PTSD and why war could shrink your brain

When I have time, (lately that hasn't happened much)I pop into different news sites and see what they have reported on in the past. Occasionally I come up with something that supports PTSD is not new and the studies on PTSD have been done before. It galls me no end that there are still "experts" acting as if the studies they do are brand new. Tonight is just one of those nights. I came across this report out of Scotland from 2003.

There has been a lot of talk from parts of this nation acting as if PTSD is new, that the numbers of veterans claiming PTSD are fakes or frauds, looking for a free ride, along with a whole host of character assignations. It's almost as if these people live in some kind of alter-reality where they are touched by nothing.

PTSD is not new. It's been documented since man first knew how to write. Veterans get PTSD just as ancient warriors did. It has nothing to do with what nation they live in or if they support their mission or not. It has nothing to do with courage either. Had it involved courage, they would fall apart before their first mission, not after the risk to their life is over and they are home and certainly not after their second, third or fourth tour.

I hope that Raj Persaud, the reporter on this forgives me for posting this in its entirety but as I was trying to pull out different sections, it was just too good to break up. kc

Why war could shrink your brain
Published Date: 25 March 2003
Source: The Scotsman
Location: Scotland

"‘PTSD could soon be an exclusionary factor for some types of military service’"
By Raj Persaud

Doctors have long known that stress can have crippling and tangible effects on the body, directly contributing to physical problems including stomach ulcers, heart disease and asthma. But new medical research suggests it could actually shrink our grey matter, causing physical brain damage.

The finding came about through the study of one of the most stressful experiences of all - war. In the mid-1990s military combat veterans in the US had their brains scanned with the latest imaging machines. The surprising finding was that those who had seen more action, who had been nearer and longer at the front line, tended to have a significantly smaller brain structure called the hippocampus. It looked as if being at war actually caused parts of the brain to shrink and wither away.

The hippocampus - the word derives from the ancient Greek sea horse because this small, paired structure near the centre of the brain resembles the shape of a tiny sea horse - now appears to be the part of the brain most vulnerable to sustaining structural damage secondary to mental stress.

Stress causes an increase in a variety of hormones released into our bloodstream, but of most interest is a group called glucocorticoids, which raise the heart rate, boost the immune system and suppress energy-intensive systems such as reproduction. Such changes are clearly useful for an animal trying to escape from a predator, but a side-effect of decades of chronic stress is that over-exposure to these particular stress hormones seems to shrink the hippocampus.

But do you have to go to war to damage your brain? Is less extreme stress still a danger? Sure enough, studies have now established that the longer people have experienced symptoms of mere depression, the smaller their hippocampus.

Yvette Sheline of Washington University School of Medicine in St Louis recently reported a brain imaging study which revealed that the hippocampi of depressed patients were on average 12 per cent to 15 per cent smaller than those of controls of the same age, height and level of education. Numerous other studies have found similar results. "It is absolutely clear that really prolonged major depression is associated with loss of hippocampal volume," concludes Robert Sapolsky of Stanford University - the first neuroscientist to discover how vulnerable the hippocampus was to stress from his work with primates.

Exactly why the hippocampus shrinks is still open to debate, but we also know that it is one of the few parts of the brain where new nerve cell growth occurs. This may be because it is a key part of the nervous system involved in memory. It now seems that when we lay down new memories it is because new nerve cells have grown in our hippocampus to code for these recollections.

The kind of memory supported by the hippocampus is spatial memory - when you are looking for your misplaced car keys it is your hippocampi that will be activated.

Taxi drivers recently given brain scans by scientists at University College London had a larger hippocampus compared with other people - it appears that their extensive geographical knowledge leads to remarkable growth in this part of the brain.

The hippocampus is significantly bigger in birds and animals for whom navigation is a vital part of their evolutionary strategy. For example, birds that use space around them to hide and locate food, and voles and deer mice that traverse large distances to find mates, all have larger hippocampal volumes than closely related species which do not.

If the hippocampus codes for spatial memory and shrinks when stressed, it is intriguing to note that stress can have important effects on our memory. Traumatic stress often leads us to avoid the place where we experienced the shock, or to become anxious as we get near that location again, particularly as a result of our vivid memories for the traumatic incident.

For example, those involved in automobile accidents often become more upset as they get closer to the precise road where the event occurred, suggesting that the hippocampus which codes for spatial memory is playing a key role in how stress effects us. A key symptom of post traumatic stress disorder is intrusive memories, nightmares that recall the original shock and flashbacks.

Princeton University neuroscientist Elizabeth Gould has found that exposing monkeys to chronic stress blocks the new nerve growth and perhaps it is cell destruction combined with a lack of new growth that produces the effects of stress on our hippocampi.

Intriguingly, several treatments for depression might have the opposite effect. Some anti-depressants, for example, increase the amount of serotonin in the gaps between brain cells, and serotonin is a well-known promoter of cell growth. Neuroscientist Ronald Duman of Yale University has found that rodents given antidepressant drugs or electroshock therapy all have significantly more newly grown cells in the hippocampus. This suggests, Duman argues, that increased nerve cell growth is a common effect of antidepressant treatment and could even be the main mechanism by which antidepressants work.

A recent study published in the Lancet confirms that patients on mood stabilising medication such as Lithium for just four weeks do seem to grow a small but measurable amount of grey matter as a result.

Doctors had assumed that depression results from changes on a more molecular scale - an imbalance in chemical messengers that communicate among brain cells. But perhaps the real issue is the way the actual physical structure of the brain is altered in depression or stress.

A more natural antidepressant - exercise - may also encourage brain cell growth. Exercise has been shown to increase the level of serotonin in the brain and can often help patients shake off mild depressive symptoms. Neuroscientist Fred Gage, of the Salk Institute for Biological Studies in California, reports that rats with access to a running wheel had more than twice as many newly growing brain cells as did mice with no running wheel. Since the rodents ran an average of nearly five kilometres per day for several months, it would seem that next time you pass an ardent jogger you should admire the size of their grey matter.

But one question continued to trouble scientists despite these exciting developments: how could they be sure that the smaller hippocampi the depressed and stressed seemed to have was a consequence of stress? Perhaps it was still remotely possible that it was having a smaller hippocampi in the first place which predisposes some to more mental problems? Which comes first: the small hippocampi or the large stress?

Now a study has been published which appears to take a big step to resolving this vital question. Mark Gilbertson, of Harvard Medical School, brain scanned 70 identical twins, one of each pair was a Vietnam combat veteran who was clearly exposed to the stress of war, while the other stayed at home and had no combat exposure. Sure enough, the men who went to war, and who ended up suffering from post traumatic stress disorder, also had smaller than average hippocampi.

But more astonishing yet was the finding that their identical non-combat twin also had smaller hippocampi, of roughly the same size as the twin who had served in war and then developed PTSD.

So one group went though combat trauma while their siblings were not in the war, yet both groups had small hippocampi. So instead of brain shrinkage happening as a consequence of stress, a small hippocampus must have preceded the war. The amazing finding suggests that having a smaller hippocampus predisposes a person to develop traumatic stress, and maybe even predicts that they will suffer from mental health problems if they are stressed.

It could well be, with more research to explore and confirm this finding, that a small hippocampus should be viewed as a risk factor for PTSD and thus, like a heart murmur, be an exclusionary factor for some types of military service. It could even be that brain scanning our hippocampi might help predict who is going to develop depression or other mental illnesses in the future.

Just because identical twins were involved in the study does not mean that having a smaller hippocampus is a purely genetic effect. Identical twins can have much more similar foetal environments than do non-identical twins. A "two hit" model is possible whereby early childhood stress causes the hippocampus to shrink a lot and it was this prior vulnerability combined with the second hit of stress from then fighting a war that later tipped those who finally got PTSD over the edge.

Some support for this "two hit" model comes from Gilbertson’s finding that those who developed PTSD had a shared higher chance of experiencing childhood abuse with their co-twin who had not gone to war.

Oddly, the "two hit" theory has dramatic implications for the population back home when an army is abroad fighting, which is that the first "hit" could be happening as mothers who are pregnant experience the stress and uncertainty of war. Recent research by psychiatrist Jim Van Os from Holland has found that the chances of a Dutch mother giving birth to a child who later grows up to develop schizophrenia went up by at least 28 per cent if she was pregnant during the very stressful time of May 1940, when the Germans invaded the Netherlands.

The maternal stress hormones or glucocorticoids, which can damage the hippocampus in adult life, might even be damaging the hippocampus of an unborn child.

It would seem that it is vital pregnant mothers try to stay as relaxed as possible during these troubled times and in particular ensure that they keep eating a healthy diet . Otherwise their stress and possible temporary loss of appetite could effect the brain development of their unborn children, leading the first part of the two hits needed to cause later problems such as depression or traumatic stress.

In other words, to echo the words of one psychiatrist Robert Sapolsky likes to quote, and who oversaw a ward full of PTSD sufferers in an American Veteran’s Administration hospital: "You have to understand that these boys had a lot of mileage under the hood before they ever set foot in Vietnam."


Dr Raj Persaud is consultant psychiatrist at the Maudsley hospital and author of From The Edge Of The Couch - Bizarre Psychiatric Cases And What They Teach Us About Ourselves, Bantam, £12.99.

The full article contains 1748 words and appears in The Scotsman newspaper.
Last Updated: 24 March 2003 6:30 PM