Depression can be thought of as a mood disorder, a syndrome involving a collection of symptoms irrespective of the presence of other psychological or medical disorders. Depression itself can be a symptom of other diagnosed disorders. As its own psychological dysfunction syndrome, depression is a constellation of signs and symptoms that cluster together (e.g., sadness, negative self-concept, sleep and appetite disturbances, loss of pleasure). In its most serious forms, depression is a disabling disorder that is associated with emotional distress, severe social and occupational disruption, increased risk for physical illness and sometimes death. Up to 15% of individuals with severe Major Depressive Disorder die by suicide. Depression is frequently a chronic disorder that can last for months or even years. Nevertheless, it has been proven that most severe depression can be improved with treatment.
The National Institute of Mental Health (NIMH) indicates that more than 19 million adult Americans experience some form of depression each year. Depression is the leading cause of disability in the U.S. According to NIMH and the costs associated with depression are more than $30 billion per year.1 Needless to say, depression is one of the most commonly encountered disorders by mental health professionals. Further estimates suggest that by 2010, depression will be the second most costly of all illnesses worldwide—in 1990 it was ranked fourth.2
Major Depressive Disorder is characterized as a period of unhappiness or low morale which lasts longer than several weeks and may include ideation of self-inflicted injury or suicide. Dysthymia, a related disorder, is characterized by depression symptoms that last two years or longer but at a lower severity. Other types of depression including postpartum depression, bipolar depression and seasonal affective disorder (SAD) are treated with different protocols as prescribed by a psychiatrist and/or clinical psychologist.
No amount of data can adequately capture or convey the personal pain and suffering experienced in depression. Yet most depressed people do not get professional help. Depression effects a fairly large number of people—20% of people are impacted but only one-quarter of them seek any type of treatment.3 Even though the vast majority of people recover from depression, they remain vulnerable to future symptoms and depressive episodes. At least 50% of individuals who suffer from one depressive episode will have another within 10 years. Those experiencing two episodes have a 90% chance of suffering a third while individuals with three or more lifetime episodes have relapse rates of 40% within 15 weeks of recovery from an episode.4
Major Depressive disorder is highlighted in this health challenge as it is the most prevalent form of depression. However, many types of depression exist.
Read more about the varied clinical diagnosis of depression: Types of Depression
Read more about Women's Depression
Read more about Men's Depression
Read more about Childhood Depression
Read more about Adolescent Depression
Read more about History of Depression
Prevalence estimates vary considerably depending upon the aspects and/or kinds of depression being estimated. When depression is defined as a negative mood, most people would probably admit to having been depressed at some point. Fewer estimates have been attempted to assess the numbers of people with the syndromal features indicative of depression. A large number of studies have been conducted to identify the number of individuals meeting diagnostic criteria for a major depressive disorder. Regarding gender, depression tends to be more common in women than in men. When variables such as socioeconomic status are controlled, current research has not detected markedly different rates of depression for different ethnicities throughout the United States.
Some studies of depression outside of North America find slight differences in lifetime and one-year prevalence rates. In the U.S., the Epidemiological Catchment Area (ECA) study found a mean lifetime prevalence rate of 4.9% for a major depressive disorder.8 Some research suggests that the rate of depression in Taiwan is generally lower. The rate in New Zealand was considerably higher than in the ECA study, with a lifetime prevalence rate of 12.6%. This difference was due to the presence of more depressed older women and younger men in the sample.10 Estimates of depression in Ghana and Nigeria have been as high as 20%.11 These differences must be considered cautiously, however, in that they may be due to differences in the samples and methods used to diagnose depression. Nevertheless, setting the differences aside, it is evident that depression is a syndrome that is experienced worldwide.
Some people have isolated episodes of depression that are separated by many years without any depressive symptoms, whereas others have clusters of episodes, and still others have increasingly frequent episodes as they age. Some evidence suggests the periods of remission generally last longer early in the course of the disorder. The number of prior episodes predicts the likelihood of developing a subsequent Major Depressive Episode. At least 60% of individuals with a single episode of Major Depressive Disorder can be expected can be expected to have a second episode. Individuals who have had two episodes have a 70% chance of having a third, and individuals who have had three episodes have a 90% chance of having a fourth.12
- National Institute of Mental Health. (1999).
- Keller, M. B., & Boland, R. J. (1998). Implications of failing to achieve successful long-term maintenance treatment of of recurrent unipolar major depression. Biological Psychiatry, 44(5), 348-360.
- Jarrett, R. B. (1995). Comparing and combining short-term psychotherapy and pharmacotherapy for depression. In E. E. Beckham & W. R. Leber (Eds.), Handbook of depression (2nd ed., pp. 435-464). New York: Guilford Press.
- Kupfer, D J., Frank, E., & Warmhoff, J. (1996). Mood disorders: Update on prevention of recurrence. In C. Mundt, M. M. Goldstein, K. Hahlweg, & P. Fielder (Eds.), Interpersonal factors in the origin and course of affective disorders (pp. 289-302). London: Gaskell/Royal College of Psychiatrists.
- Ingram, R. E., Scott, W., & Siegle, G. (1999). Depression: Social and Cognitive Aspects. In T. Millon, P. H. Blaney, & R. D. Davis' (Eds.), Oxford textbook of psychopathology (pp.203-226). New York: Oxford Press.
- Abraham, K. (1911/1960). Notes on the psychoanalytic investigation and treatment of manic-depressive insanity and allied conditions. In Selected Papers on Psychoanalysis (pp. 12-24). New York: Basic Books.
- Freud, S. (1917/1950). Mourning and melancholia. In Collected Papers (Vol. 4). London: Hogarth Press.
- Freedman, D. X. (1984). Psychiatric epidemiology counts. Archives of General Psychiatry, 41, 931-933.
- Hwu, H., Yeh, E. K., & Chang, L. Y. (1989). Prevalence of psychiatric disorders in Taiwan defined by the Chinese Diagnostic Interview Schedule. Acta Psychiatrica Scandiinavica, 79, 136-147.
- Oakley-Browne, M. A., Joyce, P. R., Wells, J. E., & Bushell, J. A. (1989). Christchurch Psychiatric Epidemiology Study: II. Six month and other period prevalence of specific psychiatric disorders. Australian and New Zealand Journal of Psychiatry, 23, 327-340.
- Flaherty, J. A., Gavira, F. M., & Val, E. R. (1982). Diagnostic considerations. In E. R. Val, F. M. Gavira, & J. A. Flaherty (Eds.), Affective disorders: Psychopathology and treatment. Chicag Year Book Medical Publishers.
- American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders, Fourth Edition: Text Revision. Washington, DC: Author.