Overlapping pathological features of Alzheimer’s and Parkinson’s diseases: Clinical implications and future directions for improving diagnostic precision

Nur Batrisyia Nizam, Nik Nasihah Nik Ramli, Nur Athirah Azlan, Muhammad Danial Che Ramli

Alzheimer's disease (AD) and Parkinson's disease (PD) are two of the most common neurodegenerative disorders, each with distinct clinical and pathological features, yet sharing significant overlaps that complicate diagnosis and management. AD is primarily characterized by cognitive decline stemming from amyloid-beta plaques and tau tangles, while PD is defined by motor dysfunction caused by alpha-synuclein-containing Lewy bodies. Despite these differences, both diseases exhibit overlapping cognitive, neuropsychiatric, and motor symptoms, along with shared underlying mechanisms like neuroinflammation and abnormal protein aggregation. This article explores these overlapping features, including memory and executive function deficits, neuropsychiatric symptoms such as depression and apathy, and motor signs like bradykinesia and rigidity. It also discusses the diagnostic challenges arising from these overlaps, highlighting the limitations of current tools and the promise of a multi-modal diagnostic strategy that integrates clinical evaluation, advanced neuroimaging, and emerging biomarkers. The review concludes by outlining future research directions, emphasizing the potential of advanced imaging, early detection of dual pathologies, and the development of integrated therapeutic approaches to enable precision medicine for these complex disorders.