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==[[Depression - Causes|Causes of depression]]==
==[[Depression - Causes|Causes of depression]]==
Major depression is generally seen as a [[mental disorder]] with multiple causes.
The understanding of the nature and causes of depression has evolved over the centuries; nevertheless, many aspects of depression are still not fully understood, and are the subject of debate and research. Both [[psychology|psychological]] and [[biology|biological]] causes have been proposed. Psychological theories and treatments are based on ideas about the personality, interpersonal communication, and unduly negative thoughts. The [[monoamine]] chemicals [[serotonin]], [[norepinephrine]], and [[dopamine]] are naturally present in the [[Human brain|brain]] and assist communication between [[Neuron|nerve cells]]. Monoamines have been implicated in depression, and most antidepressants work to increase the active levels of at least one.
==[[Depression - Evolutionary factors|Evolutionary perspective]]==
From the [[evolution]]ary standpoint, major depression might be expected to reduce an individual's [[Fitness (biology)|ability to reproduce]]. Some [[Evolutionary approaches to depression|evolutionary explanations]] for the apparent contradiction between biopsychosocial, psychological and psychosocial hypotheses and the high heritability and prevalence of depression are explained by the proposal that certain components of depression are [[adaptation]]s<ref name="Panksepp02">{{cite journal |author=Panksepp J, Moskal JR, Panksepp JB, Kroes RA |title=Comparative approaches in evolutionary psychology: Molecular neuroscience meets the mind |journal=Neuroendocrinology Letters |volume=23 |issue= Supplement 4 |pages=105–15 |year=2002 |month=December |pmid=12496741|url= |format=PDF}}</ref> such as the mechanisms underlying behaviors relating to [[attachment theory|attachment]] and [[Social class|social rank]].<ref name="Sloman2003">{{cite journal |author=Sloman L, Gilbert P, Hasey G |title=Evolved mechanisms in depression: The role and interaction of attachment and social rank in depression |journal=Journal of Affective Disorders |volume=74 |issue=2 |pages=107–21 |year=2003 |month=April |pmid=12706512 |url= |doi=10.1016/S0165-0327(02)00116-7}}</ref> Evolutionary theorists view the condition as an adaptation to regulate relationships or resources, although it may be unwanted or disordered in modern environments.<ref name="Klein07">{{cite web|author=Klein JM|date=2007-02-12|url=
|title=The mind, as it evolves|publisher=Los Angeles Times|work=Los Angeles Times (online)|accessdate=2008-10-03}}</ref> From this perspective, depression can be seen as "a species-wide evolved suite of emotional programmes that are mostly activated by a perception, almost always over-negative, of a major decline in personal usefulness, that can sometimes be linked to guilt, shame or perceived rejection".<ref name="Carey05">{{cite journal |title=Evolution, depression and counselling |journal=Counselling Psychology Quarterly | year=2005 |author=Carey TJ |volume=18 | issue=3 |pages=215–22 |url= |doi=10.1080/09515070500304508}}</ref>
==[[Depression - Genetic factors]]==
There is growing evidence for the importance of genetic factors in [[clinical depression]] and [[depressed mood]].
==[[Depression - Biological factors|Biology of depression]]==
[[Image:Biological clock human.PNG|thumb|left|300px|Depression appears to be related to disruptions in the [[circadian rhythm]], or human biological clock.]]
Major depression may also be caused in part by an overactive [[hypothalamic-pituitary-adrenal axis]] (HPA axis) that is similar to the neuro-endocrine response to stress. Investigations reveal increased levels of the hormone [[cortisol]], enlarged pituitary and adrenal glands, and a blunted [[circadian rhythm]]. Oversecretion of [[corticotropin-releasing hormone]] from the [[hypothalamus]] is thought to drive this, and is implicated in the cognitive and arousal symptoms.<ref>{{cite journal|author=Monteleone P |url=;jsessionid=JWdDsz1T6hhjhpsR47xrbhpTjhxhpdS64Yh8QzptbqR1rrNkmVfF!1600976923!181195628!8091!-1 (abstract) |title=Endocrine disturbances and psychiatric disorders |publisher=Lippincott Williams & Wilkins, Inc. |year=2001 |volume=14|issue=6|pages=605–10|journal=Current Opinion in Psychiatry |issn=0951–7367}}</ref> The [[REM sleep|REM]] stage of sleep, in which [[dream]]ing occurs, tends to be especially quick to arrive, and especially intense, in depressed people. Although the precise relationship between sleep and depression is mysterious, the relationship appears to be particularly strong among those whose depressive episodes are ''not'' precipitated by stress. In such cases, patients may be especially unaffected by therapeutic intervention.<ref name="Integrative2">{{Harvnb|Barlow|2005| pp=227–28}}</ref>
The hormone [[estrogen]] has been implicated in depressive disorders due to the increase in risk of depressive episodes after puberty, the antenatal period, and reduced rates after [[menopause]].<ref name="pmid12810759"/> Conversely, the premenstrual and postpartum periods of low estrogen levels are also associated with increased risk.<ref name="pmid12810759"/> The use of estrogen has been under-researched, and there although some small trials show promise in its use to prevent or treat depression, the evidence for its effectiveness is not strong.<ref name="pmid12810759"/> Estrogen replacement therapy has been shown to be beneficial in improving mood in [[Menopause#Perimenopause|perimenopause]], but it is unclear if it is merely the menopausal symptoms that are being reversed.<ref name="pmid12810759">{{cite journal |author=Cutter WJ, Norbury R, Murphy DG |title=Oestrogen, brain function, and neuropsychiatric disorders |journal=Journal of Neurology, Neurosurgery and Psychiatry |volume=74 |issue=7 |pages=837–40 |year=2003 |month=July |pmid=12810759 |pmc=1738534 |url=}}</ref>
==[[Depression - Psychological causes|Psychological factors in depression]]==
==[[Depression - Social causes|Social causes in depression]]==
Social depreciation, discriminative behaviour towards an individual occurring either explicitly or implicitly (i.e. the director is unaware of their negative behaviour towards the receiver), peer pressure (whether implicit (i.e. a natural attempt to conform to social standards, or to compete with social pressure)) or explicit and desynchronized social interaction primarily act as a social stimulus for depression. The absence of social sync may occur due to an imbalance amidst independence and external interaction (i.e. socializing) with their environment; independence would thus be an individual synchronizing with their internal mechanisms, ergo causing them to develop extravagant abilities (e.g. eidetic, excessive episodic or categorical memory, abnormal academia (depending on age) or abilities to achieve excess results in challenges of various subjects). Such abilities may occur as being savant-like. A synchronization period may result in de-synced abilities intervening with both aspects (i.e. the individual may lose their independence and ability to socialize as they subjectively attempt to balance their cognition). Thus, as a primary counteract to social/independence impairment, an individual would require balance amidst internal/external synchronization.
Alternative social stimuli for depression may present as requirement for relationships; an individual may find peer pressure directed towards a need for a relationship with either sex. Furthermore, an evolutionary conflict may occur between a social environment; an individual may lack the ability to sync (or otherwise refuse and thus, adhering to their own standards) with their social environment, and with additional instinctual pressure to sustain a relationship, a conflict may transpire thereby inadvertently causing depression.
==[[Depression - Theoretical approaches|Theoretical approaches]]==
==[[Depression - Theoretical approaches|Theoretical approaches]]==

Revision as of 20:56, October 31, 2013

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