According to the World Health Organisation (WHO), and despite 50 years of extensive research and tremendous enhancements in technology; WHO states that there is no single cause or explanation of depression. Rather it is suggested that a combination of biological (genetic and biochemical), sociological (stressors) and psychological (development and life experiences) factors interact to cause depression.
This definition reflects what the vast majority of mental health and wellbeing organisations from around the globe propose.
However, WHO employs a biopsychosocial model to provide a picture of depression.
1) Genetic factors: According to WHO, it has been consistently observed that depression tends to run in families. For the uninitiated, genes are like computer chips within our body that hardwire or pre-program us towards certain physical or physiological predispositions. The BlackDog Institute (Australia)suggests that "the genetic risk of developing depression is about 40%, with the remaining 60% being due to factors in the individual's own environment".
For example, in 2003, a New Zealand study suggested a certain gene - responsible for the transportation of serotonin - in conjunction with a serious life stressor was responsible for depression (Caspi et. al. Science 301: 386-389). At the time, this was heralded as a significant breakthrough in the understanding and treatment depression.
However, according to a recent meta-analysis published in the Journal of the American Medical Association, "a gene variation that has long been thought to increase the risk of depression in combination with stressful life events may have no effect after all (Serotonin Gene, Even Combined With Life Events, Has No Effect On Depression; June 17, 2009).
The search for a single gene or a combination of genes in the cause of depression continues.
2) Biological Factors: An imbalance in biochemicals within the brain, known as neurotransmitters, "may produce" depression. However, according to WHO, "the assumption that depression is the direct result of a biochemical imbalance may be an oversimplification". There is much conjecture and debate as to whether a biochemical imbalance is the cause of depression or this imbalance is a result of the depression itself -�a classic�chicken and the egg scenario.
For instance, a 2005 study suggested that there is very little scientific evidence that depression is caused by a biochemical imbalance, despite it commonly and frequently being presented in the media as fact (Lacasse JR, Leo J: Serotonin and Depression: A Disconnect between the Advertisements and the Scientific Literature). The results of studies conducted and withheld by pharmaceutical companies were examined. According to the researchers, the chemical imbalance theory, which was formulated in the 1960's, was based on the observation that mood could be artificially altered with drugs, rather than a direct observation of any chemical imbalances.
The reality is, "researchers know very little about how anti-depressants work, there is no test that can measure the amount of serotonin in the living brain, no way to know what a low or normal serotonin level is - let alone show that depression medication fixes these levels". An example commonly used is, "while antidepressant drugs increase levels of serotonin, this doesn't mean that depression is caused by a serotonin shortage. After all, aspirin may cure a headache, but it doesn't mean that headaches are caused by an aspirin deficiency" (helpguide.org/mental/medications_depression.htm).
Even more concerning is the latest report published in the Journal of the American Medical Association�examining the effectiveness of antidepressants, which demonstrated that there was no real difference between antidepressants and a placebo in the treatment outcomes of mild and moderate depression (Antidepressants aren't the only remedy for milder forms of depression: Robert DeRubeis; Jan 2010).
In other words, treating mild or moderate depression with a sugar pill was just as effective!
Furthermore, in the treatment of patients with severe depression, there was only a 4 point difference on the scale used to measure the severity of an individual's depression between the antidepressant and a placebo. Strangely, a recent newspaper article in the New York Times was extremely critical of the undue media attention of the results from this study. Its main argument was that it is the mental health system to blame for over-prescription of antidepressants for mild and moderate depression. Further, it cited that antidepressants are effective in the treatment of severe depression. However, it failed to mention that even in the treatment of severe depression there was only that 4 point difference between the use of the pill and the placebo.
Of note, for pharmaceutical companies, depression is big business. The number of Americans taking antidepressants since the mid-1990's has nearly doubled, with at least 27 million taking pills to combat depression (Archives of General Psychiatry). Further, in 2008 alone, 164 million prescriptions were written adding up to almost $10 billion in sales (IMS Health).
Worryingly, the pre-school age group (0-5 years) has been one of the fastest growing markets for antidepressants in recent years�(Psychiatric Services, April 2004).
Of interest, if depression was purely and simply due to a biochemical imbalance; why is psychotherapy or talk therapy just as effective in the treatment of depression? This fact alone calls into question the oversimplification that depression is due to a biochemical imbalance or genetic factors. How can talking about something overcome a medical illness or disease due to a biochemical imbalance, as so often and strongly advocated by the health authorities and pharmaceutical companies?
3) Psychological Factors: According to WHO, "how and what a person thinks may determine the onset of depression. If people have distorted thinking by which they view everything around them including themselves and their future as negatively and pessimistically, then their mood also becomes sad, completing the picture of depression".
