Mental illness and amyloid: A scoping review of scientific evidence over the last 10 years (2011 to 2021)

Amyloid precursor protein and its derivates represent a central factor in the process of neurodegeneration in Alzheimer’s disease (AD). Since mental illnesses share with AD cognitive impairment, amyloid indicators have been used to explore the unknown pathophysiologic mechanisms underlining psychiatric illness. This work aims to compare the role of amyloid markers, together with tau proteins, among various mental disorders evaluating the possible role of altered amyloid metabolism in the onset and in the course of psychiatric diseases, considering the relationship with cognitive impairment in dementia. This review includes articles written in English, published between 1 January 2011 and 31 January 2021, which evaluated amyloid and tau proteins in psychiatric patients. After screening, 31 studies were included in the review. Results suggest that amyloid metabolism is altered in major psychiatric disorders and that it could be a marker of cognitive impairment. Nevertheless, the role of amyloid in mental diseases seems to be related to neurodevelopmental alteration as well as neurodegeneration processes, like in AD. The role of amyloid in the pathogenesis of mental disorders is still unknown. Amyloid should not be only considered as a marker of cognitive impairment in mental illness, but also for altered neurodevelopment.