One of the best known and most common mental disorders in our society is depression. Although this mood disorder is widely known, little is said about its causes.

The reason is, among others, that this disorder cannot be explained by a single factor: its appearance and development are very complex processes. In this article we will talk about it and see, in a summarized way, what is known about the causes of depression.

What is depression?

Depression is an affective disorder through which psychological pain and discomfort is expressed .This includes both psychic and somatic symptoms, so in order to diagnose and apply the appropriate treatment it is essential to assess the patient’s environment (family, work, sentimental or marital situation…).

Depression is an acute clinical disorder affecting the brain. It goes beyond feeling “down” or “sad” some days, it is necessary to differentiate sadness from depression. The essential difference is that sadness is a natural response to a painful stimulus; this expression of emotionally expressed pain is a necessary response mechanism. However, if sadness persists over time and becomes chronic, with or without apparent cause and with severe modularity, affecting the patient’s normal functioning in all areas of daily life, then we are referring to depression.

Depression is not a natural response but a pathology that can lead to disability . Epidemiological studies reveal, for example, that in the United States 20% of the population suffers from this disease.

What are the causes of depression?

The main causes of depression are due to genetic factors (genetic predisposition) so it is very important to evaluate if the patient has a family history .

Depression can also be caused by physiological factors, as well as by personal circumstances and environmental causes. Each of these factors will be explained below.

1. Genetic factors

If a history of depression is present in the immediate family (parents and/or siblings), this may increase the chances of suffering from this disease from 25% to 30% . There are studies with monozygotic twins (from a single zygote that divides in two after fertilization) that show that in one of the siblings the probability of suffering from depression increases by up to 50% in the case of a history in the other one. The probability, however, is considerably reduced in twins (dizygotic twins), up to 25% less.

As science advances in genetics, genes related to the predisposition of an individual to be more or less susceptible to depression have been found (such as: SERTs short serotonin transporter gene). It is estimated that up to 214 genes may be involved with the risk of depression.

Physiological factors

Depression is related to the decrease in a neurotransmitter called serotonin , specifically in the dendrites that transmit the impulses from the axon of one neuron to the soma of another. For this reason psychiatrists sometimes use a group of drugs, the selective serotonin reuptake inhibitors, whose main function is to increase the predisposition of serotonergic levels in patients with depression, the most famous of which is undoubtedly the one marketed under the brand name Prozac whose active ingredient is fluoxetine.

Other medications can also be used, such as anti-anxiety medications that act on another neurotransmitter: GABA (acid γaminobutírico). Anxiety is considered the sister of depression and generally go together to a greater or lesser extent depending on the table, anti-anxiety medications such as benzodiazepines are the most commonly prescribed.

Among other causes are endocrine disorders , which are another of the most frequent causes associated with depression, among which diabetes and hyperthyroidism stand out.

On the other hand, it has been observed that inflammatory processes affecting the brain significantly increase the chances of developing clinical depression. This means that a wide variety of problems in the body can affect mental health in a more or less indirect way, because there are many biological complications that end up generating inflammations.

3. Personal factors

It has been proven that the prevalence of this disease is significantly higher for women, especially during pregnancy and postpartum (PPD) due to hormonal variations.

Postpartum depression (PPD) is defined as a transient disorder that occurs two to four days after childbirth and disappears spontaneously within two weeks. There are two types of PPD, babyblues depression and depressive disorder itself.

In medicine, babyblues is the name given to the mild alteration in the mother’s mood, with mild depressive symptoms . It is manifested by lack of concentration, anxiety, sadness, but above all by an instability of the mood with a great tendency to cry. It does not require treatment since it disappears spontaneously after a short time.

However, in the case of the DPP, the symptoms manifest themselves at 12 weeks and present a more acute picture , both psychological and physical symptoms may occur, for example in the first case there may be feelings of uselessness, suicidal ideation or thoughts linked to death, and in the case of physical symptoms, these may include headache and intestinal discomfort among others. In this case, medical treatment is required.

Age is also a determining factor . The period between 35 and 45 years of age is the one with the highest incidence of this disease. However, depression in minors should also be highlighted, mainly during the period of puberty and adolescence, an age at which we experience very important hormonal changes and at the same time we define ourselves psychologically as people. In the case of depressive behaviour during childhood, we must pay more attention as it can have a very different manifestation than in adults and sometimes it is camouflaged under other types of disorders, however it is extremely important to pay special attention to the family environment.

4.Environmental factors

Environmental causes are all those external stimuli that influence the person and that can act as a catalyst for depression .

Negative family and/or work situations can produce stress and trigger depression, especially if the person has a history of alcohol dependency or drug use. Poor relationships with others, as well as difficulty communicating and isolation are key factors that increase the likelihood that an individual will develop depression.

Bibliographic references:

  • de Zwart PL, Jeronimus BF, de Jonge P, et al. (Octubre 2019). Evidencia empírica para las definiciones de episodio, remisión, recuperación, recaída y recurrencia en la depresión: una revisión sistemática. Epidemiología y ciencias psiquiátricas. 28 (5): 544–562.
  • Köhler-Forsberg, O.; Lydholm, C.N.; Hjorthøj, C.; Nordentoft, M.; Mors, O.; Benros, M.E. (2019). Eficacia del tratamiento antiinflamatorio en el trastorno depresivo mayor o en los síntomas depresivos: metaanálisis de ensayos clínicos. Acta Psychiatrica Scandinavica, 139(5): págs. 404 a 419.
  • Kotov R, Gamez W, Schmidt F, Watson D, et al. (2010). Vinculando los “grandes” rasgos de personalidad con la ansiedad, la depresión y los trastornos por consumo de sustancias: un meta-análisis. Boletín de Psicología. 136 (5): págs. 768 a 821.