Amazon indigenous group's lifestyle may hold a key to slowing down aging

Many years ago, as a young and adventurous PhD student, I spent a year living with hunter-gatherers. I jokingly say the experience put me off camping for life. One of the things I was particularly interested in was the effect of their lifestyle on their longevity and their mental health.

One of the things I noticed was an almost complete absence of cognitive decline with old age. I attributed this—and their impressive longevity considering that they had no access to modern medicine—to their lifestyle. I surmised that this lifestyle was far more in tune with what I call our human “design-specs” and therefore created far less stress on their overall system.

For that reason, I am thrilled with research just published which, using much more sophisticated tools, confirms both my observation and my hypothesis.

A team of international researchers has found that the Tsimane indigenous people of the Bolivian Amazon experience less brain atrophy than their American and European peers. The decrease in their brain volumes with age is 70% slower than in Western populations. Accelerated brain volume loss can be a sign of dementia.

The study was published in the Journal of Gerontology, Series A: Biological Sciences and Medical Sciences.

Although people in industrialized nations have access to modern medical care, they are more sedentary and eat a diet high in saturated fats. In contrast, the Tsimane have little or no access to health care but are extremely physically active and consume a high-fiber diet that includes vegetables, fish and lean meat.

What the researchers say: “The Tsimane have provided us with an amazing natural experiment on the potentially detrimental effects of modern lifestyles on our health,” said the study’s lead author. “These findings suggest that brain atrophy may be slowed substantially by the same lifestyle factors associated with very low risk of heart disease.”

The researchers enrolled 746 Tsimane adults, ages 40 to 94, in their study. To acquire brain scans, they provided transportation for the participants from their remote villages to Trinidad, Bolivia, the closest town with CT scanning equipment. That journey could last as long as two full days with travel by river and road.

The team used the scans to calculate brain volumes and then examined their association with age for Tsimane. Next, they compared these results to those in three industrialized populations in the U.S. and Europe.

The scientists found that the difference in brain volumes between middle age and old age is 70% smaller in Tsimane than in Western populations. This suggests that the Tsimane’s brains likely experience far less brain atrophy than Westerners as they age.

The researchers note that the Tsimane have high levels of inflammation, which is typically associated with brain atrophy in Westerners. But their study suggests that high inflammation does not have a pronounced effect upon Tsimane brains.

According to the study authors, the Tsimane’s low cardiovascular risks may outweigh their infection-driven inflammatory risk, raising new questions about the causes of dementia. One possible reason is that, in Westerners, inflammation is associated with obesity and metabolic causes whereas, in the Tsimane, it is driven by respiratory, gastrointestinal, and parasitic infections. Infectious diseases are the most prominent cause of death among the Tsimane.

“Our sedentary lifestyle and diet rich in sugars and fats may be accelerating the loss of brain tissue with age and making us more vulnerable to diseases such as Alzheimer’s,” the researchers concluded. “The Tsimane can serve as a baseline for healthy brain aging.”

The indigenous Tsimane people captured scientists’—and the world’s—attention when an earlier study found them to have extraordinarily healthy hearts in older age. That prior study, published by the Lancet in 2017, showed that Tsimane have the lowest prevalence of coronary atherosclerosis of any population known to science and that they have few cardiovascular disease risk factors. The very low rate of heart disease among the roughly 16,000 Tsimane is very likely related to their pre-industrial subsistence lifestyle of hunting, gathering, and fishing.

Again, this low incidence of heart disease was something that I observed among the hunter-gatherers I studied.

“This study demonstrates that the Tsimane stand out not only in terms of heart health, but brain health as well,” said the lead author. “The findings suggest ample opportunities for interventions to improve brain health, even in populations with high levels of inflammation.”

So, what? Our present lifestyle is so far from that which we were designed to live that it is no wonder we are prone to the kinds of undue stressors that any misused organism would be subject to. We are like trees subjected to a hurricane.

We can’t return to a hunter-gatherer lifestyle—there are just too many of us and not enough wild spaces. However, there is one element of their lifestyle that we can easily copy and that is their relationship skills. The concept of loneliness and isolation—a pandemic afflicting our society predating the novel coronavirus and far more deadly than COVID will ever be—is totally unknown to either the !Kung-speaking people I lived with or the Tsimane people featured in this study.

Our modern work practices and our technology are driving us apart from each other and increasing this pandemic. But we can adopt relationship forming and maintaining skills that can help to overcome even these evils. The key to improvement is an increase in in-person communication and the use of what Alicia and I call needs-based dialogue and the PALS dialogue skills (praise, asking, listening and being specific). If we can’t live as hunter-gatherers did, at least we can use their relating skills to cure many of our present ills.