Alzheimer’s disease (AD), dementia with Lewy bodies (DLB) and Parkinson’s disease (PD) are distinct neurodegenerative diseases, but increasing evidence suggests that they can share underlying biological changes. A new EPND publication, led by Marianna Rizzo from Maastricht University, investigates this overlap by directly comparing key cerebrospinal fluid (CSF) biomarkers across the three diseases.

The study, published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring, analysed samples from 347 participants from the EPND cohort, including people with AD, DLB and PD, as well as healthy controls. Amyloid beta, phosphorylated tau (p-tau181), neurofilament light chain (NfL) and total α-synuclein were measured centrally using fully automated immunoassays.

The researchers found evidence of substantial Alzheimer’s disease pathology in people with DLB. Around 61% of participants with DLB were amyloid-positive, compared with 20% of participants with PD, while tau positivity was observed in 26% of the DLB group and 9% of the PD group. In DLB, amyloid and tau positivity were also associated with poorer global cognitive performance, but not with motor performance.

NfL levels were elevated across all three disease groups, supporting its role as a marker of neurodegeneration that is not specific to a single disease. Total α-synuclein levels did not distinguish between diagnostic groups, but were associated with tau positivity across all groups studied.

By measuring several biomarkers using the same methods across multiple neurodegenerative diseases, the study helps clarify the extent and clinical relevance of overlapping pathology. The findings could contribute to improved differential diagnosis and patient management, as well as more informed participant selection and follow-up in clinical trials.

The research makes use of EPND’s multi-disease cohort, bringing together samples and data from multiple European studies. The underlying EPND dataset is available to researchers upon request through the EPND Catalogue in collaboration with the Alzheimer’s Disease Workbench.

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