Conditions in Depth

This page contains the basic information about Major Depression .

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Major Depression

What Is It?

Major depression is an illness that is typified by its most prominent symptom — a severe and persistent low mood, profound sadness, or a sense of despair. The mood change can sometimes appear as irritability or an inability 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 over a specific event. 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 and tend to 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 susceptible to 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. How vulnerable a person is to hiccups in these functions is almost certainly influenced by genetic variations.

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 periodically. Some people who have repeated episodes of major depression also have a long pattern of a milder depressed mood called dysthymia . When major depression alternates with periods of great exuberance and energy, the illness is called bipolar disorder . 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.