%0 Journal Article %J J Alzheimers Dis %D 2018 %T Cognitive Variability Predicts Incident Alzheimer's Disease and Mild Cognitive Impairment Comparable to a Cerebrospinal Fluid Biomarker. %A Gleason, Carey E %A Norton, Derek %A Anderson, Eric D %A Wahoske, Michelle %A Washington, Danielle T %A Umucu, Emre %A Koscik, Rebecca L %A Dowling, N Maritza %A Johnson, Sterling C %A Carlsson, Cynthia M %A Asthana, Sanjay %K Aged %K Aged, 80 and over %K Algorithms %K Alzheimer Disease %K Amyloid beta-Peptides %K Biomarkers %K Cognitive Dysfunction %K Cross-Sectional Studies %K Female %K Humans %K Incidence %K Logistic Models %K Male %K Middle Aged %K Neuropsychological Tests %K Peptide Fragments %K Statistics, Nonparametric %K tau Proteins %X

BACKGROUND: Alzheimer's disease (AD) biomarkers are emerging as critically important for disease detection and monitoring. Most biomarkers are obtained through invasive, resource-intense procedures. A cognitive marker, intra-individual cognitive variability (IICV) may provide an alternative or adjunct marker of disease risk for individuals unable or disinclined to undergo lumbar puncture.

OBJECTIVE: To contrast risk of incident AD and mild cognitive impairment (MCI) associated with IICV to risk associated with well-established biomarkers: cerebrospinal fluid (CSF) phosphorylated tau protein (p-tau181) and amyloid-β 42 (Aβ42) peptide.

METHODS: Dispersion in cognitive performance, IICV, was estimated with a published algorithm, and included Trail Making Test A and B, Rey Auditory Verbal Learning Test (RAVLT), and the American National Adult Reading Test (ANART). CSF biomarkers were expressed as a ratio: p-tau181/Aβ42, wherein high values signified pathognomonic profiles. Logistic regression models included longitudinal data from 349 Alzheimer's Disease Neuroimaging Initiative (ADNI) participants who completed lumbar puncture. All subjects were cognitively healthy (n = 105) or diagnosed with MCI (n = 244) at baseline. We examined odds of conversion associated with baseline elevations in IICV and/or ratio of CSF p-tau181/Aβ42.

RESULTS: When included in models alone or in combination with CSF p-tau181/Aβ42, one standard IICV unit higher was associated with an estimated odds ratio for incident AD or MCI of 2.81 (95% CI: 1.83-4.33) in the most inclusive sample, and an odds ratio of 3.41 (95% CI: 2.03-5.73) when restricted to participants with MCI. Iterative analyses suggested that IICV independently improved model fit even when individual index components were included in comparative models.

CONCLUSIONS: These analyses provide preliminary support for IICV as a marker of incident AD and MCI. This easily-disseminated, non-invasive marker compared favorably to well-established CSF biomarkers.

%B J Alzheimers Dis %V 61 %P 79-89 %8 2018 %G eng %N 1 %1 http://www.ncbi.nlm.nih.gov/pubmed/29125485?dopt=Abstract %R 10.3233/JAD-170498