Depression Definition Depression is an illness that increasingly afflicts people worldwide, interfering with concentration, motivation and many other aspects of everyday functioning. It is a complex disorder, involving many systems of the body, including the immune system, either as cause or effect. It disrupts sleep, and it interferes with appetite, in some cases causing weight loss, in others weight gain. Because of its complexity, a full understanding of depression has been elusive（难懂的）. Characteristics or symptoms: Not everyone who is depressed or manic experiences every symptom. Some people experience a few symptoms, some many. Severity of symptoms varies among individuals and also varies over time. Persistent sad, anxious, or empty mood Feelings of hopelessness or pessimism Feelings of guilt, worthlessness, or helplessness Loss of interest or pleasure in hobbies and activities that were once enjoyed, including sex——not enjoying things you used to enjoy Decreased energy, fatigue, being "slowed down" Difficulty concentrating, remembering, or making decisions——An inability to concentrate&Trouble making decisions Insomnia(失眠症） , early morning awakening or oversleeping ——sleep problems Appetite and/or weight loss, or overeating and weight gain Thoughts of death or suicide, suicide attempts——Suicidal thoughts Restlessness, irritability Varieties of depression Depression generally takes one of two major forms. Unipolar（单极的） depression is what most people mean when they talk about depression: an unremitting（不间断的） state of sadness, apathy,（冷漠） or hopelessness, and loss of energy. It is sometimes called major depression. Bipolar （双极的） depression, or bipolar disorder, is a condition marked by periods of depression and periods of high-energy mania Causes There is no single known cause of depression. Rather, it likely results from a
combination of genetic, biochemical, environmental, and psychological factors. Trauma, loss of a loved one, a difficult relationship, or any stressful situation that overwhelms the ability to cope may trigger a depressive episode. Subsequent depressive episodes may occur with or without an obvious trigger. Treatment Appropriate treatment for depression starts with a physical examination by a physician. Once diagnosed, a person with depression can be treated a number of ways. The most common treatments are medication and psychotherapy. In addition, physical exercise is important way to combat depression. Social contact is also valuable as a way to combat the feelings of isolation that afflict the depressed.