Monoamine neurotransmitters in saliva – novel biomarkers of CNS function? Peripheral biomarkers of therapeutic response/ CNS function

Monoamine neurotransmitters, including catecholamines (i.e., norepinephrine, epinephrine, and dopamine), and the indolamine serotonin play important roles in signaling in the central and peripheral nervous systems. Alterations in neurotransmission may be suggestive of neuroendocrine or psychiatric disorders, may reflect therapeutic responses, and are often considered relevant to mental health. Monoamine modulators and their metabolites are detectable in saliva, suggesting that saliva could represent an attractive, non-invasive, and cost-effective matrix for identifying and monitoring conditions in both healthy and diseased individuals. Accordingly, measuring salivary monoamine neurotransmitters may have scientific and possible clinical relevance. In this review, we summarize and critically evaluate current evidence on salivary dopamine, norepinephrine, epinephrine, serotonin and their respective metabolites. Although further research is required to clarify their biological significance and clinical applicability, existing findings suggest that salivary monoamine measurement may hold potential, albeit with important limitations.