Tau pathology in late‐life psychiatric disorder

Abstract

Auguste Deter, first described by Alois Alzheimer in 1906, developed delusional jealousy and affective symptoms in her 40s, followed by cognitive impairment such as memory loss, aphasia, and visuospatial deficits. In modern times, psychiatric symptoms of Alzheimer’s disease are considered a peripheral symptom of cognitive impairment known as Behavioral and Psychological Symptoms of Dementia (BPSD) that emerge after some degree of cognitive decline. Previous studies on psychiatric symptoms in Alzheimer’s disease mainly focused on cases with advanced cognitive impairment. However, recent cohort studies have reported that the onset of psychiatric symptoms in late life is a risk factor for the development of dementia. In addition, postmortem brain studies have revealed the presence of tauopathy and synucleinopathy in late‐life psychiatric disorders. This paper reviews these previous studies and touches on our group’s attempt to conduct amyloid and tau PET studies on patients with late‐life psychiatric disorders. Our findings suggest that some patients with late‐life psychiatric disorders have tau lesions linked to various AD subtypes and non‐AD tauopathies indicative of distinct early‐stage frontotemporal lobar degeneration subcategories.