Structural MRI Predictors of Late-Life Cognition Differ Across African Americans, Hispanics, and Whites

Abstract

Background Structural magnetic resonance imaging (MRI) provides key biomarkers to predict onset and track progression of Alzheimer’s disease (AD). However, most published reports of relationships between MRI variables and cognition in older adults include racially, ethnically, and socioeconomically homogenous samples. Racial/ethnic differences in MRI variables and cognitive performance, as well as health, socioeconomic status and psychological factors, raise the possibility that brain-behavior relationships may be stronger or weaker in different groups. The current study tested whether MRI predictors of cognition differ in African Americans and Hispanics, compared with non-Hispanic Whites. Methods Participants were 638 non-demented older adults (29% non-Hispanic White, 36% African American, 35% Hispanic) in the Washington Heights-Inwood Columbia Aging Project. Composite scores of memory, language, speed/executive functioning, and visuospatial function were derived from a neuropsychological battery. Hippocampal volume, regional cortical thickness, infarcts, and white matter hyperintensity (WMH) volumes were quantified with FreeSurfer and in-house developed procedures. Multiple-group regression analysis, in which each cognitive composite score was regressed onto MRI variables, demographics, and cardiovascular health, tested which paths differed across groups. Results Larger WMH volume was associated with worse language and speed/executive functioning among African Americans, but not among non-Hispanic Whites. Larger hippocampal volume was more strongly associated with better memory among non-Hispanic Whites compared with Hispanics. Cortical thickness and infarcts were similarly associated with cognition across groups. Conclusion The main finding of this study was that certain MRI predictors of cognition differed across racial/ethnic groups. These results highlight the critical need for more diverse samples in the study of cognitive aging, as the type and relation of neurobiological substrates of cognitive functioning may be different for different groups.

Relationship between Cognitive Performance and Measures of Neurodegeneration among Hispanic and White Non-Hispanic Individuals with Normal Cognition, Mild Cognitive Impairment, and Dementia

“…Our results, however, point to a significant decline in volumes and increasing atrophy of the HP and the EC from CN state to dementia, in both Hispanics and WNHs, as in accordance with previous reports (DeCarli et al, 2008; Loewenstein et al, 2009; Zahonde et al, 2015). Enlargement of an inferior lateral ventricle indicates atrophy in the regions surrounding this structure, including the HP, parahippocampal gyrus, lingual and inferior temporal gyri, amygdala, and related white matter structures.…”

“…Our findings of equivalent or better cognitive scores on Digit Span Forward and Category Fluency test among WNH, than among Hispanics, despite greater severity of overall neuro-degeneration, suggests that language and cultural factors may provide an advantage to WNHs. Similar findings were reported previously by Mungas, Reed, Farias, and DeCarli (2009) and Zahodne et al (2015), who found that HPCv was larger among Hispanics than in WNHs, whereas WNHs scored better on memory and non-memory measures.…”

“…The similarities between our findings of less neurodegeneration in Hispanics in Miami and other Hispanic cohorts in California-Davis (DeCarli et al, 2008) and in New York (Zahonde et al, 2015) suggests the possibility that the same unmeasured sociocultural factors influenced these interactions and is an issue worthy of further collaborative research.…”

“…More recently, Zahodne et al (2015) in the Washington-Heights-Inwood Columbia Aging Project, found HPCvs were lower among WNHs than Hispanics, despite finding higher memory and other cognitive scores among the WNH group. However, the Hispanic participants of these two studies had on average less than 8 and 7 years of educational attainment, respectively, compared with more than 13 and 14 years for the WNH group, suggesting that factors such as higher cognitive reserve among the WNHs resulted in better cognitive performance despite greater severity of neurodegeneration.…”

Structural Image Analysis of the Brain in Neuropsychology Using Magnetic Resonance Imaging (MRI) Techniques

“…Nevertheless, in the arena of cognitive assessment neuropsychological test findings may now be explored in relation to neuroimaging defined anatomical and pathological correlates for all conditions and disorders. Traditionally neuropsychological tasks have been divided into the customary areas of motor, sensory-perceptual, language, visuospatial, speed of processing/executive functioning and emotional control when compared to neuroimaging findings (see Zahodne et al 2015). Using these different neuropsychological domains a brief overview of contemporary findings mainly using the T1-weighted FreeSurfer technique is provided below.…”