Prevalence and correlates of Capgras syndrome in Alzheimer's disease

Objectives. This study examined the prevalence and clinical correlates of Capgras syndrome (CS) in Alzheimer's disease. Design. Cross-sectional study of elderly patients evaluated at an outpatient memory disorders clinic classified according to the presence or absence of CS. Subjects. One hundred and fifty-one consecutive patients diagnosed with probable (N = 110) or possible (N = 48) Alzheimer's disease (AD) utilizing NINCDS-ADRDA diagnostic criteria. Materials. The Behavioral Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD), Mini-Mental State Examination (MMSE) and Blessed Dementia Scale (BDS). Results. CS was observed in 10% of the sample (N = 16). Associated factors included other delusions, lower MMSE scores and higher BDS scores. The relation between CS and both cognitive and functional status remained significant after controlling for other delusions. Conclusion. CS was prevalent in approximately 10% of our community-dwelling AD sample. This syndrome was more common at the later stages of the illness and showed relations with increased functional impairment and other psychotic symptomatology.