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Change in intraindividual variability over time as a key metric for defining performance-based cognitive fatigability.

ABSTRACT: Cognitive fatigability is conventionally quantified as the increase over time in either mean reaction time (RT) or error rate from two or more time periods during sustained performance of a prolonged cognitive task. There is evidence indicating that these mean performance measures may not sufficiently reflect the response characteristics of cognitive fatigue. We hypothesized that changes in intraindividual variability over time would be a more sensitive and ecologically meaningful metric for investigations of fatigability of cognitive performance. To test the hypothesis fifteen young adults were recruited. Trait fatigue perceptions in various domains were assessed with the Multidimensional Fatigue Index (MFI). Behavioral data were then recorded during performance of a three-hour continuous cued Stroop task. Results showed that intraindividual variability, as quantified by the coefficient of variation of RT, increased linearly over the course of three hours and demonstrated a significantly greater effect size than mean RT or accuracy. Change in intraindividual RT variability over time was significantly correlated with relevant subscores of the MFI including reduced activity, reduced motivation and mental fatigue. While change in mean RT over time was also correlated with reduced motivation and mental fatigue, these correlations were significantly smaller than those associated with intraindividual RT variability. RT distribution analysis using an ex-Gaussian model further revealed that change in intraindividual variability over time reflects an increase in the exponential component of variance and may reflect attentional lapses or other breakdowns in cognitive control. These results suggest that intraindividual variability and its change over time provide important metrics for measuring cognitive fatigability and may prove useful for inferring the underlying neuronal mechanisms of both perceptions of fatigue and objective changes in performance.

SUBMITTER: Wang C

PROVIDER: S-EPMC3980793 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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Change in intraindividual variability over time as a key metric for defining performance-based cognitive fatigability.

Wang Chao C Ding Mingzhou M Kluger Benzi M BM

Brain and cognition 20140130

Cognitive fatigability is conventionally quantified as the increase over time in either mean reaction time (RT) or error rate from two or more time periods during sustained performance of a prolonged cognitive task. There is evidence indicating that these mean performance measures may not sufficiently reflect the response characteristics of cognitive fatigue. We hypothesized that changes in intraindividual variability over time would be a more sensitive and ecologically meaningful metric for inv ...[more]

PMID: 24486386

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Project description:IntroductionParkinson's disease (PD) is a neurodegenerative disorder that commonly results in cognitive impairments and dementia. Intraindividual variability of neuropsychological performance is a sensitive marker of cognitive decline in other neurologic populations. However, studies have not examined the longitudinal utility of intraindividual variability in predicting future cognitive impairments among individuals with PD. In the current study, we hypothesized that increased intraindividual variability would predict future cognitive decline independent of traditional neuropsychological markers of cognitive impairment.MethodsThe sample included 423 newly diagnosed PD patients and 175 healthy controls, who were followed up to 5 years (baseline, first, second, third, fourth, and fifth annual follow-up). Participants underwent tests of learning, memory, processing speed, attention, verbal fluency, and visuospatial functioning. Cognitive status (cognitive intact, mild cognitive impairment, and dementia) was classified based on previously established criteria. Multilevel models were computed to examine the longitudinal relationship between intraindividual variability, cognitive status, and general cognitive functioning.ResultsAnalyses revealed that increased intraindividual variability was predictive of incident cognitive decline among individuals with PD. Specifically, greater dispersion in neuropsychological performance was associated with greater risk of transitioning from cognitively intact to mild cognitive impairment or transitioning from mild cognitive impairment to dementia. Additional analyses revealed a significant Intraindividual Variability × Group (PD or control) interaction, meaning that intraindividual variability was predictive of declines in cognitive functioning among PD participants only but not healthy controls.ConclusionIntraindividual variability may be a harbinger for future cognitive decline among individuals with PD. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Project description:Dementia researchers around the world prioritize the urgent need for sensitive measurement tools that can detect cognitive and functional change at the earliest stages of Alzheimer's disease (AD). Sensitive indicators of underlying neural pathology assist in the early detection of cognitive change and are thus important for the evaluation of early-intervention clinical trials. One method that may be particularly well-suited to help achieve this goal involves the quantification of intraindividual variability (IIV) in cognitive performance. The current study aimed to directly compare two methods of estimating IIV (fluctuations in accuracy-based scores vs. those in latency-based scores) to predict cognitive performance in AD. Specifically, we directly compared the relative sensitivity of reaction time (RT)-and accuracy-based estimates of IIV to cognitive compromise. The novelty of the present study, however, centered on the patients we tested [a group of patients with Alzheimer's disease (AD)] and the outcome measures we used (a measure of general cognitive function and a measure of episodic memory function). Hence, we compared intraindividual standard deviations (iSDs) from two RT tasks and three accuracy-based memory tasks in patients with possible or probable Alzheimer's dementia (n = 23) and matched healthy controls (n = 25). The main analyses modeled the relative contributions of RT vs. accuracy-based measures of IIV toward the prediction of performance on measures of (a) overall cognitive functioning, and (b) episodic memory functioning. Results indicated that RT-based IIV measures are superior predictors of neurocognitive impairment (as indexed by overall cognitive and memory performance) than accuracy-based IIV measures, even after adjusting for the timescale of measurement. However, one accuracy-based IIV measure (derived from a recognition memory test) also differentiated patients with AD from controls, and significantly predicted episodic memory performance. The findings suggest that both RT- and accuracy-based IIV measures may be useful indicators of underlying neuropathology. The present study therefore contributes toward an understanding of the relative utility of RT- and accuracy-based IIV measures in detecting neurocognitive impairment in older adults, and also advances the empirical evaluation of sensitive markers of cognitive change in patients with AD.

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Project description:PurposeHematopoietic stem cell transplant (HSCT) recipients are at risk for cognitive decline. Cross-sectional studies show patients' complaints of cognitive decline do not correlate well with concurrently measured objective neuropsychological performance, but rather with emotional variables and health-related quality of life. This longitudinal study investigated whether patient self-report of cognitive status would be concordant with objectively measured neuropsychological performance after accounting for change from their own pre-transplant objective baseline.MethodsPre-HSCT and at 30 and 100 days post-HSCT, 46 patients underwent computerized neuropsychological testing (CogState) and completed surveys assessing patient-reported cognitive complaints, emotional symptoms (depression, anxiety), sleep quality, daytime sleepiness, and physical and functional well-being. Correlations were calculated between cognitive complaints and neuropsychological performance (at each time-point and across time-points), as well as all other patient-reported variables.ResultsPatient-reported cognitive complaints were largely independent of concurrently assessed objective neuropsychological performance. Uniquely, our longitudinal data demonstrated significant medium to large effect size associations between subjective cognitive complaints post-HSCT with objectively measured change from pre-HSCT in attention, visual learning, and working memory (p < .05-.01). Subjective cognitive complaints post-HSCT were also associated with depression, anxiety, daytime sleepiness and physical well-being (p < .05-.001).ConclusionsPatients appear better able to assess their cognitive functioning relative to their own baseline and changes across time rather than relative to community norms. Thus, patient complaints of cognitive compromise justify further in-depth neuropsychological, emotional, and functional assessment. Future research into relationships between cognitive complaints and neuropsychological performance should account for changes in performance over time.

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Change in intraindividual variability over time as a key metric for defining performance-based cognitive fatigability.

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Change in intraindividual variability over time as a key metric for defining performance-based cognitive fatigability.

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