MRI Statistical region of interest best differentiates impaired from non‐impaired in the Study of Latinos‐Investigation of Neurocognitive Aging‐MRI (SOL‐INCA‐MRI)

Abstract

AbstractBackgroundWe developed a statistical region of interest (sROI) of gray matter (GM) for which cortical thickness (CT) significantly differed in a “training set” of 100 cognitively normal and 100 individuals with incident dementia in the Framingham Heart Study. sROI significantly predicts incident cognitive impairment and dementia in both FHS and the highly diverse UC Davis Alzheimer’s disease longitudinal cohort. Here we describe a similar analysis of participants of Study of Latinos‐Investigation of Neurocognitive Aging‐MRI (SOL‐INCA‐MRI).MethodsHispanics/Latinos (n=6,377 ages 50‐86) were enrolled in the Study of Latinos ‐ Investigation of Neurocognitive Aging (SOL‐INCA) of which 1,143 also participated in SOL‐INCA‐MRI ancillary study. Cognitive impairment (CI) was defined as any cognitive domain score falling below (<‐1.0 SD) the SOL‐INCA robust internal normative mean and significant cognitive decline (‐0.055 SD/yr), self‐reported cognitive decline and no or minimal functional impairment over 7 years. Participants with dementia were excluded.MRI CT was computed by the DiReCT method. sROI was derived from statistically significant (via 1,000 non‐parametric permutations) clusters of GM voxels having CT group difference t > 2 over the training set (Fig. 1). Extents of sROI overlap with standard atlas GM regions appear in Table 3.Group differences in variables were assessed by t‐test. Logistic regression assessed the impact on cognitive status of MRI factors: total brain, hippocampal, white matter hyperintensities (WMH), sROI volumes and infarction occurrence, controlling for age, sex, education, and background.ResultsThe cohort was 64.4 + 7 years of age, 69% female. Nearly 60% with high school or less education, and 21% CI. Table 1 summarizes demographic and MRI measures for CI and cognitively normal (CN). CI individuals were older, had less education, smaller brains, and greater amounts of WMH. Table 2 summarizes results of logistic regression. Education and sROI mean CT were the only significant predictors of cognitive status.ConclusionCortical thickness within the sROI was strongly associated with cognitive status, even when other commonly used MRI measures were not. sROI may therefore be a sensitive indicator of incipient CI within SOL‐INCA‐MRI where more traditional measures of Alzheimer’s pathology and vascular disease appear insensitive.