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P2‐508: COGNITIVE AND NEURAL CORRELATES OF THREE PERFORMANCE‐BASED FUNCTIONAL ASSESSMENTS IN NORMAL AGING AND MILD COGNITIVE IMPAIRMENT: A PILOT STUDY
Author(s) -
Medina Luis Daniel,
Heffernan Kate S.,
Filley Christopher M.,
Bettcher Brianne M.
Publication year - 2018
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2018.06.1202
Subject(s) - fractional anisotropy , cognition , montreal cognitive assessment , neuropsychology , effects of sleep deprivation on cognitive performance , psychology , audiology , neuropsychological assessment , cognitive impairment , diffusion mri , clinical psychology , medicine , neuroscience , magnetic resonance imaging , radiology
Background: Identification of early and reliable cognitive changes in preclinical Alzheimer’s disease (AD) is critical to target individuals at risk for decline. Recent evidence suggests that intraindividual cognitive variability (IIV), a measure of within-person variability or dispersion across cognitive measures at a single time point, is associated with progression to mild cognitive impairment (MCI) and AD to an extent comparable to established AD cerebrospinal fluid biomarkers. However, little is known regarding underlying brain changes associated with IIV. Therefore, we investigated the association between IIV and cerebral atrophy in AD-vulnerable regions in nondemented older adults. Methods: 346 Alzheimer’s Disease Neuroimaging Initiative (ADNI) participants (139 cognitively normal [CN]; 207 MCI) underwent neuropsychological testing and serial magnetic resonance imaging over 4 years. To create the IIV index, the intraindividual standard deviation across the following 6 baseline neuropsychological z-scores was computed: Animal Fluency and Boston Naming Test (language); Trail Making Test Parts A and B (attention/executive); and Auditory Verbal Learning Test Delayed Recall and Recognition (memory). Cortical thickness and volume were calculated using FreeSurfer. Linear mixed effects models examined the association between IIV and change in entorhinal cortex thickness and hippocampal volume. Results: In the overall sample, adjusting for age, sex, apolipoprotein E (APOE) e4 genotype, and mean level of cognitive performance, increased baseline IIV predicted faster rates of entorhinal and hippocampal atrophy over the 4-year follow-up period. Assessing diagnostic groups separately, increased IIV was associated with both entorhinal and hippocampal atrophy in the MCI group whereas higher IIV was associated with selective vulnerability of the entorhinal cortex in the CN group. Conclusions: Increased IIV predicts faster rates of cerebral atrophy in AD-vulnerable regions above and beyond mean level of cognitive performance and AD risk factors including age and APOE e4 genotype. IIV was associated with more widespread medial temporal lobe (MTL) atrophy in individuals with MCI relative to CN, suggesting that IIV may be tracking advancing MTL pathologic changes across the continuum of aging, MCI, and dementia. Cognitive dispersion may be a sensitive marker of neurodegeneration–even among cognitively normal individuals–and may be more sensitive relative to mean level of performance in predicting early neurodegenerative changes.