Alzheimer disease subjects with psychosis have increased schizotypal symptoms before dementia onset.

Background: Recent findings have demonstrated the familiality of psychotic symptoms occurring during Alzheimer disease (AD with psychosis, AD+P), particularly for subjects with multiple psychotic symptoms. We have proposed a model in which genes that confer a small risk for psychosis interact with neurodegenerative illness to yield manifest psychotic symptoms during AD. One prediction of this model would be that AD+P subjects would have evidence of increased degrees of subsyndromal psychosis before AD onset.