Some of those who suffered from shell shock were able to cope with it after the war, and even found that it lessened over time. But others  such as Bertram Steward's friend  were never able to readjust.
According to the American Psychological Association (APA), shell shock caused soldiers to have tremors, sensation deficits, headaches, confusion, nightmares, stammer, and extreme fatigue that together were symptomatic of 'repressed trauma' rather than any physical issue.