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Amazonian indigenous people have among of the world’s lowest dementia rates

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A new research finds that two indigenous populations in the Bolivian Amazon have among the lowest rates of dementia in the world, while experts across the globe seek remedies for Alzheimer’s disease.

An international team of experts discovered that just around 1% of senior Tsimane and Moseten people suffer from dementia. According to the Alzheimer’s Association, 11% of adults aged 65 and older in the United States have dementia.

“Something about the pre-industrial subsistence lifestyle appears to protect older Tsimane and Moseten from dementia,” said Margaret Gatz, lead study author and professor of psychology, gerontology, and preventive medicine at the USC Dornsife College of Letters, Arts, and Sciences’ Center for Economic and Social Research.

To identify dementia and cognitive impairment among the Tsimane and Moseten, researchers employed computed tomography (CT) brain scan pictures, cognitive and neurological tests, and culturally relevant questionnaires supported by a local team of qualified interpreters and Bolivian doctors.

The research, which was published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, discovered just five incidences of dementia among 435 Tsimane people and one case among 169 Moseten people aged 60 and above.

The study team detected mild cognitive impairment (MCI) in roughly 8% of Tsimane and 10% of Moseten in the same over-60 groups, which is often characterized by early stage memory loss or reduction in other cognitive abilities such as language or spatial perception. According to the study’s authors, these rates are more equivalent to MCI in high-income nations such as the United States.

Researchers were astonished to discover that individuals in the research who were diagnosed with dementia or MCI typically showed uncommon and significant calcifications of their intracranial arteries. During neurological evaluations, these research participants typically demonstrated parkinsonian symptoms as well as cognitive abnormalities in attention, spatial awareness, and executive functioning.

Although calcifications were more prevalent in the cognitively challenged, researchers saw same vascular calcifications in CT scans of those who did not have dementia or MCI. More study, they add, is required to understand the significance of vascular variables, as well as viral and inflammatory illnesses, which are common in these groups, as well as other risk factors for dementia. To that purpose, the study team is presently revisiting all of the Tsimane and Moseten communities that were previously analyzed.

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Alzheimer’s disease in Tsimane, Moseten, and other indigenous peoples

The approximately 17,000 Tsimane are physically busy throughout their lives, fishing, hunting, farming using hand tools, and gathering sustenance from the forest. The 3,000 Moseten also live in rural communities and work in agriculture for a living. In contrast to the more secluded Tsimane, they live closer to towns, have access to schools, clean water, and medical facilities, and are more likely to be literate.

The researchers compared their findings to a comprehensive assessment of 15 indigenous population studies from Australia, North America, Guam, and Brazil. Dementia frequency among indigenous older persons ranged from 0.5 percent to 20%, according to a previous study.

The fact that indigenous communities in other regions of the globe have high incidence of dementia may be attributable to increased interaction with – and adoption of – their non-indigenous neighbors’ lifestyles. They are also more likely to develop diabetes, hypertension, alcoholism, obesity, and cardiovascular disease.

The Tsimane and Moseten populations have exceptionally low levels of these dementia risk factors. Previous study published in The Lancet revealed that the Tsimane people had exceptionally healthy hearts in old age and the lowest prevalence of coronary atherosclerosis (a disease that manifests as fatty deposits within arteries) of any community known to science. This difference might be related to their subsistence lifestyle.

Another research published last year in The Journal of Gerontology, headed by USC assistant professor Andrei Irimia, who is also a co-author on the current study, discovered that Tsimane had less brain atrophy than their American and European counterparts.

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In contrast to the Tsimane, researchers believe that lifestyle variables in higher-income nations, such as a lack of physical exercise and diets heavy in sweets and fats, lead to heart disease and may also hasten brain aging.

A rush to find Alzheimer’s disease cures

The most major recognized risk factor for Alzheimer’s and other dementias is aging. Low formal education, midlife hypertension and diabetes, cardiovascular illness, physical inactivity, and, most recently, air pollution have all been identified as key modifiable risk factors for dementia and Alzheimer’s disease.

According to projections, an aging global population, along with the growth of modifiable risk factors, would result in a doubling of the number of persons with dementia globally by 2050, reaching more than 152 million.

“We’re in a race to find answers to the increasing frequency of Alzheimer’s disease and associated dementias,” said Hillard Kaplan, a research co-author and Chapman University professor of health economics and anthropology who has studied the Tsimane for two decades. “Taking a look at these different populations adds to and accelerates our knowledge of these illnesses, as well as generates fresh discoveries.”

“By working with populations like the Tsimane and the Moseten, we can gain a better understanding of global human variation and what human health was like in different environments before industrialization,” said 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. “What we do know is that the sedentary, urban, industrial life is rather unique in comparison to how our forefathers lived for more than 99 percent of humanity’s existence.”

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