Identifying Shared Determinants Underpinning Depression, Schizophrenia and Dementia: A Scoping Review

Background and Objectives: This study examines the biological, psychosocial and neuropsychological elements overlapping among depression, schizophrenia and dementia. Using a transdiagnostic approach, the review identifies shared factors, improving understanding of their connections and guiding more cohesive intervention strategies. Methods: A thorough scoping review was carried out to systematically outline the literature on these three disorders from 1990 to 2024. It utilised narrative synthesis to summarise findings and offered an in-depth visual depiction of the frequency of studies and analysis of variables. Results: An extensive evaluation of 59 studies identifies common genetic vulnerabilities, early adverse experiences and neurobiological processes such as oxidative stress and neuroinflammation shared among these disorders, clarifying their linked neurocognitive characteristics. The review also highlights the role of neuropsychology in prevention, emphasising early detection and intervention through neuropsychological assessments. Conclusion: The results highlight the links between neurodegenerative and mental health disorders, identifying factors that shape their development and progression. Studies emphasise oxidative stress, chronic inflammation, early-life stress and hypothalamic–pituitary–adrenal axis dysregulation, revealing shared cognitive deficits across dementia, schizophrenia and depression. Together, these findings pinpoint common factors contributing to all three conditions.