The relationship of hostility, negative affect and ethnicity to cardiovascular responses: an ambulatory study in Singapore.

This study tested the hypotheses that ambulatory heart rate and blood pressure would be higher for individuals high but not low in hostility when they experienced negative affect or social stress and that this interaction would be stronger for Indians compared with other Singapore ethnic groups. Ambulatory blood pressure monitoring was done on 108 male Singapore patrol officers as they went about their daily duties. After each BP measurement participants completed a computerized questionnaire including items on emotional experience. Individuals high in hostility showed higher systolic blood pressure when reporting negative affect whereas this was not true for those low in hostility. Ethnic differences were obtained such that Indians showed an increase in mean arterial pressure when angered whereas MAP was negatively related to anger for Malays and unrelated for Chinese. Also a three-way interaction between ethnicity, hostility, and social stress indicated that hostility and social stress interacted in their effects on DBP for Indian participants but not for Chinese or Malays. Finally, a three-way interaction was obtained between ethnicity, hostility and negative affect for heart rate in which heart rate increased with increasing levels of negative affect for Chinese high in hostility and Malays low in hostility but decreased with increasing negative affect for all other participants. These data are consistent with higher CHD rates among individuals high in hostility and also provide additional evidence on ethnic differences in cardiovascular reactivity in Singapore.     

The effects of Neuroticism and Extraversion on cardiovascular reactivity during a mental and an emotional stress task

Evidence suggests that physiological reactivity to mental and emotional stress may be influenced by personality traits.ObjectivesThis study aimed to examine the relationship between, emotionally based personality traits, Neuroticism (N) and Extraversion (E), and cardiovascular reactivity (CVR) during mental arithmetic (MA) and anger recall (AR).MethodsHeart rate, blood pressure, cardiac output and total peripheral resistance were measured in 114 Singaporean male patrol officers from the Singapore Police Force while they performed MA and AR tasks. N and E were assessed using the NEO PI-R.ResultsHigher N was associated with lower DBP and TPRI reactivity during MA as compared to lower N, but higher TPRI reactivity during AR. Lower E scores were associated with heightened CVR while higher E scores were associated with lower CVR. For SBP and HR, E was associated with a reduction in reactivity across tasks; whereas, for DBP and TPRI this reduction was found only during AR.ConclusionIn this population, N had differential effects on CVR depending upon the nature of the stress task, cognitive or emotional. However, higher E was consistently linked to lower CVR during stress tasks and appeared to influence how individuals express and cope with anger.     

Ethnicity, sex, trait anger, and nocturnal blood pressure decline

This study examined the relationship of trait anger to nocturnal blood pressure decline among Singaporean young adults. One hundred forty-nine participants (51 Chinese, 51 Malays, 47 Indians, 49.7% men) participated in 24-h ambulatory monitoring for blood pressure and hemodynamic measures. Significant interactions were obtained between ethnicity and trait anger for systolic blood pressure and mean arterial pressure such that trait anger was significantly and negatively related to nocturnal blood pressure decline for Indians whereas this was not true for Chinese or Malays. Significant sex x trait anger interactions were obtained for systolic blood pressure, diastolic blood pressure, and mean arterial pressure in which trait anger was negatively related to blood pressure decline for men but not for women. Overall the results suggest that trait anger is a significant factor affecting nocturnal blood pressure decline particularly among Indians and men.     

Anger, harassment, and cardiovascular reactivity among Chinese and Indian men in Singapore

OBJECTIVE: This experiment examined psychological and cardiovascular responses to experimental harassment among Chinese and Indian men in Singapore who differed in levels of dispositional anger. METHODS: Eighty-four Chinese and Indian men participated in a laboratory experiment on cardiovascular reactivity in which mood was rated and heart rate and blood pressure were measured during computer tasks in which they were either harassed or allowed to complete the tasks without interruption. RESULTS: Comparison of systolic reactivity to harassment and nonharassment indicated, as expected, that reactivity was greater after harassment. Furthermore, a significant race by dispositional anger by harassment effect was obtained for systolic reactivity that indicated different patterns of reactivity for Chinese and Indian participants. In the absence of harassment, Chinese participants showed low systolic reactivity regardless of their level of dispositional anger, whereas systolic reactivity increased as a function of dispositional anger when they were harassed. For Indians, however, systolic reactivity was a positive function of dispositional anger both when they were harassed and not harassed. CONCLUSIONS: These results suggest stronger cardiovascular reactivity to stress among Indian than among Chinese men. This seems to be particularly true for Indians high in dispositional anger.     

Ethnic variation in the impact of metabolic syndrome components and chronic kidney disease

ObjectiveTo examine the ethnic differences in the association between metabolic syndrome components and CKD in Asian populations.MethodsWe analyzed data from three independent populations in Singapore representing the three major Asian ethnic groups (n = 3167 Chinese, 3082 Malays and 3228 Indians) aged 40–80 years. CKD was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m². Factor analysis of metabolic syndrome components was conducted and factor scores were used as independent variables in multivariable logistic regression models.ResultsThe prevalence of CKD was highest among Malays (21.0% vs. 7.4%, 5.9% in Indians and Chinese). Factor analysis identified three factors among Chinese (glycemia, blood pressure [BP], and obesity/lipid) and Malays (glycemia, BP, and lipids) accounting for 70% of the variance and four factors (glycemia, BP, lipids, and obesity) among Indians accounting for 82% of the variance. Glycemia was positively associated with CKD in all three ethnic groups. BP was positively associated with CKD among Malays (OR [95% CI] of 1.16 [1.06–1.28]), whereas it showed an inverse association among Chinese (0.84 [0.71–0.99]) and Indians (0.84 [0.73–0.97]). However, this inverse association lost significance after adjusting for antihypertensive medication use in Chinese and Indians. Obesity/lipids among Chinese and obesity among Indians showed a positive association; lipids showed an inverse association among Malays.ConclusionsThese data suggest that while hyperglycemia was associated with CKD in all three ethnic groups, the impact of BP, lipids, obesity on CKD varies across ethnic groups. Understanding the specific associations may allow greater understanding of how CKD develops in different racial/ethnic groups.     

HLA haplotypes in Singapore: a study of mothers and their cord blood units

During 2005, a total of 174 cord blood units with their paired maternal samples from the Singapore Cord Blood Bank were typed for HLA-A, -B, -C at intermediate resolution and DRB1 at allelic resolution. Analysis of allele segregation in mother and child assigned 185 different four locus (HLA-A, -B, -C, -DRB1) haplotypes in Chinese, 66 in Malays, and 34 in Asian Indians. Very few four locus haplotypes were shared among population groups. To evaluate the frequencies of four locus haplotypes, the Expectation Maximization algorithm was used with HLA assignments from 536 unrelated Chinese volunteers from the Singapore Bone Marrow Donor Program registry. The paired maternal and cord blood study identified 75 different B-C associations in Chinese, 52 in Malays, and 24 in Asian Indians. Common B-C associations may be shared among population groups; for example, B*4001g-Cw*0702g was common in Chinese and Malays, whereas B*1502g-Cw*0801g and B*3501g-Cw*0401g were found in all three groups. The high diversity of four locus haplotypes originates from multiple combinations of both HLA-A and -DRB1 alleles with each B-C haplotype.     

Genetic Association in Myocardial Infarction: Ethnicity; ABO, Rh, Lea, Xga Blood Groups; G6PD Deficiency; and Abnormal Haemoglobins

Four hundred and eighty-six patients with myocardial infarction of both sexes comprising 213 Chinese, 53 Malays, 199 Indians, and 21 Europeans, resident in Singapore were investigated for differences in relative incidence, and for the ABO, Rh, Le^a, and Xg^a blood groups, G6PD deficiency, and haemoglobin types. Relative incidence of myocardial infarction was appreciably higher among Indians than Chinese and Malays in all age groups, more so in younger people. There was no significant difference in the distribution of the genetic markers between patient and control series in either Chinese, Malays, or Indians.     

Cardiovascular reactivity of younger and older adults to positive-, negative-, and mixed-emotion cognitive challenge

Although aging is associated with progressive increases in blood pressure level, previous research has been inconsistent as to whether older adults show greater or lesser cardiovascular reactivity (CVR) to emotion than do younger adults. There is reason to believe that these inconsistencies could be clarified by examining age-related differences in hemodynamic profile revealed by measuring the pattern of cardiac output and total peripheral resistance associated with changes in blood pressure reactivity. Accordingly, the present study examined the performance, CVR, and hemodynamic profile of younger and older adults during encoding and recognition of word pairs involving four valence types: positive, negative, mixed (positive/negative), and neutral word pairs. Results revealed higher baseline blood pressure, increased CVR characterized by a vascular hemodynamic profile, and more rapid recovery (especially during encoding) for older than for younger participants. Results are discussed in light of research and theory on the relationship between aging and cardiovascular health.     

The TaqIB and -629C>A polymorphisms at the cholesteryl ester transfer protein locus: associations with lipid levels in a multiethnic population. The 1998 Singapore National Health Survey

The Singapore population comprises Chinese, Malays and Asian Indians. Within this population, Asian Indians have the highest rates of coronary heart disease, whereas Chinese have the lowest. Conversely, Indians have the lowest high-density lipoprotein cholesterol (HDL-C) concentrations, followed by Malays and Chinese. We studied the TaqIB and -629C>A polymorphisms at the CETP locus in 1300 Chinese, 364 Malay and 282 Asian Indian men, and in 1558 Chinese, 397 Malay and 306 Asian Indian women, to determine whether these polymorphisms are responsible for the ethnic difference in HDL-C concentration. The frequency of the B2 allele in Chinese, Malays and Indians was 0.384, 0.339 and 0.449 in men, and 0.379, 0.329 and 0.415 in women, respectively (p < 0.001). For the A-629 allele, the relative frequencies were 0.477, 0.423 and 0.592 in men and 0.486, 0.416 and 0.575 in women (p < 0.001). The two polymorphisms were in linkage disequilibrium (D / Dmax= 0.9772, p < 0.00001). The B2 and the A-629 alleles were associated with increased HDL-C concentrations in a dose-dependent manner. The B2 allele continued to show an association with HDL-C concentration, even after controlling for the genotype at position -629. Dietary cholesterol showed a significant interaction with the TaqIB polymorphism in determining HDL-C concentrations in Indians and Malays, but not in Chinese. In conclusion, the high frequencies of these polymorphisms in Asian Indians could not explain the observed ethnic differences in HDL-C concentration. Moreover, we observed an ethnic-specific interaction among dietary cholesterol, the TaqIB polymorphism and HDL-C concentrations.     

Differential hostility profiles accompany different hemodynamic response patterns

Cardiovascular reactivity has been proposed as a mechanism by which psychosocial variables may lead lo coronary heart disease. Although reactivity as a generalized response has been linked lo psychological factors, there are specific hemodynamic profiles that underlie blood pressure reactivity. This study characterized subsets of young adults as myocardial or vascular reactors, in response to three laboratory tasks: mental arithmetic, videogame, and anger recall interview. Vascular reactors had higher diastolic blood pressure increases to all tasks, whereas reactor groups were equivalent at rest and on systolic blood pressure responses. Correlational analyses were conducted to determine whether psychological dimensions are uniquely associated with myocardial or vascular reactors' cardiovascular responses, at rest and during acute stressors. For myocardial reactors, resting systolic blood pressure was higher in hostile and suspicious individuals, whereas reactivity was linked to impulsivity. For vascular reactors, low trust, low gregariousness, and high depression were associated with diastolic reactivity to tasks. The predictive validity of hostility, distrust, sociability, and depression for cardiovascular pathology may vary with reactor type.     

Hostile attitudes predict elevated vascular resistance during interpersonal stress in men and women

OBJECTIVE: Existing research indicates that hostility is associated with enhanced blood pressure responses during social stress, but little is known about the hemodynamic patterns underlying these blood pressure increases, particularly in women. The present study examined hemodynamic responses to a low-anger interpersonal stressor, testing the hypotheses that hostile individuals show enhanced vascular responses and that low hostile individuals show enhanced myocardial responses. METHODS: Eighty undergraduate men and women were categorized as high or low in hostility on the basis of median splits of Cook-Medley Hostility Scale scores. Participants discussed a controversial topic with a confederate who disagreed with them, and hemodynamic responses were assessed with impedance cardiography. RESULTS: High hostile individuals exhibited greater increases in diastolic blood pressure and total peripheral resistance and smaller increases in cardiac output during an interpersonal stressor than did low hostile individuals. Systolic blood pressure and heart rate increases were greater among high hostile relative to low hostile females and comparable among low and high hostile males. Affective responses and task perceptions were generally similar for high and low hostile participants, but the relationship between task perception and hemodynamic responses varied on the basis of hostility level. CONCLUSIONS: These findings suggest that hostility in both men and women is associated with heightened vascular and dampened cardiac responsivity to interpersonal stress that is not deliberately anger provoking. Moreover, they indicate that the associations between task perception and hemodynamic responses vary between high and low hostile individuals.     

The Distribution of HL—A Leukocyte Antigens in Singapore Chinese, Malays, and Indians

The distribution of 19 HL—A antigens was studied in three ethnic groups in Singapore: Chinese, Malays, and Indians. Two antigens (one from each HL—A locus) were found to be significantly more frequent in each ethnic group when compared to the other two ethnic groups. These antigens were HL—A11 and W10 in Chinese, HL—A9 and W15 in Malays, and HL—A1 and W17 in Indians. The antigens HL—A10, HL—A8, and W14 had a low frequency in the three ethnic groups. The virtual absence of HL—A1 in Chinese, low frequency in Malays, and high frequency in Indians support the suggestion that this antigen is a "Caucasian" antigen.
The presence of linkage disequilibrium between the two HL—A loci was investigated by the calculation of delta values. No significant delta values were found in the Malays whereas the Chinese and Indians showed significant values for the antigen combinations HL—A2.12, HL—A9.5, HL—A9.W17, HL—A11.W15 (Chinese) and HL—A1.W17, HL—A2.W17, HL—A3.W5 (Indians).
It is suggested that the HL—A system of leukocyte antigens should be an important genetic marker in the study of origins and relationships between ethnic groups.     

A new model of individual differences in hemodynamic profile and blood pressure reactivity

A quantitative, theory-driven model of hemodynamics was developed, relating reactivity in blood pressure to orthogonal dimensions of "hemodynamic profile" and "compensation deficit," which were derived from the (multiplicative) interaction of cardiac output and total peripheral resistance. A Finapres 2300e was used to estimate blood pressure, cardiac output, and total peripheral resistance in 100 healthy men and women during mental arithmetic and cold pressor tasks on two occasions. Results were consistent with model predictions. As predicted, cardiac output and peripheral resistance reactions were curvilinearly related, and blood pressure reactivity was strongly related to compensation deficit (r = .76-.89). Conversely, the orthogonally defined hemodynamic profile remained independent of blood pressure reactivity (r = .11 or less). The data show that the present model overcomes several difficulties and inconsistencies in previous attempts to obtain an independent measure of hemodynamic profile. The new model could help to elucidate sources of cardiovascular pathogenesis not suggested from the study of blood pressure reactivity alone.     

Psychosocial Correlates of Cardiovascular Reactivity to Anticipation of an Exercise Stress Test Prior to Attending Cardiac Rehabilitation: A Preliminary Test1

We examined social and psychological correlates of cardiovascular reactivity (CVR), or exaggerated heart rate (HR) and blood pressure (BP) responses to mental stress, in 45 men (mean age = 60.1, SD = 9.9) and 17 women (mean age = 9.9, SD = 11.8) prior to cardiac rehabilitation. HR and BP increased from rest to anticipation, and women had higher resting and preexercise BP. Anxiety was positively related to HR reactivity. HR reactivity was negatively related to self‐efficacy in women and positively related to self‐efficacy in men. Men and women with more self‐efficacy had lower systolic blood pressure (SBP) reactivity, and anxiety was positively related to SBP reactivity in women. Results suggest that the relationship among psychosocial factors and CVR might differ among men and women.     

Hostility and cardiovascular reactivity to stress in women and men

The relationship of Cook Medley hostility scores (Ho) to blood pressure and heart rate reactivity was examined in 56 women and 56 men. Stress was elicited by an unsolvable anagram task that was described as easily solvable. Both men and women scoring high on Ho had greater blood pressure responses to the task. Those scoring high on Ho also reported more anger in response to the tasks, but anger was not associated with blood pressure reactivity. It was concluded that situations evoking suspiciousness and mistrust rather than anger may be necessary to elicit increased blood pressure reactivity among high Ho subjects.     

Religious Involvement and Perceived Social Support: Interactive Effects on Cardiovascular Reactivity to Laboratory Stressors

Religious involvement has been linked to reduced risk of cardiovascular morbidity and mortality. This may reflect lower cardiovascular reactivity (CVR) among individuals high in religious involvement. The relationship between religious involvement and reactivity may overlap with the effects of other psychosocial factors. This study examined religious involvement, social support, and hostility in relation to CVR in the laboratory. Results showed an interactive effect of perceived social support and religious involvement on systolic blood pressure (SBP) reactivity. Participants reporting a high level of religious involvement showed lower SBP reactivity only when they also reported high levels of social support. These findings encourage further research on the unique and conjoint effects of religiousness and other psychosocial variables on CVR.     

Hemodynamic profile of stress-induced anticipation and recovery.

Systolic and diastolic blood pressure, heart rate, stroke volume, cardiac output, and total peripheral resistance were measured in 100 healthy men and women with the aim of investigating hemodynamic profile during anticipation of, and recovery from, exposure to active and passive laboratory stressors. A 5-min anticipatory period preceded two tasks, both of which lasted 2.5 min. The tasks were mental arithmetic ('beta-adrenergic' stress) and the cold pressor test ('alpha-adrenergic' stress). Each task was followed by a 5-min recovery period. Blood pressure and heart rate were measured with a FinaPres 2300e, and stroke volume, cardiac output, and total peripheral resistance were computed from these parameters. Salivary cortisol was measured in relation to both tasks, and participants completed tests of state and trait anxiety, locus of control, and hostility. As expected, mental arithmetic and the cold pressor test elicited myocardial and vascular patterns of reactivity, respectively. However, contrary to expectations, anticipatory and recovery hemodynamic profile involved essentially vascular responding for both stressors. Salivary cortisol increased in response to both tasks but only weakly correlated with hemodynamic changes. None of the subjective measurements was a strong predictor of physiological reactivity. The findings suggest that stress-induced anticipatory and recovery reactivity may be generally vascular rather than myocardial. This could have important implications in light of suggestions that anticipatory and recovery responses may be better predictors of subsequent cardiovascular disease than direct stress-induced reactivity.     

Adult asthma prevalence, morbidity and mortality and their relationships with environmental and medical care factors in Singapore

We have conducted a series of studies on adult asthma in Singapore that describe the prevalence, morbidity and mortality and their relationships with environmental and medical care factors. There was no evidence of a temporal increase of mortality from 1976 to 1995 for adults. The prevalence rate of asthma is 2.4% in men and 2.0% in women. There is considerable morbidity among asthmatics, corticosteroids are under-used, and patients' knowledge and self-management skills is poor. Increased morbidity is significantly associated with current keeping of pets, current smoking, and the patients' knowledge and self-management skills. Occupational exposure contributes up to a third of asthma morbidity. Malays and Indians have higher rates of asthma mortality and morbidity than Chinese. They have greater exposures to airborne allergens from keeping rugs or carpets, and pets. Malays experience the most morbidity from asthma, but make less use of health services, and receive less medical attention, than Indians or Chinese.     

Cardiovascular reactivity during public speaking as a function of personality variables.

An experiment was conducted to assess the effects of a real-life stressor (public speaking) upon cardiovascular reactivity (CVR). Changes in blood pressure and heart rate from baseline to task were measured in a sample of 86 men and women. The purpose was to examine the effects of individual differences (Type A personality, hostility and gender) on CVR. Participants gave a 6-min oral presentation during which they were evaluated by their professor and with classmates as the audience. Results indicated that all participants had marked CVR during public speaking. There were differences in reactivity patterns between men and women, but personality did not play a role except for high hostile men. It is suggested that intense stressors may result in high levels of CVR independent of personality variables that moderate reactivity at lower levels of stress.