Depression can take several other forms. In bipolar disorder, sometimes called manic-depressive illness, a person's mood swings back and forth between depression and mania. People with seasonal affective disorder typically suffer from depression only during autumn and winter, when there are fewer hours of daylight. In dysthymia (pronounced dis-THI-mee-uh), people feel depressed, have low self-esteem, and concentrate poorly most of the timeoften for a period of yearsbut their symptoms are milder than in major depression. Some people with dysthymia experience occasional episodes of major depression. Mental health professionals use the term clinical depression to refer to any of the above forms of depression. Surveys indicate that people commonly view depression as a sign of personal weakness, but psychiatrists and psychologists view it as a real illness. In the United States, the National Institute of Mental Health has estimated that depression costs society many billions of dollars each year, mostly in lost work time. IIPREVALENCE
Depression is one of the most common mental illnesses. At least 8 percent of adults in the United States experience serious depression at some point during their lives, and estimates range as high as 17 percent. The illness affects all people, regardless of sex, race, ethnicity, or socioeconomic standing. However, women are two to three times more likely than men to suffer from depression. Experts disagree on the reason for this difference. Some cite differences in hormones, and others point to the stress caused by society's expectations of women.
Depression occurs in all parts of the world, although the pattern of symptoms can vary. The prevalence of depression in other countries varies widely, from 1.5 percent of people in Taiwan to 19 percent of people in Lebanon. Some researchers believe methods of gathering data on depression account for different rates.
A number of large-scale studies indicate that depression rates have increased worldwide over the past several decades. Furthermore, younger generations are experiencing depression at an earlier age than did previous generations. Social scientists have proposed many explanations, including changes in family structure, urbanization, and reduced cultural and religious influences. IIISYMPTOMS
Although it may appear anytime from childhood to old age, depression usually begins during a person's 20s or 30s. The illness may come on slowly, then deepen gradually over months or years. On the other hand, it may erupt suddenly in a few weeks or days. A person who develops severe depression may appear so confused, frightened, and unbalanced that observers speak of a "nervous breakdown." However it begins, depression causes serious changes in a person's feelings and outlook. A person with major depression feels sad nearly every day and may cry often. People, work, and activities that used to bring them pleasure no longer do. Symptoms of depression can vary by age. In younger children, depression may include physical complaints, such as stomachaches and headaches, as well as irritability, "moping around," social withdrawal, and changes in eating habits. They may feel unenthusiastic about school and other activities. In adolescents, common symptoms include sad mood, sleep disturbances, and lack of energy. Elderly people with depression usually complain of...