An isolated tribe in the Bolivian Amazon has the healthiest arteries and superior cognitive skills despite their advanced age.

Scientists who work with remote indigenous peoples in the Bolivian Amazon have found that communities have very low rates of dementia. The new study is a continuation of previous work. Previously, scientists found that in the same populations there were almost no cases of age-related heart disease.

The Tsimane are a unique population of about 17,000 living in remote areas of Bolivia. Over the past few decades, scientists have studied them to understand the reasons for their unusually good health in old age. Thus, 85% of adults in this population showed no signs of risk of cardiovascular disease. A study published in The Lancet found that the vascular age of 80-year-old Cymanes is the same as that of Americans who are 25 years younger than them.

In a new study, scientists focused on brain health and the prevalence of dementia. The project involved 435 adult Tsimane over the age of 60. With the help of a local team of carefully trained doctors and translators, the participants underwent a series of neurological examinations, including brain CT scans and cognitive tests.

Only five cases of dementia were found in the cohort, corresponding to about one percent of the study population over 60 years of age. This contrasts with the roughly 11% equivalent of the American population.

The scientists also studied 169 people from the Moseten tribe, who are genetically and linguistically similar to the Tsimane. The Mosets had the same low rate of dementia despite living in close proximity to contemporary Bolivian society.

“Something about the pre-industrial natural lifestyle seems to protect the elderly Tsimane and Moseten from dementia,” the scientists explain. In addition, it is the Cymane lifestyle that can keep the brain healthy even in the face of significant chronic inflammation, which the researchers found on CT scans. The same scientists explain the low level of dementia and cardiovascular disease. While aging is considered a major risk factor for conditions such as cognitive decline, study co-author Benjamin Trumble said studying older indigenous peoples could show how detrimental our modern lifestyles are to health in old age.