9.3.4 Adulthood

Adulthood begins around 20 years old and has three distinct stages: early, middle, and late. Each stage brings its own set of rewards and challenges.

Physical Development

By the time we reach early adulthood (20 to early 40s), our physical maturation is complete, although our height and weight may increase slightly. In young adulthood, our physical abilities are at their peak, including muscle strength, reaction time, sensory abilities, and cardiac functioning. Most professional athletes are at the top of their game during this stage. People often carry and give birth to children in the young adulthood years, so they may see additional weight gain and breast changes.

Middle adulthood extends from the 40s to the 60s (Figure 9.18). Physical decline is gradual. The skin loses some elasticity, and wrinkles are among the first signs of aging. Visual acuity decreases during this time. Fertility gradually declines with the approach to the onset of menopause, the end of the menstrual cycle, around 50 years old. Middle adulthood tends toward weight gain: in the abdominal area for men and in the hips and thighs for women. Hair begins to thin and turn gray.

Late adulthood is considered to extend from the 60s on. This is the last stage of physical change. The skin continues to lose elasticity, reaction time slows further, and muscle strength diminishes. Smell, taste, hearing, and vision, so sharp in our twenties, decline significantly. The brain may also no longer function at optimal levels, leading to problems like memory loss, dementia, and Alzheimer’s disease in later years.

Cognitive Development

Because we spend so many years in adulthood (more than any other stage), cognitive changes are numerous. In fact, research suggests that adult cognitive development is a complex, ever changing process that may be even more active than cognitive development in infancy and early childhood (Fischer, Yan, & Stewart, 2003).

Unlike our physical abilities, which peak in our mid-20s and then begin a slow decline, our cognitive abilities remain steady throughout early and middle adulthood. Our crystallized intelligence (information, skills, and strategies we have gathered through a lifetime of experience) tends to hold steady as we age—it may even improve. For example, adults show relatively stable to increasing scores on intelligence tests until their mid-30s to mid-50s (Bayley & Oden, 1955). However, in late adulthood we begin to experience a decline in another area of our cognitive abilities—fluid intelligence (information processing abilities, reasoning, and memory). These processes become slower. How can we delay the onset of cognitive decline? Mental and physical activity seems to play a part (Figure 9.19). Research has found adults who engage in mentally and physically stimulating activities experience less cognitive decline and have a reduced incidence of mild cognitive impairment and dementia (Hertzog, Kramer, Wilson, & Lindenberger, 2009; Larson et al., 2006; Podewils et al., 2005).

Researchers have examined the aging brain by comparing it to brain functioning in younger people. Forstmann and colleagues (2011) compared elderly participants to younger participants, who in the study were asked to report the direction of movement of a set of dots. They were given feedback regarding speed and accuracy. The researchers found that older participants made more errors and were slower due to degeneration of corticostriatal connections. In other words, the decreased ability typically assigned to elderly people may be due to circumstances in the brain beyond their control. Interestingly, other researchers have found similarities in spatial representations when comparing children aged 6–7 to those over the age of 80. Ruggiero, D’Errico, and Iachini (2016) reported that this is due to neurodegeneration in older adults and immature neurology in young children.

Many elderly people experience dementia, changes in the brain that negatively affect cognition. Alzheimer’s disease is one type of dementia, initially studied by medical researcher Solomon Carter Fuller. Alzheimer’s disease has a genetic basis. Plaques in the brain are due to cell death, which then causes those affected with the disease severe forgetfulness. A person can forget how to walk, talk, and eventually eat. The disease can be mitigated by assessing environmental factors (exposure to lead, iron, and zinc increase risk) and nutritional factors (the Mediterranean diet lowers risk) (Arora, Mittal, & Kakkar, 2015). Although there is no cure, there is hope. Cognitive rehabilitation can offset mild cognitive impairment, as it can evolve into dementia. Garcia-Betances, Jimenez-Mixco, Arredondo, and Cabrera-Umpierrez (2015) examined the use of virtual reality as a possible cognitive rehabilitative method. They suggested that virtual reality technology should involve daily living activities, memory, and language, among other considerations.

Psychosocial Development

There are many theories about the social and emotional aspects of aging. Some aspects of healthy aging include activities, social connectedness, and the role of a person’s culture. According to many theorists, including George Vaillant (2002), who studied and analyzed over 50 years of data, we need to have and continue to find meaning throughout our lives. For those in early and middle adulthood, meaning is found through work (Sterns & Huyck, 2001) and family life (Markus, Ryff, Curan, & Palmersheim, 2004). These areas relate to the tasks that Erikson referred to as generativity and intimacy. As mentioned previously, adults tend to define themselves by what they do—their careers. Earnings peak during this time, yet job satisfaction is more closely tied to work that involves contact with other people, is interesting, provides opportunities for advancement, and allows some independence (Mohr & Zoghi, 2006) than it is to salary (Iyengar, Wells, & Schwartz, 2006). How might being unemployed or being in a dead-end job challenge adult well-being?

Positive relationships with significant others in our adult years have been found to contribute to a state of well-being (Ryff & Singer, 2009). Most adults in the United States identify themselves through their relationships with family—particularly with spouses, children, and parents (Markus et al., 2004). While raising children can be stressful, especially when they are young, research suggests that parents reap the rewards down the road, as adult children tend to have a positive effect on parental well-being (Umberson, Pudrovska, & Reczek, 2010). Having a stable marriage has also been found to contribute to well-being throughout adulthood (Vaillant, 2002).

Another aspect of positive aging is believed to be social connectedness and social support. As we get older, socioemotional selectivity theory suggests that our social support and friendships dwindle in number, but remain as close, if not more close than in our earlier years (Carstensen, 1992) (Figure 9.20).