Major Depressive Disorder (MDD)

Reviewed by: HU Medical Review Board | February 2012 | Last updated: May 2020

Major Depressive Disorder: Introduction

Major Depressive Disorder (MDD) is characterized by one or more periods of depressed mood and/or loss of interest or pleasure in most or all activities.

It’s estimated that close to 15 million adults in the US, or 6.7% of the population, experience major depressive episodes in any given year, and that depression accounts for two-thirds of all suicides in the United States.

Diagnosing Major Depressive Disorder

This illness can be diagnosed from a single period of time meeting the criteria for a major depressive episode or from recurring episodes. Those criteria are:

  1. As mentioned above, depressed mood all day, nearly every day, for at least two weeks, and/or
  2. Distinct decrease in interest or pleasure in all or nearly all activities, most of or all day, almost every day, for at least two weeks.
  3. The symptoms, including those below, “cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.”

In addition, there must be three or more other symptoms during the same period of time. These possible symptoms are:

  • Significant weight gain or loss;
  • Trouble sleeping or sleeping too much;
  • Fatigue or loss of energy most of the time;
  • Difficulty focusing, concentrating, and/or making decisions;
  • Feeling worthless and/or excessively/inappropriately guilty;
  • Being slowed down or unusually restless in ways that others can see;
  • Recurring thoughts of death or suicide.

These symptoms may have been triggered by an event in the patient’s life, but often there is no apparent reason why the patient becomes depressed. When there are two or more major depressive episodes, there are also periods of time in between when the patient is symptom-free.

An Example of a Major Depressive Episode

Kelly, who is 30 and single, is a salon hair stylist who loves her job. In her spare time, she enjoys gardening, camping and cooking. She attends church regularly and teaches Sunday school.

But when depression hits her, everything changes. She drags herself to work and is slow doing her job. She loses her appetite, often skipping lunch altogether. After work she grabs whatever food is handy, then goes to bed, sleeping 12-14 hours. She often misses church and Sunday school, and when she does teach, others can hear and see that her speech and movements are slower than normal. She’s tired all the time. Weeds grow in her garden and she doesn’t care. She loses weight from not eating.

Eventually the depressive mood lifts and she is back to her normal, cheerful self.

Treatment of Major Depressive Disorder

The primary treatment for this illness is antidepressant medication, with or without talk therapy. A particular type of professional treatment called Cognitive Behavioral Therapy has been shown to be effective in helping people to deal with the effects of depression.

Major Depressive Disorder and Migraine

Researchers are finding a high correlation between clinical depression and migraine. For example, a study published in 2011 found that patients with migraine were 60% more likely to develop major depression than those without migraine.

Patients with MDD and with histories of stress and childhood trauma were 40% more likely to develop migraine, but without those histories, clinically depressed patients were no more likely to have migraines than non-depressed persons.

A 2006 study found that patients with MDD and migraine had more anxiety and physical symptoms than MDD patients without migraine. In addition, 50% of migraineurs with MDD said their migraines worsened during or after a depressive episode. The authors of this study recommended that headache be treated as an important co-occurring illness with major depression because of the degree of problematic interaction between the two.

The reason for the strong connection between major depressive disorder and migraine remains unknown, but there is some implication that the same neurological processes might be involved. Researchers have found that some antidepressants can decrease the frequency of migraines, notably Prozac (fluoxetine), Paxil (paroxetine) and Zoloft (sertraline).

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