DOC PREVIEW
The Utility of Intraindividual Variability in Selective Attention Tasks

This preview shows page 1-2-3-4 out of 13 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 13 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 13 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 13 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 13 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 13 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

The Utility of Intraindividual Variability in Selective Attention Tasks as anEarly Marker for Alzheimer’s DiseaseJanet M. Duchek, David A. Balota,and Chi-Shing TseWashington University in St. LouisDavid M. Holtzman, Anne M. Fagan,and Alison M. GoateWashington University School of MedicineThis study explored differences in intraindividual variability in 3 attention tasks across a large sample ofhealthy older adults and individuals with very mild dementia of the Alzheimer’s type (DAT). Threegroups of participants (healthy young adults, healthy older adults, very mild DAT) were administered 3experimental measures of attentional selection and switching (Stroop, Simon, task switching). The resultsindicated that a measure of intraindividual variability, coefficient of variation (CoV; SD/M), increasedacross age and early stage DAT. The CoV in Stroop discriminated the performance of ε4 carriers fromnoncarriers in healthy older controls and the CoV in task switching was correlated with cerebrospinalfluid (CSF) biomarkers predictive of DAT.Keywords: intraindividual variation, attention, aging, Alzheimer’s diseaseThere has been considerable interest in the ability to diagnosedementia of the Alzheimer type (DAT) in the earliest possiblestage of the disease, thus discriminating healthy aging from earlystage DAT. The elusive nature of the clinical detection of the earlyonset of DAT has been supported in longitudinal studies in pre-sumed healthy older adults (e.g., Morris et al., 1996; Price &Morris, 1999; Rubin et al., 1998). These and other studies (e.g.,Bennett et al., 2006) have indicated that the Alzheimer’s disease(AD) process may be present in the brain for years before theappearance of clinical symptoms. Thus, preclinical markers of thedisease likely are present in some older individuals who appear tobe clinically “normal,” underscoring the need to reliably identifymore specific changes that could serve as additional antecedentmarkers for DAT.Episodic memory loss has long been considered the primarymarker for the first clinical manifestation of Alzheimer’s disease(e.g., Albert, Moss, Blacker, Tanzi, & McArdle, 2007; Albert,Moss, Tanzi, & Jones, 2001; Rubin et al., 1998; Storandt, Grant,Miller, & Morris, 2006). However, there also has been accumu-lating evidence documenting clear changes in components of at-tention in both healthy aging and in early stage DAT (for reviews,see Balota & Faust, 2001; Perry & Hodges, 1999). For example, inthe classic Stroop task, Spieler, Balota, and Faust (1996) providedevidence that there is a disproportionate breakdown in the abilityto inhibit the word code when naming colors in healthy olderadults compared to young, and in DAT individuals, compared toage-matched controls. Furthermore, it has been argued that atten-tional breakdowns observed in healthy aging and in early stage ADare likely to be related to the episodic memory changes in theseindividuals (e.g., Balota, Burgess, Cortese, & Adams, 2002; Balotaet al., 1999; Castel, Balota, & McCabe, (2009); Sommers & Huff,2003). Memory researchers have long recognized the critical roleof attention in declarative memory performance in both layingdown distinct traces during encoding and directing search pro-cesses during retrieval (see e.g., Craik & Lockhart, 1972; Jacoby,1999).The standard approach in documenting cognitive decline is tocompare mean-level performance across groups of participants.For example, if one is interested in measuring a characteristic suchas processing speed, one typically uses the mean-level reactiontime (RT) performance across multiple observations within a givenparticipant. Variability across trials is often simply considerederror variance. However, recently there has been interest in exam-ining within-individual changes in variability in reaction timeacross trials within a task or occasions of testing as an indicator ofneurocognitive function (for a review, see Hultsch, Strauss, Hunter& MacDonald, 2008). Indeed, within-task variability can beviewed as consistent with a breakdown in an attentional controlsystem that maintains the goals of a task across time and controlscompeting pathways (for similar arguments, see West, 2001; West,Murphy, Armilio, Crai, & Stuss, 2002). Recent work (Bunce et al.,2007; see also Murtha, Cismaru, Waechter, & Chertkow, 2002)indicated that within-person variability in RTs was correlated withwhite matter hyperintensities in the frontal lobe, but not other brainregions (e.g., temporal or parietal areas). Stuss, Murphy, Binns,Janet M. Duchek, David A. Balota, and Chi-Shing Tse, Department ofPsychology, Washington University in St. Louis; David M. Holtzman andAnne M. Fagan, Department of Neurology, Alzheimer’s Disease ResearchCenter, Washington University School of Medicine; Alison M. Goate,Department of Psychiatry, Washington University School of Medicine.This work was supported by National Institute on Aging Grants PO1AGO3991, P50AGO5681, and PO1 AGO26276. The first two authorscontributed equally to this project. Thanks are extended to John Morris andthe clinicians at the Washington University Alzheimer’s Disease ResearchCenter for their careful recruitment and description of the healthy olderadult and DAT participant groups, Martha Storandt, and the PsychometricsCore for the neuropsychological data; the Genetics Core for the genotypingof the participants; and the Biomarkers Core for their assays and provisionof the CSF data. We also thank Meredith Minear for help with theswitching task, Keith Hutchison with the Stroop and Simon tasks, andBrian Weber and Elizabeth Hemphill for their help in collecting data atvarious stages of this project.Correspondence concerning this article should be addressed to Janet M.Duchek, Department of Psychology, Washington University, St. Louis,MO 63130. E-mail: [email protected] © 2009 American Psychological Association2009, Vol. 23, No. 6, 746–758 0894-4105/09/$12.00 DOI: 10.1037/a0016583746and Alexander (2003) also found that patients with frontal lobelesions (with the exception of ventral medial/orbitofrontal region)showed increased inconsistency in task performance. These resultsare consistent with the possibility that increased variability mayreflect a breakdown in executive control systems that are depen-dent on the coordination of multiple-brain areas (for a review, seeMacDonald, Nyberg & Ba¨ckman, 2006).There is evidence that intraindividual variability in processingspeed


The Utility of Intraindividual Variability in Selective Attention Tasks

Download The Utility of Intraindividual Variability in Selective Attention Tasks
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view The Utility of Intraindividual Variability in Selective Attention Tasks and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view The Utility of Intraindividual Variability in Selective Attention Tasks 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?