Prevalence of dementia and mild cognitive impairment in indigenous Bolivian forager‐horticulturalists
Margaret Gatz, Wendy J. Mack, Helena C. Chui, Emma Law, Giuseppe Barisano, M. Linda Sutherland, James D. Sutherland, Daniel Eid Rodriguez, Raúl Quispe Gutierrez, Juan Copajira Adrian, Jesus Bani Cuata, Amy R. Borenstein, Ellen E. Walters, Andrei Irimia, Christopher J. Rowan, L. Samüel Wann, Adel H. Allam, Randall C. Thompson, Michael I. Miyamoto, David E. Michalik, Daniel K. Cummings, Edmond Seabright, Angela R. García, Paul L. Hooper, Thomas S. Kraft, Caleb E. Finch, Gregory S. Thomas, Jonathan Stieglitz, Benjamin C. Trumble, Michael Gurven, Hillard Kaplan
Abstract
INTRODUCTION: We evaluated the prevalence of dementia and mild cognitive impairment (MCI) in indigenous Tsimane and Moseten, who lead a subsistence lifestyle. METHODS: Participants from population-based samples ≥ 60 years of age (n = 623) were assessed using adapted versions of the Modified Mini-Mental State Examination, informant interview, longitudinal cognitive testing and brain computed tomography (CT) scans. RESULTS: Tsimane exhibited five cases of dementia (among n = 435; crude prevalence = 1.2%, 95% confidence interval [CI]: 0.4, 2.7); Moseten exhibited one case (among n = 169; crude prevalence = 0.6%, 95% CI: 0.0, 3.2), all age ≥ 80 years. Age-standardized MCI prevalence was 7.7% (95% CI: 5.2, 10.3) in Tsimane and 9.8% (95% CI: 4.9, 14.6) in Moseten. Cognitive impairment was associated with visuospatial impairments, parkinsonian symptoms, and vascular calcification in the basal ganglia. DISCUSSION: The prevalence of dementia in this cohort is among the lowest in the world. Widespread intracranial medial arterial calcifications suggest a previously unrecognized, non-Alzheimer's disease (AD) dementia phenotype.