Depression has always been a bit of a taboo in society. It’s a condition that to some implies mental weakness or a failure to ‘cope’ with the trials of life, to others it represents a daily struggle. So, is this social branding fair? Are these people victims of their own failure or victims of a debilitating illness? With depression affecting 1 in 10 people at some point in their lives this is something of a phenomena. Instances of depression have recently been correlated to the rise in unemployment; with figures as high as a 15% rise since 2007 being quoted by tabloids.
So, the most common and well-known theory on the cause of depression is that of monoamine transmission in the brain, the most important being 5-HT or serotonin. It has been a long supported theory that in untreated patients the amount of monoamine oxidase A (the enzyme that breaks down neurotransmitters like noradrenaline and serotonin) is higher than in a ‘normal’ adult. One study found that on average MAO-A was 34% higher in depressed individuals. If this were true of course it would lead to lower serotonin levels and as we know serotonin affects many of the aspects we commonly see altered during depression such as appetite, sleep pattern, mood and behaviour. However this is not the only thing that has been quoted about serotonin and patients of depression. Professor Mintum et al. of Washington University have found that actually, sufferers of depression have less serotonin receptors in the brain to start with, particularly in the hippocampus, meaning regardless of the amount of serotonin available, there are less receptors available to transmit it’s effect. So which is it?
The thing is: we’re not too sure. It could be that both or either of these things may be true in any single patient of depression. We only know serotonin even affects mood because we discovered MAOIs (monoamine oxidase inhibitors) by accident when looking to treat TB in the 50’s. Doctors realised that this compound isoniazid had an amazing side effect-it made people happy. It was this the first time scientists moved away from the psychodynamic Freudian type explanations of the 20th century and considered the neurobiological aspects of depression.
But, in a modern world where depression is wrought we have to ask ourselves, why is this getting more common? Maybe we shouldn’t have been so quick to dismiss the kind of theories by psychoanalysts who said depression was anger directed inwards and therefore converted to self-loathing. I mean, we all hate ourselves a little, ‘why did I do that’, ‘how am I so stupid’ in lectures when you’re just not getting it. And yeah, self-criticism is a major symptom of depression in itself but it also causes stress, heaps of stress. And you guessed it, stress can cause depression.
Now, here’s the part where it all comes together: low serotonin levels cause depression…and a lot of people undergoing a bout of depression tend to be undergoing life stressors–problems with family, friends or work. But do these high stress levels actually cause depression? Well, they can do. Stress, particularly chronic stress-like for those unemployed people struggling to find work or those hit by the recession and struggling to make ends meet-leads to a reduction in serotonin levels. Ah, serotonin. So this can explain the recent increase in depression. As our society becomes busier, pressurised, and more time constrained in everything from work to our love lives to academia it’s no wonder depression is on the increase!
But surely this can’t be the whole story? There are so many factors involved in the onset of depression. As with most mental illnesses, it’s not that simple. For example there is respected research from Stanford University saying that up to 50% of the cause of depression could be genetically linked. This is another aspect to consider, along with data stating women are twice as likely to get depression as men. Of course as is to be expected these statistical differences are due to several hormone changes that woman go through in life like hormone imbalance and fluctuation due to puberty, pregnancy or menopause which have all been associated with vulnerability to depression.
But, my real point is, depression is such a complex and interesting illness affected by so many different variables that it’s really hard to say what’s causing a specific patients illness. Depression-as with many psychological illnesses-can seem fairly idiopathic, but under closer inspection we begin to see the mesh of interwoven factors and vulnerabilities that when brought together can be accountable for much of a person’s internal wellbeing.
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Holahan, C., & Moos, R. (1991). Life stressors, personal and social resources, and depression: A 4-year structural model. Journal of Abnormal Psychology, 100 (1), 31-38 DOI: 10.1037//0021-843X.100.1.31
Sheline, Y., & Mintum M.A. (2011). Depression and the Hippocampus: Cause or Effect? Biological Psychiatry, 70 (4), 308-309 DOI: 10.1016/j.biopsych.2011.06.006