Chronic depression can lead to shrinking of Hippocampus, region of the brain that is associated with memory and emotions
An international interdisciplinary study has now revealed that persistent depression shrinks that part of human’s brain which is responsible for emotions and memory and it further leads to drastic changes in the behavior of the person to an extent that they tend to lose their identity.
Based on the findings of this study, researchers ultimately concluded that brain damage is a consequence of recurrent depression and is not based on any predisposing or prerequisite factor as per their earlier belief.
Earlier, scientists were able link some of the brain shrinkage to depression; however there was a lack of evidence because of small sample size, a variance in types of depression as well as the corresponding treatment methods which all led to conflicting results.
However, a recent global interdisciplinary survey conducted by 15 research institute from the U.S.,UK and Australia was a combined effort of scientists, wherein the results of all the individual smaller studies was collated and finally helped them to conclude that it is the “persistent depression” which is the actual cause of shrinkage of hippocampus – which is a part of the brain’s limbic system-or also referred to as the emotional center of the brain.
Hippocampus is involved in long term memory processes as it not only forms the emotions but is also responsible for formation of new memories and then connecting the emotions to those memories as well.
Thus it can be seen that hippocampus plays a critical role in proper functioning of the brain and any damage of hippocampus can lead to severe consequences.
Philip Mitchell, scientia professor and head of the School of Psychiatry at University of South New Wales, Australia, who was also a part of the global survey said: “This study confirms – in a very large sample – a finding that’s been reported on quite a few occasions – the fact that the hippocampus is particularly vulnerable to depression.”
Leading the Australian arm of the study was professor Ian Hickie, from the University of Sydney’s brain and mind research institute. He said: “Your whole sense of self depends on continuously understanding who you are in the world – your state of memory is not about just knowing how to do Sudoku or remembering your password – it’s the whole concept we hold of ourselves.”
He added: “When you shrink the hippocampus, you don’t just change memory, you change all sorts of other behaviors associated with that – so shrinkage is associated with a loss of function.”
Scientists were able to conduct a cross sectional analysis of the brain scans of 9,000 people across the globe during this interdisciplinary study.
Researchers used the (Magnetic resonance images) MRI of the brain scans and clinical data from 1,728 patients who were suffering from a major depression and on the other hand they also used the data from 7,199 healthy volunteers and prepared a combination of 15 data sets from Europe, US and Australia including the samples from the ENIGMA group, which is an international consortium that conducts studies on psychiatric disorders.
The findings of this international survey has been published in Molecular Psychiatry on June 30.
Findings of the survey:
The study revealed that people who have a history of recurrent bouts of depression or who got depressed before attaining 21 years had a smaller hippocampus. Of the total depressed patients involved in the study, 65 percent accounted for such kind of persistent depression.
As per Hickie, findings of the study indicate that chronic depression or persistent depression is the root cause of brain damage.
He said: “I think this resolves for good the issue that persistent experiences of depression hurt the brain.”
He further added: “Those who have only ever had one episode do not have a smaller hippocampus, so it’s not a predisposing factor but a consequence of the illness state, the more episodes of depression a person had, the greater the reduction in hippocampus size.”
Hence based on the findings of the study, it can be seen that an early treatment of depression especially among teenagers and young adults is very important and can be beneficial as well.
Hickie, thus emphasized that an early identification and treatment of depression is an essential step to prevent the damage of brain in the long run. He added: “So recurrent or persistent depression does more harm to the hippocampus the more you leave it untreated.”
The study also revealed that patients who were on antidepressant medicines had a larger hippocampus, hence scientists concluded that this could probably the effect of the medicines
Hickie said:”So recurrent or persistent depression does more harm to the hippocampus the more you leave it untreated.” He further also emphasized that antidepressants “are not the only treatment” as a “broad range of treatments that should be explored” with psychotherapy “explored as the first line of treatment, not medicines.”
Professor of psychiatry at Monash University, Melbourne, Paul Fitzgerald added that this global survey definitely had a fundamental scientific value.
He said: “I don’t think there’s anything that’s really, fundamentally going to change overnight – but it’s an important part of the jigsaw puzzle to put together a better understanding of what’s going on in depression.”
Fitzgerald added that researchers would further continue their studies wherein they will compare the volumes of individual regions within the hippocampus as this would provide then the greater capacity to draw conclusions.
Based on the certain evidences, the research team also claim that with appropriate treatment at right time, it is possible to reverse the brain damage which has been inflicted due to depression.
Hickie said: “Other studies have demonstrated reversibility, and the hippocampus is one of the unique areas of the brain that rapidly generates new connections between cells, and what are lost here are connections between cells rather than the cells themselves.”
Finally Hickie has emphasized the importance of social interventions in the treatment of depression in addition to medicines by saying “treating depression effectively does not just mean medicines. Social interventions are just as important.”