Modernization and catecholamine excretion of young Samoan adults

Beyond catecholamines: Measuring autonomic responses to psychosocial context

Despite longstanding interest among human biologists in autonomic responses to socioecological context or culture change, the adoption of autonomic measures has been limited by methodological challenges. Catecholamine secretion is the most direct measure, but not all study designs are amenable to urinary sampling, and blood pressure lacks specificity to the parasympathetic or sympathetic division of the autonomic nervous system. This article reviews three alternative approaches for measuring autonomic responses: salivary α-amylase as a nonspecific autonomic marker, respiratory sinus arrhythmia as a specific parasympathetic marker, and the pre-ejection period as a specific sympathetic marker. Study design considerations are discussed in detail, including ambulatory sampling protocols that permit the evaluation of autonomic responses to everyday life. Researchers interested in how culture and social experience "get under the skin," as well as those concerned with the evolution of social engagement, can benefit from these well-validated biomarkers that are nevertheless relatively novel in human biology. Am. J. Hum. Biol. 28:309-317, 2016. © 2015 Wiley Periodicals, Inc.

Behavioral and perceived stressor effects on urinary catecholamine excretion in adult Samoans

OBJECTIVES

The effects of perceptions and behaviors related to culturally patterned socioeconomic obligations on catecholamine excretion rates were studied in a cross-sectional sample of Samoan adults.

METHODS

A total of 378 participants, ages 29-62 years, from 9 villages throughout Samoa, provided timed overnight urine specimens, and self-reported perceptions and behaviors associated with contributions to one's family, aiga, and chief, matai, and communal gift exchanges, fa'alavelave. Urinary norepinephrine and epinephrine excretion rates were measured by high performance liquid chromatography with electrochemical detection. Age (≤40 vs. >40 years) and gender-specific regression models were estimated to detect associations with catecholamine excretion.

RESULTS

Young women who contribute more to their matai, who consider fa'alavelave to be a financial strain, and who view their contribution to their matai to be "just right," had significantly higher residence-adjusted norepinephrine excretion. Young women who contribute more to their matai, who consider fa'alavelave to be a financial strain, and who consider their contribution to their aiga not to be a burden, had higher epinephrine excretion. Older men who contribute more to their aiga and who perceive their contribution to their aiga to be "just right" had increased residence-adjusted epinephrine excretion.

CONCLUSIONS

Individual-level perceptions and behaviors related to traditional socioeconomic obligations are a significant correlate of increased overnight catecholamine excretion rates. Higher excretion rates may be attributed to psychosocial stress arousal associated with a discordance between personal desires for upward social mobility, and family and community-based socioeconomic obligations. Changes in patterns of individual-level psychosocial stress arousal may contribute to cardiovascular disease risk in modernizing Samoans.

Ecological and sociodemographic effects on urinary catecholamine excretion in adult Samoans

BACKGROUND

Ecological and sociodemographic correlates of stress may contribute to cardiovascular disease risk in modernizing Samoans.

AIM

The effects of peri-urban vs rural residence, education, occupation, caffeine intake and cigarette consumption on urinary catecholamine excretion were studied in Samoan adults.

SUBJECTS AND METHODS

Five hundred and seven participants, aged 29-69 years, were randomly selected from nine villages throughout Samoa. Sociodemographic and lifestyle factors were assessed by questionnaire. Epinephrine and norepinephrine excretion rates were measured by high performance liquid chromatography with electrochemical detection in overnight urine samples. Age ( ≤ 40 vs >40 years) and gender-specific regression models were estimated to detect associations with BMI-adjusted catecholamine excretion.

RESULTS

Norepinephrine was significantly higher in peri-urban young men and older women. Epinephrine was significantly higher in peri-urban older men. Adjustment for caffeine attenuated the relationship between residence and norepinephrine in young women.

CONCLUSION

General residential exposure to modernization in urban villages is a significant correlate of increased overnight catecholamine excretion rates and is consistent with past studies. Caffeine consumption in younger women plays a complex role in stress-related catecholamine excretion. Further studies of individual level attitudinal and behavioural factors in Samoans are needed to understand psychosocial stress, physiologic arousal and health.

Culture change and stress in Western Samoan youth: Methodological issues in the cross-cultural study of stress and immune function

This study was designed to pursue three objectives: 1) investigate the impact of culture change on children and adolescents in Western Samoa; 2) introduce a cross-cultural perspective to studies of psychosocial stress and immune function; and 3) evaluate the utility of minimally invasive methods for assessing immune function. Seven hundred sixty individuals between the ages of 4 and 20 years were recruited from three distinct geographic regions within Western Samoa that differ in degree of westernization. Finger prick samples of whole blood were collected from each individual and analyzed for antibodies against the Epstein-Barr virus (EBV; an indirect marker of cell-mediated immune function) and C-reactive protein (a nonspecific marker of current infection). After controlling for age, sex, and current infection, EBV antibody levels were significantly elevated in urban Apia and rural Upolu, indicating lower levels of cell-mediated immune function. The results suggest a higher degree of psychosocial stress in these regions, possibly due to exposure to westernizing influences. Am. J. Hum. Biol. 12:792-802, 2000. Copyright 2000 Wiley-Liss, Inc.

Glycated hemoglobin as an indicator of social environmental stress among indigenous versus westernized populations

BACKGROUND

This study assessed whether glycated hemoglobin concentration, an indicator of psychogenic stress, differs between indigenous populations and non-indigenous reference groups.

METHODS

Multivariate and stratified analyses were undertaken of cross-sectional data from multi-center community-based diabetes diagnostic and risk factor screening initiatives in Canada and Australia. Population groups were Australian Aborigines (n = 116), Torres Strait Islanders (n = 156), Native Canadians (n = 155), Greek migrants to Australia (n = 117), and Caucasian Australians (n = 67). Measurements included fasting glycated hemoglobin (HbA(1c)) concentration, fasting and 2-h post-load glucose concentrations, body mass index, waist-to-hip ratio, and demographic variables.

RESULTS

Mean HbA(1c) concentrations were greater for indigenous groups than for Greek migrants and Caucasian Australians (P < 0. 0001). The covariate adjusted indigenous versus non-indigenous difference (95% CI) was 0.90 (0.58-1.22) percentage units, 18.2% higher for indigenous people. Stratified analyses indicated greater HbA(1c) for indigenous than for non-indigenous persons with normoglycemia (P = 0.009), impaired glucose tolerance (P = 0.097), and diabetes (P < 0.0001).

CONCLUSIONS

HbA(1c) concentrations are greater for indigenous than for non-indigenous groups. Social changes, low control, and living conditions associated with westernization may be inherently stressful at the biological level for indigenous populations in westernized countries.

Natural experimental models: the global search for biomedical paradigms among traditional, modernizing, and modern populations

During the past four decades, biomedical scientists have slowly begun to recognize the unique opportunities for studying biomedical processes, disease etiology, and mechanisms of pathogenesis in populations with unusual genetic structures, physiological characteristics, focal endemic disease, or special circumstances. Such populations greatly extend our research capabilities and provide a natural laboratory for studying relationships among biobehavioral, genetic, and ecological processes that are involved in the development of disease. The models presented illustrate three different types of natural experiments: those occurring in traditionally living, modernizing, and modern populations. The examples are drawn from current research that involves population mechanisms of adaptation among East African Turkana pastoralists; a search for etiology and mechanisms of pathogenesis of an emerging disease among the Yakut people of Siberia; and psychosocial stress, hypertension, and cardiovascular disease in women working outside the home in New York City and among subpopulations in Hawaii. The models in general, and the examples in specific, represent natural laboratories in which relatively small intrapopulation differences and large interpopulation differences can be used to evaluate health and disease outcomes.

Variation in epinephrine and cortisol excretion rates associated with behavior in an Australian Aboriginal community

Urinary epinephrine and cortisol hormone output in a remote Australian Aboriginal community was on average about twice as high in those individuals measured on a Thursday or Friday as those measured at the beginning of the next week (Monday or Tuesday). Diastolic blood pressure was about 6 mm Hg higher in the Thursday-Friday group, but the difference in mean systolic blood pressure between the day groups does not reach statistical significance. These physiological differences are associated with a marked dichotomy in behavior in the two time periods: on the first 2 days, virtually all adults were involved in intense gambling activity for large stakes, but this was not a feature of the latter period. This behavior pattern occurs on a regular weekly basis. If substantiated by longitudinal studies, this phenomenon may provide an additional link between human behavior and a poor health profile mediated via the physiological consequences of high stress hormone output.

Migration and acculturation among Samoans: some sources of stress and support

Daily excretion of the stress hormone, epinephrine, has been employed to study potential stressors associated with acculturation and migration. Young men and women from Samoan communities in Hawaii (HI), American Samoa (AS) and Western Samoa (WS) which differ in exposure to American culture were included. Psychosocial factors associated with elevations in hormone excretion were assumed to be stressors, while associations with reduced excretions were assumed to be supportive or buffers. Hormone excretion levels were similar in all locations, but there were different associations which could be attributed to migration and acculturation. Among all migrants (HI) ethnic networks were apparent stressors, while a high degree of community involvement was stressful for migrant women. In sites of culture contact (HI, AS) certain adult members of the extended family were supportive, as was a superior knowledge of Samoan cultural concepts. For women in Samoa (WS, AS) community involvement was supportive. In contrast for men in WS and AS, but not in HI, being of mixed ancestry or having close family of mixed ancestry was stressful. It is concluded that hormone analysis can provide meaningful clues concerning social stressors in acculturating or migrant communities. Also that migration or acculturation do not necessarily result in increased levels of stress.

The Biological Stress Response and Lifestyle: Catecholamines and Blood Pressure

Many measures in human biology that are studied as immutable traits are actually fluctuating physiological functions that adjust body systems to rapid changes in the environment. This overview discusses what has been learned about the response to the stressors inherent in continuously changing microenvironments in modern Western societies of two related physiological functions: the release of catecholamines and blood pressure. The review shows that many factors that are part of or influence lifestyle—including perception and cognitive state, the nature of the social situation, foods, stimulants and exercise—and external conditions such as temperature, continuously alter catecholamine levels and blood pressure. Because lifestyle stress may be an important selective force in human populations, studies of dynamic functions that react to it, such as catecholamine release and blood pressure, may be important in understanding the ongoing dynamics of human evolution.

Psychosocial factors in blood pressure variation: a comparative study of young Samoans

Traditional peoples contacting modern cultures frequently experience increased levels of blood pressure. The aim of this investigation was to identify some acculturation-related psychosocial factors which might contribute to those elevations. Young Samoans living in a traditional village, in modernizing American Samoa, and as migrants in Hawaii were studied. Casual blood pressure, anthropometric measurements, and extensive interview data were collected. The most important factor predicting variation in blood pressure was body mass (BMI). This finding was particularly evident among the acculturated and migrant Samoans. In those locations women's abandonment of breast feeding may contribute to their higher BMI. Among acculturated and migrant women, measures of social support favored lower blood pressures. Among men in all locations a greater number of close social ties was linked to higher blood pressures with the exception of ties with parents. Parental ties were linked to substantially lower blood pressures. A knowledge of Samoan traditions favored lower blood pressure among migrant men, while knowledge of American culture favored higher pressures. Coping strategies and complaint behavior were also significant contributors in all locations.