Tau Biomarkers in Late-onset Psychosis (LOP)

Psychotic symptoms that occur in advanced age in the absence of an acute medical condition or prominent mood symptoms can represent the late appearance of primary psychotic disorders such as very late-onset schizophrenia-like psychosis (VLOSP) or delusional disorder, or can presage the appearance of a neurodegenerative condition such as Alzheimer's disease (AD). An episode of non-affective psychosis late in life more than doubles the risk of subsequent neurodegenerative disease, with an average time from psychosis to AD diagnosis of 18 months. The biologic mechanisms responsible for the increased risk of dementia in those who experience psychosis are unclear. One hypothesis is reverse causality, in which inchoate neurodegeneration is responsible for psychotic symptoms that emerge in the absence of traditional cognitive hallmarks of dementia. The psychosis then heralds the inception of illness that will eventuate in cognitive decline. The investigators will utilize neurodegenerative biomarkers in the form of novel PET imaging tracers, plasma immunoassays and non-invasive neurophysiologic measurements to test this hypothesis in a pilot cohort of elderly subjects suffering with psychosis occurring in late-life without dementia for comparison with a cohort of healthy elderly controls (HEC)s who are participating in a study focused on those with dementia.