Why does depression make the brain smaller?
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 the cognitive and behavioral levels.
However, the effects of some of the psychopathologies are not limited to these aspects, but rather produce large changes at the physiological and cerebral level . In the case of depression, recent research suggests that the condition of this pathology may be associated with a shrinkage of some brain areas.
The results of these investigations have been obtained through the analysis of neuroimaging techniques applied to a large number of volunteers with and without depression. as well as through the analysis of donated brain tissues.
Cause or consequence?
Modifications occur in the brain in many mental disorders. These modifications in brain structure and functionality explain the symptomatology present in the disorders. But it is necessary to take into account one fundamental consideration: the fact that there is a correlation between brain changes and mental disorders does not indicate in which direction such a relationship occurs. In a large number of disorders, research shows that the cerebral alterations cause or facilitate the appearance of the disorder and its symptomatology .
In the case of depression, however, the latest research indicates that the observed reductions occur after the onset of symptoms, being an effect derived from the persistence of the symptomatology.
That is, in the brain of depressed people are observed 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 an early intervention, in order to avoid not only the persistence of symptoms but the degradation of cerebral structures.
Brain modifications produced during depression
These studies indicate that the main affectations occur in the hippocampus, which is a very important brain structure when it comes to making certain memories are stored in long-term memory. Depression is associated with a reduction in the neuronal density of this part of the brain , causing deficits in memory, attention and retention of information (which can also be observed in the depressive process itself). This hippocampal atrophy, according to studies, is increasing as the depressive episodes are repeated and as their duration is prolonged.
On the other hand, the investigations carried out until now indicate that the brain is compressed, losing internal neuronal connections and not only in the hippocampus.
Other changes in the brain during depression
In addition to the neurons themselves during depression, glial cells are affected, especially in the frontal cortex. The blood supply to the brain is slightly altered, which, together with a slowing down of glucose metabolism in the prefrontal cortex, causes it to reduce the oxygen and nutrients supply, producing a long-term reduction in this area. The cerebellar amygdala also dwarfs.
Finally, as with other disorders such as schizophrenia, the lateral ventricles suffer a dilation, occupying the space left by the neuronal loss .
Reasons for brain reduction in depression
The reason for this brain reduction is due to the activation of a transcription factor known as GATA1 which prevents the expression of a series of essential genes 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 sustained produces a neurotoxicity that ends up affecting hippocampal neurons, reducing their number and their interconnection. With that, 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 depressions in adolescents, whose brain is not yet fully developed.
In the long run, this reduction of the brain causes a decrease in the speed of processing and the ability to organize and work with information obtained from the environment, which makes it difficult to find an adaptive response to life situations.In the same way, depressive symptoms worsen, both due to the direct effect of the reduction of abilities and due to the knowledge of the decrease in ability.
Reasons for hope: alterations are partly reversible
However, that the investigations have reflected this phenomenon does not imply that depressed people have a permanent deterioration, being able to motivate the treatment (both psychological and pharmacological level) 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 the clinical level, the alterations discovered may help to clarify the reason for the delay between the initiation of antidepressant use and its therapeutic effects, requiring slow changes not only in the availability of neurotransmitters but also at the structural level. This research can contribute to the development of new antidepressant drugs, which could be used to inhibit GATA1 factor, as well as favoring the search for professional help before the problem is consolidated.
- 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 ?. Iberoamerican Society of Scientific Information.