Theory of depressive disorder: what it is and how it explains this disorder

In Spain, more than 2.4 million people suffer from depression in their daily life, which means that more than 5.2% of the Spanish population live with a sense of acute anxiety and sadness which interferes or makes you impossible . Live your life normally.

Despite the high incidence of this disorder or emotional state, there are still major disagreements within the scientific community around the true cause of it. One of these theories is the discomfort theory of depression., Which we explain throughout this article.

    What is the theory of depression?

    Also known as the inflammatory theory of depression, this explanatory model of endogenous depressive disorders created by British physician and researcher Bruce G. Charlton in 2000, he tries to explain the origin of depression from a physical or organic point of view and not as a psychological reaction.

    This theory starts from the idea that when our body falls victim to some kind of infection, our own body emits an inflammatory response whereby a series of hemodynamic alterations, lymphatic levels and the release of a series of agents such as cytokines, histamine neuropeptides, etc., are carried out in order to restore the health of our body.

    In addition, with inflammation a psychological phenomenon known as sick behavior appears. This type of psychological response is characterized by the person experiencing a series of sensations of fatigue, drowsiness, anhedonia and cognitive impairment, all of these symptoms coincide with part of the clinical picture of major depression.

    The origin of this pathological behavior can be found in the effects that certain proteins, in particular cytokines, increase in the presence of a virus or an infection, cause in our brain.

    This association between the physical or organic response to inflammation and the psychological response is what the discomfort theory suggests. According to this, endogenous depression is a pathological variety of pathological behavior. The symptoms therefore persist over time. Therefore, according to this theory, depression is caused by the effects of chronic, low-level organic inflation and by chronic activation of the immune system.

    Finally, Charlton himself suggests that the true effect of antidepressants in relieving symptoms of the disease is in the analgesic effect which most of them have, so as organic inflammation decreases, symptoms of depression also decrease.

    What evidence is this explanation based on?

    Although at first it may be a bit complicated to believe that depression is not caused by an external factor that triggers this response, the discomfort theory is based on a number of empirical evidence to support it. .

    1. Coincidence of symptoms

    As mentioned above, the symptoms of major depression coincide in many ways with those of pathological behavior, which tends to appear when we are suffering from some type of physical illness.

    In such cases symptoms such as fatigue, decreased physical energy, or feelings of anxiety and sadness they appear in order to keep our body at rest and to recover as quickly as possible.

    2. The effect of cytokines

    One of the physiological responses our bodies have to the threat of disease is increased cytokines. This protein causes inflammation with the intention of transmitting it to our body which is in a state of vigilance or threat.

    Taking into account the fact that, generally, in disorders with depressive symptoms, cytokine levels are much higher than usual, one can hypothesize some kind of relationship between these two factors.

    In addition, in the specific case of bipolar disorder, cytokine levels decrease during episodes of mania or remission of depressive symptomsSo it strengthens that association.

    3. Action of antidepressants

    Antidepressant drugs have an effect on cytokine levels, especially lowering them. Therefore, it reinforces the idea that the main cause of endogenous depression is the effects that these proteins cause in the body.

    4. The inflammatory response system and depression

    Some studies have shown that laboratory inoculation of inflammatory substances or agents, it causes a number of symptoms typical of clinical pictures of depression and anxiety.

    In addition, a clear relationship has been established between the activation of our body’s inflammatory response system and depression; as this is continually activated during this disorder.

    The inflammatory response system works by activating the hypothalamic-pituitary-adrenal axis, which affects the regulation of certain neurotransmitters such as serotonin and catecholamines, directly linked to depressive states.

    5. Antidepressant action of anti-inflammatory drugs

    Finally, some research has shown that the administration of anti-inflammatory drugs in some cases of endogenous depression not only significantly improves the symptoms of it, but also does so to a greater extent than some antidepressants.

    What if there is depression but no inflammatory disease?

    The main criticism of the explanatory model of the theory of discomfort in depression is that there are a large number of cases in which a physical cause could not be found or sign of organic inflammation in the patient.

    However, according to this theory, it is argued that psychological stress processes can cause this inflammation like any type of infection, thus causing the symptoms of depression.

    The experience of high levels of stress over a long period of time has been associated with increased levels of pro-inflammatory cytokines. Which, as we explained earlier, have a direct effect on the levels of serotonin and other neurotransmitters linked to depression.

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