Wearable device data and saliva biomarkers help assess stress resilience

A team of scientists, including researchers from HSE University, has proposed a method for assessing stress resilience using physiological markers derived from wearable devices and saliva samples. The participants who adapted better to stress showed higher heart rate variability, higher zinc concentrations in saliva, and lower potassium levels.  The findings were published in the  Journal of Molecular Neuroscience.

Stress is the body’s natural response to pressure or challenge. However, prolonged exposure can increase the risk of cardiovascular disease, anxiety and depressive disorders, and can reduce cognitive performance and overall quality of life. Because conventional assessments rely heavily on questionnaires and psychological tests, the researchers set out to identify physiological markers that could complement subjective measures.

Researchers from HSE University, the Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences, the Federal Research and Clinical Centre of Intensive Care Medicine and Rehabilitology, and Lomonosov Moscow State University conducted a study to identify objective biomarkers of stress coping ability—ie the body’s ability to adapt effectively to stress.

Seventy-three volunteers participated in the study. Before the experiment, the researchers assessed their stress coping ability using clinical interviews, questionnaires, and physiological measures, and divided the participants into three groups: 'adaptive,' 'intermediate,' and 'maladaptive.'  

Participants then completed progressively more difficult memory and attention tasks. At one stage, they were given deceptive feedback and told they had made a mistake even when their answer was correct, creating a controlled stress condition designed to challenge confidence and self-esteem.

The researchers collected saliva samples before and after completing the tasks  and measured  antioxidant capacity (AOC) together with the concentrations of trace elements such as copper, iron, zinc, and calcium. Under stress, the level of free radicals—reactive oxygen species that can damage cells—increases, contributing to premature aging and the development of chronic diseases. This condition is known as oxidative stress. Antioxidants help regulate free radical levels; the higher their concentration, the better the body’s ability to withstand oxidative stress. 

The researchers also recorded a stress index based on data from wearable devices for comparison with the biochemical measures.

Laboratory analysis showed that higher heart rate variability (corresponding to a lower stress index) is associated with better stress coping ability. Zinc concentrations in saliva were higher in participants who adapted more easily to stress, while their potassium levels were lower. 

Although all participants demonstrated similar accuracy in task performance, those in the adaptive group had a lower stress index and higher antioxidant capacity in their saliva. In the maladaptive group, self-esteem declined significantly as task difficulty increased, regardless of whether their answers were correct.

According to the researchers, the study shows that data from wearable devices and saliva biomarkers can be viewed as an integrated system of indicators reflecting individual differences in stress resilience. This approach could form the basis for more objective methods of assessing stress coping ability in the future.

‘Severe stress can trigger a wide range of health problems, but people do not respond to it in the same way,’ says study author Evgeniia Alshanskaia, Research Fellow at the Institute for Cognitive Neuroscience of HSE University. ‘That is why it is important to predict and monitor these differences. Linking physiology, biochemistry, and mental state is an important step toward personalized preventive diagnostics.’