A systematic review of the neuroanatomical correlates and predictors of psychosis in Alzheimer’s disease

Abstract

AbstractBackgroundPsychotic symptoms (delusions or hallucinations) are a particularly prevalent form of neuropsychiatric symptom in people with Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI). Notably, their presence has been associated with an aggravation of the clinical picture of AD, with features including more rapid cognitive and functional decline, increased distress for the individuals and their caregivers (resulting in a higher rate of hospitalisation), and increased mortality. A growing number of studies detailing the relationship between neuroanatomy and these symptoms have been published in the last three decades in an attempt to clarify the underlying mechanisms. The aim of this systematic review is to capture all of the studies on AD that report links between psychotic symptoms and neuroanatomy, and to synthesise and evaluate these. Differences in the neuroimaging techniques employed, psychosis assessment tools, and brain areas investigated, as well as the sample size of the studies and disease stage of the patients, are likely to produce heterogeneous results, and these factors will be investigated during the review process.MethodThe protocol for this systematic review has been pre‐registered using the Open Science Foundation (DOI 10.17605/OSF.IO/TG8XP). Searches were performed using the databases PubMed, Web of Science and PsycInfo. These were followed by screening titles and abstracts and then full texts. These steps were performed by two independent reviewers, and recorded in a PRISMA flowchart. Inclusion of the studies was determined according to the following eligibility criteria: studies were either cross‐sectional or longitudinal to investigate the brain regions/networks that predict the future manifestation of psychotic symptoms; they contained samples of people with AD and/or MCI; they had a focus on delusions and/or hallucinations; they were limited to publications in English and peer‐reviewed publications; they had no restriction on publication date.ResultData extraction on full texts is currently underway. Once extraction is complete, data will be synthesised through summary tables and narrative descriptions.ConclusionThis systematic review intends to provide a comprehensive summary and synthesis of the brain regions and networks that are associated with psychosis and will capture key elements of the studies that are likely to impact their findings.