What Is a Major Depressive Disorder? - Treatment, Symptoms & Definition

Instructor: Shamekia Thomas

Shamekia has taught English at the secondary level and has her doctoral degree in clinical psychology.

Major depressive disorder is one of the most common psychiatric illnesses described in detail in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) set forth by the American Psychiatric Association. Learn more about the types of major depression, symptoms of the disorder, and test your knowledge with a quiz.


Think back over your life. There may have been times when you socialized, thought about the future, had things to look forward to, and had a good time with family and friends. During these times you were likely happy, without a care in the world. On the other hand, there may have also been times when you sat around and watched television all day, when you didn't feel like doing anything, and when you felt like life had no meaning. During these times you are likely sad and find it hard to stay motivated to do anything. At times everyone feels this way. Most people believe their sad mood will pass after a day or two. For people who have major depressive disorder, feelings of sadness can last for weeks or months.


Major Depressive Disorder

Major depressive disorder is the most commonly diagnosed and most severe form of depression often caused by a severe psychosocial stressor, such as ending a relationship, financial difficulty, failing a test, or losing a job. A person experiencing major depressive disorder experiences a depressed mood or loss of interest in activities on a regular basis (almost daily) for at least two weeks.

Depressive symptoms range from mild to severe. For example, someone who is experiencing mild depression is likely to continue functioning in their day-to-day life but might experience anxiety or feelings of restlessness or agitation. On the other hand, someone with severe depression is likely to struggle with getting out of bed to complete day-to-day activities and might feel numb emotionally. Tragically, 15% of individuals with severe major depressive disorder die by suicide. Major depressive disorder is diagnosed when someone meets the following criteria set forth by the American Psychiatric Association in the Diagnostic and Statistical Manuel of Mental Disorders (DSM-IV-TR).

Symptoms of Depression

  • feeling tired or feeling as though you have no energy
  • getting too much or too little sleep
  • decreased appetite with weight loss or increased appetite with weight gain
  • a slowdown of mental and physical activity
  • difficulty thinking or concentrating
  • feelings of worthlessness or guilt
  • thoughts of death or suicide

When someone has major depressive disorder, they experience at least five of the above symptoms as well as feelings of sadness or loss of interest in activities for most days during a two-week period. In addition, these symptoms cause social and occupational difficulties but are not due to the effects of drug abuse, medications, a medical condition, or bereavement.

Types of Major Depressive Disorder

Major depressive disorder, single episode is characterized by one isolated depressive episode based on the symptoms of depression listed above. It is rare for most people to experience only one depressive episode in their life. If two or more major depressive episodes occur, separated by a two-month period without an instance of depression, it is known as major depressive disorder, recurrent. Major depressive disorder, recurrent is much more common than major depressive disorder, single episode, because most people who experience depression once will experience depression again at some point in their life.

Treatment of Major Depressive Disorder

Treatment for major depressive disorder is most effective with early intervention. Most people are treated with a combination of the following methods:

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