In order to diagnose someone with Major Depression, they must have had at least one Major Depressive Episode (in which they suffer from depressed mood, or the loss of interest or pleasure in nearly all activities) for at least two weeks. In addition, depressive symptoms must persist for most of the day, nearly every day, and cause problems in social interactions, work, or someone’s ability to function in daily life. For some individuals with milder depressive episodes, social and occupational functioning may appear to be normal, but the affected person is making a serious, concerted effort to appear unimpaired.
When a person has experienced only one episode of depression, it is classified as Major Depression, Single Episode. When multiple Major Depressive Episodes occur in a row, and no manic or mixed episodes are observed, the diagnoses changes to Major Depression, Recurrent.
Untreated, a Major Depressive Episode may last, on average, about 4 months. Some people only experience a single depressive episode and thereafter are symptom free. However, many people who experience one major depressive episode will go on to experience multiple major depressive episodes. The more major depressive episodes an individual experiences, the more likely they are to develop future episodes. Approximately 60% of people with MDD who experience a single depressive episode go on to have a second episode, and about 70% are likely to experience a third episode. Similarly, having had three episodes increases the chances to about 90% that a fourth episode will occur.
The course of Major Depression, Recurrent varies across individuals. Some people have isolated depressive episodes that are separated by many years during which mood is normal, whereas other individuals experience clusters of major depressive episodes that occur closely together in time. Still other people with Major Depression experience increasingly frequent episodes as they grow older.
Episodes of Major Depression can be triggered by highly stressful events. Stressors capable of triggering major depression may include the death of a loved one and other significant losses such as a job layoff; or relationship difficulties such as divorce or separation. Other more typical sorts of life changes may trigger depression as well. Even normal developmental milestones such as puberty, marriage, or retirement may serve to trigger depression when a particular event is personally distressing to a given individual. Stressors that trigger depression may be fresh, or they may be past events that are intensely remembered for some reason or another. For example, thinking deeply about stressful past experiences such as emotional, physical, or sexual abuse can be sufficient to trigger an onset of depression. Individuals with Post-Traumatic Stress Disorder (PTSD), who have experienced a traumatic event such as a military battle, rape, severe automobile accident or natural disaster, are more likely to suffer from depression than people who have not experienced such trauma.
A wide range of medical conditions and medications (see below) can also cause or worsen MDD. Major depression frequently co-occurs with other mental illnesses such as: substance-related disorders, panic disorder, obsessive-compulsive disorder, anorexia nervosa, bulimia nervosa, and borderline personality disorder.
At the present time, there is no diagnostic laboratory test (e.g., no blood test or brain scan) that can confirm whether you have Major Depression. However, some laboratory tests can appear abnormal during an active depressive episode. For example, sleep electroencephalograph (measurements of electrical activity in the brain during sleep) abnormalities have been found in 90% of people who are hospitalized for MDD. Even depressed people who do not have symptoms severe enough to require hospitalization often show EEG abnormalities. Other abnormalities in brain chemicals and hormones also occur with depression, but none of the tests examining these factors are stable, reliable, or specific enough at present to develop a foolproof way of diagnosing Major Depression.
Even though lab tests aren’t used to diagnose depression, don’t be surprised if your doctor still sends you to the lab. Medical tests can be helpful in uncovering other conditions such as thyroid trouble, cancer, arthritis, and other diseases discussed later in this article that might be causing depressive symptoms. We will discuss more about how clinicians diagnose depression using lab tests, psychiatric interviews and self-report questionnaires in a later section of this article as well.
Symptoms of Major Depression usually develop over a few days or weeks. Many people feel anxious or mildly depressed for a while before a full depressive episode becomes apparent. Often, the symptoms eventually disappear and functioning returns to normal. The DSM provides labels that describe the course of a person’s Major Depression: “full remission” means no current depressive symptoms; “partial remission” means that the person currently has fewer than five depressive symptoms or has had no symptoms at all for less than two months; and “chronic” means that a person has met all of the diagnostic criteria for Major Depression for two or more years. Approximately 20-30% of people with Major Depression experience partial remission of symptoms, while 5-10% of people have chronic MDD.
This section will focus mainly on Major Depressive Disorder (MDD), commonly referred to as “Major Depression” or simply, “Depression.” Other mood-related conditions will be explored, including Bipolar Disorders, Dysthymic Disorder, Anxiety Disorders, Seasonal Affective Disorder, Mood Disorder Due to a General Medical Condition, Substance-Induced Mood Disorders, Premenstrual Dysphoric Disorder, Schizoaffective Disorder, and Personality Disorders. This section will discuss historical understandings of depression, current biological, psychological, and social interpretations, and a range of available treatments. Use the sidebar to explore all of these topics.
Everyone has days where they feel blah, down, or sad. Typically, these feelings disappear after a day or two, particularly if circumstances change for the better. People experiencing the temporary “blues” don’t feel a sense of crushing hopelessness or helplessness, and are able, for the most part, to continue to engage in regular activities.
Prolonged anhedonia (the inability to experience pleasure), hopelessness, and failure to experience an increase in mood in response positive events rarely accompany “normal” sadness. The same may be said for other, more intense sorts of symptoms such as suicidal thoughts and hallucinations (e.g., hearing voices). Instead, such symptoms suggest that serious varieties of depression may be present, including the subject of this document: Major Depressive Disorder (MDD) or (more informally), Major Depression.
Depression is Complex and Affects Many Areas of Life
For people dealing with Major Depression, negative feelings linger, intensify, and often become debilitating.
Major Depression is a common yet serious medical condition that affects both the mind and body. It is a complex illness, creating physical, psychological, and social symptoms. Although informally, we often use the term “depression” to describe general sadness, the term Major Depression is defined by a formal set of criteria which describe which symptoms must be present before the label may be appropriately used.
Major Depression is a mood disorder. The term “mood” describes one’s emotions or emotional temperature. It is a set of feelings that express a sense of emotional comfort or discomfort. Sometimes, mood is described as a prolonged emotion that colors a person’s whole psychic life and state of well-being. For example, if someone is depressed, they may not feel like exercising. By not exercising for long periods of time, they will eventually experience the negative effects of a sedentary lifestyle such as fatigue, muscle aches and pains, and in some cases, heart disease.
A Continuum of Mood States
Many people are puzzled by the term “Unipolar Depression,” which is another term for Major Depression. The term “Unipolar Depression” is used here to differentiate Major Depression from the other famous sort of depression, Bipolar (or Manic) Depression, which is a separate illness.
It is helpful to think of mood states as occurring on a continuum. During a particular day or week, people can shift from good (or “up”) moods, to bad (or “down”) moods, or remain somewhere in the middle (“neutral” mood). A person who experiences significant impairment related to shifting between up and down moods often has Bipolar Disorder (discussed in more detail later). Bipolar Disorder can be envisioned as a seesaw movement back and forth between two poles or mood states (“bi” means “two”). In contrast to people with Bipolar Disorder, people with Major Depression remain on the down mood pole; they do not exhibit mood swings. Because they are stuck on the down or depressed end of the mood continuum; they experience a unipolar (“uni” means “one”) mood state.
Depression Has Widespread Effects
Mood disorders rank among the top 10 causes of worldwide disability, and Major Depression appears first on the list. Disability and suffering is not limited to the individual diagnosed with MDD. Spouses, children, parents, siblings, and friends of people experiencing Major Depression often experience frustration, guilt, anger, and financial hardship in their attempts to cope with the suffering of their friend or loved one.
Major Depression has a negative impact on the economy as well as the family system. In the workplace, depression is a leading cause of absenteeism and diminished productivity. Although only a minority of people seek professional help to relieve a mood disorder, depressed people are significantly more likely than others to visit a physician. Some people express their sadness in physical ways, and these individuals may undergo extensive and expensive diagnostic procedures and treatments while their mood disorder goes undiagnosed and untreated. As a result, depression-related visits to physicians account for a large portion of health care expenditures.
Understanding Depression
Although the origins of depression are not yet fully understood, we do know that there are a number of factors that can cause a person to suffer from depression. We also know that people who are depressed cannot simply will themselves to snap out of it. Getting better often requires appropriate treatment.Fortunately, there are a wide array of effective treatments available.
The current section provides an in-depth look at Major Depression by summarizing symptoms and diagnostic criteria, prevalence and course, historical and contemporary understandings of the causes of the illness, and assessment and treatment. Use the sidebar to explore all pages in this section.
This TED Ed video, by Helen M. Farrell, talks about the symptoms, possible causes, and some available treatments for depression:
Bipolar Support Groups.com blog 