The brain shrinks with age, a process called brain atrophy, and a faster rate of shrinkage is associated with dementia and cognitive and functional impairments. Heart disease risk factors such as high cholesterol, diabetes, and hypertension are common in industrialized populations and increase the risk of brain atrophy. Findings of a recent report compare rates of brain atrophy in industrialized and non-industrialized populations.
The indigenous Tsimane people of lowland Bolivia live by foraging, hunting, fishing, and horticulture in the Amazon basin. The Tsimane have the lowest prevalence of coronary heart disease of any known population, likely due to their highly active lifestyle and diet rich in fiber, unsaturated fats, and omega-3 fats. Their lifestyle also puts the Tsimane at a high risk of infection, causing chronically increased immune activity and inflammation, risk factors for both heart disease and brain atrophy.
This study included over 700 participants aged 60 years or older from a long-term study measuring lifestyle and health status in Tsimane adults. Clinic staff regularly visited participants in their villages to record infections and inflammation, heart disease risk factors, diet, and physical activity. The participants visited a nearby city to complete a computerized tomography (CT) scan of their heads to measure brain volume. The researchers compared these results to brain volume measurements from participants in the United States and Europe.
When compared to industrialized populations, the Tsimane had a significantly slower rate of brain volume loss with age. Compared to one sample of 500 participants aged 40 to 70 years in the Netherlands, Tismane adults in the same age range had half the rate of brain atrophy.
The authors concluded that slower rates of brain atrophy, along with diet and lifestyle factors and low heart disease risk among the Tsimane protect brain health despite high levels of chronic inflammation caused by infection. Future research should explore the relationship between infection, heart disease risk, and dementia.
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