The presence of a mental disorder produces great difficulty in the daily life of those who suffer from it.Schizophrenia, bipolarity, anxiety, depression… all of them generate a high level of suffering and induce modifications at a cognitive and behavioural level.

However, the effects of some of the psychopathologies are not limited to these aspects, but produce great modifications at a physiological and cerebral level . In the case of depression, recent research suggests that suffering from this pathology could be associated with a shrinkage of some brain areas.

The results of this research have been obtained by analysing neuroimaging techniques applied to a large number of volunteers with and without depression, as well as by analysing donated brain tissue.

Cause or consequence?

In many mental disorders, changes occur at the brain level. These changes in the structure and function of the brain explain the symptoms of these disorders. But one fundamental consideration must be taken into account: the fact that there is a correlation between brain modifications and mental disorders does not indicate in which direction this relationship occurs. In a large number of disorders, research shows that brain alterations cause or facilitate the appearance of the disorder and its symptomatology .

In the case of depression, however, the latest research indicates that the reductions observed occur after the appearance of symptoms, an effect derived from the persistence of the symptomatology.

In other words, in the brain of depressed people we can observe some measures and modifications of the structure that are not present in subjects without this disorder. For this reason, the research carried out reinforces the idea of the importance of early intervention, in order to avoid not only the persistence of symptoms but also the degradation of brain structures.

Brain changes produced during depression

These studies indicate that the main affectations are in the hippocampus which is a very important brain structure when it comes to making certain memories to be stored in the long term memory. Depression is associated with a reduction in the neuronal density of this part of the brain , causing in turn deficits in memory, attention and retention of information (which can also be seen in the depressive process itself). This hypocampal atrophy, according to the studies, increases as the depressive episodes are repeated and as their duration is prolonged.

On the other hand, research so far indicates that the brain is compressed, losing internal neural connections and not only in the hippocampus.

Other changes in the brain during depression

In addition to the neurons themselves, glial cells are affected during depression, especially in the frontal cortex. The blood flow in the brain is slightly altered, which together with a slowdown in the metabolism of glucose in the prefrontal cortex causes it to see a reduction in the supply of oxygen and nutrients, producing a long-term reduction in this area as well. In the same way, the cerebellar amygdala is also reduced.

Finally, as with other disorders such as schizophrenia, the lateral ventricles undergo dilatation, occupying the space left by neuronal loss .

Reasons for brain reduction in depression

The reason for this reduction of the brain is due to the activation of a transcription factor known as GATA1 which prevents the expression of a series of genes essential for the creation of synaptic connections . This transcription factor interrupts cognitive functions and emotions.

Likewise, other data reflect that recurrent depressive states, as well as stress, cause hypercortisolemia, which if maintained produces a neurotoxicity that ends up affecting the hippocampus neurons, reducing their number and interconnection. In this way, the hippocampus is reduced and its functions are also affected . For this reason it is essential to treat depressive states early, especially in the case of depression in adolescents, whose brain is not yet fully developed.

In the long run, this reduction of the brain causes a decrease in the processing speed and in the capacity to organize and work with the information obtained from the environment, making it difficult to find an adaptive response to life situations. Similarly, depressive symptoms are worsened, both due to the direct effect of the reduction in capacity and due to the knowledge of the decrease in ability.

Reasons for hope: the alterations are partly reversible

However, the fact that research has reflected this phenomenon does not imply that depressed people have a permanent impairment, which may motivate treatment (both psychological and pharmacological) and the improvement of depressive symptoms, neurogenesis and neuronal strengthening. Thus, treating depression can motivate the creation of new neurons, recovering the functionality lost during the course of the depressive disorder.

At a clinical level, the alterations discovered may help to clarify the reason for the delay between the start of antidepressant consumption and its therapeutic effects, requiring slow changes not only in the availability of neurotransmitters but also at a structural level. This research may contribute to the development of new antidepressant drugs, which could be used to inhibit GATA1, as well as to encourage the search for professional help before the problem becomes entrenched.

Bibliographic references:

  • Kang, H.J.; Voleti, B.; Hajszan, T.; Rajkowska, G.; Stockmeier, C.A.; Licznerski, P.; Lepack, A.; Majik, M.S.; Jeong, L.S.; Banasr, M.; Son, H. & Duman, R.S. (2012). Decreased expression of synapse-related genes and loss of synapses in major depressive disorder. Nat. Med; 18 (9): 1413-7.
  • Miguel-Hidalgo, J.J. & Rajkowska, G. (2002). Morphological Brain Changes Depression. Can Antidepressants Reverse Them? Ibero-American Society for Scientific Information.