English psychiatrist Henry Maudsley proposed an overarching category of affective disorder.* The term was then replaced by mood disorder, as the latter term refers to the underlying or longitudinal emotional state,* whereas the former refers to the external expression observed by others.*
Two groups of mood disorders are broadly recognized; the division is based on whether a mania|manic or hypomania|hypomanic episode has ever been present. Thus, there are depressive disorders, of which the best-known and most researched is major depressive disorder (MDD) commonly called clinical depression or major depression, and bipolar disorder (BD), formerly known as manic depression and characterized by intermittent episodes of mania or hypomania, usually interlaced with depressive episodes. However, there are also psychiatric syndromes featuring less severe Depression (mood)|depression known as dysthymic disorder (similar to but milder than MDD) and cyclothymic disorder (similar to but milder than BD).* Mood disorders may also be substance-induced or occur in response to a medical condition.
* Atypical depression (AD) is characterized by mood reactivity (paradoxical anhedonia) and positivity, significant weight gain or increased appetite ("comfort eating"), excessive sleep or somnolence (hypersomnia), a sensation of heaviness in limbs known as leaden paralysis, and significant social impairment as a consequence of hypersensitivity to perceived social rejection|interpersonal rejection.* Difficulties in measuring this subtype have led to questions of its validity and prevalence.** Melancholic depression is characterized by a loss of pleasure (anhedonia) in most or all activities, a failure of reactivity to pleasurable Stimulus (physiology)|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, excessive weight loss (not to be confused with anorexia nervosa), or excessive guilt.** Psychotic major depression (PMD), or simply psychotic depression, is the term for a major depressive episode, in particular of melancholic nature, wherein the patient experiences psychotic symptoms such as delusions or, less commonly, hallucinations. These are most commonly mood-congruent (content coincident with depressive themes).** Non-melancholic depression essentially means that the depression is not melancholic, or, put simply, not primarily biological. Instead, it has to do with psychological causes, and is very often linked to stressful events in a person's life, alone, or in conjunction with the individual's personality style. Non-melancholic depression is the most common sub-type of depression. It accounts for up to 90% of cases of depression seen in clinical practice. Non-melancholic depression can be hard to accurately diagnose because it lacks the defining characteristics of melancholic or psychotic depression (namely psychomotor disturbance or psychotic features). Also in contrast to those depressive sub-types, people with non-melancholic depression can usually be cheered up to some degree. In contrast to the more biological depressions, non-melancholic depression has a high rate of spontaneous remission. This is because it is often linked to stressful events in a person's life, which, when resolved, tend to assist the depression to lift. Non-melancholic depression responds well to different sorts of psychological treatments as a first step (such as psychotherapies and counselling), and the treatment selected should respect the cause and maintenance of that depressive episode (e.g. stress, personality style). Antidepressant medications can also be used to treat non-melancholic depression.** Catatonia|Catatonic depression is a rare and severe form of major depression involving disturbances of motor behavior and other symptoms. Here, the person is mute and almost stuporose, and either is immobile or exhibits purposeless or even bizarre movements. Catatonic symptoms can also occur in schizophrenia or a manic episode, or can be due to neuroleptic malignant syndrome.** Postpartum depression (PPD) is listed as a course specifier in DSM-IV-TR; it refers to the intense, sustained and sometimes disabling depression experienced by women after giving birth. Postpartum depression, which affects 10–15% of women, typically sets in within three months of childbirth|labor, and lasts as long as three months.* It is quite common for women to experience a short-term feeling of tiredness and sadness in the first few weeks after giving birth; however, postpartum depression is different because it can cause significant hardship and impaired functioning at home, work, or school as well as, possibly, difficulty in relationships with family members, spouses, or friends, or even problems bonding with the newborn.* In the treatment of postpartum major depressive disorders and other unipolar depressions in women who are breastfeeding, nortriptyline, paroxetine (Paxil), and sertraline (Zoloft) are in general considered to be the preferred medications.* Women with personal or family histories of mood disorders are at particularly high risk of developing postpartum depression.** Seasonal affective disorder (SAD), also known as "winter depression" or "winter blues", is a specifier. Some people have a seasonal pattern, with depressive episodes coming on in the autumn or winter, and resolving in spring. The diagnosis is made if at least two episodes have occurred in colder months with none at other times over a two-year period or longer.* It is commonly hypothesised that people who live at higher latitudes tend to have less sunlight exposure in the winter and therefore experience higher rates of SAD, but the epidemiological support for this proposition is not strong (and latitude is not the only determinant of the amount of sunlight reaching the eyes in winter). SAD is also more prevalent in people who are younger and typically affects more females than males.** Dysthymia is a condition related to unipolar depression, where the same physical and cognitive problems are evident, but they are not as severe and tend to last longer (usually at least 2 years).* The treatment of dysthymia is largely the same as for major depression, including antidepressant medications and psychotherapy.** Double depression can be defined as a fairly depressed mood (dysthymia) that lasts for at least two years and is punctuated by periods of major depression.*
*Depressive Disorder Not Otherwise Specified (DD-NOS) is designated by the DSM-IV Codes|code 311 for depressive disorders that are impairing but do not fit any of the officially specified diagnoses. According to the DSM-IV, DD-NOS encompasses "any depressive disorder that does not meet the criteria for a specific disorder." It includes the research diagnoses of recurrent brief depression, and minor depressive disorder listed below.
*Depressive personality disorder (DPD) is a controversial psychiatric diagnosis that denotes a personality disorder with depressive features. Originally included in the DSM-II, depressive personality disorder was removed from the DSM-III and DSM-III-R.* Recently, it has been reconsidered for reinstatement as a diagnosis. Depressive personality disorder is currently described in Appendix B in the DSM-IV-TR as worthy of further study.
* Recurrent brief depression (RBD), distinguished from major depressive disorder primarily by differences in duration. People with RBD have depressive episodes about once per month, with individual episodes lasting less than two weeks and typically less than 2–3 days. Diagnosis of RBD requires that the episodes occur over the span of at least one year and, in female patients, independently of the menstrual cycle.* People with clinical depression can develop RBD, and vice versa, and both illnesses have similar risks.** Minor Depressive Disorder|Minor depressive disorder, or simply minor depression, which refers to a depression that does not meet full criteria for major depression but in which at least two symptoms are present for two weeks.*
* Bipolar I is distinguished by the presence or history of one or more manic episodes or mixed episodes with or without major depressive episodes. A depressive episode is not required for the diagnosis of Bipolar I disorder, but depressive episodes are often part of the course of the illness. :* Bipolar II consisting of recurrent intermittent hypomania|hypomanic and depressive episodes or mixed episodes. :* Cyclothymia is a form of bipolar disorder, consisting of recurrent hypomanic and dysthymia|dysthymic episodes, but no full manic episodes or full major depressive episodes. :* Bipolar Disorder Not Otherwise Specified (BD-NOS), sometimes called "sub-threshold" bipolar, indicates that the patient suffers from some symptoms in the bipolar spectrum (e.g., manic and depressive symptoms) but does not fully qualify for any of the three formal bipolar DSM-IV diagnoses mentioned above. :It is estimated that roughly 1% of the adult population suffers from bipolar I, a further 1% suffers from bipolar II or cyclothymia, and somewhere between 2% and 5% percent suffer from "sub-threshold" forms of bipolar disorder. Furthermore the possibility of getting bipolar disorder when one parent is diagnosed with it is 15-30%. Risk when both parents have it is 50-75%. Also, while with bipolar siblings the risk is 15-25%, with identical twins it is about 70%.*A minority of people with bipolar disorder have high creativity, artistry or a particular gifted talent. Before the mania phase becomes too extreme, its energy, ambition, enthusiasm and grandiosity often bring people with this type of mood disorder life's masterpieces.*
Substance-induced mood disordersA mood disorder can be classified as substance-induced if its etiology can be traced to the direct physiologic effects of a psychoactive drug or other chemical substance, or if the development of the mood disorder occurred contemporaneously with substance intoxication or Drug withdrawal|withdrawal. Also, an individual may have a mood disorder coexisting with a substance abuse disorder. Substance-induced mood disorders can have features of a manic, hypomanic, mixed, or depressive episode. Most substances can induce a variety of mood disorders. For example, stimulants such as amphetamine, methamphetamine, and cocaine can cause manic, hypomanic, mixed, and depressive episodes.
Alcohol-induced mood disordersHigh rates of major depressive disorder occur in heavy drinkers and those with alcoholism. Controversy has previously surrounded whether those who abused alcohol and developed depression were self-medicating their pre-existing depression. But recent research has concluded that, while this may be true in some cases, alcohol misuse directly causes the development of depression in a significant number of heavy drinkers. Participants studied were also assessed during stressful events in their lives and measured on a Feeling Bad Scale. Likewise, they were also assessed on their affiliation with deviant peers, unemployment, and their partner's substance use and criminal offending.* High rates of suicide also occur in those who have alcohol-related problems.* It is usually possible to differentiate between alcohol-related depression and depression that is not related to alcohol intake by taking a careful history of the patient.* Depression and other mental health problems associated with alcohol misuse may be due to distortion of brain chemistry, as they tend to improve on their own after a period of abstinence.*
Benzodiazepine-induced mood disordersThe long-term use of benzodiazepines, such as Valium and Librium, may have a similar effect on the brain as alcohol, and are also implicated in depression.* Major depressive disorder can also develop as a result of chronic use of benzodiazepines or as part of a protracted withdrawal syndrome. Benzodiazepines are a class of medication commonly used to treat insomnia, anxiety, and muscular spasms. As with alcohol, the effects of benzodiazepine on neurochemistry, such as decreased levels of serotonin and norepinephrine, are believed to be responsible for the increased depression.* Major depressive disorder may also occur as part of the benzodiazepine withdrawal syndrome.* In a long-term follow-up study of patients dependent on benzodiazepines, it was found that 10 people (20%) had taken drug overdoses while on chronic benzodiazepine medication despite only two people ever having had any pre-existing depressive disorder. A year after a gradual withdrawal program, no patients had taken any further overdoses.* Depression resulting from withdrawal from benzodiazepines usually subsides after a few months but in some cases may persist for 6–12 months.*
Mood disorder due to a general medical condition"Mood disorder due to a general medical condition" is used to describe manic or depressive episodes which occur secondary to a medical condition.* There are many medical conditions that can trigger mood episodes, including neurological disorders (e.g. dementias), metabolic disorders (e.g. electrolyte disturbances), gastrointestinal diseases (e.g. cirrhosis), endocrine disease (e.g. thyroid abnormalities), cardiovascular disease (e.g. heart attack), pulmonary disease (e.g. chronic obstructive pulmonary disease), cancer, and autoimmune diseases (e.g. rheumatoid arthritis).*
OriginA number of authors have suggested that mood disorders are an natural selection|evolutionary adaptation. A low or depressed mood can increase an individual's ability to cope with situations in which the effort to pursue a major goal could result in danger, loss, or wasted effort.* In such situations, low motivation may give an advantage by inhibiting certain actions. This theory helps to explain why mood disorders are so prevalent, and why they so often strike people during their peak reproductive years. These characteristics would be difficult to understand if depression were a dysfunction.*
A depressed mood is a predictable response to certain types of life occurrences, such as loss of status, divorce, or death of a child or spouse. These are events that signal a loss of reproductive ability or potential, or that did so in humans' ancestral environment. A depressed mood can be seen as an adaptive response, in the sense that it causes an individual to turn away from the earlier (and reproductively unsuccessful) modes of behavior.
A depressed mood is common during illnesses, such as influenza. It has been argued that this is an evolved mechanism that assists the individual in recovering by limiting his/her physical activity.* The occurrence of low-level depression during the winter months, or seasonal affective disorder, may have been adaptive in the past, by limiting physical activity at times when food was scarce.* It is argued that humans have retained the instinct to experience low mood during the winter months, even if the availability of food is no longer determined by the weather.*
Sociocultural aspectsKay Redfield Jamison and others have explored the possible links between mood disorders — especially bipolar disorder — and creativity. It has been proposed that a "ruminating personality type may contribute to both [mood disorders] and art."*
Jane Collingwood notes an Oregon State University study that :“looked at the occupational status of a large group of typical patients and found that ‘those with bipolar illness appear to be disproportionately concentrated in the most creative occupational category.' They also found that the likelihood of ‘engaging in creative activities on the job' is significantly higher for bipolar than nonbipolar workers.”*.In Liz Paterek's article "Bipolar Disorder and the Creative Mind"Paterek, Liz. "Bipolar Disorder and the Creative Mind." Serendip. 2006. Web.
The relationship between depression and creativity appears to be especially strong among poets.