Intraindividual variability in cognitive performance in older adults: Comparison of adults with mild dementia, adults with arthritis, and healthy adults.

Abstract

Intraindividual variability in latency and accuracy of cognitive performance across both trials and occasions was examined in 3 groups of older adults: healthy adults, adults with arthritis, and adults diagnosed with mild dementia. Participants completed 2 reaction-time and 2 episodic-memory tasks on 4 occasions. Results indicated that intraindividual variability in latency was greater in individuals diagnosed with mild dementia than in adults who were neurologically intact, regardless of their health status. Individual differences in variability were stable over time and across cognitive domains. Intraindividual variability was also related to level of performance and was uniquely predictive of neurological status, independent of level of performance. Results suggest that intraindividual variability may be a behavioral indicator of compromised neurological mechanisms.

Implications of within-person variability in cognitive and neuropsychological functioning for the interpretation of change.

“…That is, how much a person's performance varies around his or her average level on a specific test could be an early predictor of impending change to a different level of functioning. Consistent with this interpretation are several reports of significant relations between measures of within-person variability and neurological status (e.g., Burton, Strauss, Hultsch, Moll, & Hunter, 2006;Hultsch, MacDonald, Hunter, Levy-Bencheton, & Strauss, 2000;Murtha, Cismaru, Waechter, & Chertkow, 2002;Strauss, MacDonald, Hunter, Moll, & Hultsch, 2002) and even risk of death (Shipley, Der, Taylor, & Deary, 2006).A second reason why within-person variability is important is that it suggests that single assessments may not be sufficient for accurate evaluation of an individual if another assessment with the same test could lead to a different level of performance and, possibly, to a different diagnostic classification. Little is currently known about the potential impact of this type of problem, but it will likely depend on both the magnitude of the variability and the range of variables that exhibit within-person variability.…”

Associations between reaction time measures and white matter hyperintensities in very old age

“…One proposal holds that IIV is an early indicator of neurobiological disturbance (Hultsch, MacDonald, Hunter, Levy-Bencheton, & Strauss, 2000;Hultsch, Strauss, Hunter, & MacDonald, 2008). In support of this, greater variability is evident in individuals with agerelated disorders such as mild cognitive impairment and dementia (Christensen et al, 2005;Duchek et al, 2009;Gorus, De Raedt, Lambert, Lemper, & Mets, 2008;Hultsch et al, 2000;Strauss, Bielak, Bunce, Hunter, & Hultsch, 2007), Parkinson's disease (de Frias, Dixon, Fisher, & Camicioli, 2007) and also frontal lobe lesions (Stuss, Murphy, Binns, & Alexander, 2003).…”

“…These trials were then replaced using a regression imputation procedure (replaced trials = <1% for SRT, <4% for CRT). In line with previous studies (Hultsch et al, 2000;Hultsch et al, 2008), intraindividual standard deviations (ISD) were generated using a regression procedure that partialled out the effects of extraneous influences (age, time-on-task, and trial type) and their higher order interaction from the individual RTs. To obtain the most reliable estimates, ISD and mean-RT metrics were averaged across the two assessments.…”

“…One proposal holds that IIV is an early indicator of neurobiological disturbance (Hultsch, MacDonald, Hunter, Levy-Bencheton, & Strauss, 2000;Hultsch, Strauss, Hunter, & MacDonald, 2008). In support of this, greater variability is evident in individuals with agerelated disorders such as mild cognitive impairment and dementia (Christensen et al, 2005;Duchek et al, 2009;Gorus, De Raedt, Lambert, Lemper, & Mets, 2008;Hultsch et al, 2000;Strauss, Bielak, Bunce, Hunter, & Hultsch, 2007), Parkinson's disease (de Frias, Dixon, Fisher, & Camicioli, 2007) and also frontal lobe lesions (Stuss, Murphy, Binns, & Alexander, 2003).Given the suggestion that IIV is an indicator of neurobiological disturbance, a number of magnetic resonance imaging (MRI) studies have investigated the link between variability and structural brain measures. In healthy ageing, associations have been shown between IIV and white matter hyperintensities (WMH: Bunce et al, 2010;Bunce et al, 2007), white matter volume (Jackson, Balota, Duchek, & Head, 2012;Lovden et al, 2013;Ullen, Forsman, Blom, Karabanov, & Madison, 2008;Walhovd & Fjell, 2007) and diffusion tensor imaging metrics (e.g., FA -fractional anisotropy) (Deary et al, 2006;Fjell, Westlye, Amlien, & Walhovd, 2011;Mella, de Ribaupierre, Eagleson, & de Ribaupierre, 2013; Moy et al, 2011).…”

Aging cognition: from neuromodulation to representation

“…A shift to cross-level paradigms generates more opportunities for hypothesis generation and testing across levels. For instance, neuromodulation might not only influence aging-related increases in intraindividual performance variability within individuals 53,54 , but also inter-individual diversity at the group level. Future animal pharmacological studies could directly examine the effects of dopamine agonists and antagonists on intra-individual fluctuations and their effects on inter-individual diversity.…”