In J. D. Salinger's The Catcher in the Rye, Holden Caulfield is seriously affected by his grief over his brother Allie's death, and this grief leads to mental, emotional, and social difficulties for Holden.
As the novel opens, Holden speaks about how he has been expelled from school. Holden is clearly highly intelligent and well-read. He seems to have great potential, loves books, and could do quite well. Yet he doesn't seem to care much about school at all. This is likely due to his unresolved grief over his brother's death. Holden is failing for no good reason except a lack of motivation.
Further, we can see that Holden is fixated on Allie, for he writes an essay for a classmate about Allie's baseball mitt. We might wonder why he does not write more essays for himself. Mentally, then, Holden is struggling. He is letting his grief overwhelm his talent.
When Holden leaves school and goes into New York City, we catch plenty of glimpses of his emotional upheaval. He is not content with anything. He drinks and dances, but this doesn't satisfy him. He hires a prostitute but only because he wants someone to talk to. He is cheered a bit by a child's song and by memories of childhood visits to the Museum of Natural History. Yet he cannot bring himself to tour the museum without his sister. He struggles through movies and visits with his friend Sally, but everything leaves him depressed and unsettled.
Things aren't going too well for Holden socially, either. Sally doesn't really understand him. His friend Luce tells him that he needs to see a therapist. Holden both wants to see his family and does not want to see his family. He dreads admitting that he has been expelled from school, yet he has no where to go but home. Finally, he spends time with his sister, Phoebe, and only then does he begin to find some comfort.
We can see, then, that whether or not Holden wants to admit it, his brother's death has left him struggling mentally, emotionally, and socially.