Researchers have finally concluded that persistent depression cause brain damage. The study published in “Molecular Psychiatry” has proved that depression shrinks the hippocampus- area in your brain that forms new memories. Shrinking of the hippocampus leads to loss of behavioral and emotional function.
Professor Ian Hickie from the Brain and Mind Research Institute has called “a new spirit of collaboration”- global analysis of brain scans of 9.000 people has linked brain damage to depression.
“I think this resolves for good the issue that persistent experiences of depression hurts the brain,” explained Professor Hickie.
Hippocampal shrinkage was bigger among people whose depression started before the age of 21 and those who had recurrent episodes. The professor explains that it’s the persistence that does the damage.
“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. It puts the emphasis then on early identification of the more severe persistent or recurrent cases. Importantly, in early identification systems you have to stick with those in who it persists or is recurrent, because they’re the ones who will be most harmed from a brain point of view, “explains Professor Hicks.
Researchers used MRI brain scans and clinical data from 1728 people diagnosed with severe depression and 7199 healthy people.
“This study confirms – in a very large sample – a finding that’s been reported on quite a few occasions. It’s interesting that none of the other subcortical areas of the brain have come up as consistently, so it also confirms that the hippocampus is particularly vulnerable to depression,” explains Professor Philip Mitchell, Head of the school of Psychiatry at UNSW.
The hippocampus has a major role in forming new memories and it’s also an important part of the brain’s limbic system.
“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. We’ve seen in a lot of other animal experiments that 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,” said Professor Hicks.
Professor Paul Fitzerald from the Monash University says that although the studies are important, they’re unlikely to affect medical treatments.
“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 and that obviously has implications for developing better treatments down the track. Having a better understanding of what the regional volume differences provide greater capacity to draw conclusions. Hopefully having the involvement of the hippocampus in depression confirmed in such a substantive study will stimulate attempts to better understand what this means” stated Professor Fitzerald.