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Analyze the biological etiology of Major Depressive Disorder:

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´╗┐Analyze the biological etiology of Major Depressive Disorder: This paper will analyze the biological etiology of major depressive disorder through research into related genetic, evolutionary and biochemical factors. Major depressive disorder is still a little understood disease, primarily because it is thought to be caused by a great number of factors from environmental (negative life events, stress, environmental change) to biological (hormones, neurotransmitters, and genetic predisposition). While it is not possible for psychologists or psychiatrists to attribute depression in any individual to a single cause, their understanding of the different factors can help them alleviate symptoms and suggest strategies for coping. The biological etiology is one facet of this understanding. Research suggests that genetic factors can be used to partly explain the causes of major depressive disorder. Nurnberger & Gershon (1982), for instance, conducted a review of seven twin studies and found that concordance rates were consistently higher among MZ twins (an average of 65%), when compared to DZ twins (averaged at 14%). The consistently higher concordance in MZ twins indicates that genetic factors may play a role in predisposing an individual to major depressive disorder. ...read more.


Evolutionary psychologists suggest that depression may be a previously adaptive behavior left-over by genome lag that no longer serves its adaptive purpose so clearly today. This principle is clearly demonstrated by the Social Competition Hypothesis (Price et al., 1994), which suggests that depression was an adaptive response of a person who loses a conflict in a group. Depression would force the loser to: 1) stop competing for food, 2) accept defeat, 3) Signal their submission to the winner (mitigating further conflict and self-harm). This helps keeps the individual alive and capable of reproducing. While this may have mitigated conflict over physical resources in the past, it seems to also be triggered today by losses of emotional resources ? making it maladaptive in the modern world. This research is very speculative however. It is difficult to find evidence to support it as its claims are not easily tested scientifically; thus, it remains a hypothesis. Biochemical factors, however, have a stronger body of supporting research. The most prominent hypothesis in this field is the Monoamine Hypothesis, which proposes that low levels of monoamines, such as serotonin, at the synapse are responsible for depression. ...read more.


High levels of stress hormones could damage the hippocampus, which provides a possible mechanism by which cortisol causes depression. The link between the stress hormone and the disease is not yet clearly understood, however. Fernald and Gunner (2008), for example, found instead, that low levels of cortisol were related to depression and poverty. After surveying 639 Mexican mothers and their children, they found that children of depressed mothers living in extreme poverty produced less cortisol. They suggested these low levels of cortisol, indicated that the stress system is worn out, leaving children susceptible not only to depression but also to other diseases. In conclusion, it is clear that biological factors seem to play an important role in the development of depression. Clearly, however, explaining depression?s etiology in terms of simply biological factors would be significantly reductionist ? especially in light of the relationship evident in the research between biochemical/genetic factors and environmental factors such as stress. Understanding the etiology of this disorder is important because of its high prevalence and significant impact on the individual and society. To most comprehensively approach this understanding, it is important to take a holistic, ?biopsychosocial? approach. ...read more.

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