Facial Processing and the Delusional Misidentification Syndromes

Research indicates that the delusional misidentification syndromes (DMS) are linked to right hemisphere dysfunction. However, the extent and nature of any underlying processing impairment in patients with DMS remains unclear. We investigated five paranoid schizophrenic patients diagnosed with DMS (4 Fregoli and 1 Capgras patient), in conjunction with groups of psychotic and normal controls. Neuropsychological testing included assessments of verbal and performance IQ visuospatial function, and unfamiliar and famous face processing. Deficiencies were restricted to performance IQ and face-processing tasks, and these were most evident among the DMS group. No single neuropsychological profile characterised all the Fregoli patients or differentiated the Capgras patient. These results are discussed in the context of proposals which link the DMS to right hemisphere dysfunction.