A study of two similar tribes in the Amazon – one highly isolated and the other slightly Westernised – offers more evidence that age-related blood pressure (BP) changes are related to modern life, researchers say.

A team led by Noel Mueller of Johns Hopkins University in Baltimore, US, reports that people of the Yanomami tribe, which lives in a remote part of the Venezuelan rainforest, do not show increased blood pressure as they age, unlike their counterparts in the Yekwana tribe, which lives nearby but has access to an airstrip that has brought Western medicine, missionaries, and some dietary changes.

“The rise in [blood pressure] with age may not be natural but rather a consequence of unnatural Western exposures,” they write in a research letter published in the journal JAMA Cardiology.

In industrialised nations, rising blood pressure is correlated with age. Over time, the condition, known as hypertension, can damage arteries and lead to stroke or cardiac arrest.{%recommended 4342%}

The study involved 72 Yanomami and 83 Yekwana participants aged between one and 60.

The researchers found that children in the two tribes start out with no significant difference between blood pressures, but that over time Yekwana individuals show an increase in both systolic and diastolic measures.

The researchers also found that the increase in blood pressure had a steeper slope in Yekwana aged between one and 20. Mueller and colleagues point out that in the US, blood pressure in boys and girls rises faster than it does in adults. These findings suggest early intervention for hypertension is recommended.

This is the first study to look at children’s blood pressure in the Yanomami – a society comprising 35,000 people which has long been of interest to ethnologists because of its comparatively isolated and “pure” lifestyle.

However, the results are consistent with previous research focussed on adults of the tribe, which found they enjoyed consistently low pressure levels.

They also chime with the findings of a 2006 meta-review that found that acculturation to western society is associated with higher blood pressure and “the distress associated with cultural change appears to be more influential that changes in diet or physical activity.”

“This study of blood pressure over the lifespan of two relatively isolated Amerindian communities from the Venezuelan rainforest helps to disentangle the effects of ageing versus modern lifestyle on blood pressure, supporting primordial prevention efforts to eliminate elevated blood pressure,” Meuller’s team concludes.

They concede, however, that the relatively small number of participants constitutes a potential weakness in the study design.