Depression (mental 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.

## Diagnosis
The ICD-10 is used around the world to diagnose people with illnesses like depression. As per 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). 

### Symptoms
Usually, for depression to be diagnosed, a person must have five or more of these symptoms: 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.

## Children
Depression in children can be harder to notice. 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.

## Types
**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:
* *Melancholia*, or *melancholic depression*, is very severe (bad). It can cause many physical changes, like sleep and appetite changes. It can also cause a person to change their behavior - for example, by not wanting to be around other people.
* *Psychotic depression* is much like melancholia, but with hallucinations or delusions.
* *Atypical depression* causes anxiety and panic attacks.
* *Chronic dysthymic disorder* is a long-term, mild depression that lasts for at least two years. It often begins in adolescence and lasts for many years.
* *Seasonal affective disorder* (SAD) is when the depression seems to be related to the winter season. It usually starts in the autumn and goes away in the spring every year.  It is common in Alaska, Canada, and Scandinavia (Sweden, Norway, Denmark, and Finland), but not in Iceland.

## Causes
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.

### Possible causes
There are many theories about what causes depression.  These theories include:

* **Heredity** (someone's genes): Depression often runs in families. However, people can get depression even if they are not related to anyone else who has it.
* **Physiology**: The amounts of some chemicals in the brain. Serotonin is the main chemical in the brain that has to do with happiness. Many antidepressant medications work by balancing the amount of serotonin in the brain.
* **Psychological factors**: Low self-esteem and harmful thinking
* **Early experiences**: Events such as the death of a parent or guardian, abandonment or rejection, neglect, chronic illness, and severe physical, psychological, or sexual abuse.
* **Life experiences**: Losing a job, homelessness, problems with money, death of a loved one, relationship problems, separation from a partner, being a victim of crime, or other life problems can cause depression.
* **Medical conditions**: Some illnesses, such as hypothyroidism, hepatitis, mononucleosis, or head injuries, may contribute to depression.
* **Alcohol and other drugs**: Alcohol can make people depressed. If a person abuses alcohol, benzodiazepine-based tranquillizers, sleeping medications, or narcotics, it can affect how long their depression lasts and how bad it is. Some medicines like birth control pills and steroids may also contribute to depression.
* **Pesticides**: Several scientific studies  have found statistical links between depression and some pesticide. Some depressed people also have other mental disorders, such as personality disorders and anxiety disorders.

## Treatment
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. Having a supportive group of friends and doing outside activities can also help prevent or ease depression.

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

**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: 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. 

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

* Insulin shock treatment. The doctor would lower a patient's blood sugar so much that the patient would have a seizure.
* Lobotomy. This is a form of surgery. The surgeon would use an ice pick or a surgical knife to cut nerves in the frontal lobe of the brain.

### Pet therapy
Pet therapy and animal companionship can help people suffering from depression or anxiety.

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

## Related pages
* Mania
* Melancholia
* Dysthymia, a long-lasting mild depression
* Cyclothymia, a mild form of bipolar disorder
* Bipolar disorder, a mood disorder which involves both mania and depression

## Further reading
* Study showing genetic links between depression and four other major psychiatric disorders: autism ADHD, bipolar disorder, and schizophrenia
**5 Disorders Share Genetic Risk Factors, Study Finds* (*The New York Times*, February 28, 2013)
**Psychiatric Disorders Linked Genetically* (*The Wall Street Journal*, February 27, 2013)

## Books
* 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.

## Other websites
*Clinical-Depression
*Internet Mental Health: Major Depressive Disorder
* Depression Alliance website (UK charity) [useful information]
*Depression Fact Sheets [Facts about the causes, symptoms, and treatment of depressive disorders.]
* Detailed information [concerning Emil Kraepelin, who identified Manic Depression]
* Depression – A Silent Killer!  [Major Causes, Types of Depression, Treatment for Depression]

## References