This observational study examined the feasibility, reliability, and validity of repeated ambulatory cognitive tests in fibromyalgia (FM).

Adults with FM (n = 50) and matched controls (n = 50) completed lab-based neuropsychological tests (NIH Toolbox) followed by eight days of smartphone-based ambulatory testing of processing speed (symbol search) and working memory (dot memory) five times daily. Feasibility was assessed based on response rates. Reliability was evaluated using overall average between-person reliabilities for the full assessment period and by determining the number of assessment days necessary to attain reliabilities of >.80 and >.90. To assess convergent validity, correlations were calculated between ambulatory test scores and NIH Toolbox scores. Test performance was contrasted between the FM and non-FM groups to examine known-groups validity.

Average rates of response to the ambulatory cognitive tests were 89.5% in FM and 90.0% in non-FM. Overall average between-person reliabilities were ≥.96. In FM, between-person reliability exceeded .90 after two days for symbol search and three days for dot memory. Symbol search scores correlated with NIH Toolbox processing speed scores in both groups, though there were no significant group differences in symbol search performance. Dot memory scores correlated with NIH Toolbox working memory scores in both groups. FM participants exhibited worse dot memory performance than did non-FM participants.

Repeated ambulatory tests of processing speed and working memory demonstrate feasibility and reliability in FM, though evidence for construct validity is mixed. The findings demonstrate promise for future research and clinical applications of this approach to assessing cognition in FM.

The internet serves an increasingly critical role in how older adults manage their personal health. Electronic patient portals, for example, provide a centralized platform for older adults to access lab results, manage prescriptions and appointments, and communicate with providers. This study examined whether neurocognition mediates the effect of older age on electronic patient portal navigation.

Forty-nine younger (18–35 years) and 35 older adults (50–75 years) completed the Test of Online Health Records Navigation (TOHRN), which is an experimenter-controlled website on which participants were asked to log-in, review laboratory results, read provider messages, and schedule an appointment. Participants also completed a neuropsychological battery, self-report questionnaires, and measures of health literacy and functional capacity.

Mediation analyses revealed a significant indirect effect of older age on lower TOHRN accuracy, which was fully mediated by the total cognitive composite.

Findings indicate that neurocognition may help explain some of the variance in age-related difficulties navigating electronic patient health portals. Future studies might examine the possible benefits of both structural (e.g., human factors web design enhancement) and individual (e.g., training and compensation) cognitive supports to improve the navigability of electronic patient health portals for older adults.

To evaluate the construct validity of the NIH Toolbox Cognitive Battery (NIH TB-CB) in the healthy oldest-old (85+ years old).

Our sample from the McKnight Brain Aging Registry consists of 179 individuals, 85 to 99 years of age, screened for memory, neurological, and psychiatric disorders. Using previous research methods on a sample of 85 + y/o adults, we conducted confirmatory factor analyses on models of NIH TB-CB and same domain standard neuropsychological measures. We hypothesized the five-factor model (Reading, Vocabulary, Memory, Working Memory, and Executive/Speed) would have the best fit, consistent with younger populations. We assessed confirmatory and discriminant validity. We also evaluated demographic and computer use predictors of NIH TB-CB composite scores.

Findings suggest the six-factor model (Vocabulary, Reading, Memory, Working Memory, Executive, and Speed) had a better fit than alternative models. NIH TB-CB tests had good convergent and discriminant validity, though tests in the executive functioning domain had high inter-correlations with other cognitive domains. Computer use was strongly associated with higher NIH TB-CB overall and fluid cognition composite scores.

The NIH TB-CB is a valid assessment for the oldest-old samples, with relatively weak validity in the domain of executive functioning. Computer use’s impact on composite scores could be due to the executive demands of learning to use a tablet. Strong relationships of executive function with other cognitive domains could be due to cognitive dedifferentiation. Overall, the NIH TB-CB could be useful for testing cognition in the oldest-old and the impact of aging on cognition in older populations.

Cognitive impairment is common post-stroke. There is a need to understand patterns of early cognitive recovery post-stroke to guide both clinical and research practice. The aim of the study was to map the trajectory of cognitive recovery during the first week to 90-days post-stroke using serial computerised assessment.

An observational cohort study recruited consecutive stroke patients admitted to a stroke unit within 48 hours of onset. Cognitive function was assessed using the computerised Cambridge Neuropsychological Test Automated Battery (CANTAB) daily for seven days, then 14, 30 and 90 days post-stroke. The CANTAB measured visual episodic memory and learning, information processing speed, visuo-spatial working memory, complex sustained attention and mental flexibility. Repeated measures MANOVA/ANOVA with Least Squares Difference post-hoc analyses were performed to ascertain significant change over time.

Forty-eight participants, mean age 73, primarily mild, ischaemic stroke, completed all assessment timepoints. There was a trajectory of early, global cognitive improvement, indicative of a post-stroke delirium, that largely stabilised between 6 and 14-days post-stroke. Change over time was examined within each cognitive test, with one measure stabilising by day 6 (Reaction Time) and others detecting improving performances up to 14 days post-stroke.

Serial, computerised cognitive assessment can effectively map post-stroke cognitive recovery and revealed an early phase of global improvement over 14 days that is evidence for an acute post-stroke delirium. Resolution of post-stroke delirium in the second week following mild stroke indicates more extensive neuropsychological testing may be undertaken earlier than previously thought.

Dementia, a slowly progressive disease, is poorly diagnosed. One reason is that it is difficult to use the screening tools. The six-item cognitive impairment test (6-CIT) is brief, with six items, and has a confirmed scoring system that can easily be used by an average individual. This review aimed to analyze the predictive validity of the 6-CIT including comparisons with other tools such as the Mini-Mental State Examination (MMSE).

Literature searches were performed on the MEDLINE, EMBASE, CINAHL, and PsycArticles using the dementia and 6-CITas keywords. The Quality Assessment of Diagnostic Accuracy Studies-2 was applied to assess the risk of bias.

Seven studies with 6,831 participants that met the selection criteria were included. The pooled sensitivity of the 6-CIT analyzed in seven studies was 0.82 (95% CI 0.73–0.89), the pooled specificity was 0.87, and the summary receiver operating characteristic (sROC) curve was 0.90 (SE = 0.04). The diagnostic performance of the 6-CIT and MMSE was compared in three studies. The pooled sensitivity of the 6-CIT was 0.85, the pooled specificity was 0.91, and the sROC curve was 0.91, whereas the MMSE values were 0.70, 0.93, and 0.68, respectively.

This review presents evidence that the 6-CIT has excellent dementia screening performance and could be used as a potential alternative to the MMSE. The 6-CIT may provide an opportunity for early detection of dementia.

Brain reserve, cognitive reserve, and education are thought to protect against late-life cognitive decline, but these variables have not been directly compared to one another in the same model, using future cognitive and functional decline as outcomes. We sought to determine whether the influence of these protective factors on executive function (EF) and daily function decline was dependent upon Alzheimer’s disease (AD) pathology severity, as measured by the total tau to beta-amyloid (T-τ/Aβ1-42) ratio in cerebrospinal fluid (CSF).

Participants were 1201 older adult volunteers in the Alzheimer’s Disease Neuroimaging Initiative (ADNI) study. Brain reserve was defined using a composite index of structural brain volumes (total brain matter, hippocampus, and white matter hyperintensity). Cognitive reserve was defined as the variance in episodic memory performance not explained by brain integrity and demographics.

At higher levels of T-τ/Aβ1-42, brain and cognitive reserve predicted slower decline in EF. Only brain reserve attenuated decline at lower levels of T-τ/Aβ1-42. Education had no independent association with cognitive decline.

These results point to a hierarchy of protection against aging- and disease-associated cognitive decline. When pathology is low, only structural brain integrity predicts rate of future EF decline. The ability of cognitive reserve to predict future EF decline becomes stronger as CSF biomarker evidence of AD increases. Although education is typically thought of as a proxy for cognitive reserve, it did not show any protective effects on cognition after accounting for brain integrity and the residual cognitive reserve index.

This study aims to establish reference data for nondemented adults between 80 and 84 years of age based on the German version of the Consortium to Establish a Registry for Alzheimer’s disease Neuropsychological (CERAD-NP) test battery and to assess the possible influence of hearing and vision impairments on CERAD-NP performance.

Two hundred one volunteers were examined with the German CERAD-NP test battery, and 18 test scores were calculated from the data. The sample included 99 men (49%), the mean age was 81.8 years (SD = 1.3), and the mean years of education were 13.9 (SD = 3.1). Percentiles for continuous and percentile ranks for discrete test scores were calculated separately for four norm groups. The groups were classified according to gender and education. Multiple regression analysis was used to predict cognitive performance from visual acuity and hearing ability.

The normative data obtained were consistent with other findings from younger and older age groups. Worse visual acuity predicted slower performance in the Trail Making Test (TMT). None of the other CERAD-NP tests were correlated to sensory functions.

Using age-appropriate reference data, such as that established here for the 80–84 year age group can help to improve the detection of cognitive decline and prevent biases that arise when old-old adults are compared to younger old adults. Visual acuity should be considered an influencing factor on TMT performance.

To examine the effects of pediatric traumatic brain injury (TBI) on verbal IQ by severity and over time.

A systematic review and subsequent meta-analysis of verbal IQ by TBI severity were conducted using a random effects model. Subgroup analysis included two epochs of time (e.g., <12 months postinjury and ≥12 months postinjury).

Nineteen articles met inclusion criteria after an extensive literature search in MEDLINE, PsycInfo, Embase, and CINAHL. Meta-analysis revealed negative effects of injury across severities for verbal IQ and at both time epochs except for mild TBI < 12 months postinjury. Statistical heterogeneity (i.e., between-study variability) stemmed from studies with inconsistent classification of mild TBI, small sample sizes, and in studies of mixed TBI severities, although not significant. Risk of bias on estimated effects was generally low (k = 15) except for studies with confounding bias (e.g., lack of group matching by socio-demographics; k = 2) and measurement bias (e.g., outdated measure at time of original study, translated measure; k = 2).

Children with TBI demonstrate long-term impairment in verbal IQ, regardless of severity. Future studies are encouraged to include scores from subtests within verbal IQ (e.g., vocabulary, similarities, comprehension) in addition to functional language measures (e.g., narrative discourse, reading comprehension, verbal reasoning) to elucidate higher-level language difficulties experienced in this population.

To evaluate the properties of the cognitive battery used in the MIND Diet Intervention to Prevent Alzheimer’s Disease. The MIND Diet Intervention is a randomized control trial to determine the relative effectiveness of the MIND diet in slowing cognitive decline and reducing brain atrophy in older adults at risk for Alzheimer’s dementia.

The MIND cognitive function battery was administered at baseline to 604 participants of an average age of 70 years, who agreed to participate in the diet intervention study, and was designed to measure change over time. The battery included 12 cognitive tests, measuring the 4 cognitive domains of executive function, perceptual speed, episodic memory, and semantic memory. We conducted a principal component analysis to examine the consistency between our theoretical domains and the statistical performance of participants in each domain. To further establish the validity of each domain, we regressed the domain scores against a late-life cognitive activity score, controlling for age, race, sex, and years of education.

Four factors emerged in the principal component analyses that were similar to the theoretical domains. In regression equations, we found the expected associations with age, education, and late-life cognitive activity with each of the four cognitive domains.

These results indicate that the MIND cognitive battery is a comprehensive and valid battery of four separate domains of cognitive function that can be used in diet intervention trials for older adults.

This study used multiple assessment methods to examine instrumental activities of daily living (IADLs) performance in individuals with Parkinson’s disease with mild cognitive impairment (PD-MCI) compared to individuals with mild cognitive impairment (MCI) and cognitively healthy older adults (HOA). Associations between functional performance and cognition were also examined.

Eighteen individuals with PD-MCI, 48 individuals with MCI, and 66 HOAs were assessed with multiple IADL measures, including direct observation, a performance-based measure, and self- and informant-report questionnaires. Performance on the direct-observation measure was further characterized by coding for four error types: omissions, substitutions, and inefficient and irrelevant/off-task actions.

Both the PD-MCI and MCI groups performed more poorly on the overall score for all IADL measures relative to HOAs. Although the PD-MCI and MCI groups did not differ in overall performance, on the direct-observation measure, the PD-MCI group took longer and made more inefficient and irrelevant/off-task errors relative to the HOA and MCI groups, whereas the MCI group made more omission and substitution errors relative to HOAs. Further, the pattern of cognitive correlates that associated most strongly with the functional measures varied across groups and functional assessment methods.

Compared to HOAs, PD-MCI and MCI groups demonstrated increased difficulties performing everyday activities, and cognitive and motor abilities differentially contributed to the everyday task difficulties of these two groups.

Story memory tasks are among the most commonly used memory tests; however, research suggests they may be less sensitive to memory decline and have a weaker association with hippocampal volumes than list learning tasks. To examine its utility, we compared story memory to other memory tests on impairment rates and association with hippocampal volumes.

Archival records from 1617 older adults (Mage = 74.41, range = 65–93) who completed the Wechsler Memory Scale – 4th edition (WMS-IV) Logical Memory (LM), Hopkins Verbal Learning Test – Revised (HVLT-R), and Brief Visuospatial Memory Test – Revised (BVMT-R) as part of a clinical neuropsychological evaluation were reviewed. Scores >1.5 SD below age-adjusted means were considered impaired, and frequency distributions were used to examine impairment rates. A subset of participants (n = 179) had magnetic resonance imaging (MRI) data that underwent image quality assessment. Partial correlations and linear regression analyses, accounting for age, education, and total intracranial volume (TIV), examined associations between memory raw scores and hippocampal volumes.

For delayed recall, nearly half of the sample was impaired on HVLT-R (48.8%) and BVMT-R (46.1%), whereas a little more than a third was impaired on LM (35.7%). Better performance on all three measures was related to larger hippocampal volumes (r’s =. 26–.43, p’s < .001). Individually adding memory scores to regression models predicting hippocampal volumes improved the model fit for all measures.

Despite findings suggesting that story memory is less sensitive to memory dysfunction, it was not differentially associated with hippocampal volumes compared to other memory measures. Results support assessing memory using different formats and modalities in older adults.

Cognitive dysfunction is common in multiple sclerosis (MS). The Brief International Cognitive Assessment for MS (BICAMS) battery of tests has been suggested as a measure for the evaluation of the cognitive status of MS patients. This study aims to validate the BICAMS battery in the Russian population of MS patients.

Age- and sex-matched MS patients (n = 98) and healthy individuals (n = 86) were included in the study. Symbol Digit Modalities Test (SDMT), California Verbal Learning Test, 2nd edition (CVLT-II) and the Brief Visuospatial Memory Test – Revised (BVMT-R) were administered to all participants. The battery was readministered 1 month later to 44 MS patients to investigate the test–retest reliability.

MS patients exhibited a significantly lower performance in testing with BICAMS than the control group in all three neuropsychological tests. Test–retest reliability was good for SDMT and CVLT-II (r = .82 and r = .85, respectively) and adequate for BVMT-R (r = .70). Based on the proposed criterion for impairment as z score below 1.5 SD the mean of the control group, we found that 34/98 (35%) of MS patients were found impaired at least in one cognitive domain. Patients with Expanded Disability Status Scale score ≥3.5 performed significantly worse than controls (SDMT, p < .0001; CVLT–II, p = .03; BVMT-R, p = .0004), while those with ≤3.0 scores did not.

This study demonstrates that the BICAMS battery is a valid instrument to identify cognitive impairment in MS patients and it can be recommended for routine use in the Russian Federation.

This study is based on long-term follow-up of participants in a randomized double-blind sham surgery-controlled trial (1995–1999) designed to determine the effectiveness of implantation of human embryonic mesencephalic tissue containing dopamine neuron precursors into the brains of patients with advanced Parkinson’s disease (PD). We investigated differences between long-term survivors and nonsurvivors at baseline in order to contribute to information regarding optimal patient selection for upcoming stem cell trials.

Forty participants were randomly assigned to receive either neural implantation or sham surgery. Thirty-four patients who ultimately received the implant were followed periodically with the most recent assessment occurring in 2015–2016. Demographic information, neurological measures, positron emission tomography (PET) imaging, neuropsychological assessments, and a personality assessment were included in the current analyses. T-tests were used to compare survivors and nonsurvivors. Logistic regression analyses examined predictors of survivorship.

Five of six survivors were female. They were younger than nonsurvivors (p = .03) and more neuropsychologically “intact” across a broad range of cognitive areas (significance levels ranged from <.001 to .045). There were no differences between survivors and nonsurvivors off medications at baseline on neurological or PET assessments. Survivors reported more “Openness to Experience” (p = .004) than nonsurvivors. Using empirically derived predictor variables, results of logistic regression analyses indicated that Animal Naming (cognitive task) and Openness to Experience (personality variable) were the strongest predictors of survivorship.

Variables to consider when selecting participants for future cell-based therapies include being “intact” neuropsychologically, level of Openness to Experience, younger age, and inclusion of women.

Naming difficulty is a common symptom of multiple age-related neurodegenerative disorders. As naming difficulty increases with age, valid, up-to-date naming assessment tools are crucial for differentiating between neurotypical changes in healthy aging and pathological naming difficulty. We aimed to develop and provide normative data for complementary auditory description naming and visual naming tests for older adults. Furthermore, these measures would include not only untimed accuracy, typically the sole naming performance measure, but also additional scores that incorporate features characteristic of actual word finding difficulty.

A normative sample of 407 healthy older adults, aged 56–100 years, were administered the Auditory Naming Test (ANT) and Visual Naming Test (VNT), and other standardized measures.

Item analyses resulted in 36 stimuli for both tests. Age-stratified, education-based normative data are provided for accuracy, response time, tip-of-the-tongue (i.e., delayed, yet accurate responses plus correct responses following phonemic cueing), and multiple Summary Scores. Internal and test–retest reliability coefficients were reasonable (.59–.84). Untimed accuracy scores were high across age groups, seemingly reflecting stability of naming into late adulthood; however, time- and cue-based scores revealed reduced efficiency in word retrieval with increasing age.

These complementary auditory and visual naming test for older adults improve upon the current standard by providing more sensitive performance measures and the addition of an auditory–verbal component for assessing naming. Detection of subtle naming changes in healthy aging holds promise for capturing symptomatic naming changes during the early stages of neurocognitive disorders involving expressive language, potentially assisting in earlier diagnoses and more timely treatment.

Spatial disorientation is common in Alzheimer’s disease (AD), Mild Cognitive Impairment (MCI), and preclinical individuals with AD biomarkers. However, traditional neuropsychological tests lack ecological validity for the assessment of spatial orientation and to date, there is still no gold standard. The current study aimed to determine the validity and accuracy of two virtual reality tasks for the assessment of spatial orientation.

We adapted two spatial orientation tasks to immersive virtual environments: a “survey to route” task in which participants had to transfer information from a map to their body position within a maze [Spatial Orientation in Immersive Virtual Environment Test (SOIVET) Maze], and an allocentric-type, route learning task, with well-established topographic landmarks (SOIVET Route). A total of 19 MCI patients and 29 cognitively healthy older adults aged 61–92 participated in this study. Regular neuropsychological assessments were used for correlation analysis and participant performances were compared between groups. Receiver Operating Characteristic (ROC) curve analysis was performed for accuracy.

The SOIVET Maze correlated with measures of visuoperception, mental rotation, and planning, and was not related to age, educational level, or technology use profile. The SOIVET Route immediate correlated with measures of mental rotation, memory, and visuoconstruction, and was influenced only by education. Both tasks significantly differentiated MCI and control groups, and demonstrated moderate accuracy for the MCI diagnosis.

Traditional neuropsychological assessment presents limitations and immersive environments allow for the reproduction of complex cognitive processes. The two immersive virtual reality tasks are valid tools for the assessment of spatial orientation and should be considered for cognitive assessments of older adults.

This study aimed to identify a well-fitting and theoretically justified item-level latent factor structure for the Wechsler Memory Scales (WMS)-IV verbal paired associates (VerbalPA) subtest to facilitate the ease and accuracy of score interpretations for patients with lateralized temporal lobe epilepsy (TLE).

Archival data were used from 250 heterogeneous neurosciences patients who were administered the WMS-IV as part of a standard neuropsychological assessment. Three theoretically motivated models for the latent structure of VerbalPA were tested using confirmatory factor analysis. The first model, based on cognitive principles of semantic processing from hub-and-spoke theory, tested whether performance is related to specific semantic features of target words. The second, motivated by the Cattell–Horn–Carroll (CHC) model of cognitive abilities, investigated whether the associative properties of items influence performance. A third, Hybrid model tested whether performance is related to both semantic and associative properties of items. The best-fitting model was tested for diagnostic group effects contrasting the heterogeneous neuroscience patients with subsets of left and right TLE (n = 51, n = 26, respectively) patients.

The Hybrid model was found to have the best fit. Patients with left TLE scored significantly less well than the heterogeneous neurosciences sample on selected semantic factor scores, although the effect size was small.

Future editions of the WMS may consider implementing a semantic scoring structure for the VerbalPA to facilitate test score interpretation. Additionally, these results suggest that principles of hub-and-spoke theory may be integrated into CHC cognitive ability taxonomy.

To compare the administration of neuropsychological tests by teleneuropsychology (TeleNP) and face to face (F-F) in order to determine the feasibility and reliability of TeleNP.

At the inclusion visit, all participants underwent a traditional F-F neuropsychological assessment as part of their standard care. Four months after inclusion, they were randomized to undergo an additional neuropsychological assessment either by F-F administration or by TeleNP.

A total of 150 adults with cognitive complaints, but with no major cognitive or sensorial impairment were included. At 4 months, 69 participants were randomized in the F-F arm and 71 in TeleNP arm (10 lost in the follow-up). The overall satisfaction was high: 87.1% in the TeleNP arm were “very satisfied”, and 82.9% indicated no preference between F-F and TeleNP. In agreement with previous data from the literature, neuropsychological assessments gave similar results across both administration conditions for a large majority of tests [Mini-Mental State Examination (MMSE), Free and Cued Selective Reminding Test (FCSRT) French version, Mahieux gestural praxis battery, Frontal Assessment Battery (FAB), time of completion of the Trail making Test (TMT) A and B, number of errors of the TMT B, Rey complex figure test, categorical et phonological verbal fluency tests] and minor differences for others [80-picture naming test (DO-80), FAB, Digit Span forward and backward and number of errors in the TMT A].

TeleNP is a promising method to be able to test patients as an alternative to F-F condition. Before this procedure can be generalized, it is now necessary to standardize the adaptation of certain tests and to test them in populations with more significant cognitive disorders.

Cognitive impairment is a key element in most mental disorders. Its objective assessment at initial patient contact in primary care can lead to better adjusted and timely care with personalised treatment and recovery. To enable this, we designed the Mindmore self-administrative cognitive screening battery. What is presented here is normative data for the Mindmore battery for the Swedish population.

A total of 720 healthy adults (17 to 93 years) completed the Mindmore screening battery, which consists of 14 individual tests across five cognitive domains: attention and processing speed, memory, language, visuospatial functions and executive functions. Regression-based normative data were established for 42 test result measures, investigating linear, non-linear and interaction effects between age, education and sex.

The test results were most affected by age and to a lesser extent by education and sex. All but one test displayed either linear or accelerated age-related decline, or a U-shaped association with age. All but two tests showed beneficial effects of education, either linear or subsiding after 12 years of educational attainment. Sex affected tests in the memory and executive domains. In three tests, an interaction between age and education revealed an increased benefit of education later in life.

This study provides normative models for 14 traditional cognitive tests adapted for self-administration through a digital platform. The models will enable more accurate interpretation of test results, hopefully leading to improved clinical decision making and better care for patients with cognitive impairment.

Vision and hearing impairments affect 55% of people aged 60+ years and are associated with lower cognitive test performance; however, tests rely on vision, hearing, or both. We hypothesized that scores on tests that depend on vision or hearing are different among those with vision or hearing impairments, respectively, controlling for underlying cognition.

Leveraging cross-sectional data from the Baltimore Longitudinal Study of Aging (BLSA) and the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS), we used item response theory to test for differential item functioning (DIF) by vision impairment (better eye presenting visual acuity worse than 20/40) and hearing impairment (better ear .5–4 kHz pure-tone average > 25 decibels).

We identified DIF by vision impairment for tests whose administrations do not rely on vision [e.g., Delayed Word Recall both in ARIC-NCS: .50 logit difference between impaired and unimpaired (p = .04) and in BLSA: .62 logits (p = .02)] and DIF by hearing impairment for tests whose administrations do not rely on hearing [Digit Symbol Substitution test in BLSA: 1.25 logits (p = .001) and Incidental Learning test in ARIC-NCS: .35 logits (p = .001)]. However, no individuals had differences between unadjusted and DIF-adjusted measures of greater than the standard error of measurement.

DIF by sensory impairment in cognitive tests was independent of administration characteristics, which could indicate that elevated cognitive load among persons with sensory impairment plays a larger role in test performance than previously acknowledged. While these results were unexpected, neither of these samples are nationally representative and each has unique selection factors; thus, replication is critical.

People with Multiple Sclerosis (PwMS) and healthy controls (HCs) were evaluated on cognitive variability indices and we examined the relationship between fatigue and cognitive variability between these groups. Intraindividual variability (IIV) on a neuropsychological test battery was hypothesized to mediate the group differences expected in fatigue.

Fifty-nine PwMS and 51 HCs completed a psychosocial interview and battery of neuropsychological tests and questionnaires during a 1-day visit. Fatigue in this study was measured with the Fatigue Impact Scale (FIS), a self-report multidimensional measure of fatigue. IIV was operationalized using two different measures, a maximum discrepancy score (MDS) and intraindividual standard deviation (ISD), in two cognitive domains, memory and attention/processing speed. Two mediation analyses with group (PwMS or HCs) as the independent variable, variability composite (memory or attention/processing speed) measures as the mediators, total residual fatigue (after accounting for age) as the outcome, and depression as a covariate were conducted. The Baron and Kenny approach to testing mediation and the PROCESS macro for testing the strength of the indirect effect were used.

Results of a mediation analysis using 5000 bootstrap samples indicated that IIV in domains of both attention/processing speed and memory significantly mediated the effect of patient status on total residual fatigue.

IIV is an objective performance measure that is related to differences in fatigue impact between PwMS and HCs. PwMS experience more variability across tests of attention/processing speed and memory and this experience of variable performance may increase the impact of fatigue.