Variance In Cognitive Performance Research Articles

Spatial cognitive performance is linked to thigmotaxis in field crickets

Information is acquired through cognitive processes and is essential for enhanced fitness in many animal species. However, little is known about intraspecific variation in cognitive performance, or about phenotypic correlates of this variation, especially in invertebrates. Here we quantified individual variation in spatial learning, exploration, boldness and thigmotaxis (wall hugging) in female Texas field crickets, Gryllus texensis. We trained females to locate a food reward (dish baited with food) located in one arm of a radial arm maze, followed by a cognitive test (probe) trial where no food reward was present. Our results suggest that female crickets could learn and remember the food location, as latency to find the reward dish, distance travelled, number of complete arm entries and number of errors made prior to finding the reward dish all declined with training trials and during the cognitive test trial. Furthermore, females performed equally well on all cognitive measures during the cognitive test trial and the last training trial, suggesting they did not rely on olfactory cues to locate the correct dish during the cognitive test trial. Individual variation in cognitive measures during the test trial were significantly negatively correlated with thigmotaxis during the trial, but were not correlated with body size, latency to leave the novel maze's acclimation zone or the percentage of the novel maze explored during initial exploration of the maze. Our findings suggest individuals with reduced thigmotaxis either (1) are better at learning a spatial task and/or (2) rely more heavily on vision than olfaction. These results contribute to the growing literature examining links between personality and cognition, and highlight the importance of quantifying correlated aspects of the phenotype when assessing individual variation in cognitive performance in a cognitive test.

COGNITIVE VARIABILITY AND BRAIN AGING IN LATE-LIFE DEPRESSION

Introduction Dispersion across cognitive test scores, a measure of variability in cognitive performance, may be an indication of pathological aging. The aim of the current study was to investigate the association of test dispersion with structural brain variables and cognitive decline in non-demented older adults with major depression (MD) and healthy controls (HC). We hypothesized that those with greater dispersion would have lower hippocampal volumes (HPC) and higher white matter hypointensities (WMH) and that dispersion would predict cognitive decline at one-year follow-up. Methods Subjects included 121 MD and 39 HC subjects who participated in the NBOLD study at UConn Health. Inclusion criteria were age 60+ and a psychiatrist's diagnosis of MD for the patient group. Dementia and other major neuropsychiatric illnesses were exclusion criteria. Dispersion was calculated as the standard deviation of z-scores divided by group mean z-scores of a demographically adjusted neuropsychological test performance across a comprehensive battery. Results Dispersion positively correlated with WMH in both HC (r=0.386; p =.001) and MD (r=0.318; p=0.001), and negatively correlated with left HPC volume in MD (r=-0.191; p=0.034). Linear regression analyses accounting for baseline cognitive performance, demographics, and depression found that dispersion predicted cognitive tasks performed at a year follow up. For older adults with MD word list (WL) 1-3 (p=.038), WL delayed recall (DR) (p=.020) and symbol digit modality test (SDMT) (p=.035) were predictors. For HC dispersion was predicted for logical memory (LM) DR (p=.004) and Benton test (p=.003). Conclusions Dispersion is correlated with evidence of brain aging in older adults with MD. Future studies may look at ways to reduce dispersion in older adults and help prevent cognitive decline. This research was funded by Research reported in this poster was supported by the National Institute of General Medical Sciences of the National Institutes of Health under linked Award Numbers RL5GM118969, TL4GM118971, and UL1GM118970. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Educational and research grant from the Leo and Anne Albert Charitable Trust.

Understanding cognitive functioning in glioma patients: The relevance of IDH-mutation status and functional connectivity.

IntroductionCognitive deficits occur frequently in diffuse glioma patients, but are limitedly understood. An important marker for survival in these patients is isocitrate dehydrogenase (IDH) mutation (IDH‐mut). Patients with IDH‐mut glioma have a better prognosis but more often suffer from epilepsy than patients with IDH‐wildtype (IDH‐wt) glioma, who are generally older and more often have cognitive deficits. We investigated whether global brain functional connectivity differs between patients with IDH‐mut and IDH‐wt glioma, and whether this measure reflects variations in cognitive functioning in these subpopulations beyond the associated differences in age and presence of epilepsy.MethodsWe recorded magnetoencephalography and tested cognitive functioning in 54 diffuse glioma patients (31 IDH‐mut, 23 IDH‐wt). Global functional connectivity between 78 atlas regions spanning the entire cortex was calculated in two frequency bands (theta and alpha). Group differences in global functional connectivity were tested, as was their association with cognitive functioning, controlling for age, education, and presence of epilepsy.ResultsPatients with IDH‐wt glioma had lower functional connectivity in the alpha band than patients with IDH‐mut glioma (p = 0.040, corrected for age and presence of epilepsy). Lower alpha band functional connectivity was associated with poorer cognitive performance (p < 0.034), corrected for age, education, and presence of epilepsy.ConclusionGlobal functional connectivity is lower in patients with IDH‐wt diffuse glioma compared to patients with IDH‐mut diffuse glioma. Moreover, having lower functional alpha connectivity relates to poorer cognitive performance in patients with diffuse glioma, regardless of age, education, and presence of epilepsy.

GRIN2B promoter methylation deficits in early-onset schizophrenia and its association with cognitive function.

We investigated GRIN1 and GRIN2B promoter methylation in first-episode schizophrenia patients compared with siblings and controls, testing for correlations between DNA methylation, cognitive performance and clinical variables. Blood-derived DNA from all groups underwent bisulfite conversion and pyrosequencing to determine methylation at CpG sites within the GRIN1 and GRIN2B promoters and results were compared with the measure of global methylation LINE-1. We found hypomethylation among all CpGs analyzed within GRIN2B promoter in patients and greater LINE-1 methylation in patients and siblings. CpG4 was correlated to a measure of intellectual function. Changes in GRIN2B promoter methylation may represent an environmental influence contributing to glutamatergic dysfunction in psychosis and relate to lower cognitive performance in subjects with first-episode schizophrenia.

Cognitive Fitness to Drive in Huntington's Disease: Assessing the Clinical Utility of DriveSafe DriveAware.

DriveSafe DriveAware (DSDA) has been validated as an off-road screening tool for predicting on-road driving performance in clinical populations, but its utility in people with Huntington's disease (HD) is unknown. Our aim was to evaluate the utility of DSDA in people with HD by demonstrating sensitivity of DSDA scores to HD progression and exploring associations between DSDA performance and cognitive functions that are essential to driving and impaired in people with HD. We administered the iPad application version of DSDA to 26 pre-symptomatic and symptomatic participants with HD. Disease progression was assessed via measures of motor impairment, disease burden and functional capacity. Standardised neuropsychological tests were used to assess cognitive function across several domains including attention, processing speed, planning, and visuoperception. Results underscore the sensitivity of DSDA to HD progression and cognitive impairment; that is, poorer DSDA performance was associated with greater HD severity and poorer cognitive ability across the domains of attention, processing speed, and planning. Nevertheless, we identified a proportion of participants with HD who were predicted to pass on-road testing based on DSDA, but scored in the impaired range on multiple cognitive tests. These participants tended to score closer to the cut-off score used by DSDA to categorise pass/fail outcomes. Our findings demonstrate potential for use of DSDA in the HD population, however, significant variability in cognitive performance among those predicted to 'pass' on-road driving assessment suggests the screening tool requires further development for use with HD drivers.

Precise relative-quantity judgement in the striped field mouse Apodemus agrarius Pallas.

Applying the classical experimental scheme of training animals with food rewards to discriminate between quantities of visual stimuli, we demonstrated that not only can striped field mice Apodemus agrarius discriminate between clearly distinctive quantities such as 5 and 10, but some of these mice also exhibit high accuracy in discriminating between quantities that differ only by one. The latter include both small (such as 2 versus 3) and relatively large (such as 5 versus 6, and 8 versus 9) quantities of elements. This is the first evidence of precise relative-quantity judgement in wild rodents. We found striking individual variation in cognitive performance among striped field mice, which possibly reflects individual cognitive variation in natural populations. We speculate that high accuracy in differentiating large quantities is based on the adaptive ability of wild rodents to capture subtle changes in their environment. We suggest that the striped field mouse may be a powerful model species to develop advanced cognitive tests for comparative studies of numerical competence in animals and for understanding evolutionary roots of quantity processing.

The right kind of smart: emotional intelligence's relationship to cognitive status in community-dwelling older adults.

To examine whether emotional intelligence (EI) is associated with cognitive function (CF) in a sample of community-dwelling, non-demented elderly out-patients. Correlational cross-sectional study. Two memory clinics in an urban community in central Israel. Individuals age 60 and older without dementia, recruited from two memory clinics (N = 151). Health history was obtained from medical charts. All participants underwent tests measuring CF, basic and instrumental function, general mental ability (GMA), EI, and depression. Mean age of the participants was 79 years (SD = 7.00) with 96 females (63.6%). Mean score for Montreal Cognitive Assessment (MoCA) was 21.62 (SD = 3.09) and for EI was 14.08 (SD = 3.30). Linear multiple regression analysis was conducted to examine associations of CF with EI while controlling for gender, age, education, GMA, and Charlson Comorbidity Index (CCI). Age, education, GMA, and CCI were significant correlates of CF and accounted for 31.1% of the variance [F(7,143) = 10.8, p<0.01] in CF. EI was added in the second block and was the factor most strongly associated with CF, explaining an additional 9.1% (a total of 40.2%) of the variance in CF [F(8,142) = 13.2, p<0.01]. This study is the first to show the association between EI and CF in older adults. Future prospective studies are needed to explicate the possibility of EI as a protective factor against cognitive decline.

Cognitive function among older adults: ELSI-Brazil results.

ABSTRACTOBJECTIVE To investigate macroregional variations in cognitive function in a national sample representative of the Brazilian population aged 50 years and older.METHODS Data from the baseline of the Longitudinal Study of Brazilian Elderly (ELSI-Brazil), collected between 2015 and 2016, were used. Memory was measured by means of a 10-word list and executive function, by semantic verbal fluency, based on the naming of animals. Gender, age, education, and rural or urban residence were potentially confoundingRESULTS Among the 9,412 ELSI-Brazil participants, 9,085 were included in the analysis; 53.9% were women and the average age was 63.0 (0.42) years. After adjusting for potential confounding variables, average scores for memory and verbal fluency were lower in the Northeast region and higher in the Midwest and Southeast, respectively. In the South region, higher scores were found for immediate and combined memory. In all regions, older participants and those with lower schooling had worse scores for memory and verbal fluency.CONCLUSIONS There are differences in cognitive function among older adults in the different macroregions, independent of age, gender, schooling, and rural or urban residence.

Going beyond the mean: Intraindividual variability of cognitive performance in prodromal and early neurodegenerative disorders

Objective: Intraindividual variability (IIV), generally defined as short-term variations in behavior, has been proposed as a sign of subtle early impairment in neurodegenerative disorders, presumably associated with the disintegration of neuronal network connectivity. We aim to provide a review of IIV as a sensitive cognitive marker in prodromal neurodegenerative disorders.Method: A narrative review focusing not only on theoretical and methodological definitions, including an overview on the neural correlates of IIV, but mainly on results from population-based and clinical-based studies on the role of IIV as a reliable predictor of mild cognitive impairment (MCI) and conversion to dementia in neurodegenerative disorders, mostly Alzheimer’s and Parkinson’s disease.Results: Most studies focus on MCI and Alzheimer’s disease and demonstrate that IIV is a reliable cognitive marker. IIV is partly more sensitive than mean performance in the prediction of cognitive impairment or progressive deterioration and is independent of socio-demographic variables and disease mediators (e.g., genetic susceptibility). Neuroimaging data, mostly from healthy subjects, suggest a relationship between IIV and dysfunction of the default mode network, presumably mediated by white matter disintegration in frontal and parietal areas.Conclusions: IIV measures may provide valuable information about diagnosis and progression in prodromal stages of neurodegenerative disorders. Thus, further conceptual and methodological clarifications are needed to justify the inclusion of IIV as a sensible cognitive marker in routine clinical neuropsychological assessment.

Supplemental Material for Covariation of Intraindividual Variability in Cognitive Speed and Cognitive Performance Across Young, Middle, and Older Adulthood

Supplemental Material for Covariation of Intraindividual Variability in Cognitive Speed and Cognitive Performance Across Young, Middle, and Older Adulthood

NMDA receptors of blood lymphocytes anticipate cognitive performance variations in healthy volunteers

Working memory (WM) system, temporarily stores information and uses this information for complex cognitive tasks. WM connects memory, emotional feelings and perception. Evidence compelling that N-methyl d-aspartate receptor (NMDAR) expression relatively affect WM performance in animal models. It has been suggested some peripheral blood lymphocyte's (PBL) receptors are similar with neuronal receptors in the brain, so we measured PBL's receptors changes as a marker of the neuronal receptor. In this study, we examined one hundred adult men with Wisconsin Card Sorting Test (WCST) as a tool for primary screening for executive function (EF) which include WM. Then, we selected fifty individuals with high and low WCST scores. With digit span and symmetry span tasks, we screened 20 samples for high WM group and 19 samples for low WM group. After separating PBL, we measured mRNA expression level changes in NMDAR subunits with Reverse transcription-polymerase chain reaction method. We demonstrated that GluN2D increased and GluN3A decreased in individuals with high WM compared with the low WM (P < .01 and P < .001, respectively). The expression levels of GluN2A, GluN2B, and GluN3B were not altered between two groups (P > .05). Modifying the PBL receptors could be future approaches to defend memory loss and concentrate the senses over WM-related processes in physiological and pathological statuses. We hypothesized that increasing in GluN2 subunits and decreasing in GluN3 subunits led to improving current via NMDAR and subsequently affect WM.

Associations of lifestyle and vascular risk factors with Alzheimer’s brain biomarker changes during middle age: a 3-year longitudinal study in the broader New York City area

ObjectiveTo investigate the associations between lifestyle and vascular risk factors and changes in Alzheimer’s disease (AD) biomarkers (beta-amyloid load via 11C-PiB PET, glucose metabolism via 18F-FDG PET and neurodegeneration via...

A Mobile App Delivering a Gamified Battery of Cognitive Tests Designed for Repeated Play (OU Brainwave): App Design and Cohort Study.

BackgroundMobile phone and tablet apps are an increasingly common platform for collecting data. A key challenge for researchers has been participant “buy-in” and attrition for designs requiring repeated testing.ObjectiveThe objective of this study was to develop and assess the utility of 1-2 minute versions of both classic and novel cognitive tasks using a user-focused and user-driven mobile phone and tablet app designed to encourage repeated play.MethodsA large sample of app users (N=13,979 at first data collection) participated in multiple, self-paced sessions of classic working memory (N-back), spatial cognition (mental rotation), sustained attentional focus (persistent vigilance task), and split attention (multiple object tracking) tasks, along with the implementation of a comparatively novel action-learning task. The “OU Brainwave” app was designed to measure time-of-day variation in cognitive performance and did not offer any training program or promise any cognitive enhancement. To record participants’ chronotype, a full Morningness-Eveningness questionnaire was also included, which measures whether a person's circadian rhythm produces peak alertness in the morning, in the evening, or in between. Data were collected during an 18-month period. While the app prompted re-engagement at set intervals, participants were free to complete each task as many times as they wished.ResultsWe found a significant relationship between morningness and age (r=.298, n=12,755, P<.001), with no effect of gender (t13,539=−1.036, P=.30). We report good task adherence, with ~4000 participants repeatedly playing each game >4 times each—our minimum engagement level for analysis. Repeated plays of these games allowed us to replicate commonly reported gender effects in gamified spatial cognition (F1,4216=154.861, P<.001, η2ρ=.035), split attention (F1,4185=11.047, P=.001, η2ρ=.003), and sustained attentional focus (F1,4238=15.993, P<.001, η2ρ=.004) tasks. We also report evidence of a small gender effect in an action-learning task (F1,3988=90.59, P<.001, η2ρ=.022). Finally, we found a strong negative effect of self-reported age on performance, when controlling for number of plays, in sustained attentional focus (n=1596, F6,1595=30.23, P<.001, η2=.102), working memory (n=1627, F6,1626=19.78, P<.001, η2=.068), spatial cognition (n=1640, F6,1639=23.74, P<.001, η2=.080), and split attention tasks (n=1616, F6,1615=2.48, P=.02, η2=.009).ConclusionsUsing extremely short testing periods and permitting participants to decide their level of engagement—both in terms of which gamified task they played and how many sessions they completed—we were able to collect a substantial and valid dataset. We suggest that the success of OU Brainwave should inform future research oriented apps—particularly in issues of balancing participant engagement with data fidelity.

Chronic Pain, Sleep, and Cognition in Older Adults With Insomnia: A Daily Multilevel Analysis.

The goal of this study was to examine daily associations between sleep and cognition in older adults suffering from insomnia, with or without a history of chronic pain. Sixty older adults with insomnia and a history of chronic pain (HxCP; n = 33, mean age = 69.5 years, standard deviation = 7.8) or no history of chronic pain (NCP; n = 27, mean age = 69.7 years, standard deviation = 7.9) completed 14 days of diaries and actigraphy, measuring sleep onset latency (SOL), wake after sleep onset (WASO), sleep efficiency (SE), and sleep quality. Participants completed daily cognitive measures of processing speed (ie, symbol digit modalities test, SDMT), reasoning (ie, letter series), and verbal memory (ie, word list delayed recall). For HxCP and NCP, associations between sleep parameters, daily pain, depressive symptoms (ie, Beck Depression Inventory, Second Edition scores), and daily cognition, controlling for age, and global cognition were examined through multilevel modeling. For HxCP, greater self-reported WASO was associated with worse next-day SDMT performance, whereas greater actigraphic WASO was associated with better next-day SDMT performance. Greater depression was associated with worse daily letter series performance. Greater self-reported WASO and SE were associated with better next-day delayed recall. For NCP, greater self-reported WASO and depression were associated with better daily SDMT performance, whereas worse daily pain was associated with worse SDMT and delayed recall performance. In older adults with HxCP, improving sleep may benefit lower level cognition, whereas reducing depression may affect higher level cognition. Discrepancies in sleep parameters promote assessment of objective and subjective sleep outcomes when investigating effects of insomnia on cognition. Title: Intraindividual Variability in Sleep and Cognitive Performance in Older Adults (REST), Registry: ClinicalTrials.gov, Identifier: NCT02967185, URL: https://clinicaltrials.gov/ct2/show/NCT02967185.

Repetitive mild traumatic brain injury in military veterans is associated with increased neuropsychological intra-individual variability

Although across-test intra-individual variability (IIV), or dispersion, has been shown to be a valuable marker of neurological health in a variety of clinical samples, IIV has not been well examined in the context of mild traumatic brain injury (mTBI). In the present study, we examined measures of IIV in military Veterans with and without a history of mTBI. Secondly, we examined how measures of IIV relate to traditional indices of mean cognitive performance, TBI characteristics, and neuropsychiatric symptoms in mTBI. Participants included 120 Veterans (67 mTBI, 53 military controls [MCs]) who completed a comprehensive neuropsychological assessment. Two dispersion indices were calculated using 13 norm-referenced variables: an average standard deviation (ASD) score and a maximum discrepancy (MD) score. Compared to MCs, Veterans with a history of mTBI demonstrated greater IIV as indicated by the MD index after adjusting for relevant demographic variables, PTSD symptoms, and mean-level cognitive performance (p = 0.027; ηp2 = 0.043), and there was a trend finding in the same direction for the ASD index (p = 0.091; ηp2 = 0.025). Among the mTBI participants, the two IIV indices were positively correlated with each other (p < 0.001, r = 0.921) and negatively correlated with mean cognitive performance (p = 0.017–0.022, r = −[0.279–0.291]). In contrast, ASD and MD scores were not associated with a measure of premorbid intellectual functioning or neuropsychiatric symptoms (all p's > 0.05). However, higher ASD scores were positively related to lifetime number of mTBIs, such that greater cognitive variability was observed in Veterans with a history of multiple mTBIs (i.e., ≥3 mTBIs; p = 0.037, r = 0.255). Overall, our results demonstrate that Veterans with mTBI show greater IIV relative to MCs, and that repetitive mTBI is associated with increased cognitive performance variability. Findings indicate that, in the context of mTBI—which is considerably heterogeneous in nature—measures of dispersion may be more appropriate indicators of cognitive dysfunction when compared to traditional mean neuropsychological scores, especially in those with remote mTBI histories. Future longitudinal studies are needed to further establish the long-term clinical implications and brain-based correlates of these findings.

Disconnection due to white matter hyperintensities is associated with lower cognitive scores

Previous studies have linked global burden of age-related white matter hyperintensities (WMHs) to cognitive impairment. We aimed to determine how WMHs in individual white matter connections relate to measures of cognitive function relative to measures of connectivity which do not take WMHs into account. Brain connectivity and WMH-related disconnectivity were derived from 3714 participants of the population-based Rotterdam Study. Connectivity was represented by the structural connectome, which was defined using diffusion tensor data, whereas the disconnectome represented disconnectivity due to WMH. The relationship between (dis)connectivity and cognitive measures was estimated using linear regression. We found that lower disconnectivity and higher connectivity corresponded to better cognitive function. There were many more significant associations with cognitive function in the disconnectome than in the connectome. Most connectome associations attenuated when disconnection was included in the model. WMH-related disconnectivity was especially related to worse executive functioning. Better cognitive speed corresponded to higher connectivity in specific connections independent of WMH presence. We conclude that WMH-related disconnectivity explains more variation in cognitive function than does connectivity. Efficient wiring in specific connections is important to information processing speed independent of WMH presence.

Basal forebrain cholinergic system volume is associated with general cognitive ability in the elderly

ObjectiveAt the present, it is unclear whether association of basal forebrain cholinergic system (BFCS) volume with cognitive performance exists in healthy as well as in cognitively impaired elderly subjects. Whereas one small study reported an association of BFCS volume with general cognitive ability ‘g’ in healthy ageing, effects on specific cognitive domains have only been found in subjects with cognitive decline. Here we aim to clarify whether an association of BFCS volume and ‘g’ is present in a larger sample of elderly subjects without obvious symptoms of dementia and whether similar associations can also be observed in specific cognitive domains. Methods282 pre-surgical patients from the BioCog study (aged 72.7 ± 4.9 years with a range of 65–87 years, 110 women) with a median MMSE score of 29 points (range 24–30) were investigated. BFCS and brain volume as well as brain parenchymal fraction were assessed in T1-weighted MR images using SPM12 and a probabilistic map of the BFCS. Neuropsychological assessment comprised the CANTAB cognitive battery and paper-and-pencil based tests. For data analysis, generalised linear models and quantile regression were applied. ResultsSignificant associations of BFCS volume with ‘g’ and several cognitive domains were found, with the strongest association found for ‘g’. BFCS volume explained less variance in cognitive performance than brain volume. The association was not confounded by brain parenchymal fraction. Furthermore, the association of BFCS volume and ‘g’ was similar in high- and low-performers. ConclusionOur results extend previous study findings on BFCS volume associations with cognition in elderly subjects. Despite the observed associations of BFCS volume and cognitive performance, this association seems to reflect a more general association of brain volume and cognition. Accordingly, a specific association of BFCS volume and cognition in non-demented elderly subjects is questionable.

Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals.

Here we conducted a large-scale genetic association analysis of educational attainment in a sample of approximately 1.1 million individuals and identify 1,271 independent genome-wide-significant SNPs. For the SNPs taken together, we found evidence of heterogeneous effects across environments. The SNPs implicate genes involved in brain-development processes and neuron-to-neuron communication. In a separate analysis of the X chromosome, we identify 10 independent genome-wide-significant SNPs and estimate a SNP heritability of around 0.3% in both men and women, consistent with partial dosage compensation. A joint (multi-phenotype) analysis of educational attainment and three related cognitive phenotypes generates polygenic scores that explain 11-13% of the variance in educational attainment and 7-10% of the variance in cognitive performance. This prediction accuracy substantially increases the utility of polygenic scores as tools in research.

Individuals in larger groups are more successful on spatial discrimination tasks

To understand how natural selection may act on cognitive processes, it is necessary to reliably determine interindividual variation in cognitive abilities. However, an individual's performance in a cognitive test may be influenced by the social environment. The social environment explains variation between species in cognitive performances, with species that live in larger groups purportedly demonstrating more advanced cognitive abilities. It also explains variation in cognitive performances within species, with larger groups more likely to solve novel problems than smaller groups. Surprisingly, an effect of group size on individual variation in cognitive performance has rarely been investigated and much of our knowledge stems from impaired performance of individuals reared in isolation. Using a within-subjects design we assayed individual learning performance of adult female pheasants, Phasianus colchicus, while housed in groups of three and five. Individuals experienced the group sizes in a different order, but were presented with two spatial discrimination tasks, each with a distinct cue set, in a fixed order. We found that across both tasks individuals housed in the large groups had higher levels of success than individuals housed in the small groups. Individuals had higher levels of success on their second than their first task, irrespective of group size. We suggest that the expression of individual learning performance is responsive to the current social environment but the mechanisms underpinning this relationship require further investigation. Our study demonstrates that it is important to account for an individual's social environment when attempting to characterize cognitive capacities. It also demonstrates the flexibility of an individual's cognitive performance depending on the social context.

Genome‐wide association study of cognitive flexibility assessed by the Wisconsin Card Sorting Test

Cognitive flexibility is a critical component of executive function and is strongly influenced by genetic factors. We conducted a genome-wide association study of cognitive flexibility (as measured by perseverative errors on the Wisconsin Card Sorting Test) in two sets of African American (AA) and European American (EA) subjects (Yale-Penn-1: 1,411 AAs/949 EAs; Yale-Penn-2: 1,178 AAs/1,335 EAs). We examined the association of cognitive flexibility with genotyped or imputed SNPs across the genome. In AAs, two correlated common single nucleotide polymorphisms (SNPs) (rs7165213/rs35633795) in the downstream region of the noncoding gene LOC101927286 on chromosome 15 showed genome-wide significant (GWS) associations with cognitive flexibility (Yale-Penn-1: p = 6.0 × 10-9 /1.3 × 10-8 ; Yale-Penn-2: p = .029/.010; meta-analysis: p = 4.2 × 10-7 /1.0 × 10-7 ) in the same effect direction. In EAs, no GWS associations were observed. Enriched gene sets identified by Data-driven Expression-Prioritized Integration for Complex Traits (DEPICT) analysis of the top SNPs (pmeta-analysis < 10-5 ) included the signalosome and ubiquitin-specific peptidase 9, X-linked (USP9X) subnetwork in AAs, and abnormal frontal and occipital bone morphology in EAs. We also performed polygenic risk score (PRS) analysis to examine the genetic correlation of cognition-proxy phenotypes (general cognitive function, education attainment, childhood intelligence, and infant head circumference) and cognitive flexibility in EAs. The PRS derived from general cognitive function-associated SNPs was significantly associated with cognitive flexibility. Nongenetic factors (age, education, sex, and tobacco recency) also exerted significant effects on cognitive flexibility. Our study demonstrates that both genetic and nongenetic factors impact cognitive flexibility, and variants in genes involved in protein degradation and brain development may contribute to population variation in cognitive function.