Intraindividual Cognitive Variability and Magnetic Resonance Imaging in Aging American Indians: Data from the Strong Heart Study

Article type: Research Article

Authors: Mascarenhas Fonseca, Luciana^{a; b; *} | Sage Chaytor, Naomi^a | Olufadi, Yunusa^a | Buchwald, Dedra^{a; c} | Galvin, James E.^d | Schmitter-Edgecombe, Maureen^e | Suchy-Dicey, Astrid^{a; c}

Affiliations: [a] Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, USA | [b] Department and Institute of Psychiatry, Programa Terceira Idade (PROTER, Old Age Research Group), University of São Paulo School of Medicine, São Paulo, Brazil | [c] Institute for Research and Education to Advance Community Health, Washington State University, Seattle, WA, USA | [d] Department of Neurology, Comprehensive Center for Brain Health, University of Miami Miller School of Medicine, Miami, FL, USA | [e] Department of Psychology, Washington State University, Pullman, WA, USA

Correspondence: [*] Correspondence to: Luciana Mascarenhas Fonseca, 665N Riverpoint Blvd, Office 453, Department of Community and Behavioral Health, Elson S. Floyd College of Medicine,Washington State University, Spokane, WA, USA. Tel.: +1 509 368 6948; E-mail: luciana.fonseca@wsu.edu.

Abstract: Background:American Indians have high prevalence of risk factors for Alzheimer’s disease and related dementias (ADRD) compared to the general population, yet dementia onset and frequency in this population are understudied. Intraindividual cognitive variability (IICV), a measure of variability in neuropsychological test performance within a person at a single timepoint, may be a novel, noninvasive biomarker of neurodegeneration and early dementia. Objective:To characterize the cross-sectional associations between IICV and hippocampal, total brain volume, and white matter disease measured by magnetic resonance imaging (MRI) among older American Indians. Methods:IICV measures for memory, executive function, and processing speed, and multidomain cognition were calculated for 746 American Indians (aged 64–95) who underwent MRI. Regression models were used to examine the associations of IICV score with hippocampal volume, total brain volume, and graded white matter disease, adjusting for age, sex, education, body mass index, intracranial volume, diabetes, stroke, hypertension, hypercholesterolemia, alcohol use, and smoking. Results:Higher memory IICV measure was associated with lower hippocampal volume (Beta = –0.076; 95% CI –0.499, –0.023; p = 0.031). After adjustment for Bonferroni or IICV mean scores in the same tests, the associations were no longer significant. No IICV measures were associated with white matter disease or total brain volume. Conclusion:These findings suggest that the IICV measures used in this research cannot be robustly associated with cross-sectional neuroimaging features; nonetheless, the results encourage future studies investigating the associations between IICV and other brain regions, as well as its utility in the prediction of neurodegeneration and dementia in American Indians.

Keywords: Alzheimer’s disease, American Indians, cognitive variability, dementia, dispersion, indigenous, magnetic resonance imaging, Native Americans, neurodegeneration

DOI: 10.3233/JAD-220825

Journal: Journal of Alzheimer's Disease, vol. 91, no. 4, pp. 1395-1407, 2023