Growing Older
Senescence causes a universal slowdown during adulthood, but aging is often imperceptible because organ reserve maintains capacity. Most adults are quite strong and capable.
Probably the most crucial health habit for adults is regular exercise, in part because it makes other good health habits more likely. Sedentary people have more illnesses of almost every kind.
Adults in North America smoke fewer cigarettes than they once did, and rates of lung cancer and other diseases are falling, largely for that reason. Gender differences in smoking show cohort effects. For all drugs, national context is crucial; cigarette smoking is increasing in some nations, especially for women.
Although illegal drug abuse declines in adulthood, prescription drug overuse and abuse remains a problem. Alcohol use disorder remains a major health problem in North America, with even worse rates worldwide.
Nutrition keeps adults healthy and strong, but metabolism slows over adulthood, which may result in weight gain. Research suggests that some diets are better than others.
Losses and Gains
Appearance changes with age, especially evident in the skin. Ease of movement decreases as people become less agile. Shape and reaction time change as well.
463
Sexual satisfaction may improve with age, but infertility becomes more common. Sperm count gradually decreases in men, and every step of female reproduction—
A number of assisted reproductive technology (ART) procedures, including in vitro fertilization (IVF), offer potential answers to infertility.
At menopause, ovulation ceases and estrogen is markedly reduced. Hormone production declines more gradually in men. For both sexes, hormone replacement therapy should be used cautiously, if at all.
The Aging Brain
The brain slows down and begins a gradual decline. The brain benefits from measures to improve overall health, especially exercise, and is harmed by most psychoactive drugs.
It was traditionally assumed that there is one general intelligence (g), measurable by IQ tests. That idea is not accepted by all current cognitive scientists.
Crystallized intelligence, reflecting accumulated knowledge, increases, but fluid, flexible reasoning declines in adults. That makes IQ, overall, steady over the decades of adulthood until old age.
Sternberg proposed three fundamental forms of intelligence: analytic, creative, and practical. Cultural values encourage development of some cognitive abilities more than others. Each person responds to these cultural priorities, which may not be reflected in IQ scores. Practical intelligence is particularly useful in daily life.
Selecting and Protecting
The rate of homicide has decreased, but the rate of disasters has increased. In addition, people experience many stresses and hassles over the 40 years of adulthood, which affects their health.
People use many methods of coping with stress. Avoidant copying is destructive, but both problem-
As people grow older, they select certain aspects of their lives to focus on, optimizing development in those areas and compensating for declines in others. Selective optimization with compensation is apparent in many aspects of adult life.
In cognition, people become experts in some aspects of knowledge and intellect, allowing others to fade. Expertise is characterized by more intuitive, automatic, strategic, and flexible thinking.
Experienced adults may surpass younger adults if they specialize, compensating for any deficits. According to a study of taxi drivers in London, as well as research on musicians, brains grow to support selective expertise.