Delusions about people

A cognitive neuropsychological case study approach is used to document the case of a deluded schizophrenic patient (TG), who has severe difficulty naming famous faces and providing semantic information about famous people. This deficit occurs in the context of no significant deterioration from his estimated premorbid level of intellectual functioning. The evidence converges on the conclusion that he has a semantic deficit for famous people, and that this deficit has the characteristics associated with a degradation of person semantics, rather than a problem of access. One striking and unexpected finding was a preserved ‘island’ of face naming and semantic knowledge for a particular category of people. Furthermore, this spared knowledge corresponded to the major focus of his delusions. The possible relationship between such preserved knowledge and his delusions is discussed and a cognitive model of delusions is proposed; this is based on established principal information-processing subsystems involved in the retrieval of memories.