Many of us have likely experienced recent high blood pressure. Whether it’s from well-meaning but very inquisitive relatives, or the winding lines at the airport, most of us are acquainted with a temporary rise in blood pressure under stress. And unfortunately, high blood pressure (BP) is a common chronic issue for millions of people worldwide. We’ve long believed that blood pressure is associated with age — the older we get, the higher it inevitably rises. Yet researchers from The Johns Hopkins University and the Bloomberg School of Public Health recently published findings that contradict this long believed theory. They found that in non-Westernized groups, there is no increase in blood pressure corresponding to increasing age.

High blood pressure plays a role in the pathology of many diseases, from cardiovascular disease to cognitive impairment. Many studies in Western countries have followed adults over time to examine how changes in blood pressure relate to age. The broad consensus is that BP increases with age, although this correlation may be due to a variety of factors such as diet, environmental pollutants and structural integrity of arteries. This rise in BP is generally correlated with higher risk of coronary heart disease. In contrast, non-Westernized countries appear to have less of a relationship between age and BP — an increase in age is not associated with as great an increase in BP as one would expect in a Westernized country. With this lower BP comes lower risk of coronary heart disease.

However, no studies have measured BP in children and adults in a non-Westernized culture, in areas that are relatively similar geographically. By examining communities in similar locations, researchers can control for variables such as pollutants or other environmental factors. Such a study would allow us to examine BP over a person’s life course, rather than as just a snapshot of adult health. This gap was filled by Noel Mueller and Lawrence Appel at Johns Hopkins, as well as colleagues from the Amazonic Center for Research and Control of Tropical Diseases, Universidad Central de Venezuela, the Venezuelan Institute for Scientific Research and Rutgers University. Their study compared two South American populations — one that is thought to be one of the least Westernized in the world, and one that has had moderate Western contact and influence — and sampled BP across diverse ages to understand if the correlation between BP and age is innate or more a result of culture and diet.

To examine the relationship between age and BP in non-Westernized and Westernized cultures, the researchers focused on two South American communities that are in similar environments, geographically. The Yanomami community is one of the least Westernized, most remote villages in South America. Very rarely contacted by outsiders, the Yanomami have a seminomadic, hunter-gatherer culture. The Yekwana (also Ye’cuana and Yekuana) people live in the same region as the Yanomami, but in an area that was involved in a government-sponsored development plan. This exposed them to trade with Western countries, and hence, they are considered moderately Westernized. The researchers worked with the Venezuelan Institute for Scientific Research and gained consent from adults and children in these communities, with approximately 80 individuals examined from each over the course of four months. To obtain the BP measurements from the communities, members of the research team and translators worked together to take BP using stethoscopes — a noninvasive, quick technique. One of the study’s unique elements was that the authors specifically measured BP across a wide range of ages, from individuals between 1 and 60 years old. Through this, they were able to identify any age-related differences in blood pressure between the two groups.

The researchers found that, overall, the Yanomami people had lower BP than the Yekwana. As a brief reminder, systolic BP (the top number) is the maximum pressure a person’s blood vessels experience when the heart beats, measured in millimeters/hectograms (mm/Hg). The diastolic BP (the bottom number) is the pressure in the arteries between heartbeats, or when the heart is resting. Both systolic and diastolic BP were significantly lower in the Yanomami when all ages were combined. Researchers also found that, while very young individuals had similar BPs between the two groups, there was a steady increase in average BP in the Yekwana community that correlated with increasing age, an increase of approximately 0.26 mm/Hg per year. In contrast, the Yanomami showed no change in average BP between the younger and older study participants. This means that by age 50, individuals in the Yekwana community would, on average, have a systolic BP approximately 15.9 mm/Hg higher than someone of the same age in the Yanomami community.

The researchers also found that the magnitude of the change in age-BP relationship is most drastic in early life, with the average change from age 1 to 20 being 0.98 mm/Hg per year in the Yekwana people. This is relative to the overall average value of 0.26 mm/Hg per year when all age groups were combined in the Yekwana community. The authors went on to compare this to the rise in systolic BP in the United States, where girls and boys have an average increase of 1.5 and 1.9 mm/Hg per year, respectively. It should be noted that even in the Yekwana community, the average BP was considered “normal” under the current U.S. guidelines. In addition, the sample sizes of each group are relatively small, but still provide novel data that could inspire further studies. These data indicate that without exposure to Western culture, there is no relationship between age and BP. It should be noted that this study was cross-sectional, meaning that samples from many age groups were taken within a short period of time, and the subjects were not followed throughout their lives. The data still suggest that across many age groups, BP remains low and does not change in the Yanomami community. A long-term study, if possible, that follows individuals throughout their lives to examine BP changes could be interesting. Western influences, perhaps including diet and medicines, in the Yekwana community appeared to have a discernible effect on the age-BP relationship, with increasing age showing a significant correlation with increased BP.

The findings of this study, then, suggest that the relationship between age and BP is most relevant in Westernized cultures. The data support previous reports of particularly low BP in Yanomami adults, but also add an important element by the comparison to a geographically similar but culturally different group, the Yekwana people. The research suggests that the rise in BP with increasing age is not necessarily intrinsic to the human aging process, but is influenced by contact with Western culture. The authors did not attempt to specify which exact factors appeared to impact BP, but emphasized that their results pointed to adolescence as a critical time during which BP is particularly susceptible to change. Consequently, efforts to improve BP should start in childhood and center on avoidance of risk factors for elevated BP. Understanding which factors influence BP over one’s lifetime can only improve our cardiovascular health in the future, and learning how environment plays a role is an essential step in expanding this knowledge to prevent cardiac disease.

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