Depression

Clinical depression is state of sadness or melancholia that has advanced to the point of being disruptive to an individual's social functioning and/or activities of daily living. The diagnosis may be applied when an individual meets a sufficient number of the symptomatic criteria for the depression spectrum as suggested in the DSM-IV-TR or ICD-9/10. It is important to note that an individual may suffer from what is termed a "clinical depression" without fully meeting the criteria for a specific diagnosis on the depression spectrum. Clinically, this is referred to as a "depressed mood". This state is typically psycho-social in nature, as opposed to organic (chemical). A strict clinical diagnosis of Depression, and/or its various corollaries, almost invariably maintains the presence of a biological component.

Although a mood characterized by sadness is often colloquially referred to as depression, clinical depression is something more than just a temporary state of sadness. Symptoms lasting two weeks or longer, and of a severity that begins to interfere with typical social functioning and/or activities of daily living, are considered to constitute clinical depression.

Clinical depression affects about 16%[1] of the population on at least one occasion in their lives. The mean age of onset, from a number of studies, is in the late 20s. About twice as many females as males report or receive treatment for clinical depression, though this imbalance is shrinking over the course of recent history; this difference seems to completely disappear after the age of 50 - 55, when most females have passed the end of menopause. Clinical depression is currently the leading cause of disability in the US as well as other countries, and is expected to become the second leading cause of disability worldwide (after heart disease) by the year 2020, according to the World Health Organization[2].

On a historical note, the modern idea of depression appears similar to the much older concept of melancholia. The name melancholia derives from 'black bile', one of the 'four humours' postulated by Galen.

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 evinces a long tradition of empirical practice and observation.

Contents
1 Signs and symptoms
2 Types of depression
3 Anxiety and Stress in Depression

Signs and symptoms
According to the DSM-IV-TR criteria for diagnosing a major depressive disorder (see also: DSM cautionary statement) one 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 the seeming inability to feel emotion.
A decrease in the amount of pleasure derived from what were previously pleasurable activities.
Changing appetite and marked weight gain or weight loss.
Disturbed sleep patterns, such as insomnia, loss of REM sleep, or excessive sleep.
Changes in activity levels, such as restlessness or a slowing of movement.
Fatigue, either/both mental and physical.
Feelings of guilt, helplessness, hopelessness, anxiety, and/or fear.
A decrease in self-esteem.
Trouble concentrating or making decisions, or a generalized slowing and obtunding of cognition.
Self-harm or ruminating on self-harm.
Ruminating on death and/or suicide.
Reduced memory.
Depression in children is not as obvious as it is in adults. Here are some symptoms that children might display:

Loss of appetite.
Sleep problems, such as recurrent nightmares.
Learning or memory problems where none existed before.
Significant behavioural changes; such as withdrawal, social isolation and aggression.
An additional indicator could be the excessive use of drugs or alcohol. Depressed adolescents are at particular risk of further destructive behaviors, such as eating disorders and self-harm.

One of the most widely used instruments for measuring depression severity is the Beck Depression Inventory, a 21 question multiple choice survey.

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 serious, potentially lethal systemic disorder characterized by interlocking physical, affective, and cognitive symptoms which have consequences for function and survival well beyond sad or painful feelings.

Types of depression
Major Depression, or, more properly, 'Major Depressive Disorder' (MDD) is characterized by a severely depressed mood that persists for at least two weeks, and is generally recognized to contain an organic (chemical) component. Major Depressive Disorder is specified as either "a single episode" or "recurrent", as periods of depression may occur as discrete events or as recurrent over the lifespan.

Diagnosticians recognize several sub-types of Major Depressive Disorder.

Catatonic Features Specification - Catatonia is characterized by motoric immobility evidenced by catalepsy or stupor. This MDD sub-type may also manifest excessive, non-prompted motor activity (akathesia), extreme negativism and/or mutism, and peculiarities in movement, including stereotypical movements, prominent mannerisms, and/or prominent grimacing. There may also be evidence of echolalia or echopraxia.
Melancholic Features Specification - Melancholia is characterized by a loss of pleasure (anhedonia) in most or all activities, a failure of reactivity to pleasurable stimuli, a quality of depressed mood more pronounced than that of grief or loss, a worsening of symptoms in the morning hours, early morning waking, psychomotor retardation, anorexia (excessive weight loss, not to be confused with Anorexia Nervosa), and/or excessive guilt.
Atypical Features Specification Atypicality is characterized by mood reactivity (paradoxical anhedonia) and positivity, significant weight gain or increased appetite, excessive sleep or somnolence (hypersomnia), leaden paralysis, and/or significant social impairment as a consequence of hyper-sensitivity to perceived interpersonal rejection.
Psychotic Features Specification presents with hallucinations or delusions that are either mood-congruent (content coincident with depressive themes) or non-mood-congruent (content not coincident with depressive themes). It is clinically more common to encounter a delusional system as an adjunct to depression than to encounter hallucinations, whether visual or auditory.
Dysthymia is a long-term, mild depression that lasts for a minimum two years. By definition the symptoms are not as severe as with Major Depression, although those with Dysthymia are vulnerable to co-occurring episodes of Major Depression. This disorder often begins in adolescence, and crosses the lifespan.
Bipolar I Disorder is an episodic illness in which moods may cycle between mania and depression. In the US, Bipolar Disorder was previously referred to as "Manic Depression". This term is no longer favored by the medical community as not all Bipolar individuals will present depressive symptoms. "Manic Depression" is still often used in the non-medical community.
Bipolar II Disorder is an episodic illness that is defined primarily by depression, but evidences episodes of hypomania.

Anxiety and Stress in Depression
The different types of Depression and Anxiety are classified separately by the DSM-IV-TR, with the exception of hypomania, which is included under the Bipolar Disorder category. Despite the different categories, depression and anxiety can indeed be co-occurring (occurring together, independently, and without mood congruence), or co-morbid (occurring together, with overlapping symptoms, and with mood congruence). In an effort to bridge the gap between the DSM-IV-TR categories and what clinicians actually encounter, experts such as Herman Van Praag of the Maastricht University have proposed ideas like anxiety/aggression-driven depression [citation needed]. This idea, and others like it, refers to an anxiety/depression spectrum for these two disorders, which differs from the mainstream perspective of discreet diagnostic categories.

While there is no specific diagnostic category for the co-morbidity of depression and anxiety in the DSM or ICD, the National Comorbidity Survey (US) reports that some 58 percent of those with major depression also suffer from lifetime anxiety citation. Supporting of this finding, two widely accepted clinical colloquiallisms include:

agitated depression - referring to a state of depression that presents as anxiety, that includes akathisia, suicide, insomnia (not early morning wakefulness), non-clinical (meaning “doesn’t meet the standard for formal diagnosis”) and non-specific panic, and a general sense of dread.
akathitic depression - referring to a state of depression that presents as anxiety, suicide, and includes akathisia, your face, but does not include symptoms of panic.
It is also clear that even mild anxiety symptoms can have a major impact on the course of a depressive illness, and the co-mingling of any anxiety symptoms with the primary depression is important to consider. A pilot study by Ellen Frank PhD, et. al., at the University of Pittsburgh found that depressed or bipolar patients with lifetime panic symptoms experienced significant delays in their weeks to remission. [citation needed] These patients also had higher levels of residual impairment, or the ability to get back into the swing of things. On a similar note, Robert Sapolsky PhD of Stanford University, and others, also argue that the relationship between stress, anxiety, and depression could be measured and demonstrated biologically. [citation needed]. To that point, a study by Heim and Nemeroff, et. al., of Emory University found that depressed and anxious women with a history of childhood abuse recorded higher heart rates and the stress hormone ACTH when subjected to a stressful situation.