Investigation of conscious recollection, false recognition and delusional misidentification in patients with schizophrenia

Background: Recognition memory (RM) is impaired in patients with schizophrenia, as they rely largely on feelings of familiarity rather than conscious recollection. It has been suggested that this abnormality may reflect a breakdown in strategic memory processes involved in both encoding and retrieval. By studying 2 patients with false recognition (FR; patient C.T.) and delusional misidentification (DM; patient B.C.), and a group of psychotic control patients, we examined proposals that FR and DM exist on a continuum of increasingly severe impairment in strategic memory function. Methods: Executive function, autobiographical memory and verbal and facial RM were assessed using standard neuropsychological tests and the remember/know paradigm. Results: The psychotic control group displayed a significantly reduced reliance on remember judgements and compensatory elevation in know judgements on both RM tasks compared with the normal control group. Patient B.C. also followed this trend, but in a much more pronounced manner. In contrast, patient C.T. displayed a qualitatively different performance profile, which was marked by an increased dependence on remember responses. Conclusions: We have presented evidence which support proposals that a breakdown in strategic memory and executive dysfunction are more pronounced in DM than FR. However, the small sample size precludes any firm conclusions being drawn.