Performance during Face Processing Differentiates Schizophrenia Patients with Delusional Misidentifications

Abstract

Background: Delusional misidentification syndrome (DMS) is of considerable interest, but rarely diagnosed clinically. It is supposed to occur relatively frequently in schizophrenia, and to be related to the pathophysiology of face processing. Two antagonistic forms of DMS are the hypoidentification (Capgras) and hyperidentification (Fregoli) syndromes. We aimed to highlight differences between these subtypes using a face recognition memory task. Methods: Twenty schizophrenia patients (10 with DMS) and 21 healthy controls memorized the images of unknown neutral faces (targets). After a 10-min interval, accuracy and reaction times were recorded during a recognition task consisting of targets (newly learned faces), as well as familiar and unfamiliar face images. The 10 DMS patients could be further subdivided into 6 patients with Fregoli syndrome and 4 with Capgras syndrome. Results: Patients with DMS had longer reaction times than controls or patients without DMS (p < 0.001). Fregoli patients had longer reaction times (p < 0.001) and lower discrimination accuracy than Capgras patients (p = 0.019). These results were independent of other clinical variables. Conclusions: Face recognition differs between clinically identified subgroups of schizophrenia and between types of DMS. The results indicate independent pathophysiological mechanisms for Capgras (hypoidentification) and Fregoli (hyperidentification) syndromes in schizophrenia.