After anxiety, depression is the most common mental health disorder. Depression may result from a recent loss or other sad event, but it lasts longer than normal sadness and is often out of proportion to the event.

Depression usually lasts about six months if not treated, but it can last two or more years. It tends to recur several times over a lifetime. 

People who become depressed typically do so in their 20s, 30s or 40s, although it can begin at any age.


The symptoms of depression usually build up gradually. A person may be sluggish, sad, irritable or anxious. Depressed people often have a hard time falling asleep, and they wake up often, especially early in the morning. Sometimes symptoms include loss of appetite, withdrawal, silence and inability to sleep. On the other hand, a person may experience fear and anxiety that leads them to a larger appetite, weight gain and sleeping excessively. They may also lose sexual desire. About 15 percent of depressed people, usually those with severe depression, have delusions and may see or hear things that are not there (hallucinations).

Many people with depression cannot feel emotions in a normal way. A person may see the world as colorless and lifeless and may be overcome with guilt and lack self worth. They may feel loneliness, helplessness and hopelessness, and they may think about death and suicide. As many as 15 percent of depressed people who do not get treatment end their lives in suicide.

Some depressed people may have mild symptoms that last for years. Called dysthymia, this type of depression often begins early in life. Victims may be gloomy, overly quiet and passive. They may be too critical, have low energy, be unable to have fun and be critical of themselves.


Causes and Risk Factors

Several risk factors increase the likelihood of depression, including:

  • A family history of depression
  • Taking certain drugs
  • An event or experience that involves a loss

Depression may occur or become worse even when no obvious life stresses are involved. Painful health conditions, such as arthritis, may cause depression. Conditions that involve physical limitations can also result in depression.

Women are twice as likely as men to have depression. This increased likelihood may be a result of hormonal changes involved with menstruation or childbirth. It may also be the result of abnormal thyroid function, which is fairly common in women.


To diagnose depression, a doctor evaluates the symptoms and the individual's personal and family history. Questionnaires can be used to help measure the degree of depression, including the Hamilton Depression Rating Scale and the Beck Depression Inventory. Lab tests may reveal that physical factors are involved, such as thyroid problems.


Drugs therapy, psychotherapy or electroconvulsive therapy can be used to treat depression, and sometimes a combination of these therapies is used. Psychotherapy, either alone with the therapist or in a group, can help people and may also work to improve the effect of drug therapy. Electroconvulsive therapy is used to treat seriously depressed people who are threatening suicide, refusing to eat or psychotic.