Heritability of psychosis in Alzheimer disease

Objective: The authors have previously demonstrated familial clustering of psychotic symptoms in late-onset Alzheimer disease ( LOAD + P) and sought to estimate and explore the nature of the heritability of LOAD + P. Methods: The heritability of LOAD + P, defined by single and multiple psychotic symptoms, was estimated with data from the National Institute of Mental Health AD Genetics Initiative. Results: The estimated heritability for LOAD + P defined by multiple psychotic symptoms was 61%; for LOAD + P defined by any occurrence of psychotic symptoms, it was 30%. Conclusion: Multiplicity of symptoms may represent a useful means for defining a genetically determined LOAD + P phenotype.