KF: What are the main advantages of saliva as a research biospecimen?

DG: Over the years, the answer to this question has evolved. At first, the focus was on minimally invasive alternatives to venipuncture. Then, the more interesting advantages were related to enabling the study of biology and behavioral relationships in the context of everyday life. Today, we also realize that a key advantage is the ability to study many biological data points for each individual. When combined with modern statistical tactics, multiple biological determinations per participant provides a wide range of opportunities to explore new research questions.

KF: What would you say is the most interesting finding from your studies to date?

DG: That’s a tough one. So many interesting observations have been made since we started this journey. I would say, among the top five most interesting observations is that the strongest correlate of an individual’s salivary cortisol level at any moment in time may not be their own behavior but may be the cortisol level of the people sharing their immediate social experience. The notion of social contagion, dyadic attunement, synchrony, or concordance for biological measures is fascinating. It challenges some of our conceptual models in interesting ways and creates opportunities for innovation in our methodological and analytical approach but also with respect to translation.

KF: What are the most often overlooked issues when incorporating saliva as a biospecimen into research protocols?

DG: Hum, another good question. Many investigators assume that if you can measure an analyte in saliva, the variation reflects the variation of that analyte in the circulation, or that the interpretation of the saliva levels can be based on literature that measured that analyte in blood. That is not always the case. It is very important to know how an analyte of interest gets into saliva. The route could be passive diffusion, active transport, or local production in the mouth. The route is directly related to whether there is a strong serum-saliva association and thus makes a big difference in our interpretation. Another big one is that there are many different types of oral fluids that compose “saliva”, and each can have a unique analyte profile. Understanding these issues is critical because it influences decisions about how and where oral fluid is collected in the mouth.

KF: What advice would you give to aspiring researchers interested in salivary bioscience?

DG: Two words, “team science”. The research questions we are trying to answer are complex. The simpler “main effects” type of questions have largely already been addressed in the literature. The complex nature of the most important research questions requires teams of investigators representing multiple areas of expertise. The diversity of ideas and training is very important. Think about a soccer team. Each player is a specialist and collectively they move the ball and adapt to challenges. Same thing here, get involved with a team, play the role that you know, and learn from the other players about what you don’t know. Don’t wait, jump right in… find a team and get involved. You don’t have to be the expert on everything to get the job done, but you do need to be a good team player though.

KF: How do you stay updated on the latest advancements and trends in the field?

DG: Some time ago, we worked with a publisher to propose a Salivary Bioscience journal. The feedback we received was that investigators need to publish in the journals that are aligned most closely with their home disciplines. So unfortunately, but fortunately publications that involve salivary bioscience can be found across a wide range of journal outlets. That makes it a challenge to keep up with the most recent findings. In the past, it has taken some special effort to search and find the latest. Salimetrics posts a weekly research item that we think is noteworthy, but there are of course many others. One thing for sure is that the field is moving too fast to wait to learn about “what’s new” at your annual conference. I am sure that those of us that are tech savvy will be able to use AI in ways that will regularly summarize and raise awareness about new observations that match our particular research interests.

KF: Have there been any moments in your career where you’ve had to pivot or adapt your research direction due to circumstances or new information?

DG: Every day. HaHa. No really, this is the name of the game for sure. Expect the unexpected. By the way, this isn’t always a bad thing, right? Some of the most interesting scientific discoveries have been revealed by surprising or unexpected findings. Twisting the question a little, we all need to be on the lookout for observations that don’t fit our assumptions which may reveal something more important and interesting than what we were actually trying to do. This is what keeps science so interesting. Rethinking, pivoting, making contingency plans for options A, B, and C, walking your neighborhood and thinking through 10’s of “what ifs”… How boring would it be if your assumptions were always right, your hypotheses were always correct, and your studies always successful? Yuck. The pursuit and the process are where the challenge is.

KF: What are you most excited about that is happening in salivary bioscience today?

DG: We have made advances in the measurement of glucose and insulin in saliva. These measurements should be very, very important to those of us who have spent our academic lives studying cortisol and the stress response. Sometimes, we have to speculate in our discussion sections as to why our cortisol-related findings are important relative to the bigger picture and for human health. For instance, the literature extensively describes for whom and under what circumstances cortisol changes in response to changes in our environment. A big question is “So what?” Enabling investigators to link changes in salivary cortisol to changes in glucose and insulin in saliva has direct implications for advancing our understanding of metabolic health (e.g., diabetes).

KF: Looking through your crystal ball, what’s next for salivary bioscience?

DG: Saliva testing has at times been viewed as the “Diagnostic fluid of the future”. Multiple times during my life, the headlines repeat this type of statement. We have learned that saliva will not replace blood testing for a long list of reasons. However, saliva affords self-collection of samples at home. Post-pandemic the population has become more aware of the value of home testing in the context of monitoring the impact of lifestyle choices on health and wellness. There will be consumer-focused opportunities that will enable all of us to learn more about how our biology and behavior impact our health.

KF: What’s next for Salimetrics?

DG: This year we celebrated Salimetric’s 25th birthday. Our mission has stayed true over these years, but we have several new initiatives. A key initiative provides logistic support to researchers collecting biospecimens remotely from their participants (i.e., saliva on dried spots, cold chain management improvements, an APP that enables real-time monitoring of specimen collection). We also realize that not every analyte of interest can be measured in a meaningful way in oral fluid and when that is true, a new technology that enables near painless self-collection of blood spots can fill an important gap. So, our testing services now provide a wider range of biological testing as we add testing blood spots to our services. Another initiative involves providing patients and providers with specialized diagnostic tests using saliva. Our Dim Light Melatonin Onset (DLMO) testing program is on the front edge of our work in this space (See biologyofsleep.com).

KF: In closing, is there anything else you’d like to comment on?

DG: It is very clear that most faculty at U.S. Universities are struggling to rebuild their research programs post-pandemic. The rebuilding is taking much longer than any of us anticipated. The stories we hear are heartbreaking — interrupted funding, difficulty rehiring or retaining staff, budget cuts, and restricted access to local resources that were once provided on campus. I think there is a new era of issues we face as members of the academy. Going forward I think university researchers will need to rely more on outsourcing aspects of project logistic support, coordination of supply chain, and sample collection, and laboratory services. It just won’t be possible to maintain these activities on campus in the way we were able to do so pre-pandemic. It’s not something that we are used to because we apprenticed with mentors and advisors in the day when each faculty member had their own lab. Those days appear to be in the rearview mirror now, but there is a bright side here. Outsourcing will make investigators less dependent on the ups and downs of campus budgets, priorities and politics and enable us all to focus more on what’s most important – our science.

KF: Thanks for taking the time today to answer my questions, Dr. Granger. Additionally, for our audience, if you have any questions or want to continue the conversation, feel free to connect with us through the Collaboratory.