Provided by the National Institute of Mental Health
Depression is a serious medical condition. In
contrast to the normal emotional experiences of sadness, loss, or passing mood
states, clinical depression is persistent and can interfere significantly with
an individual's ability to function. There are three main types of depressive
disorders: major depressive disorder, dysthymic disorder, and bipolar disorder
(manic-depressive illness).
Symptoms and Types of Depression
Symptoms of depression include sad mood, loss of interest or pleasure in
activities that were once enjoyed, change in appetite or weight, difficulty
sleeping or oversleeping, physical slowing or agitation, energy loss, feelings
of worthlessness or inappropriate guilt, difficulty thinking or concentrating,
and recurrent thoughts of death or suicide. A diagnosis of major depressive
disorder is made if a person has five or more of these symptoms and impairment
in usual functioning nearly every day during the same 2-week period. Major
depression often begins between ages 15 to 30 but also can appear in children.1
Episodes typically recur.
Some people have a chronic but less severe form of depression, called dysthymic
disorder, which is diagnosed when depressed mood persists for at least 2 years
(1 year in children) and is accompanied by at least two other symptoms of
depression. Many people with dysthymia develop major depressive episodes.
Episodes of depression also occur in people with bipolar disorder. In this
disorder, depression alternates with mania, which is characterized by abnormally
and persistently elevated mood or irritability and symptoms including
overly-inflated self-esteem, decreased need for sleep, increased talkativeness,
racing thoughts, distractibility, physical agitation, and excessive risk taking.
Because bipolar disorder requires different treatment than major depressive
disorder or dysthymia, obtaining an accurate diagnosis is extremely important.
Facts About Depression
Major depression is the leading cause of disability in the U.S. and worldwide.2
Depressive disorders affect an estimated 9.5 percent of Americans ages 18 and
over in a given year,3 or about 18.8 million people in 1998.4
Nearly twice as many women (12 percent) as men (7 percent) are affected by a
depressive disorder each year.3
Depression can be devastating to family relationships, friendships, and the
ability to work or go to school. Many people still believe that the emotional
symptoms caused by depression are "not real," and that a person should be able
to shake off the symptoms. Because of these inaccurate beliefs, people with
depression either may not recognize that they have a treatable disorder or may
be discouraged from seeking or staying on treatment due to feelings of shame and
stigma. Too often, untreated or inadequately treated depression is associated
with suicide.5
Treatments
Antidepressant medications are widely used and effective treatments for
depression.6 Existing antidepressants influence the functioning of certain
chemicals in the brain called neurotransmitters. The newer medications, such as
the selective serotonin reuptake inhibitors (SSRIs), tend to have fewer side
effects than the older drugs, which include tricyclic antidepressants (TCAs) and
monoamine oxidase inhibitors (MAOIs). Although both generations of medications
are effective in relieving depression, some people will respond to one type of
drug, but not another. Other types of antidepressants are now in development.
Certain types of psychotherapy, specifically cognitive-behavioral therapy (CBT)
and interpersonal therapy (IPT), have been found helpful for depression.
Research indicates that mild to moderate depression often can be treated
successfully with either therapy alone; however, severe depression appears more
likely to respond to a combination of psychotherapy and medication.7 More than
80 percent of people with depressive disorders improve when they receive
appropriate treatment.8
In situations where medication, psychotherapy, and the combination of these
interventions prove ineffective, or work too slowly to relieve severe symptoms
such as psychosis (e.g., hallucinations, delusional thinking) or suicidality,
electroconvulsive therapy (ECT) may be considered. ECT is a highly effective
treatment for severe depressive episodes. The possibility of long-lasting memory
problems, although a concern in the past, has been significantly reduced with
modern ECT techniques. However, the potential benefits and risks of ECT, and of
available alternative interventions, should be carefully reviewed and discussed
with individuals considering this treatment and, where appropriate, with family
or friends.9
One herbal supplement, hypericum or St. John's wort, has been promoted as having
antidepressant properties. However, results from the first large-scale,
controlled study of St. John's wort for major depression, which was funded in
part by NIMH, revealed that the herb was no more effective than placebo for
treating major depression of moderate severity.10 More research is needed to
comfirm the role of St. John's wort in managing less severe forms of depression.
Note: There is evidence that St. John's wort can reduce the effectiveness of
certain medications. Use of any herbal or natural supplements should always be
discussed with your doctor before they are tried.
Research Findings
Brain imaging research is revealing that in depression, neural circuits
responsible for moods, thinking, sleep, appetite, and behavior fail to function
properly, and that the regulation of critical neurotransmitters is impaired.11
Genetics research, including studies of twins, indicates that genes play a role
in depression. Vulnerability to depression appears to result from the influence
of multiple genes acting together with environmental factors.12
Other research has shown that stressful life events, particularly in the form of
loss such as the death of a close family member, may trigger major depression in
susceptible individuals.13
The hypothalamic-pituitary-adrenal (HPA) axis, the hormonal system that
regulates the body's response to stress, is overactive in many people with
depression. Research findings suggest that persistent overactivation of this
system may lay the groundwork for depression.14
Studies of brain chemistry, mechanisms of action of antidepressant medications,
and the cognitive distortions and disturbed interpersonal relationships commonly
associated with depression, continue to inform the development of new and better
treatments.
Clinical Trials
NIMH conducts and supports a range of clinical trials—research studies that
involve patients—on depressive disorders in both adults and children. Trials may
test methods for diagnosis, treatment, risk assessment/prediction, or prevention
of depressive disorders and are conducted with well-crafted safeguards to
protect participants. For more information about ongoing trials, visit the
Clinical Trials: Mood Disorders page of the NIMH Web site.
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For More Information
Please visit the following link for more information about organizations that
focus on depression.
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All material in this fact sheet is in the public domain and may be copied or
reproduced without permission from the Institute. Citation of the source is
appreciated.
NIH Publication No. 01-4591
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References
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depression: a review of the past 10 years. Part I. Journal of the American
Academy of Child and Adolescent Psychiatry, 1996; 35(11): 1427-39.
2 World Health Organization. The World Health Report 2001 - Mental Health: New
Understanding, New Hope. Geneva World Health Organization, 2001.
3 Regier DA, Narrow WE, Rae DS, et al. The de facto mental and addictive
disorders service system. Epidemiologic Catchment Area prospective 1-year
prevalence rates of disorders and services. Archives of General Psychiatry,
1993; 50(2): 85-94.
4 Narrow WE. Table: One-year prevalence of depressive disorders among adults 18
and over in the U.S.: NIMH ECA prospective data. Population estimates based on
U.S. Census estimated residential population age 18 and over on July 1, 1998.
Personal communication.
5 Conwell Y, Brent D. Suicide and aging I: patterns of psychiatric diagnosis.
International Psychogeriatrics, 1995; 7(2): 149-64.
6 Mulrow CD, Williams JW Jr., Trivedi M, et al. Evidence report on treatment of
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409-795.
7 Hyman SE, Rudorfer MV. Depressive and bipolar mood disorders. In: Dale DC,
Federman DD, eds. Scientific American® Medicine. Volume 3. New York: Healtheon/WebMD
Corp., 2000, Sect. 13, Subsect. II, p. 1.
8 National Advisory Mental Health Council. Health care reform for Americans with
severe mental illnesses. American Journal of Psychiatry, 1993; 150(10): 1447-65.
9 U.S. Department of Health and Human Services. Mental health: a report of the
Surgeon General. Rockville, MD: U.S. Department of Health and Human Services,
Substance Abuse and Mental Health Services Administration, Center for Mental
Health Services, National Institutes of Health, National Institute of Mental
Health, 1999.
10 Hypericum Depression Trial Study Group. Effect of Hypericum perforatum (St.
John's wort) in major depressive disorder: a randomized, controlled trial.
Journal of the American Medical Association, 2002; 287(14):1807-14.
11 Soares JC, Mann JJ. The functional neuroanatomy of mood disorders. Journal of
Psychiatric Research, 1997; 31(4): 393-432.
12 NIMH Genetics Workgroup. Genetics and mental disorders. NIH Publication No.
98-4268. Rockville, MD: National Institute of Mental Health, 1998.
13 Mazure CM, Bruce ML, Maciejewski PW, et al. Adverse life events and
cognitive-personality characteristics in the prediction of major depression and
antidepressant response. American Journal of Psychiatry, 2000; 157(6): 896-903.
14 Arborelius L, Owens MJ, Plotsky PM, et al. The role of corticotropin-releasing
factor in depression and anxiety disorders. Journal of Endocrinology, 1999;
160(1): 1-12.
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