Amazonian tribe could show how to beat dementia
Studies reveal that Tsimané have very low levels of heart disease and much better brain health
The Tsimané are an indigenous people of the Bolivian Amazon in South America. You have probably never heard of them. I had not. I had to look up how to pronounce Tsimané: chee-mah-nay.
They are a tiny population of about 9,000 spread across 80 villages and living in communities of 20 to 30 families.
And yet this small group is extraordinary. A few years ago, scientists studied them to understand their exceptional heart health: 85 per cent had almost no evidence of the calcification of the arteries that is the marker for atherosclerosis. Even those who did have some had very little.
Atherosclerosis causes the hardening of the arteries that plagues Western communities and keeps them popping statins to control cholesterol.
The Tsimané’s exceptional heart health is thought to be the consequence of a farming, fishing and foraging lifestyle. This includes a diet high in carbohydrates – from eating staples such as rice, plantains and maize – and a lot of walking.
Their lives are spent on the move looking for food; they can cover 20km during a hunt that could last eight hours. This is why researchers suggest an 80-yearold Tsimané has the physiology of a 50-year-old American.
The Tsimané people walk, run, ride bikes or row boats from one place to another up and down the river. They live in rural communities and do not watch television as they do not have electricity.
Not only are their hearts more healthy than those of people in Western countries, but researchers found that their brains are, too.
One measure of a healthy brain is brain volume; as we age, our brains tend to shrink. The decrease in the Tsimané’s brain volumes as they age is much, much lower than people who live in the West. This may explain why they have an 80 per cent lower incidence of dementia than people in the United States or Europe.
Among older Tsimané people, only about 1 per cent suffer from dementia. In the US, 11 per cent of people aged 65 and older do. An obvious link that can be made is that what is good for the heart is good for the brain.
Other factors could play a role in keeping dementia at bay in the Tsimané. Having a healthy diet – with no ultra-processed foods – and an active lifestyle certainly helps their hearts and brains.
Living in communities assures they are not socially isolated – another risk for dementia. They also live in nature, so there’s little air pollution.
Their lifestyle has been described as pre-industrial. Other groups of people that benefited from this lifestyle – who were more physically active, had a better diet and lived in communities – were the ancient Greeks and Romans, who also suffered less dementia than modern communities do.
The average lifespan in ancient Greece was about 70 years old and Hippocrates – the father of modern medicine – is believed to have lived into his eighties, possibly nineties.
Old texts describe plenty of the ailments we associate with old age: loss of sight or hearing, becoming frail and less mobile. But not memory loss.
The Roman politician Cicero described the “four evils” of old age: we become less active, we grow weaker, old age deprives us of physical pleasures, and it’s not far from death. He does not mention memory loss.
It would definitely be considered among the evils – possibly the evil – of old age today. Dementia is currently the seventh biggest cause of death globally and the leading cause of death in the United Kingdom.
Better brain health in our later years “is now known to depend on heart health”, says the University of Southern California’s Professor Caleb Finch. He recently published a study that explored the low levels of dementia among ancient Greeks and Romans and found that lifestyle factors such as diet and exercise were key.
But the case of the Tsimané is a puzzling one, he continues, which does not fully explain why dementia is more prevalent in the US than for them.
They might walk 15,000 steps a day for farming and jungle foraging, and their diet is low fat, low sugar, low salt. But, Finch says, “the Tsimané have high life-long levels of systemic inflammation”.
Compared with other populations, the Tsimané have high levels of inflammatory markers in their blood – 1.5 times higher than people in the US. One important biomarker for inflammation, C-reactive protein (CRP), was referred to as “chronically high”.
And, as Finch says, “inflammation is considered a risk for both heart and brain disease”.
Inflammaging, defined by the National Institute of Health as “an age-related increase in the levels of pro-inflammatory markers in blood and tissues”, is “a strong risk factor for multiple diseases that are highly prevalent and frequent causes of disability in elderly individuals”.
Why, then, might the Tsimané, despite the risks of a lifelong inflammatory process, be protected from the effects of inflammaging?
Also, the Tsimané live in a natural environment as opposed to our increasingly sterile one, so perhaps their immune systems are in a state of constant high alert, anticipating the need to fight against bacteria and parasites.
Whatever the explanation, the Tsimané’s low risk of brain and heart disease despite high levels of inflammation speaks to the power of lifestyle: we cannot all live in forests. But we can all eat better, engage with our community and move more.
This is the 34th instalment in a series on dementia, including the research into its causes and treatment, advice for carers, and stories of hope.