Causes of Depressive Disorder
Despite the innumerable efforts made, and the scientific community continues to make, in order to answer this question, currently, there is no answer.
What can be said is that, unlike the widely spread idea in society, depressive disorders are not directly caused by a lack or deficit of serotonin in the body. It is known that to ingest foods or chemical products that increase the amount of serotonin in the blood, does not improve the depressive illness.
Based on the higher prevalence in women than in men, the possible causal implication of a hormonal factor in the development of a depressive disorder has also been widely studied, but, at the moment, it is not a line of investigation that has shown favourable results.
Another widely explored route has been, and is, the possible existence of a biological alteration in the brain; but again, the results have not been able to suggest a particular change at this level.
Risk factors of Depressive Disorder
Presence of high levels of stress or anxiety for a prolonged period of time.
Physical or psychic abuse in the first years of life.
Other factors that increase the risk of suffering a depressive disorder are:
Genetic. To have one or more first or second degree relatives affected by a depressive disorder, a bipolar disorder, or an anxiety disorder. It is possible that to have a family history of alcohol abuse may also be a risk factor.
Personality. To have a very extreme personality trait, for example, intense insecurity, elevated perfectionism, etc.
Non-psychiatric illnesses. In particular, some endocrinological, rheumatological, cardiovascular, and neurological diseases.
Use of drugs. Especially the corticosteroids, interferon, and some anti-hypertensives.
However, it is very important to highlight that not everybody that has a depressive disorder presents with one of these risk factors (the exception to this is the depressive disorder subtype called adjustment disorder that, by definition, does require the presence of a severe stressing factor as a trigger of the illness).
It is also very relevant to point out the widely held idea that the individual that has a depressive disorder is “immature” or must be very worried about something, is totally erroneous. The dysthymia and the depressive episode (or major depression) can appear spontaneously.
Hormonal changes and Depressive Disorder
For many years, there is the undemonstrated hypothesis in medicine that the hormonal changes that a woman experiences during the menstrual cycle, pregnancy, post-partum, and the menopause, could be one of the causes of the elevated incidence of depressive disorders in females.
Contrary to what was thought in the past, pregnancy, like post-partum, and the menopause, are stages of life of women in which there is an increase in the incidence of depressive disorders. Likewise, in the context of the menstrual cycle, up to 5% of women have a sub-type of a “minor” depressive disorder called pre-menstrual dysphoric disorder. This disorder consists of the presence of irritability, affective lability (ease of having sudden changes in mood), sadness, and sensation of constant tension, during the last 7-10 days of the cycle and the first 2-4 days of the following cycle.
The mechanism by which these hormonal changes can lead to the appearance of depressive disorders is currently unknown. What is known is that the different female sex hormones (progesterone and oestrogens) have common receptors in several areas of the brain.
It appears that there could be that a woman with a higher vulnerability to these hormonal changes, as such that whoever has experienced a premenstrual dysphoric disorder or other type of depressive disorder coinciding with a hormonal change (pregnancy or post-partum), would have a higher risk of suffering clinical relapses in the future, coinciding with intense hormonal fluctuations (pregnancy, post-partum period, menopause) than those that had never had a depressive disorder.
The use of hormonal contraceptives does not appear to predispose to the development of any depressive disorder in itself, although it could be associated with the occasional development of mild depressive symptoms.
One of the stages of life in which there is a particularly elevated risk of developing a depressive disorder is the postpartum period. There are two types of postpartum depressive disorders: the one called baby blues and the postpartum depression itself.
- Baby blues. Baby blues, or postpartum blues syndrome, is defined as the existence of a slight change in the mood of the postpartum mother. These mild depressive symptoms are very common. The person that suffers from postpartum blues syndrome, more than having feelings of incompetence or lack of motivation, what usually manifests is a very unstable mood with a great tendency to cry. Often, also, they are irritable, anxious, with headaches, insomnia and subjective complaints of lack of concentration. These symptoms usually subside spontaneously within a maximum period of two weeks. No treatment is necessary. It is not considered as an illness in itself.
- Postpartum depression. It is referred to as a depressive period (not an adjustment disorder or a dysthymic disorder) that starts in the first twelve weeks after childbirth. The signs and symptoms observed are similar to any depressive episode (major depression): sadness, feelings of despair and depreciation, drowsiness, loss of appetite, psychomotor slowing down, recurrent thoughts of death, various physical symptoms (gastrointestinal discomfort, headaches, and fatigue), elevated anxiety, etc. Postpartum depression does require treatment. If suitable treatment is not given, the postpartum depressive period usually lasts for a period of between 6 and 12 months. The treatment of postpartum depression is similar to that of any depressive episode. Despite the widely held belief that the postpartum depression patient has a tendency to harm their newborn child, this, in reality, is exceptional.
The cause of the elevated incidence of depressive disorders during the postpartum period is unknown. In the hours and days after childbirth, there are intense and sudden hormonal changes in the body of the woman. These changes particularly affect the sex hormones (oestrogens, progesterone), prolactin, the thyroid hormones, and cortisol. These changes probably have a key role in the development of postpartum depressive disorders.
Although it cannot be predicted 100% on who will suffer from a postpartum depressive disorder and who will not, it is known that there are several risk factors of having a depressive disorder during the postpartum period. Among all the known risk factors, having suffered a previous episode of postpartum depression is what will have a higher predictive power of future relapses.
The main risk factors of suffering a postpartum depressive disorder
Personal history of a depressive disorder (an especially increased risk if the personal history is postpartum depression)
To have anxious and/or depressive signs and symptoms during the pregnancy
|To have little social-family support during the pregnancy|
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