Variance In Cognitive Performance Research Articles

Mapping cognitive trajectories in older adults with essential tremor

AbstractBackgroundOlder adults with essential tremor (ET) are at increased risk for Alzheimer’s disease (AD) and related disorders. Examining cognitive trajectories within this population will enable better identification of individuals who evidence accelerated rates of change. Here we examine how variability in baseline cognitive performance affects trajectories of cognitive change within three subgroups of cognitively normal older adults: 1) those whose baseline neuropsychological scores were entirely within normal limits (WNL); 2) those with at least one low score considered to have unlikely clinical significance (UCS); and 3) those with at least one low score considered to have possible clinical significance (PCS).MethodOlder adults with ET completed comprehensive neuropsychological testing and clinical interviews, and 159 received a consensus diagnosis of cognitively normal. Participants were then subdivided into one of three categories defined above: WNL (N = 66, 75.38 ± 8.96 years of age), UCS (N = 54, 76.35 ± 10.25 years), and PCS (N = 37, 80.22 ± 9.00 years). Generalized estimating equations (GEE) were used to compare rates of change in global cognition, memory, executive function, attention, visuospatial, and language z‐scores over time across these groups. Participants were seen for two to four visits (24.98 ± 20.29 months). Models were adjusted for age, gender, and years of education.ResultAll three groups, WNL (β = ‐.005, p = .028), UCS (β = ‐.006, p = .011), and PCS (β = ‐.012, p = .002), evidenced decline in their memory performance over time, with the latter groups declining faster than the WNL group. Relative to the WNL and UCS groups, the PCS group also declined faster over time in overall cognition (β = ‐.010, p = .029) and in language (β = ‐.024, p = .035).ConclusionHeterogeneity in cognitive performance among cognitively normal older adults with ET predicts trajectories of cognitive decline longitudinally. Specifically, rates of decline were slowest in those with entirely normal test scores, and greatest in those whose scores were considered to have possible clinical significance. These preliminary results provide a starting point for further inquiry into the role of nuanced cognitive profiles in predicting rates of decline, impairment, and dementia in ET cases who may initially be labeled as “cognitively normal.”

Cognitive impairment after sleep deprivation: The role of precuneus related connectivity on the intra-individual variability changes

ObjectiveIntra-individual variability (IIV) in cognitive performance is thought to reflect the efficiency with which attentional resources are allocated in different circumstances requiring cognitive control. IIV in cognitive performance is associated with the strength of the negative correlation between task-positive network and default mode network (DMN) activity. In this study, we investigated the impact of sleep deprivation (SD) on functional connectivity (FC) between the DMN and psychomotor vigilance task-related network (PVT-RN), and its relationship with IIV in cognitive performance. MethodsTwo analyses, network-level independent component analysis (NL-ICA) and region-level (RL)-ICA, were employed to compare the coefficient of variation (CV) of the PVT between normal sleep and SD conditions across 67 healthy participants. ResultsAfter SD, in NL-ICA, the FC between the PVT-RN and DMN was positively correlated with the CV of the PVT, as well as the changes therein, compared with normal sleep. Using a mask derived from the DMN and PVT-RN, the RL-ICA revealed that 12 edges/connections between DMN and PVT independent components were associated with the CV of the PVT, with nine of these connections involving the precuneus. ConclusionsThese findings suggest that the precuneus may play a crucial role in the interactions of various brain functions during the PVT, with the connections between the precuneus and frontoparietal and somatosensory networks being significantly altered after SD. Moreover, following SD, weakened negative FC between the precuneus and bilateral inferior parietal lobule may disrupt the balance between cognitive and executive control functions, leading to a decline in cognitive performance.

Assessing depression recurrence, cognitive burden, and neurobiological homeostasis in late life: Design and rationale of the REMBRANDT study

BackgroundLate-life depression is characterized by disability, cognitive impairment and decline, and a high risk of recurrence following remission. Aside from past psychiatric history, prognostic neurobiological and clinical factors influencing recurrence risk are unclear. Moreover, it is unclear if cognitive impairment predisposes to recurrence, or whether recurrent episodes may accelerate brain aging and cognitive decline. The purpose of the REMBRANDT study (Recurrence markers, cognitive burden, and neurobiological homeostasis in late-life depression) is to better elucidate these relationships and identify phenotypic, cognitive, environmental, and neurobiological factors contributing to and predictive of depression recurrence. MethodsAcross three sites, REMBRANDT will enroll 300 depressed elders who will receive antidepressant treatment. The goal is to enroll 210 remitted depressed participants and 75 participants with no mental health history into a two-year longitudinal phase focusing on depression recurrence. Participants are evaluated every 2 months with deeper assessments occurring every 8 months, including structural and functional neuroimaging, environmental stress assessments, deep symptom phenotyping, and two weeks of ‘burst’ ecological momentary assessments to elucidate variability in symptoms and cognitive performance. A broad neuropsychological test battery is completed at the beginning and end of the longitudinal study. SignificanceREMBRANDT will improve our understanding of how alterations in neural circuits and cognition that persist during remission contribute to depression recurrence vulnerability. It will also elucidate how these processes may contribute to cognitive impairment and decline. This project will obtain deep phenotypic data that will help identify vulnerability and resilience factors that can help stratify individual clinical risk.

Cognitive Function among Young Women's Football Players in the Summer Heat.

Recently, there has been a growing focus on studies related to women's football. However, the cognitive function of female football players has not been extensively characterized. Thus, we explored how the cognitive function of female football players was altered during a series of matches in summer and examined day-to-day variations in cognitive function with regard to dehydration status. Resting cognitive function was assessed from 17 young women football players during the Japan Club Youth Women's football tournament, which spanned eight consecutive days. Cognitive function initially improved, with this improvement sustained throughout the tournament. It is worth noting that ten participants experienced symptoms of dehydration at least once during the tournament; however, these symptoms were not found to be linked to impaired cognitive function, suggesting that resting cognitive function remains unaffected during summer matches, even in the presence of dehydration symptoms.

34 Variability in RBANS Performance and Neurocognitive Impairment in Older Adults with Cognitive Concerns

Objective:Risk factors that contribute to brain pathology and cognitive decline among older adults include demographic factors (e.g., age, educational attainment), genetic factors, health factors, and depression (Plassman et al., 2010). Variability within an individual’s performance across cognitive tasks is referred to as dispersion (Hultsch et al., 2002), which appears sensitive to subtle cognitive impairments associated with neurodegenerative pathology in older adults (Bangen et al., 2019; Kälin et al., 2014). Thaler and colleagues (2015) found that dispersion across domains of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was a useful indicator of cognitive changes associated with cardiovascular disease and mortality. Also, research by Manning and colleagues (2021) found that elevated ratings of depression and anxiety in older adults was associated with greater dispersion across neuropsychological testing. The present study aimed to replicate findings that greater dispersion in neuropsychological performance is associated with impaired neurocognitive performance and greater self-reported depression among older adults who present for neuropsychological evaluation with cognitive concerns.Participants and Methods:Neuropsychological testing data was obtained from a university hospital. Chart reviews were conducted on 369 participants who met initial criteria (60 years or older with testing data from the RBANS Form A, Wechsler Test of Adult Reading, and Geriatric Depression Scale [GDS]). Retrospective analyses were conducted on a final sample of 293 participants from 60 to 94 years old (Mage = 74.41, SDage = 7.43; 179 females, 114 males). Diagnoses were used for group comparisons between cognitively intact individuals with subjective cognitive complaints (SCC, n = 49), persons with Mild Neurocognitive Disorder (mND, n =137), and persons with Major Neurocognitive Disorder (MND, n = 107).Results:As expected, results indicated that higher dispersion was related to lower Total RBANS Scores (r = -0.54, p < .001) and significant differences across diagnostic groupings (F(2, 289) = 29.19, p < 0.001; SCC, mND, MND) indicated that variability in performance was an indicator of greater neurocognitive impairment. Contrary to expectations, greater dispersion was very weakly associated with lower reported depressive symptomatology (r = -0.13, p = 0.03). A three-stage hierarchical linear regression was conducted with the RBANS Coefficient of Variation (CoV) as the dependent variable and three predictor variables (Age, Total RBANS, Total GDS). The regression analysis results indicated that age was not a significant predictor, but both Total RBANS and GDS Scores were. The most important predictor was Total RBANS Scores which uniquely explained 21% of the variation in dispersion.Conclusions:This study adds to the current literature regarding the clinical utility of dispersion in neuropsychological performance as an indicator of early and subtle neurocognitive impairment. Depressive symptom reporting was expected to help predict the degree of variability, but this factor was only weakly associated with the RBANS CoV.Limitations of this study include its retrospective use of archival data and the restricted range on some variables of interest. Further research is needed to examine the relative utility of different measures of dispersion and why increased cognitive performance variability is related to neurocognitive impairment and decline.

Neuroanatomical Correlates of Cognitive Tests in Young-onset MCI.

Mild Cognitive Impairment (MCI) is a heterogeneous condition characterised by cognitive changes that do not affect everyday functioning and may represent a predementia phase. Research on the neuroanatomical correlates of cognitive tests used to diagnose MCI is heterogeneous and has mainly focused on elderly populations of patients with MCI, usually well above the age of 65. However, the effect of ageing on brain structure is known to be substantial and to affect brain-behaviour associations in older people. We explored the brain correlates of different cognitive tests in a group of young-onset MCI (i.e., with symptoms onset before the age of 65) to minimise the effect of ageing on brain-behaviour associations. Patients with a clinical diagnosis of young-onset MCI underwent extensive cognitive assessment and multimodal Magnetic Resonance Imaging (MRI) including high-resolution T1-weighted and Diffusion Tensor Imaging (DTI) sequences. Their scores on cognitive tests were related to measures of grey matter (GM) density and white matter (WM) integrity using, respectively, Voxel Based Morphometry (VBM) and Tract-Based Spatial Statistics (TBSS). 104 young-onset MCI were recruited. VBM and TBSS whole-brain correlational analyses showed that between-subject variability in cognitive performance was significantly associated with regional variability in GM density and WM integrity. While associations between cognitive scores and focal GM density in our young-onset MCI group reflected the well-known lateralization of verbal and visuo-spatial abilities on the left and right hemispheres respectively, the associations between cognitive scores and WM microstructural integrity were widespread and diffusely involved most of the WM tracts in both hemispheres. We investigated the structural neuroanatomical correlates of cognitive tests in young-onset MCI in order to minimise the effect of ageing on brain-behaviour associations.

Epigenetic Age Acceleration and Chronological Age: Associations With Cognitive Performance in Daily Life.

DNA methylation-derived epigenetic clocks offer the opportunity to examine aspects of age acceleration (ie, the difference between an individual's biological age and chronological age), which vary among individuals and may better account for age-related changes in cognitive function than chronological age. Leveraging existing ambulatory cognitive assessments in daily life from a genetically diverse sample of 142 adults in midlife, we examined associations between 5 measures of epigenetic age acceleration and performance on tasks of processing speed and working memory. Covarying for chronological age, we used multilevel models to examine associations of epigenetic age acceleration (Horvath 1, Horvath 2, Hannum, PhenoAge, and GrimAge clocks) with both average level and variability of cognitive performance. Positive age acceleration (ie, epigenetic age greater than chronological age) was associated with poorer mean processing speed (Horvath 1 and 2) and working memory (GrimAge). Higher chronological age was also associated with poorer mean processing speed and working memory performance. Further, positive age acceleration was generally associated with greater intraindividual variability in working memory and processing speed tasks, whereas being chronologically older was associated with less intraindividual variability. Although further work is needed, our results indicate age acceleration effects have comparable or greater size as those for chronological age differences, suggesting that epigenetic age acceleration may account for additional risk and interindividual variation in cognitive performance above chronological age.

Exercise counters the negative impact of bed rest on executive functions in middle-aged and older adults: A proof-of-concept randomized controlled trial

ObjectivesProlonged bed rest is prevalent among middle-aged and older adults and is associated with multiple negative health outcomes. Therefore, it is important that we better understand the utility of exercise training as a countermeasure to the adverse effects of bed rest. We examined the effect of exercise training on intraindividual variability in cognitive performance among adults aged 55–65 exposed to 14 days of physical inactivity modelled via 6° head-down tilt bed rest. MethodsThe study is a non-blinded, parallel-group, proof-of-concept randomized controlled trial. Twenty-three healthy middle-aged and older adults (12 males, 11 females) aged 55–65 were randomized to: (1) 14 days of 6° head-down tilt bed rest (Control) or (2) 14 days of 6° head-down tilt bed rest with daily exercise (Exercise). The National Institutes of Health Toolbox Cognitive Battery assessed executive functions (Flanker incongruent/congruent and Dimensional Change Card Sort) and processing speed (Pattern Comparison). We assessed cognitive function at baseline, 6° head-down tilt bed rest midpoint, completion, and seven days following completion. We indexed intraindividual variability with two metrics: (1) residual intraindividual standard deviation and (2) intraindividual coefficient of variation. Flanker congruent and incongruent residual intraindividual standard deviations were the primary outcomes. Linear mixed models assessed between-group differences and the moderating effect of biological sex. ResultsAt bed rest completion, Exercise had significantly lower (better) Flanker incongruent residual intraindividual standard deviation (estimated mean difference = −3.63, 95%CI -6.10;-1.17, p = 0.005) and intraindividual coefficient of variation (estimated mean difference = −0.10, 95%CI -0.19;-0.003, p = 0.022) vs. Control. Sex moderated the effect of exercise on Flanker incongruent intraindividual coefficient of variation. Exercise females had significantly lower intraindividual coefficient of variation vs. Control (estimated mean difference = −0.23; 95%CI -0.34;-0.12, p < 0.001). There were no significant between-group differences in processing speed intraindividual variability and summary scores of executive functions and processing speed (ps > 0.05). ConclusionExercise training during bed rest preserved intraindividual variability of executive functions but not processing speed. Trial registrationClinicalTrials.gov NCT04964999

Low serum 25‑hydroxy-vitamin D levels are associated with cognitive impairment in multiple sclerosis

BackgroundCognitive impairment frequently affects people with multiple sclerosis (MS). Low vitamin D has been associated with cognitive dysfunction in different neurodegenerative diseases, and, in MS, with motor disability and disease activity. We aim to investigate associations between vitamin D and cognitive status in MS. MethodsIn this cross-sectional study, we included 181 MS patients, recruited consecutively at the MS Unit of the Policlinico Federico II University Hospital of Naples, Italy, between January and April 2022, with serum 25‑hydroxy (25-OH) vitamin D measurements using Chemiluminescence-ImmunoAssay, and cognitive assessment using the Brief International Cognitive Assessment for MS (BICAMS), which includes Symbol Digit Modalities Test (SDMT), California Verbal Learning Test-II (CVLT-II) and Brief Visuospatial Memory Test-Revised (BVMT-R). We collected demographics (age, sex, education), and clinical variables (disease duration, disease subtype, expanded disability status scale (EDSS), disease modifying treatment, relapses in previous 12 months, vitamin D supplementation, comorbidities). For a subset of patients (n = 41, 23.2% of the total sample), we collected Beck Depression Inventory-II, Beck Anxiety Inventory, and Modified Fatigue Impact Scale. ResultsAt univariable linear regression models, serum 25-OH-vitamin D levels were 0.9 ng/mL higher for each unit increase of SDMT adjusted scores (Coeff=0.93; 95%CI=0.81, 1.04; p<0.01), 0.7 ng/mL higher for each unit increase of CVLT-II adjusted scores (Coeff=0.68; 95%CI=0.53, 0.83; p<0. 01), 0.6 ng/mL higher for each unit increase of BVMT-R adjusted scores (Coeff=0.58; 95%CI=0.43, 0.73; p<0.01), -9.63 ng/mL lower for each impaired BICAMS test (Coeff=-9.63; 95%CI=-11.48, -7.79; p<0.01), and -2.2 ng/mL lower for each unit increase of EDSS (Coeff=-2.16; 95%CI=-3.57, -0.75; p<0.01). At multivariable linear regression models, we confirmed associations between 25-OH-vitamin D and EDSS (Coeff=-2.09; 95%CI=-4.45, -0.43; p<0.01), SDMT (Coeff=0.75; 95%CI=0.60, 0.90; p<0.01), and CVLT-II (Coeff=0.14; 95%CI=0.01, 0.28; p = 0. 04). Results remained unchanged when including depression, anxiety and fatigue scores. ConclusionsLower serum 25-OH-vitamin D was associated with worse cognitive function in MS. Future studies should consider longitudinal variations in cognitive function in relation to vitamin D supplementation.

Effects of stochastic vestibular stimulation on cognitive performance in children with ADHD

Previous work has shown that exposure to auditory white noise (WN) can improve cognitive performance in children with ADHD, but it is unknown whether this improvement generalizes to other sensory modalities. To address this knowledge gap, we tested the effect of Stochastic Vestibular Stimulation (SVS) on cognitive performance and reaction time (RT) variability in two groups: children with ADHD and typically developing children (TDC). Children with ADHD (N=42) and TDC (N=28) performed three cognitive tasks (Spanboard, Word Recall and N-back tasks) at two different occasions, with and without exposure to SVS, in a double blinded design. The results showed no main effects of SVS on neither performance nor RT variability for children in any of the groups, and no interactions between SVS and group. Based on these results we conclude that, using our stimulation protocol, the positive effects of WN exposure on cognition in children with ADHD do not generalize to Stochastic Vestibular Stimulation.

Validating virtual administration of neuropsychological testing in Parkinson disease: a pilot study

COVID-19 has highlighted the need for remote cognitive testing, but the reliability and validity of virtual cognitive testing in Parkinson disease (PD) is unknown. Therefore, we assessed PD participants enrolled in an observational, cognition-focused study with an extensive cognitive battery completed both in-person and via video conference close in time. Data for 35 PD participants with normal cognition to mild dementia were analyzed. Only one test (semantic verbal fluency) demonstrated a difference in score by administration type, with a significantly better score virtually. Only three tests demonstrated good reliability for in-person versus virtual testing, but reliability values for visit 1 versus visit 2 were similarly low overall. Trail Making Test B was successfully administered virtually to only 18 participants due to technical issues. Virtual and in-person cognitive testing generate similar scores at the group level, but with poor to moderate reliability for most tests. Mode of test administration, learning effects, and technical difficulties explained little of the low test–retest reliability, indicating possible significant short-term variability in cognitive performance in PD in general, which has implications for clinical care and research. In-person cognitive testing with a neuropsychologist remains the gold standard, and it remains to be determined if virtual cognitive testing is feasible in PD.

Unexpected cognitive similarities between older adults and young people: Scores variability and cognitive performances

BackgroundIncreased interindividual variability in cognitive performance during aging has been proposed as an indicator of cognitive reserve. ObjectiveTo determine if interindividual variability performance in episodic memory (PAL), working memory (SWM), reaction time (RTI), and sustained attention (RVP) could differentiate clusters of differential cognitive performance in healthy young and older adults and search for cognitive tests that most contribute to these differential performances. MethodsWe employed hierarchical cluster and canonical discriminant function analyses of cognitive scores using the Cambridge Neuropsychological Test Automated Battery (CANTAB) to identify cognitive variability in older and young adults using the coefficient of variability of cognitive performances between and within groups. We also analyzed potential influences of age, education, and physical activity. ResultsCluster analysis distinguished groups with differential cognitive performance and correlation analysis revealed coefficient of variability and cognitive performance associations. The greater the coefficient of variability the poorer was cognitive performance in RTI but not in PAL and SWM. Older adults showed diverse trajectories of cognitive decline, and better education or higher percentage of physically active individuals exhibited better cognitive performance in both older and young adults. ConclusionPAL and SWM are the most sensitive tests to investigate the wide age range encompassing older and young adults. In older adults’ intragroup analysis PAL showed greater discriminatory capacity, indicating its potential for clinical applications late in life. Our data underscore the importance of studying variability as a tool for early detection of subtle cognitive declines and for interpreting results that deviate from normality.

Strength and multiple types of physical activity predict cognitive function independent of low muscle mass in NHANES 1999–2002

AbstractIntroductionMultiple domains of cognitive function decline with age, resulting in a significant burden on quality of life and the healthcare system. Recent studies increasingly point to links between muscle mass, particularly low muscle mass, and risk of cognitive decline. However, complex relationships exist between muscle mass, muscle function, physical activity, and overall health.MethodsData from 1,424 adults 60+ years old in the 1999‐2000 and 2001‐2002 editions of the National Health and Nutrition Examination Survey (NHANES) were used to investigate the relationship between low muscle mass and cognitive function after accounting for strength, physical activity, and nutritional and metabolic risk factors for cognitive decline.ResultsMuscle strength and physical activity independently predicted performance in the digit symbol substitution test, with muscle mass and muscle strength explaining 0.5% and 5% of the variance in cognitive function, respectively. In graphical network analyses, the association between low muscle mass and cognitive function appeared to be primarily mediated by neuromuscular function. Physical activity was associated with strength but, surprisingly, not muscle mass, which was instead more closely related to total mass.ConclusionsLow muscle mass is a relatively poor predictor of cognitive function after accounting for physical activity and strength in older individuals from a representative population dataset in the US. Future studies should account for the way in which muscle mass is accrued, which is likely to confound any association between muscle mass and health outcomes.

Bidirectional genetic overlap between autism spectrum disorder and cognitive traits

Autism spectrum disorder (ASD) is a highly heritable condition with a large variation in cognitive function. Here we investigated the shared genetic architecture between cognitive traits (intelligence (INT) and educational attainment (EDU)), and risk loci jointly associated with ASD and the cognitive traits. We analyzed data from genome-wide association studies (GWAS) of INT (n = 269,867), EDU (n = 766,345) and ASD (cases n = 18,381, controls n = 27,969). We used the bivariate causal mixture model (MiXeR) to estimate the total number of shared genetic variants, local analysis of co-variant annotation (LAVA) to estimate local genetic correlations, conditional false discovery rate (cond/conjFDR) to identify specific overlapping loci. The MiXeR analyses showed that 12.7k genetic variants are associated with ASD, of which 12.0k variants are shared with EDU, and 11.1k are shared with INT with both positive and negative relationships within overlapping variants. The majority (59–68%) of estimated shared loci have concordant effect directions, with a positive, albeit modest, genetic correlation between ASD and EDU (rg = 0.21, p = 2e−13) and INT (rg = 0.22, p = 4e−12). We discovered 43 loci jointly associated with ASD and cognitive traits (conjFDR<0.05), of which 27 were novel for ASD. Functional analysis revealed significant differential expression of candidate genes in the cerebellum and frontal cortex. To conclude, we quantified the genetic architecture shared between ASD and cognitive traits, demonstrated mixed effect directions, and identified the associated genetic loci and molecular pathways. The findings suggest that common genetic risk factors for ASD can underlie both better and worse cognitive functioning across the ASD spectrum, with different underlying biology.

Impact of sleep deprivation on neurocognition and inflammation in rhesus macaques

Sleep deprivation in humans is associated with both cognitive impairment and immune dysregulation. An animal model of neuropathogenesis may provide insight to understand the effects of sleep deprivation on the brain. Human neurocognition is more closely mirrored by nonhuman primates (NHP) than other animals. As such, we developed an NHP model to assess the impact of sleep deprivation on neurocognition and markers of systemic immune activation. Six male rhesus macaques underwent three rounds of sleep deprivation (48 h without sleep) at days 0, 14, and 28. We performed domain specific cognitive assessments using the Cambridge Neuropsychological Test Automated Battery (CANTAB) via a touch screen before and after 24 and 48 h of sleep deprivation. Immune activation markers were measured in the blood by multiplex assay and flow cytometry. Although we observed variability in cognitive performance between the three rounds of sleep deprivation, cognitive impairments were identified in all six animals. We noted more cognitive impairments after 48 h than after 24 h of sleep deprivation. Following 48 h of sleep deprivation, elevations in markers of immune activation in the blood were observed in most animals. The observed impairments largely normalized after sleep. The co-occurrence of systemic immune alterations and cognitive impairment establishes this model as useful for studying the impact of sleep deprivation on neurobehavior and immune perturbations in rhesus macaques.

Multivariate prediction of cognitive performance from the sleep electroencephalogram

Human cognitive performance is a key function whose biological foundations have been partially revealed by genetic and brain imaging studies. The sleep electroencephalogram (EEG) is tightly linked to structural and functional features of the central nervous system and serves as another promising biomarker. We used data from MrOS, a large cohort of older men and cross-validated regularized regression to link sleep EEG features to cognitive performance in cross-sectional analyses. In independent validation samples 2.5–10% of variance in cognitive performance can be accounted for by sleep EEG features, depending on the covariates used. Demographic characteristics account for more covariance between sleep EEG and cognition than health variables, and consequently reduce this association by a greater degree, but even with the strictest covariate sets a statistically significant association is present. Sigma power in NREM and beta power in REM sleep were associated with better cognitive performance, while theta power in REM sleep was associated with worse performance, with no substantial effect of coherence and other sleep EEG metrics. Our findings show that cognitive performance is associated with the sleep EEG (r = 0.283), with the strongest effect ascribed to spindle-frequency activity. This association becomes weaker after adjusting for demographic (r = 0.186) and health variables (r = 0.155), but its resilience to covariate inclusion suggest that it also partially reflects trait-like differences in cognitive ability.

Cognitive performance is linked to fitness in a wild primate.

Cognitive performance varies widely across animal species, but the processes underlying cognitive evolution remain poorly known. For cognitive abilities to evolve, performance must be linked to individual fitness benefits, but these links have been rarely studied in primates even though they exceed most other mammals in these traits. We subjected 198 wild gray mouse lemurs to four cognitive and two personality tests and subsequently monitored their survival in a mark-recapture study. Our study revealed that survival was predicted by individual variation in cognitive performance as well as body mass and exploration. Because cognitive performance covaried negatively with exploration, individuals gathering more accurate information enjoyed better cognitive performance and lived longer, but so did heavier and more explorative individuals. These effects may reflect a speed-accuracy trade-off, with alternative strategies yielding similar overall fitness. The observed intraspecific variation in selective benefits of cognitive performance, if heritable, can provide the basis for the evolution of cognitive abilities in members of our lineage.

Intra-individual variability adaptively increases following inhibition training during middle childhood

There is ongoing debate on the relationship between intra-individual variability (IIV) of cognitive processes and task performance. While psychological research has traditionally assumed that lower intra-individual variability (IIV) aids consistent task performance, some studies suggest that greater IIV can also be adaptive, especially when flexible responding is required. Here we selectively manipulate inhibitory control (Stopping) and response speed (Going) by means of a training paradigm to 1) assess how this manipulation impacts Stopping IIV and its relationship to task performance, and 2) replicate previous findings showing that reductions in Going IIV are adaptive. A group of 208 6–13-year-old children were randomly allocated to an 8-week training targeting Stopping (experimental group) or Going (control group). The stop signal task was administered before and after training. Training Stopping led to adaptive increases in Stopping IIV, where greater flexibility in cognitive processing may be required to meet higher task demands. In line with previous studies, training Going led to adaptive reductions in Going IIV, which allows more consistent and efficient Going performance. These findings provide systematic and causal evidence of the process-dependent relationship of IIV and task performance in the context of Stopping and Going, suggesting a more nuanced perspective on IIV with implications for developmental, ageing and intervention studies.

The impact of early adversity and education on genetic and brain morphological predictors of cognitive ability.

Cognitive ability is a strong predictor of occupational achievement, quality of life and physical health. While variation in cognition is strongly heritable and has been robustly associated with early environment and brain morphology, little is known about how these factors combine and interact to explain this variation in cognition. To address this, we modelled the relationship between common genetic variation, grey matter volume, early life adversity and education and cognitive ability in a UK Biobank sample of N = 5237 individuals using structural equation modelling. We tested the hypotheses that total grey matter volume would mediate the association between genetic variation and cognitive ability, and that early life adversity and educational attainment would moderate this relationship. Common genetic variation, grey matter volume and early life adversity were each significant predictors in the model, explaining ~15% of variation in cognitive ability. Contrary to our hypothesis, grey matter volume did not mediate the relation between genetic variation and cognition performance. Neither did early life adversity or educational attainment moderate this relation, although educational attainment was observed to moderate the relationship between grey matter volume and cognitive performance. We interpret these findings in terms of the modest explanatory value of currently estimated polygenic scores accounting for variation in cognitive performance (~5%), making potential mediating and moderating variables difficult to confirm.

The role of cognitive factors in second language writing and writing to learn a second language

AbstractThis article revisits the role of cognitive individual differences in creating synergies between second language (L2) writing and second language acquisition research that were proposed by Kormos (2012). It takes stock of the advances in research findings, in the past decade, on the role of working memory and language learning aptitude in L2 writing processes and performance. The article offers an overview of how cognitive factors can mediate learning gains when L2 users engage in writing. Using theoretical accounts of cognitive individual differences, the article discusses how the characteristics of writing tasks can interact with individual variation in cognitive functioning. The article concludes by proposing a Task-Mediated Cognitive Model of L2 Writing and Writing to Learn that describes the role of cognitive factors in L2 writing processes and in learning through writing, and an outline of a research agenda for future studies.