Abstract
A case study of late onset psychopathology following brain injury is presented to illustrate the effects of cognitive and perceptual loss on personality functions. Based on Hughling Jackson''s notion of the duality of the symptom, a model was proposed for the development and process of psychopathology following brain injury, which views the development of the psychopathological behavior as a product of acquired cognitive and perceptual defects and ensuing compensatory strategies. For the present case study of paranoia, this involved defects in long-term memory, conceptual ability and compensatory strategies of confabulation and self-referential orientation. Neuropsychological testing established defects in concept formation tasks including the Raven Progressive Matrices, the Leiter International Performance Scale and the Wisconsin Card Sorting Test, as well as long-term memory defects where cognitive reorganization was needed. The paranoid process was understood as a product of disordered conceptual ability in interpersonal situations, and a self-referential conceptual classification system, which took time to emerge, changed social relations. The implications of this model for psychotherapy with brain injury are elaborated in a case study in which psychotherapeutic intervention included training on interpersonal hypothesis formation.