Two hundred and sixty case reports of misidentification syndromes were evaluated. One hundred and seventy-four patients had a Capgras syndrome misidentifying other persons, 18 a Fregoli syndrome, 11 intermetamorphosis, 17 reduplicative paramnesia and the rest had other forms or combinations of mistaken identification. Schizophrenia (127 cases), mostly of paranoid type, affective disorder (29), and organic mental syndromes including dementia (46) were the most common diagnoses in patients who misidentified others or themselves. The patients with reduplicative paramnesia more frequently suffered from head trauma or cerebral infarction and showed more features of right hemisphere lesions on neuropsychological testing or CT scan than the patients with other misidentification syndromes. Forty-one case-reports implicated underlying medical conditions. Forty-six of the patients were reported to show violent behavioaur.
The misidentification of persons can be a manifestation of any organic or functional psychosis, but the misidentification of place is frequently associated with neurological diseases, predominantly of the right hemisphere. Misidentification syndromes show a great degree of overlap and do not represent distinctive syndromes nor can they be regarded as an expression of a particular disorder. These patients deserve special diagnostic and therapeutic attention because of the possible underlying disorders and their potentially dangerous behavioura.