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

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.

Executive function, autobiographical memory and verbal and facial RM were assessed using standard neuropsychological tests and the remember/know paradigm.

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.

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.