The authors examined the association of Apolipoprotein-E (APO-E) genotype to symptoms of psychosis and depression in 501 patients diagnosed with probable (n=343) or possible (n=158) Alzheimer's disease (AD) according to NINCDS-ADRDA criteria. They observed the following APO-E genotypes: &epsis;2/&epsis;3 (n=19); &epsis;2/&epsis;4 (n=14); &epsis;3/&epsis;3 (n=228); &epsis;3/&epsis;4 (n=203); &epsis;4/&epsis;4 (n=37). In contrast to previous reports, the results did not indicate a relationship between either the &epsis;4 allele or the &epsis;2 allele and symptoms of mood disturbance in AD. However, an elevated risk for psychosis was shown, specifically, at the severe stage of cognitive impairment, among AD patients carrying the &epsis;4 allele, after effects of age, gender, education, and level of cognitive impairment were controlled.