Holden Caulfield is depicted as a troubled, neurotic adolescent who is extremely judgmental and depressed. He struggles to form meaningful relationships with his peers and flunks out of Pencey Prep at the beginning of the story. He is also an unreliable narrator, continually lying and over-exaggerating.
In addition to Holden's social difficulties, he also struggles with appropriately expressing his emotions and coping with his negative feelings. Before the start of the story, Holden experienced two notably traumatic incidents. Holden's beloved younger brother, Allie, died from leukemia, and Holden witnessed one of his classmates commit suicide by jumping out of a dormitory window.
These two events have significantly impacted Holden's mental health, and one can argue that he suffers from post-traumatic stress disorder. Holden experiences similar symptoms of PTSD by reliving his brother Allie's tragic death, suffering from terrifying daydreams, struggling to form healthy relationships, and engaging in self-destructive behavior. For example, Holden speaks to his deceased brother, Allie, and believes that he will disappear when he crosses the street. Holden also contemplates suicide and proceeds to make reckless decisions like binge drinking, soliciting a prostitute, chain-smoking, and wandering around New York City alone.
In addition to suffering from PTSD, Holden could possibly be diagnosed with psychosis and severe depression. His symptoms of psychosis include experiencing hallucinations, delusional thoughts, and constant mood swings. Holden's mental health problems prevent him reaching his potential in school, forming meaningful relationships with his peers, and experiencing feelings of contentment and happiness in his life.