It is common to feel sad, discouraged, or "down" once in a while, and anyone in this state might say they are suffering from a depressed mood. But for some people, this mood persists. For depression, or any other condition, to be termed "clinical" it must reach criteria which are generally accepted by clinicians. When symptoms last two weeks or more, and are so severe that they interfere with daily living, one can be said to be suffering from clinical depression. Using DSM-IV-TR terminology, someone with a major depressive disorder can, by definition, be said to be suffering from clinical depression.

Clinical depression affects about 16%1 of the population at one time or another in their lives. The mean age of onset from a number of studies is in the late 20s. About twice as many women as men report or receive treatment for clinical depression, though the gap is shrinking and this difference disappears after menopause. Clinical Depression is expected to become the second leading cause of disability worldwide (after Heart Disease) by the year 2020 according to the World Health Organization5.


Signs and symptoms
According to the DSM-IV-TR criteria for diagnosing a major depressive disorder one or both of the following two required elements need to be present:

Depressed mood, or Loss of interest or pleasure. 

It is sufficient to have either of these symptoms in conjunction with four of a list of other symptoms, these include:

Feelings of overwhelming sadness or fear, or seeming inability to feel emotion. 
Marked decrease of interest in pleasurable activities. 
Changing appetite and marked weight gain or weight loss. 
Disturbed sleep patterns, either insomnia or sleeping more than normal. 
Changes in activity levels, restless or moving significantly slower than normal. 
Fatigue, both mental and physical. 
Feelings of guilt, helplessness, anxiety, and/or fear. 
Lowered self-esteem. 
Decreased ability to concentrate or make decisions. 
Thinking about death or suicide. 
The diagnosis does not require "loss of interest in life, anhedonia". Likewise, "lack of energy and motivation" is not at all a required symptom of a major depressive episode.

Improper drug or alcohol use is not a diagnostic symptom, but often accompanies and may be a causal factor in major depression.

Andrew Solomon in his book The Noonday Demon (p.20) states that the DSM IV list of symptoms is, "entirely arbitrary [and] having slight versions of all the symptoms may be less of a problem than having severe versions of two symptoms".

Depression in children is not as obvious as it is in adults; symptoms children demonstrate include:

Loss of appetite. 
Sleep problems such as nightmares. 
Problems with behavior or grades at school where none existed before. 
Significant behavioral changes; becoming withdrawn, sulky, aggressive. 
In older children and adolescents, an additional indicator may be the use of drugs or alcohol. Moreover, depressed adolescents are at risk for further destructive behaviours, such as eating disorders and self-harm.

It is hard for people who have not experienced clinical depression, either personally or by regular exposure to people suffering it, to understand its emotional impact and severity, interpreting it instead as being similar to "having the blues" or "feeling down". As the list of symptoms above indicates, clinical depression is a syndrome of interlocking symptoms which goes far beyond sad or painful feelings. A variety of biological indicators, including measurement of neurotransmitter levels, have shown that there are significant changes in brain chemistry and an overall reduction in brain activity. One consequence of a lack of understanding of its nature is that depressed individuals are often criticized by themselves and others for not making an effort to help themselves. However, the very nature of depression alters the way people think and react to situations to the point where they may become so pessimistic that they can do little or nothing about their condition. Because of this profound and often overwhelmingly negative outlook, it is imperative that the depressed individual seek professional help. Untreated depression is typically characterized by progressively worsening episodes separated by plateaus of temporary stability or remission. If left untreated it will generally resolve within six months to two years although occasionally depression becomes chronic and lasts for many years or indefinitely. In many cases (but not all) treatment can shorten the period of distress to a matter of weeks. While depressed, the person may damage themselves socially (e.g. the break up of relationships), occupationally (e.g. loss of a job), financially and physically. Treatment of depression can significantly reduce the incidence of this damage, including reducing the risk of suicide which is otherwise a common and tragic outcome. For all of these reasons, treatment of clinical depression is seen by many as very useful and at times life saving.

Some people can experience anhedonia for long periods of time before they discover it is a mental illness. The inability to feel pleasure can advance negativity already present in a depressed person's mental state.


Historical perspective
The modern idea of depression seems to be the same as the much older concept of melancholia. The name melancholia derives from 'black bile', one of the 'four humours' postulated by Hippocrates.

The Ebers papyrus (ca 1550 BC) contains a short description of clinical depression. Though full of incantations and foul applications meant to turn away disease-causing demons and other superstition, it also evidences a long tradition of empirical practice and observation.


Types of major depression
Major depression is also referred to as major depressive disorder or biochemical, clinical, endogenous, unipolar, or biological depression. It is characterized by a severely depressed mood that persists for at least two weeks. Episodes of depression may start suddenly or slowly and can occur several times through a person's life. Major depressive disorder may be categorized as "single episode" or "recurrent" depending on whether previous episodes have been experienced before.

Clinicians recognize several subtypes of major depression.

Psychotic depression is accompanied by hallucinations or delusions. 
Melancholic depression (what used to be referred to as endogenous depression) is characterized by insomnia, poor appetite and weight loss, less responsive mood, and morning worsening. 
Atypical depression is characterized by "reversed vegetative symptoms" which include oversleeping, overeating, leaden paralysis, rejection sensitivity and temporary brightening of mood in response to positive events. It may overlap with anxiety and panic attacks. It is often more chronic than melancholic depression. 
Dysthymia is a long-term, mild depression that lasts for at least two years. By definition the symptoms are not as severe as in major depression, although those with dysthymia are highly likely to have superimposed major depressive episodes (known as "double depression"). It often begins in adolescence and spans several decades. 
Major depression may also be referred to as unipolar affective disorder, a term which emphasizes its relatedness to bipolar disorder.


Unipolar vs bipolar disorder
Bipolar disorder is a cyclical illness in which moods fluctuate between mania (extreme happiness or giddiness and frantic activity) and clinical depression. Bipolar disorder has also been commonly called "manic depression", although this usage is now unpopular with psychiatrists, who have standardised on Kraepelin's usage of the term "manic depression" to describe the whole bipolar spectrum that includes both bipolar disorder and unipolar depression; they now usually use the term bipolar disorder. This then leaves the term unipolar depression which is used to differentiate it from bipolar disorder.


Causes of depression
No specific cause for depression has been identified, but there are a number of factors believed to be involved.

Heredity The tendency to develop depression may be inherited; there is some evidence that this disorder may run in families. 

Brain chemicals called neurotransmitters allow electrical signals to move from the axon of one nerve cell to the neuron of another. A shortage of neurotransmitters impairs brain communication.Physiology There may be changes or imbalances in chemicals which transmit information in the brain, called neurotransmitters. Many modern antidepressant drugs attempt to increase levels of certain neurotransmitters, like serotonin. While the causal relationship is unclear, it is known that antidepressant medications do relieve certain symptoms of depression. Seasonal affective disorder (SAD) is a type of depressive disorder that occurs in the winter when daylight hours are short. It is believed that the body's production of melatonin, which is produced at increased levels in the dark, plays a major part in the onset of SAD, and that many sufferers respond well to bright light therapy, also known as phototherapy. 
Psychological factors Low self-esteem and self-defeating or distorted thinking are connected with depression. While it is not clear which is the cause and which is the effect, it is known that sufferers who are able to make corrections to their thinking patterns can show improved mood and self-esteem. Psychological factors include the complex development of one's personality and how one has learned to cope with external environmental factors, such as stress. 
Early experiences Events such as the death of a parent, abandonment or rejection, neglect, chronic illness, and severe physical, psychological, or sexual abuse can also increase the likelihood of depression later in life. Post-traumatic stress disorder (PTSD) includes depression as one of its major symptoms. 
Life experiences Job loss, financial difficulties, long periods of unemployment, the loss of a spouse or other family member, or other traumatic events may trigger depression. Long-term stress, at home, work or school, can also be involved. 
Medical conditions Certain illnesses including hepatitis or mononucleosis may contribute to depression, as may certain prescription drugs such as birth control pills and steroids. 
Alcohol and other drugs Alcohol can have a negative effect on mood, and misuse or abuse of alcohol, benzodiazepine-based tranquillizers and sleeping medications, or narcotics can all play a major role in the length and severity of depression. 
Post-partum depression About ten percent of new mothers experience some form of depression after childbirth. When it occurs, the onset is typically within three months after delivery, and it may last for several months. About two new mothers out of a thousand have depression so severe it includes hallucinations or delusions. 
Living with a depressed person Those living with someone suffering from depression experience increased anxiety, and life disruption, which increases the possibility of their also becoming depressed. 

Treatment
Treatment of depression varies broadly, and is different for each individual. Various types and combinations of treatments may have to be tried. There are two primary modes of treatment, typically employed in conjunction with one another, medication and psychotherapy. A third treatment, electroconvulsive therapy (ECT) may be used where chemical treatment fails. Other alternative treatments used for depression include exercise, and the use of vitamins, herbs, or other nutritional supplements.

The effectiveness of treatment often depends on factors such as the amount of optimism and hope the sufferer is able to maintain, the control s/he has over stressors, the severity of symptoms, the amount of time the sufferer has been depressed, the results of previous treatments, and the degree of support of family, friends, and significant others.

While treatment is generally effective there are some cases of where the condition fails to respond. Treatment resistant depression requires a full assessment which may lead to the addition of psychotherapy, higher medication doses, changes of medication or combination therapy, a trial of ECT or even a change in the diagnosis with subsequent treatment changes. Although this process helps many, some people continue with their symptoms unabated.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Clinical_depression"

First Aid - Health & Medical Information Disclaimer