{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,30]],"date-time":"2026-10-30T02:01:44Z","timestamp":1793325704465,"version":"4.5.0"},"reference-count":37,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2018,3,1]],"date-time":"2018-03-01T00:00:00Z","timestamp":1519862400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000024","name":"Canadian Institutes of Health Research","doi-asserted-by":"publisher","award":["CGS-D"],"award-info":[{"award-number":["CGS-D"]}],"id":[{"id":"10.13039\/501100000024","id-type":"DOI","asserted-by":"publisher"}]},{"name":"National Institute on Aging at the National Institutes of Health","award":["R21 AG045575"],"award-info":[{"award-number":["R21 AG045575"]}]},{"DOI":"10.13039\/501100000038","name":"Natural Sciences and Engineering Research Council of Canada","doi-asserted-by":"publisher","award":["RGPIN\/06468-2017"],"award-info":[{"award-number":["RGPIN\/06468-2017"]}],"id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Intell."],"abstract":"<jats:p>Objective: Increased intraindividual variability (IIV) in function has been linked to various age-related outcomes including cognitive decline and dementia. Most studies have operationalized IIV as fluctuations across trials (e.g., response latencies) for a single task, with comparatively few studies examining variability across multiple tasks for a given individual. In the present study, we derive a multivariable operationalization of dispersion across a broad profile of neuropsychological measures and use this index along with degree of engaged lifestyle to predict risk of cognitive impairment. Participants and Methods: Participants (n = 60) were community-dwelling older adults aged 65+ years (M = 74.1, SD = 6.5) participating in a cross-sectional investigation of risk factors for amnestic mild cognitive impairment (a-MCI) and probable Alzheimer\u2019s Disease (AD). Participants were classified into three subgroups based on test performance and clinical judgement. Healthy controls (n = 30) scored better than \u22121 SD relative to existing norms on all classification measures, in the absence of memory complaints or functional impairments. The a-MCI group (n = 23) had self- or informant-reported memory complaints and scored 1 SD or more below the mean for at least one memory task while scoring better than 1 SD below the mean for all other cognitive domains, in the absence of functional impairments. The AD group (n = 7) scored at least 2 SD below the mean for two cognitive domains (including memory) with impairments in functioning. Measures spanned a range of cognitive domains (episodic memory, executive function, language), with the derived dispersion estimates reflecting variability across an individual\u2019s neuropsychological profile relative to the group average. Further, an Activities Lifestyle Questionnaire, indexing social, cognitive, and physical behaviors, was administered to assess the protective benefits of engaged lifestyle. Results: Multinomial logistic regression models examined the risk of being classified as a-MCI or AD as a function of increased dispersion, (dis)engaged lifestyle, and their interaction. Greater dispersion was associated with an increased likelihood of being classified with AD, with protective engaged-lifestyle benefits apparent for a-MCI individuals only. Conclusion: As a measure of IIV, dispersion across neuropsychological profiles holds promise for the detection of cognitive impairment.<\/jats:p>","DOI":"10.3390\/jintelligence6010012","type":"journal-article","created":{"date-parts":[[2018,3,1]],"date-time":"2018-03-01T12:15:44Z","timestamp":1519906544000},"page":"12","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":34,"title":["Intraindividual Variability across Neuropsychological Tests: Dispersion and Disengaged Lifestyle Increase Risk for Alzheimer\u2019s Disease"],"prefix":"10.3390","volume":"6","author":[{"given":"Drew","family":"Halliday","sequence":"first","affiliation":[{"name":"Department of Psychology, University of Victoria, Victoria, BC V8P 5C2, Canada"},{"name":"Institute on Aging and Lifelong Health, University of Victoria, Victoria, BC V8P 5C2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Robert","family":"Stawski","sequence":"additional","affiliation":[{"name":"School of Social and Behavioral Health Sciences, Oregon State University, Corvallis, OR 97331, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eric","family":"Cerino","sequence":"additional","affiliation":[{"name":"School of Social and Behavioral Health Sciences, Oregon State University, Corvallis, OR 97331, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Correne","family":"DeCarlo","sequence":"additional","affiliation":[{"name":"Department of Psychology, University of Victoria, Victoria, BC V8P 5C2, Canada"},{"name":"Institute on Aging and Lifelong Health, University of Victoria, Victoria, BC V8P 5C2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karl","family":"Grewal","sequence":"additional","affiliation":[{"name":"Department of Psychology, University of Victoria, Victoria, BC V8P 5C2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stuart","family":"MacDonald","sequence":"additional","affiliation":[{"name":"Department of Psychology, University of Victoria, Victoria, BC V8P 5C2, Canada"},{"name":"Institute on Aging and Lifelong Health, University of Victoria, Victoria, BC V8P 5C2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2018,3,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"534","DOI":"10.1080\/13803395.2015.1136598","article-title":"Comparing individual differences in inconsistency and plasticity as predictors of cognitive function in older adults","volume":"38","author":"Grand","year":"2016","journal-title":"J. Clin. Exp. Neuropsychol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1159\/000111582","article-title":"Gait variability is associated with subclinical brain vascular abnormalities in high-functioning older adults","volume":"29","author":"Rosano","year":"2007","journal-title":"Neuroepidemiology"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"214","DOI":"10.1111\/psyp.12319","article-title":"Focusing neurovisceral integration: Cognition, heart rate variability, and cerebral blood flow","volume":"52","author":"Jennings","year":"2015","journal-title":"Psychophysiology"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3978","DOI":"10.1523\/JNEUROSCI.2517-14.2016","article-title":"Brain signal variability differentially affects cognitive flexibility and cognitive stability","volume":"36","author":"Fiebach","year":"2016","journal-title":"J. Neurosci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"610","DOI":"10.1016\/j.neubiorev.2013.02.015","article-title":"Moment-to-moment brain signal variability: A next frontier in human brain mapping?","volume":"37","author":"Garrett","year":"2013","journal-title":"Neurosci. Biobehav. Rev."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Diehl, M., Hooker, K., and Sliwinski, M. (2015). Intraindividual Variability\u2014An Indicator of Vulnerability or Resilience in Adult Development and Aging?. Handbook of Intraindividual Variability across the Life Span, Routledge.","DOI":"10.4324\/9780203113066"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"381","DOI":"10.1037\/0894-4105.21.3.381","article-title":"Neurocognitive markers of cognitive impairment: Exploring the roles of speed and inconsistency","volume":"21","author":"Dixon","year":"2007","journal-title":"Neuropsychology"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"746","DOI":"10.1037\/a0016583","article-title":"The utility of intraindividual variability in selective attention tasks as an early marker for Alzheimer\u2019s disease","volume":"23","author":"Duchek","year":"2009","journal-title":"Neuropsychology"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"588","DOI":"10.1037\/0894-4105.14.4.588","article-title":"Intraindividual variability in cognitive performance in older adults: Comparison of adults with mild dementia, adults with arthritis, and health adults","volume":"14","author":"Hultsch","year":"2000","journal-title":"Neuropsychology"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"792","DOI":"10.1037\/a0017798","article-title":"Neural underpinnings of within-person variability in cognitive functioning","volume":"24","author":"MacDonald","year":"2009","journal-title":"Psychol. Aging"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"214","DOI":"10.1076\/anec.6.3.214.779","article-title":"Dispersion in cognitive ability as a function of age: A longitudinal study of an elderly community sample","volume":"6","author":"Christensen","year":"1999","journal-title":"Aging Neuropsychol. Cogn."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1093\/geronb\/57.2.P101","article-title":"Variability in reaction time performance of younger and older adults","volume":"57B","author":"Hultsch","year":"2002","journal-title":"J. Gerontol. Psychol. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"412","DOI":"10.1080\/13803390802232659","article-title":"Intraindividual variability across cognitive domains: Investigation of dispersion levels and performance profiles in older adults","volume":"31","author":"Hilborn","year":"2009","journal-title":"J. Clin. Exp. Neuropsychol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1080\/13803395.2015.1089979","article-title":"Dispersion in cognitive functioning: Age differences of the lifespan","volume":"38","author":"Mella","year":"2016","journal-title":"J. Clin. Exp. Neuropsychol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1080\/13803390490515496","article-title":"Neuropsychological subgroups of cognitively-impaired-not-demented (CIND) individuals: Delineation, reliability, and predictive validity","volume":"27","author":"Peters","year":"2005","journal-title":"J. Clin. Exp. Neuropsychol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"481","DOI":"10.1037\/a0033023","article-title":"Intraindividual cognitive variability before and after sports-related concussion","volume":"27","author":"Rabinowitz","year":"2013","journal-title":"Neuropsychology"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"823","DOI":"10.1001\/jama.300.7.823","article-title":"Within-person across-neuropsychological test variability and incident dementia","volume":"300","author":"Holtzer","year":"2008","journal-title":"JAMA"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Vaughan, L., Leng, I., Dagenbach, D., Resnick, S.M., Rapp, S.R., Jennings, J.M., and Espeland, M.A. (2013). Intraindividual variability in domain-specific cognition and risk of mild cognitive impairment and dementia. Curr. Gerontol. Geriatr. Res.","DOI":"10.1155\/2013\/495793"},{"key":"ref_19","first-page":"1","article-title":"Enrichment effects on adult cognitive development","volume":"9","author":"Hertzog","year":"2009","journal-title":"Psychol. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1873","DOI":"10.1016\/j.neurobiolaging.2014.02.015","article-title":"Neuroprotective pathways: Lifestyle activity, brain pathology, and cognition in cognitively normal older adults","volume":"35","author":"Wirth","year":"2014","journal-title":"Neurobiol. Aging"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Wang, H.-X., MacDonald, S.W.S., Dekhtyar, S., and Fratiglioni, L. (2017). Association of lifelong exposure to cognitive reserve-enhancing factors with dementia risk: A community-based cohort study. PLoS Med., 14.","DOI":"10.1371\/journal.pmed.1002251"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1111\/j.1745-6916.2006.00005.x","article-title":"Mental exercise and mental aging","volume":"1","author":"Salthouse","year":"2006","journal-title":"Perspect. Psychol. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1093\/geronb\/gbw124","article-title":"Lifecourse activity participation from early, mid, and later adulthood as determinants of cognitive aging: The Lotian Birth Cohort 1921","volume":"72","author":"Gow","year":"2017","journal-title":"J. Gerontol. Psychol. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1001\/archneur.56.3.303","article-title":"Mild cognitive impairment: Clinical characterization and outcome","volume":"56","author":"Petersen","year":"1999","journal-title":"Arch. Neurol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1447","DOI":"10.1001\/archneurol.2009.266","article-title":"Mild cognitive impairment: Ten years later","volume":"66","author":"Petersen","year":"2009","journal-title":"Arch. Neurol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1111\/j.1365-2796.2004.01388.x","article-title":"Mild cognitive impairment as a diagnostic entity","volume":"256","author":"Petersen","year":"2004","journal-title":"J. Int. Med."},{"key":"ref_27","unstructured":"American Psychiatric Association (2000). Diagnostic and Statistical Manual of Mental Disorders: DSM-IV-TR, American Psychiatric Association."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"479","DOI":"10.1080\/01688639608405871","article-title":"Development and validation of a demographic correction system for neuropsychological measures used in the Canadian study of health and aging","volume":"18","author":"Tuokko","year":"1996","journal-title":"J. Clin. Exp. Neuropsychol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"262","DOI":"10.1080\/13854049608406689","article-title":"Neuropsychologists tests\u2019 norms above age 55: COWAT, BNT, MAE token, WRAT-R reading, AMNART, STROOP, TMT, and JLO","volume":"10","author":"Ivnik","year":"1996","journal-title":"Clin. Neuropsychol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"464","DOI":"10.1080\/13854040590945193","article-title":"Mayo\u2019s older American normative studies: Age- and IQ-adjusted norms for the auditory verbal learning test and the visual spatial learning test","volume":"19","author":"Steinberg","year":"2005","journal-title":"Clin. Neuropsychol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1037\/a0017662","article-title":"Assessing adult leisure activities: An extension of a self-report activity questionnaire","volume":"22","author":"Jopp","year":"2010","journal-title":"Psychol. Assess."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"346","DOI":"10.1080\/13825580490511161","article-title":"The Victoria Longitudinal Study: From characterizing cognitive aging to illustrating changes in memory compensation","volume":"11","author":"Dixon","year":"2004","journal-title":"Aging Neuropsychol. Cogn."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1037\/0882-7974.3.4.407","article-title":"Age, variability, and speed: Between-subjects diversity","volume":"3","author":"Hale","year":"1998","journal-title":"Psychol. Aging"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Stawski, R.S., MacDonald, S.W.S., Brewster, P.H., Munoz, E., Cerino, E.S., and Halliday, D.R.W. (2017). A comprehensive comparison of quantifications of intraindividual variability in response times: A measurement burst approach. J. Gerontol. B Psychol. Sci. Soc. Sci.","DOI":"10.1093\/geronb\/gbx115"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"436","DOI":"10.1176\/appi.ajp.159.3.436","article-title":"Differential evolution of cognitive impairment in nondemented older persons: Results from the Kungsholmen project","volume":"159","author":"Palmer","year":"2002","journal-title":"Am. J. Psychiatry"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"2278","DOI":"10.1212\/WNL.0000000000001084","article-title":"Motoric cognitive risk syndrome: Multicenter incidence study","volume":"83","author":"Verghese","year":"2014","journal-title":"Neurology"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"412","DOI":"10.1093\/gerona\/gls191","article-title":"Motoric cognitive risk syndrome and the risk of dementia","volume":"68","author":"Verghese","year":"2013","journal-title":"J. Gerontol. Med. Sci."}],"container-title":["Journal of Intelligence"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-3200\/6\/1\/12\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T14:57:07Z","timestamp":1760194627000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-3200\/6\/1\/12"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,3,1]]},"references-count":37,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2018,3]]}},"alternative-id":["jintelligence6010012"],"URL":"https:\/\/doi.org\/10.3390\/jintelligence6010012","relation":{},"ISSN":["2079-3200"],"issn-type":[{"value":"2079-3200","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,3,1]]}}}