudiwe & others, 2011). On average, from 30 to 50 years of age, men lose about one inch in height, then may lose another inch from 50 to 70 years of age (Hoyer & Roodin, 2009). The height loss for women can be as much as 2 inches from 25 to 75 years of age. Note that there are large variations in the extent to which individuals become shorter with aging. The decrease in height is due to bone loss in the vertebrae. On average, body fat accounts for about 10 percent of body weight in adolescence; it makes up 20 percent or more in middle age.
Obesity increases from early to middle adulthood. In a national survey, 38 percent of U.S. adults 40 to 59 years of age were classified as obese (National Center for Health Statistics, 2011). Nearly, 27 percent of U.S. adults age 20 to 39 were classified as obese. Being overweight is a critical health problem in middle adulthood (Simon & others, 2011). For example, obesity increases the probability that an individual will suffer a number of other ailments, among them hypertension (abnormally high blood pressure), diabetes, and digestive disorders (Cheong & others, 2012; Dorresteijn, Visseren, & Spiering, 2012; Nezu & others, 2013). A large-scale study found that being overweight or obese in middle age increases an individual’s risk of dying earlier (Adams & others, 2006). More than 500,000 50- to 71-year-olds completed surveys about their height and weight, and the researchers examined the participants’ death records across a 10-year period. Those who were overweight (defined as a body mass index, which takes into account height and weight, of 25 or more) at 50 had a 20 to 40 percent higher risk of earlier death, whereas those who were obese (a body mass index of 30 or more) had a 100 to 200 percent higher risk of premature death.


Maximum physical strength often is attained in the twenties. The term sarcopenia is given to age-related loss of muscle mass and strength (Doria & others, 2012; Drey & others, 2012). Muscle loss with age occurs at a rate of approximately 1 to 2 percent per year after age 50 (Marcell, 2003). A loss of strength especially occurs in the back and legs. Researchers are seeking to identify genes that are linked to the development of sarcopenia (Tan & others, 2012). Obesity is a risk factor for sarcopenia (Li & Heber, 2012). A recent research review concluded that management of weight loss and resistance training were the best strategies to slow down the decline of muscle mass and muscle strength (Rolland & others, 2011).
Peak functioning of the body’s joints also usually occurs in the twenties. The cushions for the movement of bones (such as tendons and ligaments) become less efficient in the middle-adult years, a time when many individuals experience joint stiffness and more difficulty in movement.
Maximum bone density occurs by the mid- to late thirties, after which there is a progressive loss of bone. The rate of this bone loss begins slowly but accelerates with further aging (Baron, 2012). Women lose bone mass twice as fast as men do. By the end of midlife, bones break more easily and heal more slowly (Rachner, Khosia, & Hofb auer, 2011).


Accommodation of the eye—the ability to focus and maintain an image on the retina—experiences its sharpest decline between 40 and 59 years of age. In particular, middle-aged individuals begin to have difficulty viewing close objects.
The eye’s blood supply also diminishes, although usually not until the fifties or sixties. The reduced blood supply may decrease the visual field’s size and account for an increase in the eye’s blind spot. At 60 years of age, the retina receives only one-third as much light as it did at 20 years of age, much of which is due to a decrease in the size of the pupil (Scialfa & Kline, 2007).
Hearing also can start to decline by age 40. Auditory assessments indicate that hearing loss occurs in up to 50 percent of individuals 50 years and older (Fowler & Leigh-Paffenroth, 2007). Sensitivity to high pitches usually declines first. The ability to hear low-pitched sounds does not seem to decline much in middle adulthood, though. Men usually lose their sensitivity to highpitched sounds sooner than women do. However, this gender difference might be due to men’s greater exposure to noise in occupations such as mining, automobile work, and so on.
Researchers are identifying new possibilities for improving the vision and hearing of people as they age. One way this is being carried out is through better control of glare or background noise (Natalizia & others, 2010). Laser surgery and implantation of intraocular lenses have become routine procedures for correcting vision in middle-aged adults (Ang, Evans, & Mehta, 2012; Pasquali & Krueger, 2012). In addition, recent advances in hearing aids have dramatically improved hearing for many individuals (Banerjee, 2011).


Midlife is the time when high blood pressure and high cholesterol often take adults by surprise (Lachman, 2004). Cardiovascular disease increases considerably in middle age (Chantler & Lakatta, 2012; Emery, Anderson, & Goodwin, 2013).
The level of cholesterol in the blood increases through the adult years and in midlife begins to accumulate on the artery walls, increasing the risk of cardiovascular disease (Emery & others, 2013). The type of cholesterol in the blood, however, influences its effect (Gadi, Amanullah, & Figueredo, 2012). Cholesterol comes in two forms: LDL (low-density lipoprotein) and HDL (high-density lipoprotein). LDL is often referred to as “bad” cholesterol because when the level of LDL is too high, it sticks to the lining of blood vessels, which can lead to atherosclerosis (hardening of the arteries). HDL is often referred to as “good” cholesterol because when it is high and LDL is low, the risk of cardiovascular disease is lessened (Sakuma, 2012).
High blood pressure (hypertension), too, often begins to appear for many individuals in their forties and fifties (Roberie & Elliott, 2012). At menopause, a woman’s blood pressure rises sharply and usually remains above that of a man through life’s later years (Taler, 2009). The health benefits of cholesterol-lowering and hypertension-lowering drugs are a major factor in improving the health of many middle-aged adults and increasing their life expectancy (de la Sierra & Barrios, 2012; Gadi & others, 2012). An increasing problem in middle and late adulthood is metabolic syndrome, a condition characterized by hypertension, obesity, and insulin resistance. A recent research review concluded that chronic stress exposure is linked to metabolic syndrome (Tamashiro, 2011). Metabolic syndrome often leads to the development of diabetes and cardiovascular disease (Friese & others, 2012). Several recent studies have provided information about risk factors for metabolic syndrome:
• A meta-analysis revealed that metabolic syndrome was an important risk factor for any cause of death (Wu, Liu, & Ho, 2010).
• Individuals with metabolic syndrome who were physically active reduced their risk of developing cardiovascular disease (Broekhuizen & others, 2011).
• In one life course pathway, a high level of BMI in adolescence was related to metabolic syndrome in middle-aged men and women; in a second pathway, socioeconomic disadvantage in adolescence was linked to metabolic syndrome in middle-aged women (Gustafsson, Persson, & Hammarstrom, 2011).
Exercise, weight control, and a diet rich in fruits, vegetables, and whole grains can often help to stave off many cardiovascular problems in middle age (Currie, McKelvie, & MacDonald, 2012). For example, although cholesterol levels are influenced by heredity, LDL can be reduced and HDL increased by eating food that is low in saturated fat and cholesterol and by exercising regularly (Logan, 2011). One study of postmenopausal women revealed that 12 weeks of aerobic exercise training improved their cardiovascular functioning (O’Donnell, Kirwan, & Goodman, 2009). The good news is that deaths due to cardiovascular disease have been decreasing in the United States since the 1970s. Why the decrease? Advances in drug medication to lower blood pressure and cholesterol, diet, and exercise in high-risk individuals have led to the reduction in deaths due to cardiovascular disease (Emery & others, 2013).
Does your fitness level in your young adult years have much impact on your risk of cardiovascular disease in middle age? To find out, see Connecting Through Research.


There is little change in lung capacity through most of middle adulthood for many individuals. However, at about age 55, the proteins in lung tissue become less elastic. This change, combined with a gradual stiffening of the chest wall, decreases the lungs’ capacity to shuttle oxygen from the air people breathe to the blood in their veins. The lung capacity of individuals who are smokers drops precipitously in middle age, but if the individuals quit smoking, their lung capacity improves, although not to the level of individuals who have never smoked. Recent research also has found that low cognitive ability in early adulthood is linked to reduced lung functioning in middle age (Carroll & others, 2011). And reduced lung functioning is related to lower cognitive ability later in development (Shipley & others, 2007). Such links between reduced lung functioning and cognitive ability are likely related to the influence of pulmonary functioning on brain structure and function, which in turn affects cognition (MacDonald, DeCarlo, & Dixon, 2011).


Some aspects of sleep become more problematic in middle age (Green & others, 2012; Polo-Kantola, 2011). The total number of hours slept usually remains the same as in early adulthood, but beginning in the forties, wakeful periods are more frequent and there is less of the deepest type of sleep (stage 4). The amount of time spent lying awake in bed at night begins to increase in middle age, and this can produce a feeling of being less rested in the morning. Sleep-disordered breathing and restless legs syndrome become more prevalent in middle age (Polo-Kantola, 2011). A recent study also found that middle-aged adults who sleep less than six hours a night on average had an increased risk of developing stroke symptoms (Ruiter & others, 2012). And a recent study found that change in sleep duration across five years in middle age was linked to cognitive functioning (Ferrie & others, 2011). In this study, a decrease from 6, 7, or 8 hours of sleep and an increase from 7 or 8 hours were related to lower scores on most assessments of cognitive functioning. Also, sleep problems in midlife are more common among individuals who use a higher number of prescription and nonprescription drugs, are obese, have cardiovascular disease, or are depressed (Loponen & others, 2010).


Stress is increasingly identified as a factor in many diseases (Dougall & Baum, 2012; Schwarzer & Luszczynska, 2013). The cumulative effect of stress often takes a toll on the health of individuals by the time they reach middle age. David Almeida and his colleagues (2011) recently described how chronic stress or prolonged exposure to stressors can have damaging effects on physical functioning, including an unhealthy overproduction of corticosteroids such as cortisol. Chronic stress can interfere with immune functioning, and this stress is linked to disease not only through the immune system but also through cardiovascular factors (Emery & others, 2013; Stowell, Robles, & Kane, 2013).
The Immune System and Stress  The immune system keeps us healthy by recognizing foreign materials such as bacteria, viruses, and tumors and then destroying them (Jennings & Egizio, 2012; Stowell, Robles, & Kane, 2013). Immune system functioning decreases with normal aging (Cavanaugh, Weyland, & Goronzky, 2012; Dougall & others, 2013).
The immune system’s machinery consists of billions of white blood cells located in the circulatory system. The number of white blood cells and their effectiveness in killing foreign viruses or bacteria are related to stress levels. When a person is under stress, viruses and bacteria are more likely to multiply and cause disease. One study in young and middle-aged adults revealed that persistently unemployed individuals had lower natural killer (NK) cell levels than their previously unemployed counterparts who became reemployed (Cohen & others, 2007). NK cells are a type of white blood cell that is more likely to be present in lowstress circumstances (see Figure 15.1). Lower levels of NK cells in stressful situations indicate a weakened immune system. A recent study indicated aerobic fitness was related to the presence of a lower level of senescent T cells (prematurely aging cells that result from persistent immune activation) (Spielmann & others, 2011).
Stress and the Cardiovascular System  Stress and negative emotions can affect the development and course of cardiovascular disease by altering underlying physiological processes (Dougall & Baum, 2012). Sometimes, though, the link between stress and cardiovascular disease is indirect. For example, people who live in a chronically stressed condition, such as persistent poverty, are more likely to take up smoking, start overeating, and avoid exercising (Wilcox & others, 2011). All of these stress-related behaviors are linked with the development of cardiovascular disease (Dorresteijn, Visseren, & Spiering, 2011).
Culture and Health  Culture plays an important role in coronary disease. Cross-cultural psychologists maintain that studies of immigrants shed light on the role culture plays in health (Harris, 2012; Noymer & Lee, 2012). When people migrate to another culture, their health practices are likely to change while their genetic predispositions to certain disorders remain constant. There also are differences within ethnic groups as well as among them. The living conditions and lifestyles of individuals within an ethnic group are influenced by their socioeconomic status, immigrant status, social and language skills, occupational opportunities, and such social resources as the availability of meaningful support networks—all of which play a role in health (Whitfield, Thorpe, & Szanton, 2011).
Despite these variations within ethnic groups, it is useful to know about differences among ethnic groups (Cichy, Stawski, & Almeida, 2012). Aging African Americans, for example, have above-average rates of high blood pressure and stroke (Delgado & others, 2012). A recent study revealed that social support had a positive influence on reducing the link between cardiovascular disease and depression in aging African Americans (Heard & others, 2011). Diabetes occurs at an above-average rate among Latinos, and a recent analysis indicated that diabetes poses a greater mortality risk for Latinos than non-Latino Whites (Hunt & others, 2011).
Prejudice and racial segregation are the historical underpinnings for the chronic stress of discrimination and poverty that adversely affects the health of many African Americans and Latinos (Berensen & others, 2012; Bhutta & Reddy, 2012). Support systems, such as an extended family network, may be especially important resources to improve the health of ethnic minorities and help them cope with stress.



Although many diseases increase in middle age, having a sense of control is linked to many aspects of health and well-being (Scheier, Carver, & Armstrong, 2012; Lachman, Neuport, & Agrigoraei, 2011). Researchers have found that having a sense of control peaks in midlife then declines in late adulthood (Lachman, 2006; Lachman, Rosnick, & Rocke, 2009). However, in any adult age period, there is a wide range of individual differences in beliefs about control. Margie Lachman and her colleagues (2011) argue that having a sense of control in middle age is one of the most important modifiable factors in delaying the onset of diseases in middle adulthood and reducing the frequency of diseases in late adulthood.


Infectious disease was the main cause of death until the middle of the twentieth century. As infectious disease rates declined and more individuals lived through middle age, rates of chronic disorders increased (Keiley-Moore, 2009). Chronic diseases are now the main causes of death for individuals in middle adulthood.
In middle age, many deaths are caused by a single, readily identifiable condition, whereas in old age, death is more likely to result from the combined effects of several chronic conditions (Pizza & others, 2011). For many years heart disease was the leading cause of death in middle adulthood, followed by cancer; however, since 2005 more individuals 45 to 64 years of age in the United States died of cancer, followed by cardiovascular disease (Kochanek & others, 2011). The gap between cancer and the second leading cause of death widens as individuals age from 45 to 54 and 55 to 64 years of age (National Center for Health Statistics, 2008). Men have higher mortality rates than women for all of the leading causes of death (Kochanek & others, 2011).


Menopause is the time in middle age, usually during the late forties or early fifties, when a woman’s menstrual periods cease. The average age at which U.S. women have their last period is 51 (Wise, 2006). However, there is a large variation in the age at which menopause occurs—from 39 to 59 years of age. Later menopause is linked with increased risk of breast cancer (Mishra & others, 2009).
The timing of menarche, a girl’s first menstruation, has significantly decreased since the midnineteenth century, occurring as much as four years earlier in some countries (Susman & Dorn, 2013). Has there been a similar earlier onset in the occurrence of menopause? No, there hasn’t been a similar earlier corresponding change in menopause, and there is little or no correlation between ages at menarche and the onset of menopause (Gosden, 2007).
Perimenopause is the transitional period from normal menstrual periods to no menstrual periods at all, which often takes up to 10 years. Perimenopause usually occurs during the forties but can occur in the thirties (Derry & Derry, 2012; Prior & Hitchcock, 2011). One study of 30- to 50-year-old women found that depressed feelings, headaches, moodiness, and palpitations were the perimenopausal symptoms that these women most frequently discussed with health-care providers (Lyndaker & Hulton, 2004). Lifestyle factors such as whether women are overweight, smoke, drink heavily, or exercise regularly during perimenopause influence aspects of their future health such as whether they develop cardiovascular disease or chronic illnesses (ESHRE Capri Workshop Group, 2011).
In menopause, production of estrogen by the ovaries declines dramatically, and this decline produces uncomfortable symptoms in some women—“hot flashes,” nausea, fatigue, and rapid heartbeat, for example. A recent study revealed that increased estradiol and improved sleep, but not hot flashes, predicted enhanced mood in women during their menopausal transition (Joffe & others, 2011).
Cross-cultural studies also reveal variations in the menopause experience (Lerner-Geva & others, 2010; Sievert & Obermeyer, 2012). For example, hot flashes are uncommon in Mayan women (Beyene, 1986). Asian women report fewer hot flashes than women in Western societies (Payer, 1991). It is difficult to determine the extent to which these cross-cultural variations are due to genetic, dietary, reproductive, or cultural factors.
Menopause overall is not the negative experience for most women that it was once thought to be (Henderson, 2011). Most women do not have severe physical or psychological problems related to menopause. For example, a recent research review concluded that there is no clear evidence that depressive disorders occur more often during menopause than at other times in a woman’s reproductive life (Judd, Hickey, & Bryant, 2012).
However, the loss of fertility is an important marker for women—it means that they have to make final decisions about having children. Women in their thirties who have never had children sometimes speak about being “up against the biological clock” because they cannot postpone choices about having children much longer. Until recently, hormone replacement therapy was often prescribed as treatment for unpleasant side effects of menopause. Hormone replacement therapy (HRT) augments the declining levels of reproductive hormone production by the ovaries (Yang & Reckelhoff, 2011). HRT can consist of various forms of estrogen, usually in combination with a progestin. A study of HRT’s effects was halted as evidence emerged that participants who were receiving HRT faced an increased risk of stroke (National Institutes of Health, 2004). Since the link between HRT and increased risk of stroke was reported, there has been a 50 percent or more reduction in the use of HRT (Pines, Sturdee, & Maclennan, 2012). However, recent research has found a reduction of cardiovascular disease and minimal risks with HRT when it is initiated before 60 years of age and/or within 10 years of menopause and continued for six years or more (Hodis & others, 2012). Recent research studies on HRT have revealed that coinciding with the decreased use of HRT, research is mixed regarding changes in the incidence of breast cancer (Baber, 2011; Chlebowski & others, 2010; Gompel & Santen, 2012; Howell & Evans, 2011).
The National Institutes of Health recommends that women who have not had a hysterectomy who are currently taking hormones should consult with their doctor to determine whether they should continue the treatment. If they are taking HRT for short-term relief of symptoms, the benefits may outweigh the risks. Many middle-aged women are seeking alternatives to HRT such as regular exercise, dietary supplements, herbal remedies, relaxation therapy, acupuncture, and nonsteroidal medications (Holloway, 2010).


Do men go through anything like the menopause that women experience? That is, is there a male menopause? During middle adulthood, most men do not lose their capacity to father children, although there usually is a modest decline in their sexual hormone level and activity (Yassin & others, 2011). They experience hormonal changes in their fifties and sixties, but nothing like the dramatic drop in estrogen that women experience. Testosterone production begins to decline about 1 percent a year during middle adulthood, and sperm count usually shows a slow decline, but men do not lose their fertility in middle age. What has been referred to as “male menopause,” then, probably has less to do with hormonal change than with the psychological adjustment men must make when they are faced with declining physical energy and with family and work pressures. Testosterone therapy has not been found to relieve such symptoms, suggesting that they are not induced by hormonal change.
The gradual decline in men’s testosterone levels in middle age can reduce their sexual drive (O’Connor & others, 2011). Their erections are less full and less frequent, and men require more stimulation to achieve them. Researchers once attributed these changes to psychological factors, but increasingly they find that as many as 75 percent of the erectile dysfunctions in middle-aged men stem from physiological problems. Smoking, diabetes, hypertension, elevated cholesterol levels, obesity, and lack of exercise are at fault in many erectile problems in middle-aged men (Javaroni & Neves, 2012; Kolotkin, Zunker, & Ostbye, 2012).
Erectile dysfunction (ED) (difficulty attaining or maintaining penile erection) affects approximately 50 percent of men 40 to 70 years of age (Berookhim & Bar-Charma, 2011). Treatment for men with erectile dysfunction has focused on Viagra and similar drugs such as Levitra and Cialis (Lowe & Costabile, 2012; Rubio-Aurioles & others, 2012). Viagra works by allowing increased blood flow into the penis, which produces an erection. Its success rate is in the 60 to 85 percent range (Claes & others, 2010).


Although the ability of men and women to function sexually shows little biological decline in middle adulthood, sexual activity usually occurs less frequently in midlife than in early adulthood (Waite, Das, & Laumann, 2009). Figure 15.2 shows the age trends in frequency of sex from the Sex in America survey. The frequency of having sex was greatest for individuals aged 25 to 29 years old (47 percent had sex twice a week or more) and dropped off for individuals in their fifties (23 percent of 50- to 59-year-old males said they had sex twice a week or more, and only 14 percent of the females in this age group reported this frequency) (Michael & others, 1994). Note, though, that the Sex in America survey may underestimate the frequency of sexual activity of middle-aged adults because the data were collected prior to the widespread use of erectile dysfunction drugs such as Viagra. Other research indicates that middle-aged men want sex, think about it more, and masturbate more often than middle-aged women (Stones & Stones, 2007). For many other forms of sexual behavior, such as kissing and hugging, sexual touching, and oral sex, male and female middle-aged adults report similar frequency of engagement (Stones & Stones, 2007). A large-scale longitudinal study of women revealed that masturbation increased in early perimenopause but declined postmenopause (Avis & others, 2009). Also in this study, women’s sexual desire decreased by late perimenopause. However, the menopausal transition was not linked to changes in the importance of sex, sexual arousal, frequency of sexual intercourse, emotional satisfaction with a partner, or physical pleasure.
If middle-aged adults have sex less frequently than they did when they were younger adults, does it mean they are less satisfied with their sex life? In a Canadian study of 40- to 64-year-olds, only 30 percent reported that their sexual life was less satisfying than when they were in their twenties (Wright, 2006).
Living with a spouse or partner makes all the difference in whether people engage in sexual activity, especially for women over 40 years of age. In one study conducted as part of the Midlife in the United States Study (MIDUS), 95 percent of women in their forties with partners said that they had been sexually active in the last six months, compared with only 53 percent of those without partners (Brim, 1999). By their fifties, 88 percent of women living with a partner have been sexually active in the last six months, but only 37 percent of those who are neither married nor living with someone say they have had sex in the last six months.
A large-scale study of U.S. adults 40 to 80 years of age found that premature ejaculation (26 percent) and erectile difficulties (22 percent) were the most common sexual problems of older men while lack of sexual interest (33 percent) and lubrication difficulties (21 percent) were the most common sexual problems of older women (Laumann & others, 2009).
A person’s health in middle age is a key factor in sexual activity. A recent study found that how often individuals have sexual intercourse, the quality of their sexual life, and their interest in sex were linked to how healthy they were (Lindau & Gavrilova, 2010).



John Horn argues that some abilities begin to decline in middle age while others increase (Horn & Donaldson, 1980). Horn maintains that crystallized intelligence, an individual’s accumulated information and verbal skills, continues to increase in middle adulthood, whereas fluid intelligence, one’s ability to reason abstractly, begins to decline in middle adulthood (see Figure 15.3).
Horn’s data were collected in a cross-sectional manner. A cross-sectional study assesses individuals of different ages at the same point in time. For example, a cross-sectional study might assess the intelligence of different groups of 40-, 50-, and 60-year-olds in a single evaluation, such as in 1980. The 40-year-olds in the study would have been born in 1940 and the 60-year-olds in 1920—different eras that offered different economic and educational opportunities. The 60-year-olds likely had fewer educational opportunities as they grew up. Thus, if we find differences between 40- and 60-yearolds on intelligence tests when they are assessed cross-sectionally, these differences might be due to cohort effects related to educational differences rather than to age.
In a longitudinal study, the same individuals are studied over a period of time. Thus, a longitudinal study of intelligence in middle adulthood might consist of giving the same intelligence test to the same individuals when they are 40, 50, and 60 years of age. As we see next, whether data on intelligence are collected cross-sectionally or longitudinally can make a difference in what is found about changes in crystallized and fluid intelligence and about intellectual decline (Abrams, 2009; Schaie, 2011a, b, 2012).



The Seattle Longitudinal Study that involves extensive evaluation of intellectual abilities during adulthood was initiated by K. Warner Schaie (1994, 1996, 2005, 2010, 2011a, b, 2012). Participants have been assessed in seven-year intervals since 1956: 1963, 1970, 1977, 1984, 1991, 1998, 2005, and 2012. Five hundred individuals initially were tested in 1956. New waves of participants are added periodically. The main focus in the Seattle Longitudinal Study has been on individual change and stability in intelligence, and the study is considered to be one of the most thorough examinations of how people develop and change as they go through adulthood.
The main mental abilities tested are:
• Verbal comprehension (ability to understand ideas expressed in words)
• Verbal memory (ability to encode and recall meaningful language units, such as a list of words)
• Number (ability to perform simple mathematical computations such as addition, subtraction, and multiplication)
• Spatial orientation (ability to visualize and mentally rotate stimuli in two- and three-dimensional space)
• Inductive reasoning (ability to recognize and understand patterns and relationships in a problem and use this understanding to solve other instances of the problem)
• Perceptual speed (ability to quickly and accurately make simple discriminations in visual stimuli)
As shown in Figure 15.4, the highest level of functioning for four of the six intellectual abilities occurred in the middle adulthood years (Schaie, 2012). For both women and men, peak performance on verbal ability, verbal memory, inductive reasoning, and spatial orientation was attained in middle age. For only two of the six abilities—number and perceptual speed—were there declines in middle age. Perceptual speed showed the earliest decline, actually beginning in early adulthood. Interestingly, in terms of John Horn’s ideas that were discussed earlier, for the participants in the Seattle Longitudinal Study, middle age was a time of peak performance for some aspects of both crystallized intelligence (verbal ability) and fluid intelligence (spatial orientation and inductive reasoning).
When Schaie (1994) assessed intellectual abilities both cross-sectionally and longitudinally, he found decline more likely in the cross-sectional than in the longitudinal assessments. For example, as shown in Figure 15.5, when assessed cross-sectionally, inductive reasoning showed a consistent decline during middle adulthood. In contrast, when assessed longitudinally, inductive reasoning increased until toward the end of middle adulthood when it began to show a slight decline. In Schaie’s (2008, 2009, 2010, 2011a, b, 2012) view, it is in middle adulthood, not early adulthood, that people reach a peak in many intellectual skills.
In further analysis, Schaie (2007) examined generational differences in parents and their children over a seven-year time frame from 60 to 67 years of age. That is, parents were assessed when they were 60 to 67 years of age; and when their children reached 60 to 67 years of age, they also were assessed. Higher levels of cognitive functioning occurred for the second generation in inductive reasoning, verbal memory, and spatial orientation, whereas the first generation scored higher on numeric ability. Noteworthy was the finding that the parent generation showed cognitive decline from 60 to 67 years of age, but their offspring showed stability or modest increases in cognitive functioning across the same age range.
Such differences across generations involve cohort effects. In a recent analysis, Schaie (2011b) concluded that the advances in cognitive functioning in middle age that have occurred in recent decades are likely due to factors such as educational attainment, occupational structures (increases of workers in professional occupations and work complexity), health care and lifestyles, immigration, and social interventions in poverty. The impressive gains in cognitive functioning in recent cohorts have been documented more clearly for fluid intelligence than for crystallized intelligence (Schaie, 2011b).
The results from Schaie’s study that have been described so far focus on average cognitive stability or change for all participants across the middle adulthood years. Schaie and Sherry Willis (Schaie, 2005; Willis & Schaie, 2005) examined individual differences for the participants in the Seattle study and found substantial individual variations. They classified participants as “decliners,” “stable,” or “gainers” for three categories—number ability, delayed recall (a verbal memory task), and word fluency—from 46 to 60 years of age. The largest percentage of decline (31 percent) or gain (16 percent) occurred for delayed recall; the largest percentage with stable scores (79 percent) occurred for numerical ability. Word fluency declined for 20 percent of the individuals from 46 to 60 years of age.
Might the individual variations in cognitive trajectories in midlife be linked to cognitive impairment in late adulthood? In Willis and Schaie’s analysis, cognitively normal and impaired older adults did not differ on measures of vocabulary, spatial orientation, and numerical ability in middle adulthood. However, declines in memory (immediate recall and delayed recall), word fluency, and perceptual speed in middle adulthood were linked to neuropsychologists’ ratings of the individuals’ cognitive impairment in late adulthood.
Some researchers disagree with Schaie that middle adulthood is the time when the level of functioning in a number of cognitive domains is maintained or even increases (Finch, 2009). For example, Timothy Salthouse (2009, 2012) recently has argued that cross-sectional research on aging and cognitive functioning should not be dismissed and that this research indicates reasoning, memory, spatial visualization, and processing speed begin declining in early adulthood and show further decline in the fifties. Salthouse (2009, 2012) does agree that cognitive functioning involving accumulated knowledge, such as vocabulary and general information, does not show early age-related decline but rather continues to increase at least until 60 years of age.
Salthouse (2009, 2012) has emphasized that a lower level of cognitive functioning in early and middle adulthood is likely due to age-related neurobiological decline. Cross-sectional studies have shown that the following neurobiological factors decline during the twenties and thirties: regional brain volume, cortical thickness, synaptic density, some aspects of myelination, the functioning of some aspects of neurotransmitters such as dopamine and serotonin, blood flow in the cerebral cortex, and the accumulation of tangles in neurons (Del Tredici & Braak, 2008; Erixon-Lindroth & others, 2005; Finch, 2009; Hsu & others, 2008; Pieperhoff & others, 2008; Salat & others, 2004).
Schaie (2009, 2010, 2011a, b, 2012) continues to emphasize that longitudinal studies hold the key to determining age-related changes in cognitive functioning and that middle age is the time during which many cognitive skills actually peak. In the next decade, expanding research on age-related neurobiological changes and their possible links to cognitive skills should further refine our knowledge about age-related cognitive functioning in the adult years (Fletcher & Rapp, 2013; Merrill & others, 2012; Schlee & others, 2012).




As we saw in Schaie’s (1994, 1996, 2011a, b, 2012) Seattle Longitudinal Study, perceptual speed begins declining in early adulthood and continues to decline in middle adulthood. A common way to assess speed of information is through a reaction-time task, in which individuals simply press a button as soon as they see a light appear. Middle-aged adults are slower to push the button when the light appears than young adults are. However, keep in mind that the decline is not dramatic—under 1 second in most investigations.
A current interest focuses on possible causes for the decline in speed of processing information in adults (Salthouse, 2009, 2012). The causes may occur at different levels of analysis, such as cognitive (“maintaining goals, switching between tasks, or preserving internal representations despite distraction”), neuroanatomical (“changes in specific brain regions, such as the prefrontal cortex”), and neurochemical (“changes in neurotransmitter systems” such as dopamine) (Hartley, 2006, p. 201).


In Schaie’s (1994, 1996) Seattle Longitudinal Study, verbal memory peaked in the fifties. However, in some other studies verbal memory has shown a decline in middle age, especially when assessed in cross-sectional studies (Salthouse, 2009, 2012). For example, in several studies in which people were asked to remember lists of words, numbers, or meaningful prose, younger adults outperformed middle-aged adults (Salthouse & Skovronek, 1992). Although there still is some controversy about whether memory declines during middle adulthood, most experts conclude that it does decline at some point during this period of adult development (Hoyer & Roodin, 2009; McCabe & Loaiza, 2012; Salthouse, 2012). However, some experts argue that studies that have concluded there is a decline in memory during middle age oft en have compared young adults in their twenties with older middle-aged adults in their late fifties and even have included some individuals in their sixties (Schaie, 2000). In this view, memory decline is either nonexistent or minimal in the early part of middle age but does occur in the latter part of middle age or in late adulthood.
Cognitive aging expert Denise Park (2001) argues that starting in late middle age, more time is needed to learn new information. The slowdown in learning new information has been linked to changes in working memory, the mental “workbench” where individuals manipulate and assemble information when making decisions, solving problems, and comprehending written and spoken language (Baddeley, 2007, 2012). In this view, in late middle age working memory capacity becomes more limited. Think of this situation as an overcrowded desk with many items in disarray. As a result of the overcrowding and disarray, long-term memory becomes less reliable, more time is needed to enter new information into long-term storage, and more time is required to retrieve the information. Thus, Park concludes that much of the blame for declining memory in late middle age is a result of information overload that builds up as we go through the adult years.
Memory decline is more likely to occur when individuals don’t use effective memory strategies, such as organization and imagery (Small & others, 2012). By organizing lists of phone numbers into different categories, or imagining the phone numbers as representing different objects around the house, many individuals can improve their memory in middle adulthood.


Because it takes so long to attain, expertise often shows up more in middle adulthood than in early adulthood (Charness & Krampe, 2008). Expertise involves having extensive, highly organized knowledge and understanding of a particular domain. Developing expertise and becoming an “expert” in a field usually is the result of many years of experience, learning, and effort.
Strategies that distinguish experts from novices include these:
• Experts are more likely to rely on their accumulated experience to solve problems.
• Experts often process information automatically and analyze it more efficiently when solving a problem in their domain than novices do.
• Experts have better strategies and shortcuts to solving problems in their domain than novices do.
• Experts are more creative and flexible in solving problems in their domain than novices are.


Everyday problem solving is another important aspect of cognition (Allaire, 2012; Margrett & Deshpande-Kamat, 2009). Nancy Denney (1986, 1990) observed circumstances such as how young and middle-aged adults handled a landlord who would not fix their stove and what they did if a bank failed to deposit a check. She found that the ability to solve such practical problems improved through the forties and fifties as individuals accumulated practical experience.
However, since Denney’s research other studies on everyday problem-solving and decisionmaking effectiveness across the adult years have been conducted (Allaire, 2012; Margrett & Deshpande-Kamat, 2009). A recent analysis of research found no evidence for significant changes in everyday cognition from 20 to 75 years of age (Salthouse, 2012). One possible explanation for the lack of any decline in everyday cognition is the increase in accumulated knowledge individuals possess as they grow older (Allaire, 2012).


The role of work, whether one works in a full-time career, a part-time job, as a volunteer, or a homemaker, is central during middle adulthood. Many middle-aged adults reach their peak in position and earnings. However, they may also be saddled with multiple financial burdens including rent or mortgage, child care, medical bills, home repairs, college tuition, loans to family members, or bills from nursing homes.
In the United States, approximately 80 percent of individuals 40 to 59 years of age are employed. In the 51-to-59 age group, slightly less than 25 percent do not work. More than half of this age group say that a health condition or an impairment limits the type of paid work that they do (Sterns & Huyck, 2001).
Do middle-aged workers perform their work as competently as younger adults? Agerelated declines occur in some occupations, such as air traffic controllers and professional athletes, but for most jobs, no differences have been found in the work performance of young adults and middle-aged adults (Sturman, 2003; Salthouse, 2012).
For many people, midlife is a time of evaluation, assessment, and reflection in terms of the work they do and want to do in the future (Moen, 2009). Among the work issues that some people face in midlife are recognizing limitations in career progress, deciding whether to change jobs or careers, deciding whether to rebalance family and work, and planning for retirement (Sterns & Huyck, 2001).
Couples increasingly have both spouses in the workforce who are expecting to retire. Historically retirement has been a male transition, but today far more couples are planning two retirements—his and hers (Moen, 2009; Moen, Kelly, & Magennis, 2008).
The recent economic downturn and recession in the United States has forced some middle-aged individuals into premature retirement because of job loss and fear of not being able to reenter the work force. Such premature retirement also may result in accumulating insufficient financial resources to cover an increasingly long retirement period (Lusardi, Mitchell, & Curto, 2012; Szinovacz, 2011; Wang, 2012).


Middle-aged workers face several important challenges in the twenty-first century (Blossfeld, 2009). These include the globalization of work, rapid developments in information technologies, downsizing of organizations, early retirement, and concerns about pensions and health care.
Globalization has replaced what was once a primarily White male workforce with employees of different ethnic and national backgrounds. To improve profits, many companies are restructuring, downsizing, and outsourcing jobs. One of the outcomes of these changes is to offer incentives to middle-aged employees to retire early—in their fifties, or in some cases even forties, rather than their sixties.
The decline in defined-benefit pensions and increased uncertainty about the fate of health insurance are decreasing the sense of personal control among middleaged workers. As a consequence, many are delaying retirement.
Some midlife career changes are self-motivated; others are the consequence of losing one’s job (Moen, 2009). Some individuals in middle age decide that they don’t want to spend the rest of their lives doing the same kind of work they have been doing (Hoyer & Roodin, 2009). One aspect of middle adulthood involves adjusting idealistic hopes to realistic possibilities in light of how much time individuals have before they retire and how fast they are reaching their occupational goals (Levinson, 1978). If individuals perceive that they are behind schedule, if their goals are unrealistic, they don’t like the work they are doing, or their job has become too stressful, they could become motivated to change jobs.
A final point to make about career development in middle adulthood is that cognitive factors earlier in development are linked to occupational attainment in middle age. In one study, task persistence at 13 years of age was related to occupational success in middle age (Andersson & Bergman, 2011).


As adults, not only must we learn how to work well, but we also need to learn how to relax and enjoy leisure (Gibson, 2009). Leisure refers to the pleasant times after work when individuals are free to pursue activities and interests of their own choosing—hobbies, sports, or reading, for example. In one analysis of research on what U.S. adults regret the most, not engaging in more leisure was one of the top six regrets (Roese & Summerville, 2005).
Leisure can be an especially important aspect of middle adulthood (Parkes, 2006). By middle adulthood, more money is available to many individuals, and there may be more free time and paid vacations. In short, midlife changes may produce expanded opportunities for leisure.
In one study, 12,338 men 35 to 57 years of age were assessed each year for five years regarding whether or not they took vacations (Gump & Matthews, 2000). Then the researchers examined the medical and death records over nine years for men who lived for at least a year after the last vacation survey. Compared with those who never took vacations, men who went on annual vacations were 21 percent less likely to die over the nine years and 32 percent less likely to die of coronary heart disease.
Adults at midlife need to begin preparing psychologically for retirement. Constructive and fulfilling leisure activities in middle adulthood are an important part of this preparation (Danigelis, 2007). If an adult develops leisure activities that can be continued into retirement, the transition from work to retirement can be less stressful.


Can religion be distinguished from spirituality? Recent analysis by Pamela King and her colleagues (2011) provides the following distinctions:
• Religion is an organized set of beliefs, practices, rituals, and symbols that increases an individual’s connection to a sacred or transcendent other (God, higher power, or ultimate truth).
• Religiousness refers to the degree of affiliation with an organized religion, participation in its prescribed rituals and practices, connection with its beliefs, and involvement in a community of believers.
• Spirituality involves experiencing something beyond oneself in a transcendent manner and living in a way that benefits others and society.
In the MacArthur Study of Midlife Development, more than 70 percent of U.S. middle-aged adults said they are religious and consider spirituality a major part of their lives (Brim, 1999).
In thinking about religion, spirituality, and adult development, it is important to consider the role of individual differences. Religion and spirituality are powerful influences for some adults but hold little or no significance for others (McCullough & others, 2005). Further, the influence of religion and spirituality in people’s lives may change as they develop (Sapp, 2010). In John Clausen’s (1993) longitudinal investigation, some individuals who had been strongly religious in their early adult years became less so in middle age, while others became more religious in middle age. In a longitudinal study of individuals from their early thirties through their late sixties/early seventies, a significant increase in spirituality occurred between late middle (mid-fifties/early sixties) and late adulthood (Wink & Dillon, 2002) (see Figure 15.6).
Women have consistently shown a stronger interest in religion and spirituality than men have. In the longitudinal study just described, the spirituality of women increased more than men in the second half of life (Wink & Dillon, 2002).



How might religion influence physical health? Some cults and religious sects encourage behaviors that are damaging to health, such as ignoring sound medical advice (Williams & Sternthal, 2007). For individuals in the religious mainstream, researchers increasingly are finding that spirituality/religion is positively linked to health (McCullough & Willoughby, 2009). Researchers have found that religious commitment helps to moderate blood pressure and hypertension, and that religious attendance is linked to a reduction in hypertension (Gillum & Ingram, 2007). And in a recent analysis of a number of studies, adults with a higher level of spirituality/religion had an 18 percent reduction in mortality (Lucchetti, Lucchetti, & Koenig, 2011). In this analysis, a high level of spirituality/religion had a stronger link to mortality than 60 percent of 25 other health interventions (such as eating fruits and vegetables and taking statin drugs for cardiovascular disease). In Connecting Development to Life, we explore links between religion, spirituality, and coping.
In sum, various dimensions of religion and coping can help some individuals cope more effectively with their lives (Olson & others, 2012; Park, 2010, 2012a; Thune-Boyle & others, 2012). Religious counselors often advise people about mental health and coping.


Austrian psychiatrist Viktor Frankl’s mother, father, brother, and wife died in the concentration camps and gas chambers in Auschwitz, Poland. Frankl survived the concentration camp and went on to write about meaning in life. In his book, Man’s Search for Meaning, Frankl (1984) emphasized each person’s uniqueness and the finiteness of life. He argued that examining the finiteness of our existence and the certainty of death adds meaning to life. If life were not finite, said Frankl, we could spend our life doing just about whatever we pleased because time would continue forever.
Frankl said that the three most distinct human qualities are spirituality, freedom, and responsibility. Spirituality, in his view, does not have a religious underpinning. Rather, it refers to a human being’s uniqueness of spirit, philosophy, and mind. Frankl proposed that people need to ask themselves such questions as why they exist, what they want from life, and what the meaning of their life might be.
It is in middle adulthood that individuals begin to be faced with death more often, especially the deaths of parents and other older relatives. Also faced with less time in their life, many individuals in middle age begin to ask and evaluate the questions that Frankl proposed (Cohen, 2009). And, as indicated in Connecting Development to Life, meaning-making coping is especially helpful in times of chronic stress and loss.
Having a sense of meaning in life can lead to clearer guidelines for living one’s life and enhanced motivation to take care of oneself and reach goals. A higher level of meaning in life also is linked to a higher level of psychological well-being and physical health (Park, 2012b).
Roy Baumeister and Kathleen Vohs (2002, pp. 610–611) argue that the quest for a meaningful life can be understood in terms of four main needs for meaning that guide how people try to make sense of their lives:
Need for purpose.  “Present events draw meaning from their connection with future events.” Purposes can be divided into (1) goals and (2) fulfillments. Life can be oriented toward a future anticipated state, such as living happily ever after or being in love.
• Need for values.  This “can lend a sense of goodness or positive characterization of life and justify certain courses of action. Values enable people to decide whether certain acts are right or wrong.” Frankl’s (1984) view of meaning in life emphasized value as the main form of meaning that people need.
Need for a sense of efficacy.  Th is involves the “belief that one can make a difference. A life that had purposes and values but no efficacy would be tragic. The person might know what is desirable but could not do anything with that knowledge.” With a sense of efficacy, people believe that they can control their environment, which has positive physical and mental health benefits (Bandura, 2009).
Need for self-worth.  Most individuals want to be “good, worthy persons. Self-worth can be pursued individually.”
Researchers are increasingly studying the factors involved in a person’s exploration of meaning in life and whether developing a sense of meaning in life is linked to positive developmental outcomes. Research indicates that many individuals state that religion played an important role in increasing their exploration of meaning in life (Krause, 2008, 2009). Studies also suggest that individuals who have found a sense of meaning in life are more physically healthy, happier, and experience less depression than their counterparts who report that they have not discovered meaning in life (Debats, 1990; Krause, 2004,2009; Parquart, 2002).