Understanding Alzheimer's disease through biomarkers: pathology, progression, and clinical application.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the leading cause of dementia worldwide accounting for an estimated 60% to 80% of cases. Biomarkers play an integral role in AD randomized clinical trials (RCTs), providing objective measures of disease pathology, progression, and therapeutic efficacy. Key biomarkers, including amyloid-beta (Aβ), tau proteins, neuroinflammatory and neurodegeneration markers, as well as various neuroimaging modalities can help to facilitate the assessment of disease-modifying therapies, enable earlier detection of pathological changes before clinical symptoms emerge, and inform regulatory decision-making by demonstrating target engagement and possible treatment efficacy when linked to cognitive outcomes. This review examines the most salient biomarkers in AD RCTs and underlines their importance in advancing diagnostics, guiding therapeutic development, and improving clinical trial design to enable effective disease-modifying treatments. [Relevant literature was identified through searches of PubMed and Google Scholar for studies published through June 2026].