Abstract

Chronic stress is a major public health issue associated with diverse adverse physical and psychological outcomes. It is strongly linked to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, a central regulator of the physiological stress response. Cortisol, a glucocorticoid hormone regulated by this axis, is among the most widely studied stress biomarkers. It can be measured non-invasively in saliva, hair, or urine, each reflecting distinct aspects of stress exposure. Despite increasing research, the global landscape of cortisol-based biomarker studies remains fragmented and insufficiently integrated across disciplines. This bibliometric study analyzed 354 peer-reviewed articles published between 2005 and 2025, retrieved from the Scopus database using a predefined keyword strategy. Eligible studies were limited to English-language journal articles. Data were processed using VOSviewer and the Biblioshiny package in R to examine publication trends, author and institutional productivity, geographical distribution, keyword co-occurrence, citation patterns, and thematic evolution. The analysis revealed a substantial increase in publications over the past decade. The United States, Canada, and Germany were leading contributors. Major themes included HPA axis regulation, allostatic load, and mental health. Hair cortisol emerged as a key indicator of chronic stress, while interest in salivary cortisol declined. Research gaps include limited longitudinal studies, insufficient cross-cultural validation, and inconsistent methodological approaches. This study provides a structured overview of global research on cortisol as a biomarker of chronic stress. Mapping research trends, themes, and collaborations, it highlights existing limitations and offers direction for future interdisciplinary studies to enhance methodological rigor and clinical applicability