A new lab at ASU studies saliva to unlock information on everything from stress to social bonding.
Dr. Douglas Granger sets a timer as I maneuver an oral swab shaped like a foam bullet beneath my tongue. “Can you feel it absorbing?” he asks.
Two rows of lab equipment away, a robot’s green probes pipette saliva samples into vials to be tested for cortisol. The samples might be from Nepalese babies, California sea lions, or subjects in any of the 85-plus studies underway here at the Institute for Interdisciplinary Salivary Bioscience Research (IISBR). Opened last year, this Arizona State University laboratory is an international hub for spit, flown in frozen from collaborating scientists in fields from sociology to immunology.
Time’s up. I put my saturated swab in a plastic syringe and squeeze, centrifuging the saliva into a vial. As quick and easy as brewing tea, it’s ready for analysis. Except we’re not here for a study, so Granger unceremoniously disposes it. “It’s a biohazard,” he says.
I am mildly insulted. It may be a biohazard, but that liquid contains a Rosetta Stone of hieroglyphics about hormones, inflammatory markers and environmental chemicals. Scientists like Granger – the IISBR’s director – can use that information to improve stress interventions, investigate social bonding and streamline medical diagnosis. It’s part of ASU’s “vision for what universities are supposed to be: entrepreneurial, innovative, focused on solving real-world problems,” Granger says. “And saliva, believe it or not, fits into that niche pretty well.”
Granger came to saliva via the brain. Trained as a psychologist at UC Irvine, he used cognitive therapies to treat children with emotional issues but suspected their behavior had biological underpinnings. Later, at UCLA, he mixed immunology and endocrinology into his postdoctoral concentration in child development. But the necessary tests required blood samples, and families didn’t want to to take part in studies involving needles. “We needed an alternative,” he says, “and stumbled across saliva.”
Unlike blood, saliva is easy to collect through minimally invasive methods, so more people are likely to participate in studies, and some experiments that would have been logistically impossible become a cinch. People can also self-test: Scientists have developed saliva tests to diagnose HIV as well as measure estrogen in women undergoing fertility treatments. Saliva tests could also speed diagnosis of infectious diseases in developing nations, where clinic doctors often have one chance to assess and treat a patient.
When Granger started, saliva diagnostics was imprecise, he says. Thus began 25 years of studies. Along the way, Granger founded Salimetrics, which manufactures salivary diagnostic devices for more than 20 countries, and moved his research facility to ASU.
IISBR is post-geographical, Granger says. “Our interest is to create a hub where scientists can engage, not all here at ASU but all around the world, connected in a network.” Hence, ASU is working with scientists in Nepal using saliva to investigate why massaging babies with sunflower oil instead of mustard oil reduces infant mortality by 25 percent. They’re partnering with the San Diego Zoo to measure elephants’ stress levels in response to environmental changes. They’re running military nurses and medical students through simulations to track their stress.
Stress biomarkers are the prime diagnostic ingredient in spit. Of these, “the king in saliva testing,” Granger says, is cortisol, which surges when you’re feeling overwhelmed or defeated. This stress hormone also offers a window into social bonding. Years ago, Granger discovered mothers and their newborns, newlywed couples, and families of four coordinate their cortisol levels like outfits on a Christmas card. It led him and a team of researchers to investigate social bonding on a larger scale: the ASU marching band.
Band members filled out surveys identifying their friends and antagonists, and provided saliva to measure their cortisol and testosterone. The research, still under analysis, will have wide-ranging implications on how social situations affect biology and behavior. “This is cutting edge,” Granger says. “It’s the first time anybody’s ever looked.”
It’s just the beginning for salivary bioscience. Geneticists recently uncovered thousands of measurable biomarkers in saliva, waiting to be explored like unmapped islands. “We feel,” Granger says, “we’re just scratching the surface of the iceberg.”
Saliva contains a cocktail of illuminating biomarkers:
Alpha-amylase: Digestive enzyme that amplifies apace with adrenaline during fight-or-flight scenarios. Useful for measuring stress levels.
Cortisol: Hormone that surges in unfamiliar situations. People in relationships coordinate their cortisol levels, but we don’t know how. “We know it’s not magic, and we know it’s not pheromones,” Granger says.
Testosterone: Kicks in during competition. ASU researchers discovered people tend to befriend people with testosterone levels similar to their own.
Estrogen: Useful for measuring fertility in women undergoing in-vitro fertilization.
Inflammatory markers: Can reveal heart disease and periodontal disease.
Antibodies: Allow doctors to diagnose diseases such as HIV.
Environmental chemicals: Cotinine, for example, indicates first- or second-hand exposure to tobacco. Helpful when diagnosing kids with respiratory distress syndrome.
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