Understanding Acute Hyposalivation

Spread the word!





What is the purpose of this research?
For a complete overview of all three hyposalivation-related studies underway in the Relman Lab, please view the Projects Page. This page introduces the rationale motivating the Understanding Acute Hyposalivation Study.

drought_pinyon_losalamosIn this project, we seek to identify in the mouths of healthy adults the bacterial
populations that are sensitive to temporary reductions in salivary flow, such as those caused by the temporary use of a medication. We hypothesize that a temporary reduction in salivary flow may alter bacterial communities in the same way that a drought can visibly impact plant communities in natural environments. The image to the right shows the effect of the 2002-2003 drought on pinyon trees in the Los Alamos National Forest. For more information about this drought, please visit The University of Arizona Website.

In this study, we seek to understand the extent to which temporary reductions in salivary flow impact oral microbial communities. To achieve this aim, we ask volunteers to use an FDA-approved medication for a maxium of 16 days to simulate a temporary drought. 


We will temporarily manipulate the salivary flow rate in healthy adults by administering the anticholinergic drug Transderm Scop.

TScopWe will use the FDA-approved drug Transderm Scop, which is commonly used to treat motion sickness in healthy adults, to modulate salivary flow in at most 77 healthy, non-smoking volunteers who are between the ages of 18 and 55. We will ask volunteers to use the Transderm Scop patch for at most 16 days while enrolled in the study. Transderm Scop temporarily reduces the amount of salivary flow by  about 50%.

About 70% of individuals who take this drug will begin to experience dry mouth, and hyposalivation, within 12-24 hours of first applying the patch to the skin. Importantly, the salivary flow rate returns to normal levels when individuals stop taking the drug, so the effect of reduced salivary flow is temporary and reversible.


1. Our first objective is to determine the extent to which an acute reduction in salivary flow impacts the spatial structure of oral microbial communities.  

bottle-water-full-half-empty-three-glass-bottles-first-one-second-one-third-one-nearly-vector-illustration-45725248We seek to test the hypothesis that the oral microbial communities residing in very wet environments (i.e., those located adjacent to the major salivary glands) will be disproportionately impacted, as compared to communities in environments that are normally dry (i.e., those isolated from salivary flow), following an acute, temporary reduction in salivary flow. We believe that by identifying the ways in which  hyposalivation alters the spatial structure of human oral microbial communities, we may be able to define the role that saliva naturally plays in maintaining human oral health. 

2. Our second objective is to determine whether and how acute hyposalivation modulates the rate at which microbial communities change.

We don’t currently know whether hyposalivation alters the rate at which microbial community change occurs, but if it either increases or decreases the rate of community compositional change, our findings could have important implications for managing human oral health.

We are specifically interested in understanding whether the rates of community compositional change at some sites in the mouth differ as compared to the rates of change at other sites following the acute onset of reduced salivary flow.

Finally, we are interested in understanding the speed to and extent with which microbial communities recover following withdrawal of Transderm Scop and resumption of normal salivary flow.

Why is this research important?

Most researchers who have evaluated the impact of hyposalivation on oral microbial communities have done so by studying patients who have experienced reduced salivary flow for months to years. The aim of our study, by comparison, is to improve our understanding of a form of hyposalivation that impacts most people at some point in their lives: temporary, medication-induced hyposalivation. Our short-term goal is to identify features of microbial communities that are associated with the early onset of hyposalivation so that in the long-term, diagnostics targeting early indicators can be developed. 

What can I do to help?

stock-photo-66304589-group-of-people-pointing-at-the-cameraWe are recruiting 77 healthy, non-smoking volunteers who are between the ages of 18 and 55 for this study. Our volunteers should not be under the treatment of a physician for any chronic medical condition, and should not be taking any medication besides birth control on a daily basis. 

If you are interested in participating in this research study, please take a close look at the risks and benefits of this research, as well as what we will ask you to do by clicking on Participate in the Acute Hyposalivation Study.

If you are a clinician, and you would be willing to send letters to your patients on our behalf, please email Diana Proctor at hyposalivation@gmail.com,  and she will send template forms to you. You may also call Diana at (650)-485-3793.

You can follow @brushwithucsf on Instagram/Twitter/Facebook.

You can also spread the word to others who may be interested in our research by tweeting or reblogging.

Thank you for your interest in our research study!


nidcr_logoThis not-for-profit research project is funded by a National Institute of Dental and Craniofacial Research grant (R01-DE23113-001) to Dr. David Relman.