Saliva is an important biological testing fluid of the future.
"Saliva can be used to index the levels of a variety of biological markers known to be linked to developmental processes, social behavior, cognitive and behavioral sex differences, and high-risk health behaviors," says Dr. Douglas Granger, assistant professor of biobehavioral health in Penn State's College of Health and Human Development and director of Penn State's Behavioral Endocrinology Laboratory (BEL).
"It has distinct advantages over more traditional fluids used in biological testing. For instance, the levels of saliva biomarkers often represent the biologically active amount of the chemical in the body, and sampling saliva is less invasive, less costly, less hazardous, and more convenient than when using fluids like blood or urine."
The laboratory specializes in the design of assays and testing saliva samples for all different kinds of biological markers. Technicians sort through thousands of small tubes, frozen at ultra-cold temperatures that come from as far away as Sweden and Australia for analysis.
"This is a one of a kind facility. Its focus is exclusively on salivary biomarkers and the integration of these measures into research in health and human development. The laboratory facilitates projects at the cutting edge of biobehavioral science that involve interdisciplinary collaborations across multiple fields and levels of analysis," says Granger.
Projects now underway are exploring hormones and emotional development in teenage pregnancy; social and pubertal development in sexually abused girls; effects of pharmacological and behavioral interventions on the stress-response to acute pain in pediatric populations; family process, and child development; cognitive sex; emotionality and adolescent psychopathology; developmental psychopathology; and, stress and social affiliation in women.
Saliva can be used to test for testosterone. Granger recently co-authored a study examining the link between testosterone and health in a sample of 4,393 men. The study, "Testosterone and Men's Health," was co-authored with Dr. Alan Booth, professor of sociology and human development; and Dr. David R. Johnson, professor of sociology at the University of Nebraska-Lincoln, was published, in a recent issue of the Journal Of Behavioral Medicine.
The study found that higher levels of testosterone have significant health benefits for some middle-aged men.
"Men with higher testosterone are less vulnerable to high blood pressure, heart attacks, frequent colds and obesity," says Booth, professor of sociology and human development. "In addition, they are more likely to rate their health as excellent or good rather than fair or poor. Studies show self ratings of health correlate highly with physicians' assessments.
"The benefits of higher testosterone levels have a down side, however," Booth notes. "Some, but not all, men with higher levels of testosterone are more likely to engage in behavior that cancels out the beneficial effects of testosterone."
The study examined men between the ages of 32 and 44 who had served in the military between 1965 and 1971. The men were interviewed and medically examined. Comparison of men with slightly below average levels of testosterone with men with slightly above average levels revealed significant differences in the indicators of health. Men with higher levels of testosterone were less likely to have high blood pressure, less likely to have experienced a heart attack, less likely to have three or more colds in a year, and 45 percent less likely to rate their health as fair or poor.
On the negative side, men at the higher level were 25 percent more likely to report one or more injuries, 32 percent more likely to imbibe five or more drinks in a single day and 151 percent more likely to smoke.
Salvia assays can also be used to test cortisol levels. Cortisol is a hormone linked to stress, anxiety, depression, and socially withdrawn behavior. Granger has shown in past research that children who are more socially withdrawn or anxious are more likely to have an increased level of cortisol in their bodies. This is in response to stresses like social conflicts with their parents. Other research has shown that high levels of cortisol are associated with changes in the immune system, emotional problems, and perhaps memory impairments
Granger and his colleagues at the laboratory are also studying DHEA (dehydroepiandrosterone) levels in children and adults.
"Many people look at DHEA as a supplement to enhance aspects of their cognition, mood, and health," explains Granger.
Research also shows that DHEA plays a key role in the physiology of stress, is associated with major developmental milestones during middle childhood that set the stage of the transition to puberty, and DHEA is the major precursor of testosterone in females.
Granger and his team recently discovered that DHEA can be accurately measured in saliva.
"This methodological advance is important because researchers can now monitor the levels of this important hormone in people's everyday social worlds. By studying hormones and behavior in social context we expect to learn new information about the how biology and behavior interact with the environment to produce differences in developmental and health outcomes." says Granger.
Saliva assays have just begun to be used for diagnostic purposes. One of the first applications has been to screen for HIV infection. In the future, Granger says, it is possible that saliva might be used to diagnose other infections and possibly cancer.
"The practical implications of using saliva as a diagnostic fluid are enormous, but we still have some work ahead of us before we can realize the full potential", notes Granger.
Samples can be collected non-invasively. Samples can be collected in remote areas where resources aren't available to refrigerate blood or urine samples. They can also be gathered repeatedly and safely since The Centers For Disease Control do not consider saliva a biohazard unless it is visibly contaminated with blood. Samples can be self-collected, or collected easily in special populations for whom blood sampling is traumatic or problematic.
This research and service laboratory is also unique because it is the first university lab to be located in new Penn State Research Park. The BEL is an interesting case study in university facilities because it is an example of the ultimate "shared" lab, notes Granger. It is supported entirely by user fees assessed to the fifty to sixty investigators worldwide who use the unit each year. It is like a giant co-operative.
"We realized that there were many investigators interested in integrating biological measures into their studies who do not have the resources, training, or interest in maintaining their own labs. We provide the highest quality testing on a strict cost recovery basis. We have undertaken the development of this lab with a vision of contributing to biobehavioral sciences on a grand scale. Through this lab, we are able to improve the quality of studies, and facilitate studies that would never have been possible because of limited resources," says Granger.
The BEL even created a spin-off company in State College called Salimetrics. Salimetrics manufacturers and distributes reagents and materials for testing labs. For example, it produces a salivary cortisol enzyme immunoassay kit. The HS Cortisol EIA was developed by the Behavioral Endocrinology Laboratory and is licensed from Penn State by Salimetrics.
Editors: For more information on the laboratory, contact Granger at 814-863-5577. If you need any assistance, contact Steve Infanti at [email protected]
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