Trajectories of Self-Awareness Across the Alzheimer's Disease Spectrum: A Systematic Review of Its Potential Contribution to Early Diagnosis.

Background/Objectives: Self-awareness constitutes a key metacognitive construct supporting self-regulation and adaptive functioning in aging. This systematic review examined how self-awareness fluctuates across the Alzheimer's disease (AD) continuum and explored its associations with cognitive performance and neuroimaging markers. Methods: A systematic search was conducted in databases including PubMed, Scopus, Science Direct and Web of Science covering the period from 2016 to 2026, and the review was registered on the Open Science Framework (OSF). The selection process followed PRISMA guidelines, and a total of 334 studies were screened for eligibility while 42 met the inclusion criteria. Studies were eligible if they examined self-awareness in relation to cognitive and/or neuroimaging parameters, with individuals in the preclinical and clinical spectrum of AD as the reference population. Results: The included studies highlighted self-awareness as a dynamic construct closely linked to cognitive performance and neural integrity, with measurable deviations emerging along the continuum from subjective cognitive decline to dementia. Accordingly, the findings suggest that alterations in self-awareness may reflect the stage-dependent cognitive and neurobiological changes that characterize the progression of AD. Conclusions: Converging evidence suggests that assessing fluctuations of self-awareness, ranging from heightened awareness to reduced awareness, may contribute to the early identification of individuals at risk of progression across the AD continuum. However, the substantial methodological heterogeneity across studies precludes definitive conclusions regarding its clinical utility. Future longitudinal studies employing standardized assessment protocols are needed to determine whether these changes can reliably predict disease progression.