IS THE Iraq war another Vietnam? The debate will run and run, but on one level at least the answer is clear. The psychological damage done to American soldiers in Iraq is as bad, in terms of the proportion affected and the degree of harm, as anything Vietnam veterans endured.

We have known about post-traumatic stress disorder for decades. Sufferers experience flashbacks, emotional detachment, rage, sleeplessness and depression. There are hints that people who develop it as a result of intense and persistent trauma can end up with a dramatically reduced hippocampus, a part of the brain critical to memory. Now we know something else about this illness that should give presidents and prime ministers pause for thought before they send soldiers to the front: PTSD induced by direct combat is a lot more debilitating than we thought, with sufferers more likely to die of heart disease and cancer later ...