Did we read the same Wikipedia? It seems the exposure to continuous shelling you can't escape from is one of the physical causes of this.

2015 research by Johns Hopkins University has found that the brain tissue of combat veterans who have been exposed to improvised explosive devices (IEDs) exhibit a pattern of injury in the areas responsible for decision making, memory and reasoning. This evidence has led the researchers to conclude that shell shock may not only be a psychological disorder, since the symptoms exhibited by sufferers from the First World War are very similar to these injuries.[13] Immense pressure changes are involved in shell shock. Even mild changes in air pressure from weather have been linked to changes in behavior.[14]