Saliva as a Relevant Biofluid for Huntington’s Disease Biomarker Research

Fluid biomarkers have traditionally been measured in cerebral spinal fluid and blood and the identification of markers in these biofluids has led to critical advances in biomarker discovery for neurodegenerative diseases, such as Huntington’s disease, a progressive, inherited disease associated with disrupted motor abilities and cognitive decline. Nonetheless, there remains a need for biomarkers that can be reliably measured in more easily-accessible bodily fluids. Accordingly, there has been long-standing interest in saliva for non-invasive diagnostics and health monitoring. Saliva has the capability to mirror systemic health conditions, due to its highly complex mixture of substances originating from multiple local and systemic sources. This makes salivary measures intrinsically important in their own right, and capable of reflecting the presence of disease throughout the body. This chapter will review findings from the literature that have explored saliva as a non-invasive biofluid for biomarker research in Huntington’s disease and have identified factors, such as huntingtin, cortisol, uric acid and cytokines, in saliva that track with features of the disease. These studies offer up a compelling argument for the inclusion of saliva biomarkers to aid in clinical care for patients with Huntington’s disease.