The Indigenous South American Tsimane Exhibit Relatively Modest Decrease in Brain Volume With Age Despite High Systemic Inflammation

Andrei Irimia; Nikhil N Chaudhari; David J Robles; Kenneth A Rostowsky; Alexander S Maher; Nahian F Chowdhury; Maria Calvillo; Van Ngo; Margaret Gatz; Wendy J Mack; E Meng Law; M Linda Sutherland; James D Sutherland; Christopher J Rowan; L Samuel Wann; Adel H Allam; Randall C Thompson; David E Michalik; Daniel K Cummings; Edmond Seabright; Sarah Alami; Angela R Garcia; Paul L Hooper; Jonathan Stieglitz; Benjamin C Trumble; Michael D Gurven; Gregory S Thomas; Caleb E Finch; Hillard Kaplan

doi:10.1093/gerona/glab138

The Indigenous South American Tsimane Exhibit Relatively Modest Decrease in Brain Volume With Age Despite High Systemic Inflammation

J Gerontol A Biol Sci Med Sci. 2021 Nov 15;76(12):2147-2155. doi: 10.1093/gerona/glab138.

Authors

Andrei Irimia^{1

2}, Nikhil N Chaudhari¹, David J Robles¹, Kenneth A Rostowsky¹, Alexander S Maher¹, Nahian F Chowdhury¹, Maria Calvillo¹, Van Ngo¹, Margaret Gatz³, Wendy J Mack⁴, E Meng Law^{5

6

7}, M Linda Sutherland⁸, James D Sutherland⁸, Christopher J Rowan^{9

10}, L Samuel Wann¹¹, Adel H Allam¹², Randall C Thompson¹³, David E Michalik^{14

15}, Daniel K Cummings^{16

17}, Edmond Seabright¹⁶, Sarah Alami¹⁸, Angela R Garcia¹⁹, Paul L Hooper¹⁶, Jonathan Stieglitz²⁰, Benjamin C Trumble¹⁹, Michael D Gurven¹⁸, Gregory S Thomas^{8

21}, Caleb E Finch^{1

22}, Hillard Kaplan¹⁷

Affiliations

¹ Ethel Percy Andrus Gerontology Center, Leonard Davis School of Gerontology, University of Southern California, Los Angeles, USA.
² Corwin D. Denney Research Center, Department of Biomedical Engineering, University of Southern California, Los Angeles, USA.
³ Center for Economic and Social Research, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, USA.
⁴ Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, USA.
⁵ iBRAIN Research Laboratory, Departments of Neuroscience, Computer Systems and Electrical Engineering, Monash University, Melbourne, Victoria, Australia.
⁶ Department of Radiology, The Alfred Health Hospital, Melbourne, Victoria, Australia.
⁷ Department of Neurology, Keck School of Medicine of USC, University of Southern California, Los Angeles, USA.
⁸ MemorialCare Heart & Vascular Institute, Fountain Valley, California, USA.
⁹ Renown Institute for Heart and Vascular Health, Reno, Nevada, USA.
¹⁰ School of Medicine, University of Nevada, Reno, USA.
¹¹ Ascension Healthcare, Milwaukee, Wisconsin, USA.
¹² Department of Cardiology, School of Medicine, Al-Azhar University, Al Mikhaym Al Daem, Cairo, Egypt.
¹³ Saint Luke's Mid America Heart Institute, University of Missouri, Kansas City, USA.
¹⁴ Department of Pediatrics, School of Medicine, University of California at Irvine, Orange, USA.
¹⁵ MemorialCare Miller Children's & Women's Hospital, Long Beach Medical Center, California, USA.
¹⁶ Department of Anthropology, University of New Mexico, Albuquerque, USA.
¹⁷ Economic Science Institute, Argyros School of Business and Economics, Chapman University, Orange, California, USA.
¹⁸ Department of Anthropology, University of California, Santa Barbara, USA.
¹⁹ Center for Evolution & Medicine, School of Human Evolution and Social Change, Arizona State University, Tempe, USA.
²⁰ Institute for Advanced Study in Toulouse, Toulouse 1 Capitol University, France.
²¹ Division of Cardiology, University of California, Irvine, Orange, USA.
²² Departments of Biological Sciences, Anthropology and Psychology, Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, USA.

Abstract

Brain atrophy is correlated with risk of cognitive impairment, functional decline, and dementia. Despite a high infectious disease burden, Tsimane forager-horticulturists of Bolivia have the lowest prevalence of coronary atherosclerosis of any studied population and present few cardiovascular disease (CVD) risk factors despite a high burden of infections and therefore inflammation. This study (a) examines the statistical association between brain volume (BV) and age for Tsimane and (b) compares this association to that of 3 industrialized populations in the United States and Europe. This cohort-based panel study enrolled 746 participants aged 40-94 (396 males), from whom computed tomography (CT) head scans were acquired. BV and intracranial volume (ICV) were calculated from automatic head CT segmentations. The linear regression coefficient estimate β^T of the Tsimane (T), describing the relationship between age (predictor) and BV (response, as a percentage of ICV), was calculated for the pooled sample (including both sexes) and for each sex. β^T was compared to the corresponding regression coefficient estimate β^R of samples from the industrialized reference (R) countries. For all comparisons, the null hypothesis β T = β R was rejected both for the combined samples of males and females, as well as separately for each sex. Our results indicate that the Tsimane exhibit a significantly slower decrease in BV with age than populations in the United States and Europe. Such reduced rates of BV decrease, together with a subsistence lifestyle and low CVD risk, may protect brain health despite considerable chronic inflammation related to infectious burden.

Keywords: Brain aging; Cardiovascular disease; Neurodegeneration.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Adult
Aged
Aged, 80 and over
Bolivia / epidemiology
Brain* / diagnostic imaging
Coronary Artery Disease* / ethnology
Female
Humans
Indigenous Peoples
Inflammation / ethnology*
Life Style*
Male
Middle Aged
Organ Size
South America / epidemiology

Abstract

Publication types

MeSH terms

Grants and funding