Dementia Prevention: What Indigenous Amazonians are Teaching Us!

The Lowest Prevalence of Dementia Worldwide

Dementia cure, prevention, and lowering risk are key focuses of governments globally.

A recent study has shown that Amazonian indigenous communities have the lowest incidence of dementia globally.

There is now growing evidence that their lifestyle choices may provide hints to avoiding Alzheimer’s and other dementias.

As experts worldwide work frantically to find a dementia cure, academics at the University of Southern California in the United States found that two indigenous populations in the Bolivian Amazon have the lowest incidences of dementia globally.

A multinational team of scientists uncovered that dementia affects just approximately 1% of older Tsimane and Moseten residents. In comparison, the Alzheimer’s Association in the United States reports that 11% of people aged 65 and older in the US have dementia, while Alzheimer’s Society report 7.1% in the UK.

Research into Preventing Dementia and Lowering Risk

To identify cognitive impairment and dementia among the Moseten and Tsimane, researchers employed computed tomography (CT) brain scan pictures, neurological and cognitive examinations, and culturally relevant questionnaires supported by a local team of Bolivian physicians and qualified interpreters. Participants in the research study were transported to Trinidad in Bolivia for the scan. This journey often took several days.

In their report, published March 2022 in The Alzheimer’s & Dementia Research: The Journal of the Alzheimer’s Association, the researchers discovered just one case among 169 Moseten people (aged 60 and over) and five incidences of dementia among 435 Tsimane people.

Commenting on the findings, the author of the study, Margaret Gatz, professor of gerontology, preventive medicine, and psychology at the University of Southern California, stated:

“A little about the pre-industrial subsistence lifestyle seems to prevent elderly Tsimane and Moseten against dementia.”

With little or no access to formal healthcare, the Tsimane communities keep physically busy throughout their lives, hunting, farming, fishing using hand tools, and gathering sustenance from the forest. Similarly, The Moseten also live in rural areas and work the land to provide food, keeping physically active throughout their lives.

Amazonian tribe finishing

In comparison and commenting on western lifestyle and diet, study co-author Hillard Kaplan, a professor of health economics and anthropology at Chapman University who has studied the Tsimane for nearly two decades, had this to say:

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 Tsimane can serve as a baseline for healthy brain aging.”

Dementia Prevention: Indigenous Populations Globally

The researchers also compared their findings to a previous review of 15 studies of indigenous populations in Australia, North America, Guam, and Brazil that found dementia rates ranging from 0.5% to 20% among older adults.

Contact with and adoption of the lifestyles of non-indigenous people among these communities are believed to be the primary cause. This is thought to be due to an increased dementia risk linked to diabetes, high blood pressure, alcohol abuse, obesity, and heart disease found to be more prevalent in western societies.

However, these dementia risk factors remain extremely low among the Tsimane and Moseten populations.

In summing up the research findings, Andrea Irimia, an assistant professor of gerontology, neuroscience, and biomedical engineering at the USC Leonard Davis School of Gerontology and the USC Viterbi School of Engineering:

“The Tsimane have provided us with an amazing natural experiment on the potentially detrimental effects of modern lifestyles on our health.”

Lowering Dementia Risk: Healthy Hearts lead to Healthy Brains

This isn’t the first time the Tsimane people have captured the interests of researchers. A previous study published in The Lancet in 2017 revealed that the Tsimane people have the lowest prevalence of coronary atherosclerosis (a disease that manifests as fatty deposits inside arteries). In other words, they have extremely healthy hearts in old age.

Furthermore, research published in The Journal of Gerontology in 2021, headed by Professor Andrei Irimia, a co-author of the latest paper, discovered that Tsimane has less brain atrophy than their European and American counterparts.

Despite the increased inflammatory risk, the research team believes that low-cardiovascular risks and healthy hearts in old age are significant in explaining the low prevalence of dementia.  In contrast, researchers believe that lifestyle variables in higher-income nations, such as diets heavy in sweets and fats, lead to heart disease and hasten brain aging.

women of amazonian tribes working the land

Dementia Cure: A rush to find one

Risk factors for dementia are well documented. The major recognized non-modifiable risk factor for Alzheimer’s and other dementias is aging. Modifiable risk factors include formal education, physical inactivity, cardiovascular illness, midlife hypertension and diabetes, and, more recently, air pollution. Read more about research into 12 key risk factors for dementia and dementia prevention here.

Commenting on ways to promote dementia prevention, Hillard Kaplan, a research co-author and Chapman University professor of health economics and anthropology who has studied the Tsimane for two decades, said that “Everyone is in the race to find answers to the increasing frequency of Alzheimer’s disease and associated dementias.”

This is not surprising. By 2050, the number of people with dementia is expected to triple.

Professor Kaplan adds:

“Looking at these varied groups contributes to and improves our awareness of these difficulties while also yielding fresh results.”

Benjamin Trumble, study co-author and associate professor in Arizona State University’s School of Human Evolution and Social Change and the Center for Evolution and Medicine stated:

“By working with communities such as the Moseten and the Tsimane, we can better understand global human variation and what human health was like in various atmospheres before industrialization.”

“We know now that the urban, inactive, industrial existence is different from how our forefathers lived for more than 99 percent of human history.

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