University of Alberta scientists have identified three biomarkers for detecting mild cognitive impairment and Alzheimer's disease in saliva samples. The research has promising results for application in a clinical setting.

The research team combines expertise in metabolomics from Liang Li, professor in the Department of Chemistry, and neurodegenerative disorders from Roger Dixon, professor in the Department of Psychology. "All projections point to an impending and staggering global impact of neurodegenerative disease and dementia," said Dixon of the critical importance of this research.

Li and Dixon examined saliva samples from three sets of patients, those with Alzheimer's disease, those with mild cognitive impairment, and those with normal cognition. Using a powerful mass spectrometer, the pair examined more than 6,000 metabolites-compounds that are part of our body's metabolic processes-to identify any changes or signatures between groups.

"In this analysis, we found three metabolites that can be used to differentiate between these three groups," said Li. "This is preliminary work, because we've used a very small sample size. But the results are very promising. If we can use a larger set of samples, we can validate our findings and develop a saliva test of Alzheimer's disease."

A saliva test would prove useful in clinical settings for its ease and non-invasive nature. It also has the potential to detect neurodegenerative diseases earlier on, allowing for early intervention.

"So far, no disease-altering interventions for Alzheimer's disease have been successful," explained Dixon. "For this reason, researchers are aiming to discover the earliest signals of the disease so that prevention protocols can be implemented."

Another added benefit of identifying these biomarkers is the ability to conduct efficacy testing for treatments. "Using the biomarkers, we can also do testing to see what types of treatments are most effective in treating Alzheimer's disease-from diet to physical activity to pharmaceuticals," added Li.

The research has been published in two papers. The first, "Metabolomics Analyses of Saliva Detect Novel Biomarkers of Alzheimer's Disease," was published in the Journal of Alzheimer's Disease (doi: 10.3233/JAD-180711). The second, "Alzheimer's Biomarkers From Multiple Modalities Selectively Discriminate Clinical Status: Relative Importance of Salivary Metabolomics Panels, Genetic, Lifestyle, Cognitive, Functional Health and Demographic Risk Markers," was published in Frontiers in Aging Neuroscience (doi: 10.3389/fnagi.2018.00296).