Two new salivary biomarkers to diagnose the second most common form of dementia after Alzheimer's disease
Dementia is a heterogeneous condition comprising different clinical and neuropathological pictures. In the early stages the different pathologies show similar clinical features, which makes specific diagnosis within the broad spectrum of these neurodegenerative diseases more difficult.
After Alzheimer's disease, dementia with Lewy bodies (DLB) is the second most common form of neurodegenerative dementia. Clinically, patients with the condition present with cognitive fluctuations, parkinsonism, visual hallucinations and REM sleep disturbances. Due to the clinical and neuropathological overlap, more than 80% of DLB cases are initially misdiagnosed and confused with other diseases, in particular Parkinson's and Alzheimer's diseases.
The new study, co-authored by Giuseppe Bruno and Fabrizia D'Antonio from the Department of Human Neuroscience at Sapienza University of Rome and published in the Journal of Alzheimers' disease, identified two salivary biomarkers that could facilitate the diagnosis of dementia with Lewy bodies, making it easier to distinguish DLB from other forms of neurodegenerative pathologies. These are the salivary alpha-synuclein species and the tau protein, another biomarker of neurodegeneration.
Researchers from Sapienza University of Rome, in collaboration with Campus Biomedico, studied the levels of these proteins in four groups of people: three groups of patients suffering from a neurodegenerative disease (DLB, Alzheimer's and Parkinson's) and one group of healthy people. The results showed that all the pathological groups had higher levels of alpha-synuclein and tau protein than healthy people.
In particular, the finding of elevated levels of phosphorylated tau protein (ps199-tau) makes it possible to distinguish patients with Parkinson's disease from patients with Alzheimer's disease and dementia with Lewy bodies. In addition, patients with Lewy body dementia have higher levels of oligomeric alpha-synuclein than patients with Alzheimer's disease. These findings, if confirmed in future research, could make it possible to differentiate three of the most common neurodegenerative diseases using a simple saliva sample.
The work was supported by a Sapienza grant as part of the 2021 small research project call.
References:
D’Antonio F, Vivacqua G, Serrentino M, et al. Salivary biomarkers for the molecular diagnosis of dementia with Lewy bodies. Journal of Alzheimer’s Disease. 2025;0(0). doi: 10.1177/13872877251317720
Further Information
Giuseppe Bruno
Department of Human Neuroscience
Fabrizia D’Antonio
Department of Human Neuroscience