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A western lifestyle might be the reason blood pressure tends to rise with age, according to a study of remote tribal communities.
Hypertension is a key risk factor for cardiovascular disease, and in many developed countries, including the UK, the likelihood of developing increases with age. More than a quarter of adults in England have high blood pressure, with recent figures showing the proportion rises to 58% among those aged 65-74.
A study of remote communities in the Venezuelan rainforest has backed the idea that hypertension is not an inherent part of ageing, but a result of longer exposure to risks arising from lifestyle, such as high levels of salt in the diet, lack of exercise and heavy drinking.
Dr Noel Mueller, an assistant professor at Johns Hopkins University, who led the research, said: “The idea that blood pressure rises with age as part of a natural phenomenon is increasingly being dispelled through evidence, including our findings here, which show that in a population that is largely free of exposure to western influences, there is no age-related rise in blood pressure.”
Writing in the Jama Cardiology journal, Mueller and his colleagues report how they contacted two rainforest communities. One, the Yanomami, has had very little contact with the western world. The group has a hunter-gatherer-gardener lifestyle and does not eat much salt.
The other is the nearby Yekwana community, which has experienced some aspects of western life through trade facilitated by an airstrip, including commodities such as processed food and salt, as well as the presence of visitors – including missionaries, medical professionals and miners.
The team took the blood pressure of 72 Yanomami people and 83 from the Yekwana community aged between one to 60. While previous research has highlighted the low blood pressure of the Yanomami, this is the first time children were included in such work.
Yekwana participants showed an increase in blood pressure with age – albeit at a far lower level than seen in the US, for example. However, in the Yanomami community, blood pressure stayed approximately the same.
While infants in both communities had similarly low measurements, the team noted that by the age of 10, Yekwana and Yanomami children showed significant differences in blood pressure, with the divergence increasing with age.
“[That] to us indicates that interventions to prevent the rise in blood pressure and high blood pressure need to start early in life, where we can still have the opportunity to modify some of the exposures that might lead to high blood pressure,” Mueller said.
However, the study is very small – only 11 Yekwana individuals over the age of 40 took part in the research – and the research did not unpick exactly which lifestyle and diet differences might be behind the trends for age and blood pressure.
“It is unclear whether these factors fully explain the results, which may also be partly due to genetic factors,” said Dr James Sheppard, an expert in hypertension at Oxford University who was not involved in the study. He added that another problem was that the research did not measure the participants’ blood pressure as they aged, and participants were relatively young.
Prof Bryan Williams, a specialist in hypertension at University College Hospital in London, said: “[The study] gives us a glimpse at what a normal blood pressure trajectory would be like without the impact of westernisation – many more people would have a normal blood pressure throughout life.”
The hypertension seen older people in western countries such as the UK, he added, was caused by a stiffening of the large arteries. “This most likely represents some genetic predisposition but is powerfully influenced by lifestyle, as suggested by this study. It points once again to the importance of a healthy lifestyle to delay ageing of the arteries and delay the rise in blood pressure with age.”
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