The Main Causes of Depression

Depression is an affective disorder through which a person experiences psychological distress. It is an acute clinical disorder that affects the brain. Depression goes beyond feeling "low" or "sad" some days, and hence it is important that we differentiate sadness from depression. The essential difference is that sadness is a natural response of emotionally-manifested pain to a painful stimulus. If the sadness is present over a period and becomes chronic, with or without an apparent cause, and is severe enough that it affects normal functioning in all areas of life, then we are dealing with depression.

Depression is not a natural response. Instead, it is a pathology that can lead to disability. Epidemiological studies reveal that in the United States 20% of the population suffers from this disease. In South Africa, it is estimated that one in six people suffer from depression. There are 22 suicides in South Africa every day, with a  further 220 attempted suicides. With numbers like these, what causes depression?

The main causes of depression are linked to genetic factors (genetic predisposition), so it is critical to evaluate if the person has a family history of depression. Likewise, depressive symptoms may also be due to physiological factors, as well as personal situational and environmental causes. I will explain each of these factors below.

1. Genetic factors

If the presence of a history of depression is found in the immediate family (parents or siblings), this can increase the probability of having this disease from 25% to 30%. There are studies with monozygotic twins (from a single zygote that divides into two through fertilisation) which show that in one of the siblings the probability of suffering depression increases up to 50% in the case of antecedents in the other. The likelihood, however, is substantially reduced in twins (dizygotic twins), up to 25% less.

As science advances in the field of genetics, genes related to the predisposition of being susceptible to depression have been found (e.g., the serotonin short-chain transporter gene). It is estimated that up to 214 genes may be involved with the risk of suffering from depression.

2. Physiological factors

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

Other medications that act on other neurotransmitters can also be used. 
These include serotonin and norepinephrine reuptake inhibitors (SNRI) as well as drugs that target norepinephrine and dopamine, to name some.

3. Personal factors

It is proven that the prevalence of depression is significantly higher in the case of 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 delivery and disappears spontaneously within two weeks. There are two types of DPP, depression baby blues and the depressive disorder itself.

In medicine, baby blues is considered a slight alteration in the mother's mood, with mild depressive symptoms. It manifests as a lack of concentration, anxiety, and sadness, but mainly with a high tendency to cry. It does not require treatment as it disappears spontaneously after a short period.

However, in the case of PPD, symptoms manifest at 12 weeks and present a more acute picture. Both psychological and physical symptoms can occur. For example, in the first case feelings of worthlessness, suicidal ideation or related thoughts can be present. In regard to physical symptoms, these may include headaches and intestinal discomfort among others. In this case, medical treatment is required.

Age is also a determining factor. Between the ages of 35 and 45 years is a period with the highest incidence of depression. It is also possible to highlight depression in minors, occurring mainly in the stages of puberty and adolescence. This is an age in which youngsters experience important hormonal changes while at the same time trying to define themselves as people. In the case of depressive episodes during childhood, it is important to note that it may have a very different manifestation from that of adults. Also, like adults, teenage depression can sometimes be camouflaged under other types of behaviour or disorders.

4. Environmental factors

Environmental causes are all those external stimuli that influence the person and can act as catalysts of depression. Negative situations, family and work, can produce stress and trigger depression, especially if the individual has a history of alcohol dependence or drug use. Poor relationships with others, as well as difficulty communicating and isolation are key factors that enhance the likelihood of an individual developing depression.

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