A remote and unique indigenous population in the Bolivian Amazon called the Tsimane (pronounced chee-MAH-nay) sparked the interest of scientists when they were found to show almost no cases of age-related heart disease.
Since then, scientists have carried out various studies into the Tsimane community due to their exceptional health even in old age. In 2017, researchers from The Tsimane Health and Life History Project were astonished to find that the elderly Tsimane experienced unusually low levels of vascular aging, and a study in The Lancet reported that the average 80-year-old Tsimane adult demonstrated the same vascular age as a 55-year-old American.
Researchers are now looking into the brain health of the Tsimane community, in particular the prevalence of dementia. For this study, a local team of trained physicians and translators assessed 435 Tsimane adults, all over the age of 60, and had them complete several neurological assessments, including CT brain scans and cognitive tests.
Out of this sample, only five cases of dementia were detected, which equates to about one percent of the population studied—significantly below the 11 percent of the equivalent American population known to be living with dementia.
Researchers also studied 169 individuals hailing from the Moseten community, a community genetically and linguistically similar to the Tsimane. The Moseten also showed very low levels of dementia, even though they lived in closer proximity to modern Bolivian society.
“Something about the pre-industrial subsistence lifestyle appears to protect older Tsimane and Moseten from dementia,” says Margaret Gatz, lead author of the study.
Another recent study published in 2021 discovered that the Tsimane also demonstrated much lower rates of age-related brain atrophy in comparison to Western populations. No one’s brain is exempt from losing volume as they age. The CT scans in this study, however, show that Tsimane brains appear to shrink 70 percent slower than their Western counterparts.
One bizarre finding of the CT brain study was that Tsimane brains showed remarkably high levels of neuroinflammation, even though they also experienced a reduction in brain atrophy. To explain this discordancy, the scientists hypothesized that the high levels of inflammation stem from persistent exposure to infectious disease while overarching lifestyle factors played a larger role in maintaining brain health (along with low rates of cardiovascular disease) despite chronic inflammation.
Studies like these that investigate older indigenous populations can help us determine the ways in which our modern Western lifestyles ultimately damage our health as we age.
“By working with populations like the Tsimane and the Moseten, we can get a better understanding of global human variation and what human health was like in different environments before industrialization,” explains study co-author Benjamin Trumble. “What we do know is the sedentary, urban, industrial life is quite novel when compared with how our ancestors lived for more than 99 percent of humanity’s existence.”
Source study: Alzheimer’s Association—Prevalence of dementia and mild cognitive impairment in indigenous Bolivian forager-horticulturalists