The main causes of depression

We explain the genetic, psychological and environmental conditions involved in depression.

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

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

What is depression?

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

Depression is an acute clinical disorder that affects 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 pain manifested emotionally is a necessary response mechanism. However, if the sadness lasts over time becoming chronic, without or with no apparent cause and with a 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 that for example 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 assess whether the patient has a family history of depression. it is very important to evaluate if the patient has a family history of depression.. 

Likewise, depressive symptoms may also be due to physiological factors, as well as to personal situation and environmental causes. Each of these factors will be explained below.

Genetic factors

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

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

2. Physiological factors

Depression is related to the decrease of a neurotransmitter called serotonin, specifically in the dendrites of the brain.specifically in the dendrites that transmit impulses from the axon of one neuron to the soma of another. For this reason psychiatrists sometimes use a group of drugs, selective serotonin reuptake inhibitors, whose function, mainly, 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 anxiolytics that act on another neurotransmitter: GABA (γaminobutyric acid), anxiety is considered the sister of depression and generally go together to a greater or lesser extent depending on the picture, anxiolytic drugs such as benzodiazepines are the most commonly prescribed.

Other causes include endocrine alterationsThese are another of the most frequent causes with which depression is associated, among which Diabetes and hyperthyroidism stand out.

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

3. Personal factors

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

Postpartum depression (PPD) is defined as a transient disorder whose onset is two to four days after delivery and which disappears spontaneously within two weeks. There are two types of PPD, the babyblues and the depressive disorder itself.

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

However, in the case of PPD, the symptoms manifest themselves after 12 weeks and present a more acute picture.For example, in the first case, there may be feelings of worthlessness, suicidal ideation or thoughts related to death, and in the case of physical symptoms, these may include headaches 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. Although it is also worth mentioning depression in children, mainly in the period of puberty and adolescence, age in which we experience very important hormonal changes while psychologically we define ourselves as people. In the case of depressive behaviors during childhood, it is necessary to pay more attention since it can have a very different manifestation from that of 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

The following are considered environmental causes all those external stimuli that influence the person and that can act as catalysts of the depression. 

Negative family and/or work situations can produce stress and trigger depression, especially if the person has a history of alcohol dependence or drug use. La escasa relación con otras personas, tanto como la dificultad de comunicarse y el aislamiento son factores clave que potencian la probabilidad de que un individuo desarrolle un cuadro de depresión.

Referencias bibliográficas:

• de Zwart PL, Jeronimus BF, de Jonge P, et al. (October 2019). Empirical evidence for definitions of episode, remission, recovery, relapse and recurrence in depression: a systematic review. Epidemiology and Psychiatric Sciences. 28 (5): 544–562.
• Köhler‐Forsberg, O.; Lydholm, C.N.; Hjorthøj, C.; Nordentoft, M.; Mors, O.; Benros, M.E. (2019). Efficacy of anti‐inflammatory treatment on major depressive disorder or depressive symptoms: meta‐analysis of clinical trials. Acta Psychiatrica Scandinavica, 139(5): pp. 404 - 419.
• Kotov R, Gamez W, Schmidt F, Watson D, et al. (2010). Linking "big" personality traits to anxiety, depressive, and substance use disorders: a meta-analysis. Psychological Bulletin. 136 (5): pp. 768 - 821.