The Serotonergic Hypothesis of Depression

This explanation of depression is based on the functioning of brain chemistry.

Depression is, together with anxiety disorders, one of the most frequent and well-known disorders or psychopathologies worldwide throughout history. Research into exactly what it is and what causes it is therefore very relevant for the scientific community and for the population in general. Based on the data reflected by research, a large number of explanatory models have been proposed that take into account both Biological and environmental factors.

Among the former, there are frequent attempts to explain depression as a product of problems in the balance or levels of certain neurotransmitters. Among these hypotheses, one of the most popular and recognized is the serotonergic hypothesis. the serotoninergic hypothesis of depression.

Serotonin

Serotonin is one of the main and best known neurotransmitters present in the brain. This hormone, which in addition to the nervous system can be found in other body systems (in fact most of the serotonin in our body is found outside the nervous system, especially in the digestive tract), was one of the first neurotransmitters in the human body. one of the first neurotransmitters to be identified.. It is synthesized from tryptophan, which in turn can be introduced into the body through the diet.

Among its many functions, it is considered to be linked to the regulation of circadian rhythms and energy levels (especially due to its important presence in the suprachiasmatic, ventromedial and paraventricular nuclei), thermal control, appetite, libido, relaxation and feelings of well-being and comfort. It is also considered one of the main hormones linked to the maintenance of mood, being altered in those people who have problems of depressive type.

Serotonergic hypothesis of depression

The serotonergic hypothesis of the depression is one of the most known hypotheses of biological type that try to explain the causes of depression. to explain the possible causes of depression.. It proposes that the causes of depression are found in a deficit or lack of serotonin in the brain. This theory is based on the role of serotonin in the regulation of mood, indicating that a decrease in serotonin levels in the nervous system or in key points such as the limbic system would be responsible for the depressive symptomatology.

Likewise, the so-called permissive serotonin hypothesis indicates that the alteration and decrease of serotonin at brain level generates a dysregulation of other neurotransmitter systems, such as noradrenaline. of other neurotransmission systems, such as noradrenaline. It is part of the monoaminergic hypothesis, which states that the mental alterations typical of depression are due to a malfunction, synthesis or transmission of neurotransmitters such as serotonin and catecholamines (dopamine and noradrenaline).

Pharmacological treatments

Different models and techniques have been used to treat depression, both in terms of psychotherapy and pharmacological treatment. In the latter aspect, the main psychotropic drugs that are used for the pharmacological treatment of depression are those that regulate or alter are those that regulate or alter the levels of monoamines, being especially used those that increase the levels of serotonin.

Specifically, nowadays the most common psychotropic drugs used to combat depression are SSRIs, Specific Serotonin Reuptake Inhibitors. This is a group of drugs whose main mechanism of action is (as the name suggests) to prevent the presynaptic neurons from reuptake or absorb the serotonin they have emitted, so that it remains in the synaptic space and the level of this neurotransmitter in the brain is generally increased.

However, it should be noted that serotonin is not the only neurotransmitter involved, and that there are alternatives that focus on the stimulation of the levels of other substances, whether secondary or primary. For example, drugs that in addition to serotonin increase the levels of noradrenalineISRN, generating an equivalent level of symptomatological improvement.

Nor should it be forgotten that pharmacological treatment generates changes in the brain that reduce symptoms, but generally do not treat the underlying problem that the person links to depression (e.g. absence of reinforcers, low perception of control, prolonged stress or anxiety). Psychological therapy has been shown to be more effective in the long term.This suggests that depression is not merely a serotonergic problem.

Caution: we are talking about a hypothesis

The existence of alterations in serotonin levels in the brain has been documented, and it is assumed that one of the main neurobiological problems presented by patients with depression is a serotonin deficit. It has also been observed that the decrease in the levels of this hormone generates depressive symptomatology..

However, it remains true that these deficits are simply linked to depressive symptomatology, without necessarily being the cause. In fact, the causes of depression are not yet fully known, being generated by a combination of biological and socio-environmental elements. Likewise, other neurotransmitters related to depressive symptomatology or that may participate in its improvement, such as noradrenaline, dopamine or GABA, have been found.

Thus, it should not be assumed that the serotonergic hypothesis describes the ultimate cause of depression, since there are many factors that play a role in its genesis. That is why today the serotonergic hypothesis has lost its power and has come to be seen not as the cause of depression but as the generator of a biological vulnerability to it.

The serotonergic hypothesis and the use of medications such as SSRIs have been widely criticized, among other things because they have been overly focused on and have greatly limited the development of other models and drugs. The debate about the actual effectiveness of antidepressants in treating the problem itself is also widely known.