Cross sectional sex differences in cortical atrophy across an indigenous Bolivian population
Poster No:
1152
Submission Type:
Abstract Submission
Authors:
Nikhil Chaudhari1, Phoebe Imms1, Nahian Chowdhury1, Margaret Gatz1, Benjamin Trumble2, Wendy Mack1, Meng Law3, Linda Sutherland4, James Sutherland4, Christopher Rowan5, Samuel Wann6, Adel Allam7, Randall Thompson8, David Michalik9, Michael Miyamoto10, Guido Lombardi11, Daniel Cummings12, Edmond Seabright6, Sarah Alami6, Angela Garcia2, Daniel Rodriguez13, Raul Quispe Gutierrez14, Paul Hooper15, Kenneth Buetow2, Jonathan Stieglitz16, Michael Gurven15, Gregory Thomas4, Hillard Kaplan12, Caleb Finch1, Andrei Irimia1
Institutions:
1University of Southern California, Los Angeles, CA, 2Arizona State University, Tempe, AZ, 3Monash University, Melbourne, Victoria, 4MemorialCare Health Systems, Fountain Valley, CA, 5Renown Institute for Heart and Vascular Health, Reno, NV, 6University of New Mexico, Albuquerque, NM, 7Al-Azhar University, Cairo, Al Mikhaym Al Daem, 8University of Missouri, Kansas City, MO, 9MemorialCare Miller Children’s & Women’s Hospital, Long Beach, CA, 10Providence Health, Mission Viejo, CA, 11Universidad Peruana Cayetano Heredia, Lima, Peru, 12Chapman University, Orange, CA, 13San Simon University, Cochabamba, Cochabamba, 14Tsimane Health and Life History Project, San Borja, Beni, 15University of California, Santa Barbara, CA, 16Institute for Advanced Study in Toulouse, Toulouse, Toulouse
First Author:
Co-Author(s):
Introduction:
The cross-sectional relationship of brain volume with age is a surrogate measure of brain atrophy, a proxy for brain health. Comparing atrophy trajectories across industrialized and non-industrialized populations can provide insights into lifestyle correlates of brain health. The Tsimane, a native Bolivian population, have lifestyles similar to those of our pre-modern ancestors (Gurven, Stieglitz et al. 2017). In contrast to the average person in developed countries, the Tsimane have higher levels of physical activity (Kraft, Stieglitz et al. 2018) and a diet richer in fiber. This unique combination of lifestyle factors renders the Tsimane uniquely attractive for studying brain atrophy. We compared Tsimane atrophy rates to those of a UK Biobank (UKBB) sample.
Methods:
746 Tsimane (346 males) aged 40-94 were scanned using computed tomography (CT). The regional brain volumes of 148 cortical brain structures were calculated using an automatic head CT tissue segmentation algorithm. These same regional volumes were computed from T1-weighted magnetic resonance imaging for 19,973 UKBB participants (same age range) using Freesurfer. Regional brain volumes were normalized by total intracranial volume to account for variation in head sizes. Linear regression coefficients describing the associations between age and Tsimane regional brain volumes (βT) were compared with those of UKBB participants (βUK). For each brain structure, Welch's two-tailed t-test for independent samples with unequal variances tested the null hypotheses H(0):βT= βUK at α = 0.05.
Results:
Notably, in Tsimane males, a small but significant cross-sectional positive trend of brain volume with age was observed in occipital and parietal structures (red structures in Fig. 1A-B). Over the entire cortex, Tsimane males exhibit slower rates of volume decrease than UKBB males in frontotemporal structures (blue structures in Fig. 1E). Conversely, Tsimane females exhibit faster rates of regional brain volume decrease with age than UKBB females (red structures in Fig. 1F).
In structures supporting visuospatial skills, the Tsimane exhibit age-related regional brain hypertrophy. This has not been observed in any other human population and may reflect Tsimane's high dependence on visuospatial navigation in dense Amazonian forests, a terrain with few visuospatial aids. Sex differences may involve differences in hormones, lifestyle, or health trajectories (Cowell, Turetsky et al. 1994, Blatter, Bigler et al. 1995, Coffey, Lucke et al. 1998, Trumble, Stieglitz et al. 2015). Tsimane females exhibit higher obesity rates than males (Bethancourt, Leonard et al. 2019), which may be a byproduct of lifestyle differences. Tsimane females spend more time caring for children (breastfeeding, grooming), preparing food, and engaging in light physical activity. Males, especially those under 60, engage in more moderate-to-vigorous physical activity outside the home.
Figure 1. Regression coefficients for the association between cortical structures and age in Tsimane males (A), Tsimane females (B), and British males (C) and females (D) in the UK Biobank. Brighter color indicates a larger magnitude of the regression coefficient for the corresponding structures. (E, F): Structures whose regression coefficients differ significantly from the UKBB in Tsimane. Blue indicates faster volume decrease in the UKBB compared to the Tsimane. Red indicates faster volume decrease in the Tsimane compared to the UKBB.
In structures supporting visuospatial skills, the Tsimane exhibit age-related regional brain hypertrophy. This has not been observed in any other human population and may reflect Tsimane's high dependence on visuospatial navigation in dense Amazonian forests, a terrain with few visuospatial aids. Sex differences may involve differences in hormones, lifestyle, or health trajectories (Cowell, Turetsky et al. 1994, Blatter, Bigler et al. 1995, Coffey, Lucke et al. 1998, Trumble, Stieglitz et al. 2015). Tsimane females exhibit higher obesity rates than males (Bethancourt, Leonard et al. 2019), which may be a byproduct of lifestyle differences. Tsimane females spend more time caring for children (breastfeeding, grooming), preparing food, and engaging in light physical activity. Males, especially those under 60, engage in more moderate-to-vigorous physical activity outside the home.
Figure 1. Regression coefficients for the association between cortical structures and age in Tsimane males (A), Tsimane females (B), and British males (C) and females (D) in the UK Biobank. Brighter color indicates a larger magnitude of the regression coefficient for the corresponding structures. (E, F): Structures whose regression coefficients differ significantly from the UKBB in Tsimane. Blue indicates faster volume decrease in the UKBB compared to the Tsimane. Red indicates faster volume decrease in the Tsimane compared to the UKBB.
Conclusions:
Living without modernization may protect men's brain health but not women's. Alternatively, unknown factors associated with industrialization may attenuate women's rate of regional volume decrease with age. Future research should clarify the relationships between regional volume trends with age, physical activity, diet, neurodegenerative disease risk, and cognitive functioning.
Lifespan Development:
Aging 1
Neuroanatomy, Physiology, Metabolism and Neurotransmission:
Cortical Anatomy and Brain Mapping 2
Keywords:
ADULTS
Aging
Computational Neuroscience
Computed Tomography (CT)
Cortex
MRI
NORMAL HUMAN
Plasticity
Segmentation
Univariate
1|2Indicates the priority used for review
Provide references using author date format
Blatter, D. D., E. D. Bigler, S. D. Gale, S. C. Johnson, C. V. Anderson, B. M. Burnett, N. Parker, S. Kurth and S. D. Horn (1995). "Quantitative volumetric analysis of brain MR: normative database spanning 5 decades of life." American journal of Neuroradiology 16(2): 241-251.
Coffey, C. E., J. F. Lucke, J. A. Saxton, G. Ratcliff, L. J. Unitas, B. Billig and R. N. Bryan (1998). "Sex differences in brain aging: a quantitative magnetic resonance imaging study." Archives of neurology 55(2): 169-179.
Cowell, P. E., B. I. Turetsky, R. C. Gur, R. I. Grossman, D. Shtasel and R. Gur (1994). "Sex differences in aging of the human frontal and temporal lobes." Journal of Neuroscience 14(8): 4748-4755.
Gurven, M., J. Stieglitz, B. Trumble, A. D. Blackwell, B. Beheim, H. Davis, P. Hooper and H. Kaplan (2017). "The Tsimane health and life history project: integrating anthropology and biomedicine." Evolutionary Anthropology: Issues, News, and Reviews 26(2): 54-73.
Kraft, T. S., J. Stieglitz, B. C. Trumble, M. Martin, H. Kaplan and M. Gurven (2018). "Nutrition transition in 2 lowland Bolivian subsistence populations." The American journal of clinical nutrition 108(6): 1183-1195.
Trumble, B. C., J. Stieglitz, M. E. Thompson, E. Fuerstenberg, H. Kaplan and M. Gurven (2015). "Testosterone and male cognitive performance in T simane forager‐horticulturalists." American Journal of Human Biology 27(4): 582-586.