Capgras syndrome: analysis of nine cases.

Three hundred and sixty-four patients, 158 males and 206 females, were admitted to an acute psychiatric ward between November 1994 and October 1995, and only 9 patients (2 males and 7 females) fulfilled the clinical criteria for Capgras syndrome. The crude prevalence of Capgras syndrome in the acute psychiatric ward was 2.5% (1.3% for men and 3.4% for women), which is not uncommon. Medical records and laboratory examinations, including brain images and electroencephalographic examinations (EEG), were reviewed in the nine patients with Capgras syndrome. Four cases were proven to have apparently abnormal anatomical lesions on EEG, brain computed tomography, magnetic resonance imaging or single photon emission computed tomography (99mTc-HMPAO) examinations and five cases were associated with major physical illness. These findings support that organic factors could be important in the pathogenesis of Capgras syndrome.