Chapter 20 Summary

1. Senescence causes a universal slowdown of body systems during adulthood, but the changes due to aging are often imperceptible because organ reserve maintains capacity. The entire body adjusts to changes in the short term (homeostasis) and the long term (allostasis).
2. The brain slows down and begins a gradual decline that is not usually initially perceptible. In addition to measures that protect overall health, the brain is also affected by psychoactive drugs, poor circulation, viruses, and genetics.
3. A person’s appearance undergoes gradual but noticeable changes as middle age progresses, including more wrinkles, less hair, and more fat, particularly around the abdomen. With the exception of excessive weight gain and related conditions, changes in appearance have little impact on health.
4. The rate of senescence is most apparent in the sense organs. Vision becomes less sharp with age, with both nearsightedness and farsightedness increasing gradually beginning in the 20s. Hearing also becomes less acute.

5. Sexual responsiveness slows down with age, as does speed of recovery after orgasm. This is only a physical decline; many couples find that, overall, sexual interaction improves with age.
6. Fertility problems become more common with increased age, for many reasons. The most common one for men is a reduced number of sperm, and for women, ovulation failure or blocked fallopian tubes. For both sexes, not only youth but also overall good health—especially sexual health—correlates with fertility.
7. A number of assisted reproductive technology (ART) procedures, including IVF (in vitro fertilization), offer potential solutions to infertility. Donor sperm, donor ova, and/or donor wombs have helped thousands of infertile couples become parents.
8. At menopause, as a woman’s menstrual cycle stops, ovulation ceases and levels of estrogen are markedly reduced. This hormonal change produces various symptoms in some women, including vaginal dryness and body temperature disturbance as well as erratic moods, energy surges, and depression. Other women seem unaffected.
9. Hormone production declines in men, too, though not as suddenly as in women. For both sexes, hormone replacement therapy (HRT) should be used cautiously, if at all.

10. Adults in North America are smoking far less than they once did, and rates of lung cancer and other diseases are falling, largely for that reason. Alcohol abuse remains a major health problem worldwide.
11. Good health habits include exercising regularly and proper nutrition. On both of these counts, today’s adults worldwide are faring worse than did previous generations. This is especially true in the United States. There is a worldwide “epidemic of obesity,” as more people have access to abundant food and overeat as a result.

12. Variations in health can be measured in terms of mortality, morbidity, disability, and vitality. Although death and disease are easier to quantify, disability and vitality may be more significant in terms of the health of a population. Quality-adjusted life years (QALYs) and disability-adjusted life years (DALYs) help doctors and public health advocates figure out how to allocate limited resources.
13. Aging and health status can be greatly affected by SES. In general, those who have more education and money are more likely to live longer and avoid illness than their poorer counterparts. However, low SES does not inevitably lead to poor health since genes and health habits are protective. Avoiding drugs and obesity is possible at any income level.