The specific aims of this application are:~To measure the regional distribution of tau aggregation in AD patients with psychosis (AD+P) compared to AD without psychosis (AD-P) and Cognitively Unimpaired Healthy (CUH) participants with the PET radiotracer [18F]-PI2620;~To measure structural and functional brain networks properties in AD+P compared to AD-P patients and CUH participants using MRI;~To examine the association of tau pathology with structural/functional network properties; electrophysiologic biomarkers of neurotransmission and neuroplasticity; and psychotic symptoms. The current project will determine whether identification of tau pathology, and associated network connectivity disruptions and sensorimotor gating impairments, may be informing as potential biomarkers for psychosis in AD. As severe adverse events are associated with atypical antipsychotics in AD psychosis, this work will provide insights into whether anti-tau therapies such as monoclonal antibodies to tau, now being investigated in clinical trials, may be effective in the antipsychotic treatment of AD.
This research project aims to understand the brain mechanisms behind the manifestation of psychotic symptoms in Alzheimer´s disease (AD), and nature of the unique relationship with tau pathology. Amongst the cognitive manifestations of psychosis are impairments related to frontal circuits (social cognition, working memory and executive function deficits). The investigator's previous work suggests a role of tau pathology (one of the hallmarks of AD neuropathology) in the manifestation of psychosis in AD. However, the cerebral mechanisms that underly this association remain poorly understood. The overarching aim of the study is is to investigate the mechanisms by which tau network pathology may promote the presentation of psychosis in AD.