Psychosis in Alzheimer's Disease in the National Alzheimer's Disease Coordinating Center Uniform Data Set: Clinical Correlates and Association with Apolipoprotein E

Approximately 50% of late-onset Alzheimer's disease (AD) patients develop psychosis (AD+P), a heritable phenotype associated with more rapid cognitive decline. Prior studies conflict regarding whether apolipoprotein E (APOE) ϵ4 alleles are associated with AD+P, possibly due to small sample sizes, inconsistent diagnostic criteria, and different methodologies to assess psychosis. We used the National Alzheimer's Coordinating Center Uniform Data Set to evaluate the largest uniformly characterized sample of AD+P subjects studied to date for the association of APOE ϵ4 genotype, along with other demographic and clinical variables. Greater cognitive impairment and depressive symptoms were associated with AD+P, while the Caucasian race was protective. Neither APOE ϵ4 carrier status nor allele number was associated with psychosis. The AD+P phenotype is not associated with the APOE ϵ4 genotype. AD+P may represent a useful phenotype for the discovery of non-APOE ϵ4 genetic variation contributing to the risk of AD.