Since the movie never really said if Forrest Gump was mentally retarded or autistic, people have been debating the issue for years. In many ways, Forrest comes across as being mentally slow. However, his lack of picking up on social cues, his ability to outplay anyone at table tennis, and his ability to run for days, is more characteristic of an idiot savant. Whatever his diagnoses, Forrest certainly displayed autistic-like behaviors.