Age may be less of a determining factor in the increase of BP compared with the amount of exposure to a Western lifestyle, according to a study published in JAMA Cardiology.
Researchers from Johns Hopkins University Bloomberg School of Public Health examined two tribes, the Yekwana and the Yanomami, living in an isolated area of the Venezuelan rainforest.
According to the study background, the Yanomami are considered the least acculturated in the world and are hunter-gatherer-gardeners, whereas the Yekwana live near the Yanomami but have been affected by missions and an airstrip, allowing medical deliveries and sporadic exposure to facets of Western culture, including processed foods and salt.
“While the Yanomami have fascinated hypertension researchers, their isolation combined with restricted government access has prevented substantive research in this population,” Noel T. Mueller, PhD, MPH, from the Welch Center for Prevention, Epidemiology, and Clinical Research at Johns Hopkins Bloomberg School of Public Health, and colleagues wrote in a research letter.
The sample consisted of 155 participants — 83 Yekwana and 72 Yanomami — aged from 1 to 60 years and the two groups had little difference in mean age (Yekwana, 22.2 years; Yanomami, 22.4 years), sex distribution (Yekwana, 33 men and 50 women; Yanomami, 39 men and 33 women) or height (Yekwana, 141.7 cm; Yanomami, 138 cm).
Data were collected from October 2015 to February 2016, after which the researchers calculated the age-BP slopes and intercepts.
Although there was no difference between the Yanomami and Yekwana in the age-systolic BP intercept, the systolic BP slope was significantly steeper for the Yekwana participants than the Yanomami individuals (difference, 0.26 mm Hg per year; 95% CI, 0.04-0.47; P for interaction = .02).
In the Yanomami, there was a mean age-systolic BP slope of 0.00 mm Hg per year, whereas the mean age-systolic BP slope in the Yekwana was 0.25 mm Hg per year (P = .003). Although both groups started with similar BP, the gaps widened over time, Mueller and colleagues found.
At age 10 years, the mean systolic BP was 5.8 mm Hg higher in the Yekwana group than the Yanomami group, and by age 50 years, there was a 15.9-mm Hg gap. Divergent BP trends may start at childhood due to a steeper age-systolic BP slope in Yekwana individuals compared with Yanomami individuals aged 1 to 20 years, the researchers wrote.
Mueller and colleagues wrote that the study helps disentangle the effects of aging vs. modern lifestyle on BP.
“To put our findings into context, in the United States, [systolic] BP increases by approximately 1.5 mm Hg per year among girls, approximately 1.9 mm Hg per year among boys, and approximately 0.6 mm Hg per year in adults. Although our study is cross-sectional and limited by small sample size, it adds to findings in Yanomami adults showing the rise in BP with age may not be natural but rather a consequence of unnatural Western exposures,” Mueller and colleagues wrote. – by Earl Holland
Disclosure: One author reports he received personal fees from UpToDate outside the submitted work.