Biological Factors
Biological factors contributing to depression includes:
1. Genetics
2. Neurotransmitters
3. Gender
GENETICS
Source: Raising Twins
Genetic plays a big role in depression. As much as 50% of the cause is from genetics. A person risks 20%-30% if their parents or siblings suffer from this disorder while others risk just 10% (Levinson and Nichols). A study by Kendler and Prescott, done in 1999, supports the fact that genetics influence depression. They used twin studies because twins share the same genetic codes. Monozygotic, or identical twins, share almost 100% of the genes. While Dizygotic, or fraternal twins, share only about 50% of their genes just like normal siblings (“Twin Studies”). Therefore they are able to compare how much genetics can be an influence. Kendler and Prescott used ten thousands of twins as participants to find depression rates among them. The results were, monozygotic twins shared a concordance rate of depression higher than dizygotic twins. Conclusion is depression is more prevalent in monozygotic twins than dizygotic twins. Therefore genes can definitely be a cause of depression.
NEOROTRANSMITTERS
Abnormal levels of neurotransmitters can also cause depression. Currently, there are four neurotransmitters that plays a role in this mental disorder. The first is serotonin which is responsible for our moods. The lower the serotonin level you have, the more prone to depression you are. The second is the norepinephrine, or noradrenaline. Similar to serotonin, the lower level of norepinephrine you have in your body, the more you risk depression (Nemade, Reiss and Dombeck). Supported by a research done by Delgado and Moreno (2000), they have found imbalances of both norepinephrine and serotonin levels in depressive patients. The third neurotransmitter is dopamine which is responsible for our ability to experience pleasure. Again, low levels of this neurotransmitter is linked to depression. The last one is glutamate which has just been recently found. However, there is still not enough research to clearly state that this neurotransmitter plays a part in the disorder (Nemade, Reiss and Dombeck).
GENDER
Source: Live Science and Mom's Blog {The Fight Against Cancer}
Gender is also associated with depression. Susan Nolen-Hoeksema (2001) found reasons to why women are known to be more vulnerable to depression. Compared to men, women are twice as likely to suffer from it. That is because women tend to have a lower status and less power than men in most countries’ cultural norms. Therefore they are likely to experience more trauma and conflicts from the society. Moreover, the way women think and the way women cope with stress is different from men. This might be because of the hormone called estrogen and progesterone. Negative self-concept about oneself also contributes to stress.
Bibliography
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<http://depressiongenetics.stanford.edu/mddandgenes.html>.
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Neurotransmitters." Emergence Health Network. N.p., n.d. Web. 12 Nov. 2012.
<http://info.emergencehealthnetwork.org/poc/view_doc.php?&id=12999&cn=5>.
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