Females in Combat
ONE look at the effects of a bomb blast suggests that you'd have to be extremely lucky to emerge from one unscathed. If you were not burned by the explosion or blasted by shrapnel, the chances are you'd be hit by the shock wave. Traveling at several hundred meters per second, this causes massive fluctuations in air pressure which can knock you unconscious, rupture air-filled organs such as eardrums, lungs and bowels, and stretch and distort other major organs.
Soldiers serving with coalition forces in Afghanistan and Iraq know only too well how devastating bombs can be. The effect of shrapnel on bodies - amputated limbs, broken bones, lacerated and burned flesh - is plain enough. Less obvious and harder to understand are the long-term effects of the shock wave on the brain.
Weeks, months, or sometimes years after being concussed in an explosion, thousands of soldiers are reporting a mysterious clutch of problems. Dubbed post-concussion syndrome (PCS), symptoms include memory loss, dizziness, headaches, unexplained pains, nausea, disturbance of sleep, inability to concentrate and emotional problems.
The US military and veterans' groups see PCS as a growing problem, and the US government is pouring millions of dollars into investigating it. Some doctors, however, particularly in the UK, believe that for many patients the symptoms ascribed to PCS are not caused by concussion at all, but by the shock and stress of wartime events. It may even be getting mixed up with post-traumatic stress disorder (PTSD), an acknowledged psychological reaction to disturbing events. "Some people are saying it's a hideous mistake and that we're talking up a problem," says Simon Wessely, a psychiatrist and director of the King's Center for Military Health Research at King's College London.
Simple concussion from a blow to the head is not a new problem, of course. Common causes are falls, car accidents or sports such as rugby and football. It can lead to a brief loss of consciousness, amnesia or confusion. Although longer-lasting symptoms are occasionally reported, sufferers usually recover within days or weeks.
Battlefield explosions are nothing new either. For soldiers serving in Iraq and Afghanistan, one of the biggest threats they face is from roadside bombs, often improvised from cast-off artillery shells or other weapons. While more soldiers than ever are surviving such blasts, thanks to better body and vehicle armor, they are often left with concussion, or mild traumatic brain injury (mTBI) as it is usually termed in this context.
In the 1990s, soldiers returning from the first Gulf war started to report persistent cognitive problems after an mTBI. The Brain Injury Association of America and others have described mTBI as a "signature injury" of the Iraq and Afghanistan conflicts. Veterans organizations have voiced growing concerns and are even using words like "epidemic".
But why should a bomb blast be more likely to trigger PCS than a sports injury? The jury is still out, although various theories are being investigated (see "Blasted"). Despite the uncertainties, the US military, government and patient groups designate mTBI and PCS as battlefield disabilities with a high priority. The Defense and Veterans Brain Injury Center (DVBIC) in Washington DC was set up in 1992 to help military personnel with brain injuries. In 2007, the US Congress agreed to provide $900 million for research into and treatment of battlefield traumatic brain injuries and PTSD. Then in 2008, President George W. Bush reauthorized the Traumatic Brain Injury Act, which compels federal health bodies to improve care and treatment of both civilians and soldiers suffering brain injuries and to fund monitoring and research.
Meanwhile, attempts to identify soldiers with mTBI have been stepped up. Both the British and the American military routinely carry out simple mental tests on soldiers exposed to blasts, investigating symptoms and what they remember of the event. Anyone with concussion should be removed from combat and given light duties until they recover. "The key is to limit the exposures [to concussion] and limit the exposures that come on top of each other," says Jeffrey Barth, a neuropsychologist at the University of Virginia, Charlottesville, and an expert on concussion injuries.
The US army also screens for symptoms of mTBI when soldiers return from a tour of duty, and again three months later. The army is also carrying out neurocognitive tests on recruits before they are sent into combat so that doctors can check for deterioration in later tests. However, even if PCS is diagnosed there is no specific treatment. All doctors can do is target individual symptoms, for example, with antidepressants, analgesics and sleeping pills, as well as psychotherapy and behavioral therapy. And the intense focus on identifying cases of mTBI and PCS belies the fact that the mechanism by which mTBI could lead to PCS is still unclear. PCS is not so much a discrete entity as a constellation of symptoms that overlap widely with other mental and physical illnesses. There is no blood test or brain scan that can diagnose it - doctors can only ask if the patient ever had an mTBI, run through the check-list of symptoms, and rule out other causes.
Those skeptical about PCS do not dispute that a worryingly large number of soldiers are returning from Iraq and Afghanistan with persistent cognitive problems. What they question is whether these symptoms can be attributed to an mTBI. "There was this sudden view that we'd stumbled on something completely new," says Wessely. "But blasts are not a new problem in warfare."
The debate has heated up in the past year with the publication of three studies that have cast doubt on the view that PCS is a direct consequence of concussion. In one, a team at Macquarie University looked at 175 civilians admitted to hospital because of physical injuries (Journal of Neurology, Neurosurgery and Psychiatry, vol 79, p 300). About half of the group had sustained an mTBI, and after a few days 43 per cent of them had symptoms consistent with PCS. But 44 per cent of the other group, whose injury was not brain related, also had these symptoms. While this study looked at patients in the first few days after their trauma rather than months, it shows that PCS symptoms aren't necessarily the result of brain injuries.
The other two papers are perhaps more significant as they involve large epidemiological studies in soldiers, rather than civilians, and looked at symptoms over the long term. Both research teams concluded that persistent cognitive problems after an mTBI were in most cases due to psychological causes such as depression and PTSD.
In the first study, researchers questioned more than 2500 US infantry soldiers three to four months after they returned from a year-long tour of duty in Iraq, asking them about their combat experience, any injuries they had suffered and any persistent symptoms. Around 15 per cent of them had suffered an mTBI, and these soldiers had significantly more mental and physical problems than those with other injuries (The New England Journal of Medicine, vol 358, p 453). Charles Hoge at the Walter Reed Army Institute of Research in Silver Spring, Maryland, who led the study, thinks the primary cause of their ill health was probably not concussion but "exposure to a very intense traumatic event that significantly increases the risk of PTSD".
Hoge reasons that PTSD is a more likely cause than mTBI, having many common symptoms. In addition, the psychological symptoms of PTSD persist, while the effects of concussion usually disappear quickly. "When a soldier gets concussed as a result of a blast on the battlefield, that is clearly a close call," says Hoge. "Such traumatic events can set up a cascade of neurochemical events that happen with PTSD, and that can lead to a host of symptoms."The second study is call "I saw dead people" and is available to read.