The role of acute stress, blood pressure and interoception in pain perception in individuals with borderline hypertension

Background and aims: Hypertension is a risk factor for major causes of death worldwide. A prominent characteristic of hypertension is blood pressure (BP)-related hypoalgesia, wherein pain perception decreases with elevated BP [1]. Hypoalgesia is a risk factor for early diagnosis of ischemia and silent myocardial infarction. Additionally, a reduction of pain perception occurs during acute and chronic stress conditions. This project aims to clarify the role of BP and stress in pain perception, as well as to explore the moderating role played by interoception (the ability to read and interpret visceral body signals) in individuals with borderline hypertension. Materials and Methods: A group of individuals with borderline hypertension and of normotensive individuals matched for sex and age, participated in the study. The heartbeat counting task [2] provided us with a measure of interoception. Measures of BP, pain perception, explicit (ratings on visuo-analogue scales) and implicit (levels of cortisol) indices of stress response, and heart rate were obtained in three different blocks (baseline pre-stress induction T0, stress induction T1, baseline post-stress induction T2). Stress was induced through a validated virtual reality (VR) scenario (IMVEST) [3], in which participants had to solve mental arithmetic calculations in short time windows. Preliminary results: We found that both perceived stress (F2,26 = 5.57, p < 0.01) and heart rate (F2,26 = 34.65, p <0.001) varied across the blocks. Specifically, after the virtual reality stress induction, participants self-reported higher levels of stress compared to baseline (t = -3.16; p < 0.01) and an increase of heart rate compared to baseline (t = -6.95; ps < 0.01). Moreover, in the group of individuals with borderline hypertension, we found a significant positive correlation between the stress response following the virtual reality scenario and interoceptive accuracy (r = 0.54; p < 0.05). We also found a significant negative correlation between pain threshold measured at baseline and perceived stress (r= -0.64; p < 0.01) and anxiety (r= -0.55; p < 0.05) measured immediately after the stressful induction. Finally, we only found a trend showing higher levels of pain threshold measured after the stressful induction compared to the baseline conditions (t = 1.96, p = 0.07). Conclusion and Discussion: These preliminary results suggest an association between interoception, pain perception and the stress response in individuals with borderline hypertension, providing insights into how stressful conditions may affect the early stages of the development of high BP and consequently, BP-related hypoalgesia. References: 1. Makovac, E., Porciello, G., Palomba, D., Basile, B., & Ottaviani, C. Blood pressure-related hypoalgesia: A systematic review and meta-analysis. Journal of Hypertension,2020, 38(8), 1420-1435. 2. Schandry, R. Heart Beat Perception and Emotional Experience. Psychophysiology, 1981,18(4), 483–488. 3. Rodrigues, J., Studer, E., Streuber, S., & Sandi, C. IMVEST, an immersive multimodal virtual environment stress test for humans that adjusts challenge to individual’s performance. Neurobiology of Stress, 2021, 15, 100382.