Childhood Trauma, The Hippocampus, Depression And Neurogenesis.

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Childhood Trauma Can Harm Brain And Increase Risk Of Depression. However, The Good News Is The Brain Can Recover. This Article Explains How.

When we are at our most depressed, we may look at (as others perceive it) a beautiful sunset and derive no more pleasure from it than we would from looking at a rubbish dump or ugly building site. In short, nothing can lift our spirits and we feel unvaryingly, utterly desolate. It is as if the part of our brain that once experienced pleasure is now dead and unresponsive, never to be revived.

In fact, the latest research suggests that, indeed, a part of the brain, known as the hippocampus (a structure involved with long-term memory, the formation of new memories, and associating emotions with such memories), is impaired in function and reduced in volume in those suffering from severe, recurrent depression.

The good news, however, is that research also suggests that this brain region’s functioning is NOT irrevocably impaired due to a specific type of brain neuroplasticity (the ability the brain has to repair and rewire itself) known as NEUROGENESIS (the brain’s ability to generate new neurons).


The research to which I refer has discovered that, in individuals who are severely depressed and suffer recurrent depressive episodes, the hippocampus has become significantly reduced in size. (We know, too, from numerous other articles that I have published on this site, that those who have suffered severe and chronic childhood trauma and, as a result, have gone on to develop conditions such as borderline personality disorder or complex posttraumatic stress disorder are also liable to have incurred developmental damage to this particular brain region; and, indeed, sufferers of these conditions frequently also receive a co-morbid diagnosis of clinical depression).

The study involved 8,927 participants of whom 1,728 had received a diagnosis of major depression. This allowed the researchers to compare the brains of the depressed individuals with the brains of the healthy individuals using data that had been obtained using a brain-scanning technique known as magnetic resonance imaging (MRI).

Of the depressed individuals, 65 percent had recurrent depression and it was this subset of the depressed individuals who were found to have shrunken hippocampi (those participants who were experiencing their FIRST depressive episode had hippocampi which were of normal size).


As the researchers pointed out, these findings suggest that it is the depression that causes the damage to the hippocampus, rather than the other way around and this discovery helps to emphasize how important it is to commence treatment for depression at the earliest possible opportunity, especially in teenagers and young adults whose brains may be more susceptible to physical damage due to their greater plasticity when compared to the brains of adults, in order to prevent such organic damage to the brain from occurring.

Indeed, the researchers. underlining this point, drew attention to the fact that the longer depression goes on, and the more depressive episodes an individual suffers, the greater the reduction in the size of that individual’s hippocampus is likely to be.


There now exists an increasing body of evidence that one of the functions of the brain’s HIPPOCAMPUS may be the recognition of novelty and it has been theorized that, because, as we saw above, it may be damaged in depressed individuals, particularly those individuals who have suffered long-standing, recurrent depressive episodes, these people may lose the ability to respond to novelty and this loss then contributes significantly to their depressive state. For instance, it helps explain why they may not respond with pleasure to a beautiful sunset (see opening paragraph) and why they are prone to seeing whatever they do as ‘being the same’, by which is meant everything produces the same feelings of flatness, emptiness, meaninglessness ; in short, a state of anhedonia.


The good news, however, as has already been alluded to above, is that numerous studies have demonstrated that such damage to the brain is, in fact, reversible; this is due to a quality that the brain possesses known as neuroplasticity (which I have written extensively about in many other articles that I have already published on this site – e.g. see my article about three ways in which the brain is able to repair itself in relation to the damage it has sustained as a result of childhood trauma).

Indeed, one of the leading researchers involved in the study, Hickie, described how the hippocampus was one of the brain regions within which it is known that cells can rapidly generate new connections between themselves (this process is known as neurogenesis, see above) to replace the connections that were lost during the periods of untreated depression.


Hickie further states that there is some evidence that medication (antidepressants) protect, to some degree, the hippocampus from shrinking but also stressed the importance of meaningful social interventions as a form of treatment, pointing out that if, when depressed, we simply sit alone in a room and isolate ourselves, failing to interact socially with others, then this lack of social interaction, in itself, is likely to reduce the size of the hippocampus – a good social support system, then, is an extremely important factor to be considered when deciding how best to treat depression.

Furthermore, Hickie states that there is also evidence that treatment using fish oils can be ‘neuroprotective.’

In the case of young people, Hickie suggests that psychotherapy may often be the first-line treatment offered, rather than medication. (N.B. Always consult an appropriately qualified professional when considering medical treatments).

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David Hosier BSc Hons; MSc; PGDE(FAHE).