Depression is an emotional state characterized by one or more of these symptoms: sad mood, low energy, poor concentration, sleep or appetite changes, feelings of worthlessness or hopelessness, and thoughts of suicide.

Depressive disorders

Depressive disorders
SOURCE: Academy of American Family Physicians,

Depression can be traced to a combination of physical, psychological, and environmental factors. Depressive disorders involve a person's body, mood, and thoughts. Depression in adolescents is often called masked depression because it appears as angry behavior rather than sadness. Women with PMS or PMDD can be highly irritable. Some people with depression are extremely agitated and filled with rage rather than vegetative and sad. Depression is not always the image of sadness and psychomotor retardation that society imagines.

Genetic inheritance makes some people highly vulnerable to depression. More than 60% of people who are treated for depression have family members who have been depressed at some time, and there is a 15% chance that the immediate biological relatives of a depressed person will develop depression. Twin studies further support the existence of a genetic predisposition to depression, particularly for bipolar depression. Researchers have found that depression is associated with changes in brain chemistry. The normal balance and functioning of two neurotransmitters—serotonin and norepinephrine—appear to be disrupted in depressed people. This finding led to the development of a variety of antidepressant drugs. Depression is also associated with an imbalance of cortisol, the main hormone secreted by the adrenal glands. Other physiological factors sometimes associated with depression include viral infections, low thyroid levels, and biological rhythms, including women's menstrual cycles. Depression is a prominent symptom of premenstrual syndrome (PMS).

A woman undergoes transcranial magnetic stimulation (TMS).

A woman undergoes transcranial magnetic stimulation (TMS).
(© Simon Fraser/University of Durham/Photo Researchers, Inc.)

A different explanation of depression centers on the concept of learned helplessness. This phenomenon was first observed in a laboratory when animals with no control over their situations (such as the ability to get food by pressing a lever) showed striking signs of depression. The feeling of agency is important for mental health, and the lab animals were deprived of any sense of efficacy. One in four women becomes depressed, a rate twice that of men, suggesting that women may lack a sense of agency in society. Until puberty the ratio of girls to boys who are depressed is equal. The profound biological and hormonal changes that continue after puberty may add to women's vulnerability to depression over the lifespan. Women are more likely to self-report for depression and to present for treatment. Men are more likely to self-medicate with drugs, alcohol, or other addictive behaviors. Men are more likely to feel tired, irritable, or experience depression as a physical symptom than women. Finally, the tendency to dwell on negative events, a cognitive style research has shown to be more common for women, may also make then vulnerable to depression. Men appear to distract themselves from negative feelings by engaging in various forms of activity.

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5), produced by the American Psychiatric Association, categorizes depression as an affective, or mood, disorder. The DSM-5 criterion for clinical depression is the presence of at least five of the following symptoms almost every day for at least two weeks: depressed mood; loss of interest in activities; significant changes in appetite or weight; disturbed sleep patterns; agitated or slowed movements; fatigue; feelings of worthlessness or inappropriate guilt; trouble concentrating; and preoccupation with death or suicide. In a major depressive episode, these symptoms can persist for six months or longer without treatment. Usually, major depression first occurs in one's late twenties. In severe cases, people may be almost completely incapacitated, losing the ability to work, socialize, and even care for themselves. The depressive episode may eventually lift completely, or some symptoms may persist for as long as two years. More than half the people who suffer from major depression experience more than one episode. A serious complication of major depression is the threat of suicide. Some 60% of people who commit suicide are depressed, and 15% of those diagnosed with depression eventually commit suicide.

In dysthymia, a less severe form of depression, the symptoms are more prolonged but not disabling. Depressed mood is the major symptom. The depressed mood lasts at least two years for adults or one year for children, with two or more of the other symptoms of clinical depression present. Bipolar disorder (manic depression) is characterized by the alternation of depression and mania, an overly elated, energetic state. Characteristic symptoms of mania include an inappropriately cheerful mood; inflated optimism and self-esteem; grandiose notions; excessive energy with a decreased need for sleep; racing thoughts; increased talking; and irritability when confronted by obstacles or opposition. During manic episodes, people characteristically use poor judgement, make irrational decisions, and may even endanger their own lives. In bipolar disorder, manic episodes lasting days, weeks, or even months, alternate with periods of depression. There may be a period of normalcy between them, or an immediate mood swing from one mode to the other.

Cyclothymic disorder, the bipolar equivalent of dysthymia, resembles bipolar disorder but consists of a less extreme pattern of mood swings. Another type of depression, seasonal affective disorder (SAD), follows an annual cycle triggered by seasonal variations in light, and usually involves depression during the winter months; it is thought to be due to an excess of the sleep-inducing hormone melatonin.

Sometimes depressions become severe enough to include features of psychosis. These cases, which account for about 10% of all clinical depressions, are characterized by delusions or hallucinations and an especially high incidence of suicide.

Many people with clinical depression do not recognize that they have it and fail to seek treatment, blaming stress or physical ailments for their lack of well-being. Of those who do seek treatment through psychotherapy, medication, or a combination, 80% improve within a matter of weeks. Psychotherapy alone is generally effective for people with mild or moderate depression; medication is advised for those whose depression is severe or who have developed physical symptoms. Treatment methods vary among different schools of therapy and individual therapists. Cognitive behavior therapy focuses on helping patients identify and change negative thought patterns; interpersonal and family therapies emphasize strategies for improving one's relationships with others; and behavioral therapy involves monitoring one's actions and modifying them through a system of incentives and rewards.

Two types of medication were traditionally used to treat depression; tricyclic antidepressants and monoamine oxidase inhibitors (MAOI) increase the brain's supply of certain neurotransmitters, including norepinephrine and dopamine. Both medications were effective for many patients but caused a variety of side effects. The new generation of antidepressants affect levels of serotonin rather than norepinephrine. Among these drugs, known as selective serotonin reuptake inhibitors (SSRIs), is fluoxetine (Prozac), the most widely used antidepressant in the United States. It is effective in 60–80% of those who take it and has fewer side effects than previous types of antidepressants. Other SSRIs include sertraline (Zoloft) and paroxetine (Paxil). Electroconvulsive therapy (ECT) has recently reemerged as a treatment for highly resistant depression.

Whenever possible, people who have depression should seek treatment through a private therapist, clinic, or hospital. A complete physical examination by a family physician or internist is the first step to getting appropriate treatment. Since certain medications and medical conditions, such as a viral infection, can cause depression-like symptoms, a physician can rule out these possibilities first.

See also Antidepressant drugs ; Bipolar disorder ; Psychosis ; Psychotherapy ; Suicide/Suicidal behavior.



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