Depression (mental illness)

all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities
(Redirected from Depression (illness))

Depression (also called major depressive disorder, unipolar depression or clinical depression) is a mental illness. Many people think that depression just means a person is very sad. However, depression can cause many symptoms in the body as well as mood problems.

Major depressive disorder
Classification and external resources
Depression is common, can affect anyone, and can be treated.
ICD-10F32., F33.
ICD-9296.2, 296.3



The ICD-10 is used around the world to diagnose people with illnesses like depression. According to the ICD-10, for a person to be diagnosed with depression, their symptoms have to last for at least two weeks. The symptoms must happen every day, or almost every day. These symptoms also have to cause problems in a person's life (like their work life, family life, social life, or other important parts of their life).[1]

Usually, for depression to be diagnosed, a person must have five or more of these symptoms:[1]

  • Depressed mood for most of the day (feelings of sadness, emptiness, and/or hopelessness)
  • Feeling much less interested than usual in all, or almost all, activities; or not getting any pleasure from activities
  • Significant weight loss (when not dieting) or weight gain (generally a change of 5% or more in body weight)
  • Sleeping more than usual, or having trouble sleeping
  • Moving around more than usual (psychomotor agitation) or moving more slowly than usual (psychomotor retardation)
  • Feeling tired or not having energy, nearly every day
  • Feeling worthless or guilty
  • Not being able to think, concentrate, or make decisions normally
  • Thinking a lot about death (not just being afraid to die)

Most people who have not had depression do not completely understand its effects. Instead, they see it as simply being sad. Since it is not understood, many people criticize people with depression for not helping themselves.[source?]

Some people with depression die by suicide. Depression is one of the mental illnesses that can cause a person to have suicidal thoughts.



It is impossible to get an exact number of how many people have depression. There are many reasons for this. For example:

  • People may not admit to having depression, because of the stigma about depression.
  • Some people may not be correctly diagnosed with depression.
  • Different doctors and mental health workers may diagnose depression differently.
  • The number of people diagnosed with depression is different in different cultures, and among men and women.

In different cultures


Major depression is one of the most common mental illnesses in the United States.[2] In 2014, 15.7 million adults in the United States had at least one episode of major depression. This is about 6.7% of all adults in the United States.[2]

Around the world, depression causes more disability than any other mental health or behavioral illness, according to the World Health Organization.[2]

However, the prevalence of depression is different in different cultures and countries.

Prince (1968) found virtually no depression in most Asian and African countries. However, psychologists such as Zhang and Kleinman have found disorders with similar symptoms, but different names. For example, in the 1980s, Zhang found that in China, there was little mention of depression. However, instead, a disorder called Neurasthenia was far more common. When interviewing Neurasthenia patients, Zhang found that their symptoms matched the symptoms of depression by over 80%. While the term "depression" was practically unheard of in China, Neurasthenia could well have been a similar disorder – or the same thing.

It is also important to take in different cultures ways of classifying depression. For example, in China, many people believe doctors solve physical symptoms, not mental problems. This may have made it more likely for "depression" to be diagnosed as a medical condition like "Neurasthenia."

In men and women


Typically, in most Western cultures, women are diagnosed with depression twice as often as men. However, men are often more likely than women to die by suicide.[3]

In children


Depression in children can be harder to see. Children who are depressed may have a loss of appetite, meaning that they do not want to eat. They may also be clearly having more trouble in everyday life than before. For example, they may have sleep problems like nightmares; new problems with behaviour or grades at school; or be more irritable than usual.[4]

Types of depression


Major depressive disorder is also referred to as major, biochemical, clinical, endogenous, or biological depression. It may also be called unipolar affective disorder.

There are many subtypes of depression:

Causes of depression


As of 2016, scientists believe there is no one cause of depression. There is a lot of argument over whether depression is caused by biological, cognitive, or sociocultural factors:

  • Biological explanations of depression focus on changes in brain chemicals (neurotransmitters).
  • Cognitive explanations of depression focus on how the way we think (cognition) affects our mood. These explanations say that if a person thinks negatively, this thinking can make them feel negatively about themselves and the world around them.
  • Sociocultural explanations of depression blame stressful things like divorce, losing a job, bullying, and poverty for causing depression.

The United States National Institutes of Health say that depression comes from the brain. However, scientists are still trying to find out exactly why it happens.[5]

Possible causes


There are many theories about what causes depression. These theories include:[source?]

Some depressed people also have other mental disorders, such as personality disorders and anxiety disorders.



Depression is usually treated with a combination of medication and other therapy. Good exercise helps deal with depression, since exercise releases chemicals that put a person in a better mood.[13] Having a supportive group of friends and doing outside activities can also help prevent or ease depression.



There are many medications that can help with depression. Many of these are called antidepressants. Examples of medications used to treat depression include:[14]

  • Selective serotonin reuptake inhibitors (SSRIs). These are now the most commonly used type of antidepressant medicine. These drugs work by allowing the brain to have more serotonin. They have fewer side effects than older antidepressants. Examples include fluoxetine (Prozac), paroxetine (Paxil), and sertraline (Zoloft).
  • Tricyclic antidepressants. These are an older type of antidepressant. They are not used often today because they have many bad side effects and do not work as well as SSRIs. An example is nortriptyline (Allegron).
  • Monoamine oxidase inhibitors (MAOIs). They may be used if other antidepressant medications do not work well. This kind of medicine cannot be taken with many different foods and other medications.

Sometimes, antidepressant medicine works better when it is used together with another drug that is not an antidepressant. These "augmentor" drugs include:[14]

If people with depression do not take their medicine the right way, the depression can get worse. A doctor must help when they want to change to another medication, or to take a different amount of a medication than before.



Psychotherapy is often a helpful treatment for depression.[15] In psychotherapy, a therapist helps a person to understand and solve problems which cause depression. The therapist also helps the person learn skills for dealing with their depression. [15]

Psychotherapy can help a person make changes in the way they think, in order to help with life problems and understand what makes depression worse.[15] The most effective psychotherapy for depression is Cognitive behavioral therapy (CBT).[source?] This teaches a person to think in a more rational, positive, realistic manner.

Surgeries and procedures


Electroconvulsive therapy (ECT), also called electroshock therapy or shock therapy, is used to treat a small percentage of severely depressed people. ECT uses a small amount of electricity to cause an epileptic seizure while the patient is under anesthesia. This may cause some memory loss (amnesia) or other side effects.[16]

In the past, doctors used different ways of treating depression. These are rarely used any more. They include:

Pet therapy


Pet therapy and animal companionship can help people suffering from depression or anxiety.[19]


Further reading



  1. 1.0 1.1 "ICD-10 Resource: Coding for Major Depressive Disorder" (PDF). AAPC. 2013. Archived from the original (PDF) on 21 August 2014. Retrieved September 14, 2016.
  2. 2.0 2.1 2.2 "Major Depression Among Adults". National Institutes of Mental Health. National Institutes of Health. Retrieved September 14, 2016.
  3. "Suicide Statistics Report 2015" (PDF). Archived from the original (PDF) on 16 June 2015.
  4. ‘Child depression’ 2005, in Cambridge Encyclopedia of Child Development, Cambridge University Press, Cambridge, United Kingdom
  5. "NIMH · Causes of Depression". 2011. Archived from the original on July 27, 2011. Retrieved July 18, 2011.
  6. "Medical Scribe - Medical Scribe Training I Medical Scribe Certification". Medical Scribe. Retrieved 2022-12-01.
  7. Psychiatric disorders among Egyptian pesticide applicators and formulators.By Amr MM, Halim ZS, Moussa SS. In Environ Res. 1997;73(1-2):193-9. PMID 9311547
  8. Depression and pesticide exposures among private pesticide applicators enrolled in the Agricultural Health Study. By Beseler CL, Stallones L, Hoppin JA, Alavanja MC, Blair A, Keefe T, Kamel F. In: Environ Health Perspect. 2008 Dec; 116(12):1713-9.PMID 19079725
  9. A cohort study of pesticide poisoning and depression in Colorado farm residents. By Beseler CL, Stallones L. In Ann Epidemiol. 2008 Oct; 18(10):768-74.PMID 18693039
  10. Mood disorders hospitalizations, suicide attempts, and suicide mortality among agricultural workers and residents in an area with intensive use of pesticides in Brazil. By Meyer A, Koifman S, Koifman RJ, Moreira JC, de Rezende Chrisman J, Abreu-Villaca Y. In J Toxicol Environ Health A. 2010; 73(13-14):866-77. PMID 20563920
  11. Suicide and potential occupational exposure to pesticides, Colorado 1990-1999 , By Stallones L. In J Agromedicine. 2006; 11(3-4):107-12. PMID 19274902
  12. Increased risk of suicide with exposure to pesticides in an intensive agricultural area. A 12-year retrospective study. Di Parrón T, Hernández AF, Villanueva E. In Forensic Sci Int. 1996 May 17; 79(1):53-63.PMID 8635774
  13. Dunn, A., Exercise for Depression Rivals Drugs, Therapy. American Journal of Preventive Medicine, January 2005; vol 28: pp 1-8. National Institutes for Mental Health, "Depression." News release, University of Texas Southwestern Medical Center at Dallas.
  14. 14.0 14.1 "Antidepressants: Selecting One That's Right for You". Mayo Clinic Online. Mayo Foundation for Medical Education and Research. 2016. {{cite web}}: Missing or empty |url= (help)
  15. 15.0 15.1 15.2 "Understanding Depression and Effective Treatment". American Psychological Association. July 2010. Retrieved September 15, 2016.
  16. "Electroconvulsive Therapy (ECT)". Mayo Clinic Online. Mayo Foundation for Medical Education and Research. September 19, 2015. Retrieved September 15, 2016.
  17. "American Experience: A Brilliant Madness". WGBH. PBS. Archived from the original on 15 October 2002. Retrieved September 15, 2016.
  18. "Lobotomy".
  19. Dr. Andrew Rosen (21 May 2012). "Pet Therapy Benefits for Depression and Anxiety".
  20. Lin, H. H.; Murray, M.; Cohen, T.; Colijn, C.; Ezzati, M. (2013). "Five Very Different Major Psychiatric Disorders Have Shared Genetics". Lancet (London, England). 372 (9648). Science World Report: 1473–1483. doi:10.1016/S0140-6736(08)61345-8. PMC 2652750. PMID 18835640.
  • Books by psychologists/psychiatrists:
  • Beck, A. T., Rush, A. J., Shaw, B. F., Emery, G. (1987). Cognitive therapy of depression. New York: Guilford.
  • Klein, D. F., & Wender, P. H. (1993). Understanding depression: A complete guide to its diagnosis and treatment. New York: Oxford University Press.
  • Weissman, M. M., Markowitz, J. C., & Klerman, G. L. (2000). Comprehensive guide to interpersonal psychotherapy. New York: Basic Books.
  • Books by persons suffering or having suffered from depression:
  • Smith, Jeffery (2001). Where the roots reach for water: A personal and natural history of melancholia. New York: North Point Press.
  • Solomon, Andrew (2001). The noonday demon: An atlas of depression. New York: Sribner.
  • Styron, William (1992). Darkness visible: A memoir of madness. New York: Vintage Books/Random House.
  • Wolpert, Lewis (2001). Malignant sadness: The anatomy of depression. London: Faber and Faber.
  • Self-help (bibliotherapeutic) books:
  • Lewinsohn, P. M., Munoz, R. F, Youngren, M. A., Zeiss, A. M. (1992). Control your depression. New York: Fireside/Simon&Schuster.

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