PGD, with symptoms: excessive bitterness, disruptive yearning, and a shattered view of one’s own self and life, is closely associated with PTSD. Oftentimes, Holden displays those things.
Moreover, Holden likes to cling to his past, both in the sense of maturity and memories. His nostalgia for Allie, and his inability to accept the death and move on is shown, especially when he talks about how unique and charming Allie was.
Another (slightly less prominent) early instance in which Salinger alerts readers to Holden’s potential PTSD is when Holden sits and has a heart to heart conversation with Mr. Spencer. Old Spencer asks him multiple questions including “How do you feel about all this, boy?” (Salinger 13), indicating that he is trying to get Holden to open up and talk. It is in that conversation that it is revealed that Holden sat and talked with the headmaster Dr. Thurmer as well. The NPR Article states that scientists know talk therapy can help, so maybe his teachers understand their student’s situation and are trying to