The most prominent symptom of major depression is a severe and persistent low mood, profound sadness, or a sense of despair. The mood change can sometimes appear as irritability. Or the person suffering major depression may not be able to take pleasure in activities that usually are enjoyable.
Major depression is more than just a passing blue mood, a "bad day" or temporary sadness. The mood changes that occur in major depression are defined as lasting at least two weeks but usually they go on much longer — months or even years.
A variety of symptoms usually accompany the mood change, and the symptoms can vary significantly among different people.
Many people with depression also have anxiety. They may worry more than average about their physical health. They may have excessive conflict in their relationships and may function poorly at work. Sexual functioning may be a problem. People with depression are at more risk for abusing alcohol or other substances.
Depression probably involves changes in the areas of the brain that control mood. Neuroscientists are continuing to work out the details, but there are several places where problems can occur. Chemical reactions inside nerve cells may be altered. Communication between nerve cells or nerve circuits can make it harder for a person to regulate their mood. Changes in hormones may play a role. An individual's life experience certainly affects these processes. And how vulnerable a person is to breakdowns in these functions is almost certainly influenced by genetic makeup.
An episode of depression can be triggered by a stressful life event, such as the death of a loved one. But in many cases, depression does not appear to be related to a specific event.
Major depression may occur just once in a person's life or may return repeatedly. Some people who have many episodes of major depression also have a background pattern of a milder depressed mood called dysthymia.
Some people who have episodes of major depression also have episodes of relatively high energy or irritability. They may sleep far less than normal, and may dream up grand plans that could never be carried out. The person may develop thinking that is out of step with reality — psychotic symptoms — such as false beliefs (delusions) or false perceptions (hallucinations). The severe form of this is called "mania" or a manic episode. If a person has milder symptoms of mania and does not lose touch with reality, it is called "hypomania" or a hypomanic episode.
If a woman has a major depressive episode within the first two to three months after giving birth to a baby, it is called postpartum depression. Depression that occurs mainly during the winter months is called seasonal affective disorder, or SAD.
Episodes of depression can occur at any age. Depression is diagnosed in women twice as often as in men. People who have a family member with major depression are more likely to develop depression or drinking problems.
A depressed person may gain or lose weight, eat more or less than usual, have difficulty concentrating, and have trouble sleeping or sleep more than usual. He or she may feel tired and have no energy for work or play. Small burdens or obstacles may appear impossible to manage. The person can appear slowed down or agitated and restless. The symptoms can be quite noticeable to others.
A particularly painful symptom of this illness is an unshakable feeling of worthlessness and guilt. The person may feel guilty about a specific life experience or may feel general guilt not related to anything in particular.
If pain and self-criticism become great enough, they can lead to feelings of hopelessness, self-destructive behavior, or thoughts of death and suicide. The vast majority of people who suffer severe depression do not attempt or commit suicide, but they are more likely to do so than people who are not depressed.
The thoughts of people with major depression are often colored by their dark mood. For example, pessimistic ideas may be out of proportion with the reality of the situation. Sometimes, the depressed thinking is distorted enough to be called "psychotic;" that is, the person has great difficulty recognizing reality. Sometimes, depressed people develop delusions (false beliefs) or hallucinations (false perceptions).
Symptoms of major depression include:
Distinctly depressed or irritable mood
Loss of interest or pleasure
Decreased or increased weight or appetite
Increased or decreased sleep
Appearing slowed or agitated
Fatigue and loss of energy
Feeling worthless or guilty
Thoughts of death, suicide attempts or plans
A primary care physician or a mental health professional usually can diagnose depression by asking questions about medical history and symptoms. By definition, major depression is diagnosed when a person has many of the symptoms listed above for at least two weeks.
Many people with depression do not seek evaluation or treatment because of society's attitudes about depression. The person may feel the depression is his or her fault or may worry about what others will think. Also, the depression itself may distort a person's ability to recognize the problem.
There are no specific tests for depression. However, it is important to be evaluated by a primary care physician to make sure the problems are not being caused by a medical condition or medication.