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Major Depression and SSRIs
Selective serotonin reuptake inhibitors (SSRIs) are a category of drugs associated mainly with the treatment of depression. Serotonin is a naturally occurring substance within the body but as a neurotransmitter it is found in concentrations around the midbrain and hypothalamus. These areas of the brain are important structures in the regulation of moods such as depression. So, the questions to ask are - what exactly is serotonin, why is it so important and how can SSRIs help you to overcome major depression?
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The Action of Serotonin
The development of SSRI drugs followed the discovery that groups of antidepressants known as tricyclics and MAOIs had the effect of increasing certain types of brain chemicals, one of which was serotonin. Serotonin acts as a neurotransmitter and has the function of ensuring nerve impulses occur between nerve cells in the brain.
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The Action of SSRIs
Depression is considered to result from variations in the concentration of serotonin within the brain. Once a diagnosis of depression is made the chances are your doctor will now prescribe one of the popular SSRI drugs such as prozac, paxil or seroxat. SSRIs work by inhibiting nerve cells from taking up serotonin too quickly. Effectively this leaves more serotonin in the brain and, over time, eases the symptoms of depression.
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Do SSRIs Work?
Research has gradually revealed who is most likely to derive the greatest benefits from the pharmacological action of SSRIs. In 1995, Fisher and Greenburg published the findings of a series of literature reviews into the efficacy of SSRIs. They reported the overall effect could best be described as ‘modest’. More recently, Fournier and colleagues, writing in the Journal of the American Medical Association, stated that only people with the most severe symptoms of depression were likely to derive any significant therapeutic effect from taking SSRIs.
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Can We Have Too Much Serotonin?
Armed with the knowledge that SSRIs appear to have little clinical effect in cases of mild or moderate depression, questions have to be asked about the original assumptions upon which SSRIs were based. Is depression simply due to low serotonin levels in the brain? One researcher, Dr. Christopher Lowry, says not. Lowry argues that the brain chemistry of people with depression is far more complex than that and that in some cases too much serotonin in the brain might be the cause of depression.
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Multiple Types of Serotonin Neurons
Researchers at the Baker Heart Institute in Australia discovered up to twice the normal level of serotonin in the brains of some people with depression who were not receiving treatment. Furthermore, it has been discovered that long-term use of SSRIs actually seems to result in decreased serotonin levels, although it isn’t clear why. According to Lowry, there are subgroups of serotonin neurons that become overactive during depression, not underactive as had previously been assumed. This may explain why high levels of serotonin in some parts of the brain can lead to improved mood but elsewhere may have negative implications.
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Implications of Major Depression and SSRI
There seems little doubt that people suffering with severe major depression derive therapeutic benefits from taking SSRI drugs. The knowledge that serotonin neurons can be regulated independently points to the prospect of a new generation of drugs that can switch on or off these neurons according to need.
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Geddes, L (2010) Rethink Needed for Cause of Depression. New Scientist. 207.2770: 12. Print.
Fisher, S & Greenburg, R.P. (1995) Prescription for Happiness? Psychology Today, 28, 32-37.
Fournier, J.C. et al (2010) Antidepressant Drug Effects and Depression Severity. Journal of the American Medical Association. Jan 6, 303 (1) 47-53.