Defensive hostility has been attributed as an early risk factor of coronary heart disease. The autonomic characteristics of high defensive, high hostile (HD) and low defensive, high hostile (LD) men and women were assessed with a variety of cardiovascular (CV) measures. Reactivity and recovery to an active laboratory stressor (video game, VG) and a passive laboratory stressor (hand cold pressor, CP) of 15 HD men, 16 LD men, 16 HD women, and 16 LD women were recorded. It was predicted that the CV patterning associated with the HD participants would display more sympathetic and less vagal control as well as the least pronounced recovery from the stressors in comparison to LD participants. Results revealed differential CV responses to the lab tasks by group. HD women displayed consistently high levels of low frequency power heart rate variability (HRV) during baseline and across conditions. HD men exhibited significantly pronounced heart rate reactivity and reduced high frequency power HRV to the CP task in comparison to LD men. Interestingly, LD women displayed weaker blood pressure (BP) recovery to the VG in comparison to HD women, whereas the opposite pattern was observed in BP recovery to the CP. These results suggest that defensiveness and sex may moderate the CV reactivity and recovery to different types of stressors in hostile participants. / Master of Science

Pain perception can be drastically affected by external factors in the surrounding environment. Previous studies relying on subjective ratings of pain have shown that guided meditations supplemented by virtual reality (VR) can reduce the perception of pain more successfully than the audio alone. The research question for this study was: How does the efficacy of meditation as a means of pain mitigation differ with and without the application of VR? To answer this question, we used fNIRS to visualize changes in the dorsolateral prefrontal cortex (DLPFC), which has been shown to play a role in the larger pain matrix in the brain. To induce discomfort, we used a Cold Pressor Arm Wrap (CPAW), which is a variation of the more common Cold Pressor Task (CPT). This study was a within-subjects design where in each of the three conditions participants experienced CPAW. The three conditions were: (1) control (no VR & no audio), (2) audio (audio only), and (3) VR (audio + VR). We hypothesized that there would be a decrease in cortical activity in the DLPFC during CPAW when supplemented by VR meditation compared to audio-led meditation and no meditation, due to a decrease in perceived pain in the VR condition. Our results showed that VR meditation did significantly reduce perceived pain, according to the subjective pain ratings. Participants rated their discomfort the lowest in the VR condition, slightly higher in the audio condition, and highest for the control condition (in the absence of meditation). However, there were no significant differences in activity in the DLPFC between the conditions. The lack of any significant findings with the fNIRS data could be the result of many issues, including not having a large enough sample, physiological noise, improper localization of the pain ROIs, and not having a strong enough discomfort stimulus. The future directions for this study would seek to remedy these issues in order to obtain more informative fNIRS results. Overall, this study did show that VR meditation does effectively reduce pain perception and is therefore a promising tool for nonpharmacological pain management.

The bond between pet and owner has been shown to decrease stress-related physical, mental, and emotional disorders by lowering blood pressure and heart rate. The purpose of this study was to examine whether a nonpet canine would have the same effect in reducing physical symptoms of stress as a known dog. Human-animal bond theory, Human pressor test. Data were analyzed using repeated measures, analyses of variance, and t tests. Results indicated that interaction with a strange dog lowered heart rate and blood pressure significantly faster in the experimental group than in the control group. The positive social change implications of this research include policy and procedural accommodations for the use of canines as comfort animals for individuals in stressful conditions.

The purpose of this study was to examine the effects of the cold pressor test on skin temperature, natural killer cell activity, plasma concentrations of interleukin-1 and cortisol, and the numbers of white blood cells, CD3+ cells, CD4+ cells, CD8+ cells, and CD56+ cells in the peripheral blood. In addition, the study examined whether thermal biofeedback, when presented following the cold pressor tests, would mitigate the effects of the cold pressor tests. Four male university students completed pretest psychological inventories and were pretrained during nine laboratory sessions to increase their skin temperature to 95 degrees Fahrenheit. During the experiment, blood samples were collected at 5-minute intervals and before and after the 1-minute cold pressor tests through an 18-mm catheter inserted into each subject's arm. Subjects were randomly assigned to a matched pair and to the order of experimental conditions, including baseline, the initial cold pressor test, return to baseline, the second cold pressor test, and thermal biofeedback. Each matched pair experienced the conditions in a multiple baseline fashion across subjects during the individual 1.5-hour experimental sessions. Following the experiment, subjects completed posttest psychological inventories, exit interviews, and consumer satisfaction surveys. All subjects demonstrated a decrease in skin temperature ranging from 1 to 1.4 degrees Fahrenheit during the 1-minute cold pressor tests in a multiple baseline fashion, and repeated the temperature decreases within-subjects during the second cold pressor test. Increases in natural killer cell activity ranged from 1% to 14% during the cold pressor tests. For all subjects, both cold pressor tests were associated with increased plasma concentrations of interleukin-1, ranging from 2 to 69 pg/ml. The initial cold pressor tests were associated with increases in all cell numbers in a multiple baseline fashion, but cell numbers varied during the second cold pressor tests. For all subjects, average skin temperatures during the thermal biofeedback conditions were from .3 to .9 degrees higher than during the return to baseline conditions. For all subjects, thermal biofeedback conditions were associated with from 2 to 8 (10^4 cells/ml) higher mean numbers of CD56+ cells than the return to baseline conditions. For 3 subjects, the thermal biofeedback conditions were associated with higher numbers of white blood cells, CD3+ cells, CD4+ cells, and CD8+ cells than the return to baseline conditions. Thermal biofeedback was associated with reductions of from .2 to 26 in the standard deviations of interleukin-1 values, and with a reduced range of cortisol values following the cold pressor tests. Few changes occurred in scores from pre- to posttest on the psychological tests. Subjects rated the goal of learning to relax as very important. All of the subjects stated that they would seek relaxation training for the treatment of a medical or psychological disorder if prescribed. Implications are discussed for design of research in psychoneuroimmunology, for measurement of immune system variables, and for potential clinical applications of these data.

Smärta har stor roll i dagens samhälle och vikten av att utveckla ett effektivt behandlingsprogram bör uppmärksammas. Syftet med denna studie var att undersöka distraktionens effekt på personlig målinriktning. Om målinriktningen handlar om positivt eller negativt vinklad målinriktning. Smärta framkallades genom att deltagarna ombads utföra ett så kallat cold pressor task. Deltagarna blev indelade i tre grupper, kontrollgrupp, en grupp med positivt vinklad målinriktning och en grupp med negativt vinklad målinriktning. Resultatet indikerade på en icke signifikant skillnad mellan de tre grupperna gällande grader av smärta men deltagare som oroade sig över smärtan visade på högre smärta än de som inte oroade sig i den positiva gruppen. Resultatet kan vara vägledande för framtida studier i syftet att utveckla smärthanterings program. / Physical pain is a burden to pain patients and society. Interest has risen to develop effective pain treatment. The aim of this study was to examine if the impact of distraction on pain perception depends on the motivational characteristics of the distraction task. We examined whether the impact of distraction depended on the distraction task had a promotion or a prevention goal focus. Pain was induced using a cold pressor task. Participants were divided into three groups: a control, a promotion and a prevention group. Results indicated no significant difference between the three groups in pain intensity but among high catastrophizers in the promotion group. This result provides guidelines for further studies in the purpose of conducting effective pain treatment.

För att bättre kunna förstå och hjälpa de som drabbas av långvarig smärtproblematik är detviktigt att applicera ett biopsykosocialt perspektiv. En tidigare studie föreslog att en vissskattning av smärtintensitet i ett cold pressor test (CPT) var en biomarkör för utvecklingen avlångvarig smärtproblematik. Denna studie syftade till att undersöka huruvida dennaföreslagna biomarkör, samt variansen i sammanlagd smärtintensitet under CPT, kan förklarasav uppfattad stress respektive utmattningssymtom, utöver demografiska faktorer ochsymtomkatastrofiering. Deltagarna (n = 35) genomförde ett CPT. CPT-skattningaranalyserades tillsammans med demografiska faktorer, symtomkatastrofiering, uppfattad stressoch utmattningssymtom i hierarkiska regressionsanalyser och hierarkiska binära logistiskaregressionsanalyser. Resultaten visade att högre grad av uppfattad stress predicerade lägresmärtintensitet, utöver övriga faktorer. Utmattningssymtom hade ingen signifikant effekt påsmärtintensitet. Inga undersökta faktorer kunde förklara den föreslagna biomarkören.Resultatet indikerar att det finns en suppressoreffekt där katastrofiering och uppfattad stresspåverkar varandra ömsesidigt. Detta visar på det komplexa biopsykosociala samspel sompåverkar upplevelsen av smärta. Denna komplexitet och interaktion är viktig att ha i åtankenär individer i riskzonen för att utveckla smärtproblematik ska identifieras. / In order to help and understand patients with chronic pain, it is important to apply abiopsychosocial perspective. One previous study proposed a specific rating in a cold pressortest (CPT) as a biomarker for the development of persistent pain. This study aimed to explorewhether this proposed biomarker, and the sum of pain intensity ratings during CPT, could beexplained by perceived stress and exhaustion symptoms respectively, above and beyonddemographic factors and symptom catastrophizing. The participants (n = 35) performed aCPT. CPT-ratings were analyzed, together with demographic factors, symptomcatastrophizing, perceived stress and exhaustion symptoms, using hierarchical regressionanalyses and hierarchical binary logistic regression analyses. The results showed that higherlevels of perceived stress predicted lower pain intensity, above and beyond the other variablesexamined. Exhaustion symptoms showed no significant effect on pain intensity. None of thevariables could explain the proposed biomarker. The results indicate a suppressor effectwhere symptom catastrophizing and perceived stress interact and influence each othersimultaneously. This highlights the biopsychosocial interplay which influences painexperience. This complexity and interaction is an important factor to consider in the processof identifying individuals who are at risk for developing persistent pain.

Motivation The prevalence of cardiovascular disease is on the increase in sub-Saharan Africa largely owing to lifestyle changes associated with urbanisation. Traditional diets are being replaced with diets high in saturated fat and sugar. In addition to the nutritional transition, urbanisation in developing African countries also contributes to a more sedentary lifestyle. Together these trends contribute to a higher prevalence of obesity and hypertension that are major risk factors for the development of cardiovascular disease. Adipose tissue is now widely recognised as an endocrine organ that secretes numerous inflammatory mediators as well as adipocytokines such as leptin. The primary role of leptin is to induce satiety after a meal and to suppress appetite. However, in recent years the role of leptin in the development of obesity-related cardiovascular disease has gained increasing attention and interest. Furthermore, leptin levels not only differ with regard to gender but also ethnicity. Africans have higher leptin levels than Caucasians due to higher subcutaneous fat in Africans. Furthermore, the prevalence of hypertension and stroke are also greater in the African population. Taken together, it is important to investigate mechanisms by which elevated leptin may contribute to the development of cardiovascular disease, especially in cardiovascular disease-prone Africans. Aim The general aim of this study is to increase our understanding of the role of leptin in cardiovascular disease development by investigating associations of leptin with markers of sympathetic activity, endothelial dysfunction, and cardiovascular reactivity and recovery in Africans and Caucasians. Methodology Data from the SABPA (Sympathetic activity and Ambulatory Blood Pressure in Africans) study was used and presented in the original research articles described in Chapter 2, 3 and 4. This study included 409 African and Caucasian schoolteachers working in the Potchefstroom district in the North West Province of South Africa. Groups were stratified by ethnicity, gender and ethnicity or obesity in order to demonstrate potential differences. We performed cardiovascular measurements and determined levels of leptin, renin, cortisol, plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (vWF) and urinary albumin-to-creatinine ratio (ACR). Independent t-tests were done to compare means between groups and Chi-square tests to compare proportions. Pearson’s correlations were determined to investigate associations as well as partial correlations after minimal adjustment for potential confounders. Multiple regression analyses were performed to investigate independent associations of leptin with cardiovascular and biochemical markers according to the specific focus of each research manuscript. Results and conclusions of the individual manuscripts  Leptin may contribute to obesity-related hypertension through its sympatho-activating effects. In the first research article (Chapter 2), we compared mean leptin levels and markers of autonomic activity between Africans and Caucasians. We also investigated associations between markers of autonomic activity and leptin. Africans had higher leptin, body mass index, blood pressure and heart rate compared to Caucasians. Furthermore, Africans also demonstrated reduced heart rate variability that is indicative of autonomic imbalance. Markers of autonomic activity that collectively reflected sympathetic overactivity associated with leptin in both Africans and Caucasians, independent of significant covariates and confounders including body mass index. These findings suggest that leptin may contribute to the development of hypertension by inducing autonomic dysfunction.  Leptin exerts direct vascular effects and may thereby contribute to increased cardiovascular disease risk in the obese. We therefore investigated associations between circulating markers of endothelial dysfunction (PAI-1, vWF and ACR) and leptin in lean and obese groups, irrespective of ethnicity (Chapter 3). As expected, leptin and plasminogen activator inhibitor-1 antigen levels were higher in the obese group. We found no differences for von Willebrand factor antigen and urinary albumin-to-creatinine ratio. In the obese group, all markers of endothelial dysfunction were positively associated with leptin in univariate analysis. However, after full adjustment in multiple regression analyses, only the association with plasminogen activator inhibitor-1 remained significant. Higher leptin levels in the obese may possibly induce endothelial dysfunction through mechanisms related to thrombotic vascular disease.  Greater cardiovascular reactivity to stress and prolonged recovery thereafter associates with increased cardiovascular disease risk. In the final research article (Chapter 4), we therefore investigated the relationship between cardiovascular reactivity and recovery to acute stress, induced by the cold pressor test, and leptin in Africans and Caucasians. Africans demonstrated greater cardiovascular reactivity compared to Caucasians. Associations of blood pressure, stroke volume, cardiac output, total peripheral resistance and arterial compliance reactivity with leptin were investigated during the stressor application and 1, 3 and 5 minutes post-stressor. There were no independent associations between cardiovascular reactivity and leptin during the stressor, and a few correlations at 1 and 3 minutes post-stressor. Associations were mostly evident at 5 minutes post-stressor and in Africans. We argue that higher leptin levels relate to impaired post-stress recovery and thereby could contribute to hypertension development in Africans. General conclusion Elevated leptin relates to sympathetic overactivity, vascular damage and delayed post-stress recovery, and thereby could contribute to increased cardiovascular disease risk. / PhD (Physiology), North-West University, Potchefstroom Campus, 2015

Motivation The prevalence of cardiovascular disease is on the increase in sub-Saharan Africa largely owing to lifestyle changes associated with urbanisation. Traditional diets are being replaced with diets high in saturated fat and sugar. In addition to the nutritional transition, urbanisation in developing African countries also contributes to a more sedentary lifestyle. Together these trends contribute to a higher prevalence of obesity and hypertension that are major risk factors for the development of cardiovascular disease. Adipose tissue is now widely recognised as an endocrine organ that secretes numerous inflammatory mediators as well as adipocytokines such as leptin. The primary role of leptin is to induce satiety after a meal and to suppress appetite. However, in recent years the role of leptin in the development of obesity-related cardiovascular disease has gained increasing attention and interest. Furthermore, leptin levels not only differ with regard to gender but also ethnicity. Africans have higher leptin levels than Caucasians due to higher subcutaneous fat in Africans. Furthermore, the prevalence of hypertension and stroke are also greater in the African population. Taken together, it is important to investigate mechanisms by which elevated leptin may contribute to the development of cardiovascular disease, especially in cardiovascular disease-prone Africans. Aim The general aim of this study is to increase our understanding of the role of leptin in cardiovascular disease development by investigating associations of leptin with markers of sympathetic activity, endothelial dysfunction, and cardiovascular reactivity and recovery in Africans and Caucasians. Methodology Data from the SABPA (Sympathetic activity and Ambulatory Blood Pressure in Africans) study was used and presented in the original research articles described in Chapter 2, 3 and 4. This study included 409 African and Caucasian schoolteachers working in the Potchefstroom district in the North West Province of South Africa. Groups were stratified by ethnicity, gender and ethnicity or obesity in order to demonstrate potential differences. We performed cardiovascular measurements and determined levels of leptin, renin, cortisol, plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (vWF) and urinary albumin-to-creatinine ratio (ACR). Independent t-tests were done to compare means between groups and Chi-square tests to compare proportions. Pearson’s correlations were determined to investigate associations as well as partial correlations after minimal adjustment for potential confounders. Multiple regression analyses were performed to investigate independent associations of leptin with cardiovascular and biochemical markers according to the specific focus of each research manuscript. Results and conclusions of the individual manuscripts  Leptin may contribute to obesity-related hypertension through its sympatho-activating effects. In the first research article (Chapter 2), we compared mean leptin levels and markers of autonomic activity between Africans and Caucasians. We also investigated associations between markers of autonomic activity and leptin. Africans had higher leptin, body mass index, blood pressure and heart rate compared to Caucasians. Furthermore, Africans also demonstrated reduced heart rate variability that is indicative of autonomic imbalance. Markers of autonomic activity that collectively reflected sympathetic overactivity associated with leptin in both Africans and Caucasians, independent of significant covariates and confounders including body mass index. These findings suggest that leptin may contribute to the development of hypertension by inducing autonomic dysfunction.  Leptin exerts direct vascular effects and may thereby contribute to increased cardiovascular disease risk in the obese. We therefore investigated associations between circulating markers of endothelial dysfunction (PAI-1, vWF and ACR) and leptin in lean and obese groups, irrespective of ethnicity (Chapter 3). As expected, leptin and plasminogen activator inhibitor-1 antigen levels were higher in the obese group. We found no differences for von Willebrand factor antigen and urinary albumin-to-creatinine ratio. In the obese group, all markers of endothelial dysfunction were positively associated with leptin in univariate analysis. However, after full adjustment in multiple regression analyses, only the association with plasminogen activator inhibitor-1 remained significant. Higher leptin levels in the obese may possibly induce endothelial dysfunction through mechanisms related to thrombotic vascular disease.  Greater cardiovascular reactivity to stress and prolonged recovery thereafter associates with increased cardiovascular disease risk. In the final research article (Chapter 4), we therefore investigated the relationship between cardiovascular reactivity and recovery to acute stress, induced by the cold pressor test, and leptin in Africans and Caucasians. Africans demonstrated greater cardiovascular reactivity compared to Caucasians. Associations of blood pressure, stroke volume, cardiac output, total peripheral resistance and arterial compliance reactivity with leptin were investigated during the stressor application and 1, 3 and 5 minutes post-stressor. There were no independent associations between cardiovascular reactivity and leptin during the stressor, and a few correlations at 1 and 3 minutes post-stressor. Associations were mostly evident at 5 minutes post-stressor and in Africans. We argue that higher leptin levels relate to impaired post-stress recovery and thereby could contribute to hypertension development in Africans. General conclusion Elevated leptin relates to sympathetic overactivity, vascular damage and delayed post-stress recovery, and thereby could contribute to increased cardiovascular disease risk. / PhD (Physiology), North-West University, Potchefstroom Campus, 2015

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Previous research has shown that there are several components involved in how we perceive pain, e.g. social and psychological factors such as expectations of pain. A cold pressor experiment was conducted to investigate the impact of negative/positive information on pain perception. We also investigated if a cognitive conflict created by disconfirming information of a pain expectation influences the pain experience. 106 participants (49 men and 57 women) got to hold their hand in 5°C water for 1 minute. The main outcome variable was self-reported pain during the cold pressor test. The results show that participants receiving negative information perceived more pain than the group receiving positive information. There was no significant difference in pain perception between those who were confirmed or disconfirmed in an expectation, nor was there a difference in cognitive conflict between the two groups. This is a first attempt to explore pain and cognitive conflict and can work as an inspiration for further investigation. / Tidigare forskning har visat att det är flera komponenter involverade i en smärtupplevelse, bland annat sociala och psykologiska faktorer så som förväntningar. Ett kallvattenexperiment utfördes för att undersöka positiv/negativ information och dess påverkan på upplevelsen av smärta. Vi undersökte även om smärta påverkas av en kognitiv konflikt skapad av en disconfirmation av en smärtförväntning. 106 deltagare (49 män och 57 kvinnor) fick hålla sin hand i 5°C vatten i en minut. Vårt mätinstrument var själv-rapporterad smärta vid kallvattentestet. Resultatet visade att deltagare som fick negativ information upplevde mer smärta än de som fick positiv information. Det fanns ingen signifikant skillnad mellan de som blev disconfirmed och confirmed i sin förväntan och inte heller någon skillnad mellan grupperna i upplevd kognitiv konflikt. Detta första försök att undersöka smärta och kognitiv konflikt kan bli till en inspiration för vidare undersökningar.