Jeongok G. Logan

Allostasis and allostatic load: expanding the discourse on stress and cardiovascular disease

AIM The aim of this discursive paper is to introduce allostasis and allostatic load, which are relatively new concepts proposed to explain physiological responses to stress, and to suggest ways in which allostasis theory can be applied to the development of clinical interventions to increase resilience for producing better health outcome. BACKGROUND Common explanations of stress have failed adequately to explicate its association with health and chronic illness. Allostasis is the extension of the concept of homeostasis and represents the adaptation process of the complex physiological system to physical, psychosocial and environmental challenges or stress. Allostatic load is the long-term result of failed adaptation or allostasis, resulting in pathology and chronic illness. DISCUSSION The concepts of allostasis and allostatic load introduced the idea that external challenges initiate allostasis and chronic stress causes allostatic load that can be measured with multiple biomarkers. Finding from several studies suggests that higher allostatic load is associated with worse health outcomes. Resilience represents successful allostasis and strategies can be implemented to enhance resilience and thereby improve health outcomes. CONCLUSIONS This theoretical model provides a comprehensive explanation of the human bodys adaptation processes in response to stress and the results of failed adaptation over time. In addition, combining the concepts of allostasis and resilience may help us to understand and implement clinical strategies better to reduce or prevent the debilitating physiological and psychological effects of chronic stress and chronic illness. RELEVANCE TO CLINICAL PRACTICE Clinical practice should be based on a solid theoretical foundation to improve health outcomes. Strategies to manage stress and increase resilience along with clinical interventions to manage the physiological responses to chronic stress are necessary to assist in preventing and controlling the detrimental effects of chronic disease on human life.

Morning blood pressure surge and nighttime blood pressure in relation to nocturnal sleep pattern and arterial stiffness.

Objective:The phenomenon of morning blood pressure (BP) surge (MBPS) is known to increase the risk for cardiovascular events and stroke. The purposes of this study were to explore associations between MBPS and nighttime BP and to examine arterial stiffness and sleep pattern in association with MBPS. Methods:This study included 30 healthy Korean American women aged 25 to 60 years. Ambulatory BP was monitored for 24 hours. To evaluate MBPS, maximum morning BPpower was calculated. Arterial stiffness was measured by carotid-femoral pulse wave velocity, and sleep pattern was evaluated using an actigraphy. Results:The participants (n = 8) in the upper quartile of MBPS had higher morning systolic BPs (SBPs; P = 0.015) and lower nighttime diastolic BPs (P = 0.031). The MBPS in SBP was significantly increased in the participants who had a more wakeful night (P = 0.038) and who slept longer at night (P = 0.041). Although MBPS was not significantly related to arterial stiffness, higher morning SBP (P = 0.005), morning diastolic BP (P = 0.048), and prewake SBP (P = 0.005) were associated with arterial stiffness. Conclusions:Our findings imply a possible link between disturbed sleep and MBPS. Clinicians should understand the importance of the modification of altered sleep pattern for reducing MBPS in nonhypertensive participants.

Psychological stress and arterial stiffness in Korean Americans

OBJECTIVE Arterial stiffness is identified as a causative factor for hypertension. The purpose of this study was to explore the relationship between psychological stress and arterial stiffness in Korean Americans. METHODS A convenience sample of 102 Korean Americans (aged 21-60 years, 60% women) was recruited from North Carolina. Psychological stress was measured by the Perceived Stress Scale, the Social, Attitudinal, Familiar, and Environmental (SAFE) Acculturative Stress Scale, and the Spielbergers State-Trait Anxiety Inventory. Arterial stiffness was measured by carotid-femoral pulse wave velocity (cfPWV) using the SphygmoCor system (AtCor Medical, Australia). RESULTS This study shows that the emotional stress response, measured by anxiety, significantly predicted arterial stiffness (β=.25, p=.008), independently of such confounding factors as age, mean arterial pressure (MAP), gender, body mass index, smoking, education, and income. Anxiety was neither related to age (r=.12, p=.212) nor MAP (r=.14, p=.151). Additionally, this sample of Korean Americans had higher levels of psychological stress when compared to previous findings from studies of other racial/ethnic groups in the U.S. CONCLUSION Findings demonstrate that anxiety is a significant and independent determinant of arterial stiffness. Given that anxiety was not related to MAP, these findings suggest that arterial stiffness may be a pathway to explain the connection between anxiety and hypertension risk. Studies that scrutinize the relationship between anxiety and arterial stiffness are an important next step for future research. Further studies are also recommended to explore cultural factors and individual characteristics that may affect anxiety in Korean Americans.

Relationships among acculturative stress, sleep, and nondipping blood pressure in Korean American women.

Generally blood pressure (BP) should drop or dip by 10–20% during sleep. The phenomenon of nondipping BP during sleep has gained interest because of its association with various damaging effects to end-organs. This exploratory study examined nighttime nondipping BP, acculturative stress and quality of sleep in 30 Korean American women. Acculturative stress and sleep quality were measured using the Revised Social, Attitudinal, Familial, and Environmental Acculturative Stress Scale (R-SAFE) and the Pittsburg Sleep Quality Index (PSQI), respectively. Participants’ BP was monitored over a 24-hour period. Participants were categorized as dippers and nondippers based on the drop in nocturnal systolic BP. Of the 30 women, 8 (26.7%) were nondippers. A shorter sleep duration and more disturbed sleep were associated with nondipping and, interestingly, less acculturative stress was also associated with nondipping BP. Our finding supports that sleep evaluation is needed in caring for individuals with nondipping BP.

Exploring moderating effects of John Henryism Active Coping on the relationship between education and cardiovascular measures in Korean Americans

OBJECTIVE John Henryism Active Coping (JHAC) is defined as a strong behavioral predisposition to cope with stressors in an effortful and determined manner. The well-known inverse relationship between socioeconomic status (SES) and blood pressure (BP) has been hypothesized to be stronger for individuals who have high JHAC than those with low JHAC, suggesting that JHAC may place people with low SES at higher cardiovascular risk. Previous studies testing this hypothesis have presented mixed findings; therefore, this study was conducted to test the JHAC hypothesis by examining the main and interaction effects of SES and JHAC on cardiovascular risk (measured by BP and arterial stiffness [AS]). METHODS The sample was 102 Korean Americans (aged 21-60years). Measures included age, sex, body mass index, smoking, SES (measured by income and education), JHAC (measured by the 12-item JHAC Scale), BP, and AS. RESULTS In terms of the SES measures, only education was significantly related to systolic BP (p=0.003), diastolic BP (p=0.001), and AS (p<0.000). The interaction effects of education and JHAC on systolic BP and AS were also significant (p=0.019 and p=0.018, respectively), indicating that the inverse relationships of education to systolic BP and AS were more prominent in subjects with lower JHAC scores. CONCLUSION Contrary to the JHAC hypothesis, JHAC may be associated with low cardiovascular risk in people with low education in certain groups. Studies are recommended to examine potential beneficial effects of JHAC on cardiovascular health in a larger sample and to identify their mechanisms.

John Henryism Active Coping, Acculturation, and Psychological Health in Korean Immigrants

This study aimed to explore the levels of John Henryism (JH) active coping and its association with acculturation status and psychological health (specifically perceived stress, acculturative stress, anxiety, and depression) in Korean immigrants to the United States. In 102 Korean immigrants, JH active coping was measured by the JH Scale; acculturation by the Bidimensional Acculturation Scale; perceived stress by the Perceived Stress Scale; acculturative stress by the Social, Attitudinal, Familial, and Environmental Scale; anxiety by the State Anxiety Subscale of the Spielberger State-Trait Anxiety Inventory; and depression by the Center for Epidemiological Studies Depression Scale. The levels of JH active coping in this sample of Korean immigrants appear to be lower than the levels reported in other racial groups. Independent of demographic factors, JH active coping was a significant predictor of higher acculturation status and better psychological health as indicated by lower levels of perceived stress, acculturative stress, anxiety, and depressive symptoms.

Pulse Wave Velocity in Korean American Men and Women

Arterial stiffness is an important clinical marker of cardiovascular diseases. Although many studies have been conducted on different racial groups, less is known about arterial stiffness in Asian Americans. Korean Americans constitute the fifth largest subgroup in the Asian American population and reportedly have a noticeably high prevalence of hypertension. The aims of this study were to assess arterial stiffness and blood pressure and to examine the effect of age and gender on arterial stiffness and blood pressure in 102 Korean American men and women aged 21 to 60 years. The values of arterial stiffness for Korean Americans in this study were compared to published reference values for other racial and ethnic groups. Arterial stiffness was measured by carotid-femoral pulse wave velocity, which is the gold standard for determining arterial stiffness. Findings indicated that aging was an important determinant of arterial stiffness, which increased linearly with age. Although there was no gender difference observed in arterial stiffness, the effect of age on arterial stiffness was greater in women than in men. After adjusting for covariates including age, body mass index, and smoking, multiple regression models showed that arterial stiffness and gender were significant predictors of systolic and diastolic blood pressure. The comparisons of these findings to those from several other studies that used the same method to measure arterial stiffness showed that Korean Americans may have levels of arterial stiffness that are similar to or slightly higher than those of other racial groups. Considering that arterial stiffness is an independent predictor of future development of hypertension, more studies are required to examine cardiovascular risk of this understudied group.

Resting Heart Rate and Aortic Stiffness in Normotensive Adults

Background and Objectives Large-artery stiffness is an independent predictor of cardiovascular disease (CVD), and carotid-femoral pulse wave velocity (cfPWV) is considered the gold standard measure of arterial stiffness. A resting heart rate is an easily measured vital sign that is also associated with CVD morbidity and mortality. Previous studies have reported the significant relationship of a resting heart rate with arterial stiffness as measured by cfPWV only in hypertensive subjects; their relationship in nonhypertensive subjects remains unknown. The present study, therefore, examined their relationship in normotensive subjects. Subjects and Methods In 102 healthy Korean Americans between ages 20 and 60 years, their resting heart rate was measured by an automated blood pressure measuring device after a 10 minute rest in the supine position. Arterial stiffness was measured by cfPWV using the SphygmoCor device. Results The mean resting heart rate of participants (mean age, 39.64 years; 59% women) was 61.91 bpm (standard deviation [SD], 9.62 bpm) and mean the cfPWV was 6.99 (SD, 1.14) m/s. A multiple regression analysis showed that a resting heart rate is a significant predictor of cfPWV after controlling for age, body mass index, and mean arterial pressure. For one bpm increase of resting heart rate, cfPWV increased approximately 0.02 m/s. Conclusion Our results suggest that a higher resting heart rate is independently associated with increased arterial stiffness as measured by cfPWV in normotensive adults. Arterial stiffness may explain the prognostic role of an individuals heart rate in cardiovascular morbidity and mortality.

Genetic Determinants of Arterial Stiffness

Stiffness of large arteries (called arteriosclerosis) is an independent predictor of cardiovascular morbidity and mortality. Although previous studies have shown that arterial stiffness is moderately heritable, genetic factors contributing to arterial stiffness are largely unknown. In this paper, we reviewed the available literature on genetic variants that are potentially related to arterial stiffness. Most variants have shown mixed depictions of their association with arterial stiffness across multiple studies. Various methods to measure arterial stiffness at different arterial sites can contribute to these inconsistent results. In addition, studies in patient populations with hypertension or atherosclerosis may overestimate the impact of genetic variants on arterial stiffness. Future studies are recommended to standardize current measures of arterial stiffness in different age groups. Studies conducted in normal healthy subjects may also provide better opportunities to find novel genetic variants of arterial stiffness.

Preventing obesity: exercise and daily activities of low-income pregnant women.

Low-income women are at risk for excessive gestational weight gain. Inactive lifestyle and lack of regular moderate exercise may contribute to the risk of weight gain. This study was conducted to (1) determine the rate and characteristics of low-income pregnant women who exercised regularly and met the American College of Obstetricians and Gynecologists recommendation and (2) describe how these women spent time for other physical activities compared with those who did not exercise regularly. Medicaid-recipient or uninsured pregnant women (n = 816) were asked to complete a physical activity questionnaire at rural and urban county health departments located in North Carolina. Twenty percent of low-income women met the American College of Obstetricians and Gynecologists recommendation for moderate exercise (≥10 METs-h/wk [metabolic equivalent task-hours per week]). The women who met the recommendation spent 3 hours 45 minutes per week walking as exercise, whereas those who did not meet the recommendation spent 1 hour per week (P < .0001). Women who exercised regularly spent longer hours at work (4.25 vs 1.75 hours per day; P = .019) and on household tasks (5.25 vs 4.0 hours per day; P = .002) than women who did not exercise regularly. Time spent on domestic and occupation activities does not seem to prohibit low-income women from engaging in moderate exercise on a regular basis.