Intelligence Test Performance Research Articles

Polyphenol intake beneficially associates with inflammation and cognitive performance, and is mediated by MRI‐derived features

AbstractBackgroundEarly changes to cognitive performance and neurophysiological biomarkers offer insights into one’s future risk of developing Alzheimer’s disease or other dementias. Evidence suggests a link between polyphenol intake and reduced incidence of age‐associated cognitive decline and neurodegeneration. These relationships may be driven by the effect of dietary polyphenols on inflammation and degeneration of critical neurological structures and systems. These relationships are challenging to assess, as few cohorts allow cohesive assessment of polyphenol intake, systemic inflammation, neurophysiological measures and cognition.MethodPolyphenol intake was assessed in two UK cohorts: The Airwave Health Monitoring Study and UK Biobank (UKB). Diet diary and questionnaire data were integrated with polyphenol composition data from Phenol‐Explorer to allow for testing of associations between polyphenol intake, blood biomarkers of inflammation, and cognitive performance. 9008 Airwave participants and 209,163 UKB participants were included in a cross‐sectional analysis. C‐reactive protein (CRP) and fibrinogen were used as blood biomarkers of inflammation, and cognitive assessments included reaction time (milliseconds) and fluid intelligence (score /13). Neuroimaging assessments included grey matter volumes and white matter integrity, and were considered individually and using PCA.ResultLinear regressions showed inverse associations between total polyphenol intake and CRP: ß ‐0.00702 (Airwave) and ß = ‐0.00672 (UKB), both P <0.001, as well as fibrinogen: ß ‐0.00221; P = 0.038 (Airwave only), in addition to biomarker associations with polyphenols at the compound group level. Regarding cognition, linear regressions revealed beneficial associations between total intake and performance in fluid intelligence tests: ß 0.00657; P = 0.009 (Airwave) and ß 0.00715, P <0.001 (UKB), and reaction time ß ‐0.0000977; P = 0.020 (UKB). Mediations of the polyphenol‐fluid intelligence relationship were detected for IDPs including grey matter volumes of hippocampal‐associated regions, and white matter integrity measured using ISOVF.ConclusionWe described polyphenol intake in two large, contemporary UK cohorts, and discovered associations between higher intake and improved inflammatory markers and cognitive performance, as well as mediations of the polyphenol‐cognition relationship by physical neurological markers. This contributes to evidence supporting the health benefits of dietary polyphenols, clarifies the physiological pathways through which they may act, and highlights their relevance when considering preventative interventions for neurodegeneration.

Polyphenol intake beneficially associates with inflammation and cognitive performance, and is mediated by MRI‐derived features

AbstractBackgroundEarly changes to cognitive performance and neurophysiological biomarkers offer insights into one’s future risk of developing Alzheimer’s disease or other dementias. Evidence suggests a link between polyphenol intake and reduced incidence of age‐associated cognitive decline and neurodegeneration. These relationships may be driven by the effect of dietary polyphenols on inflammation and degeneration of critical neurological structures and systems. These relationships are challenging to assess, as few cohorts allow cohesive assessment of polyphenol intake, systemic inflammation, neurophysiological measures and cognition.MethodPolyphenol intake was assessed in two UK cohorts: The Airwave Health Monitoring Study and UK Biobank (UKB). Diet diary and questionnaire data were integrated with polyphenol composition data from Phenol‐Explorer to allow for testing of associations between polyphenol intake, blood biomarkers of inflammation, and cognitive performance. 9008 Airwave participants and 209,163 UKB participants were included in a cross‐sectional analysis. C‐reactive protein (CRP) and fibrinogen were used as blood biomarkers of inflammation, and cognitive assessments included reaction time (milliseconds) and fluid intelligence (score /13). Neuroimaging assessments included grey matter volumes and white matter integrity, and were considered individually and using PCA.ResultLinear regressions showed inverse associations between total polyphenol intake and CRP: β ‐0.00702 (Airwave) and β = ‐0.00672 (UKB), both P <0.001, as well as fibrinogen: β ‐0.00221; P = 0.038 (Airwave only), in addition to biomarker associations with polyphenols at the compound group level. Regarding cognition, linear regressions revealed beneficial associations between total intake and performance in fluid intelligence tests: β 0.00657; P = 0.009 (Airwave) and β 0.00715, P <0.001 (UKB), and reaction time β ‐0.0000977; P = 0.020 (UKB). Mediations of the polyphenol‐fluid intelligence relationship were detected for IDPs including grey matter volumes of hippocampal‐associated regions, and white matter integrity measured using ISOVF.ConclusionWe described polyphenol intake in two large, contemporary UK cohorts, and discovered associations between higher intake and improved inflammatory markers and cognitive performance, as well as mediations of the polyphenol‐cognition relationship by physical neurological markers. This contributes to evidence supporting the health benefits of dietary polyphenols, clarifies the physiological pathways through which they may act, and highlights their relevance when considering preventative interventions for neurodegeneration.

49 Examining Associations Between Intelligence and Adaptive Functioning in Adults with Down Syndrome at Risk for Alzheimer's Disease

Objective:Individuals with Down syndrome (DS) experience intellectual disability, such that measures of cognitive and adaptive functioning are near the normative floor upon evaluation. Individuals with DS are also at increased risk for Alzheimer's disease (AD) beginning around age 40; and test performances and adaptive ratings at the normative floor make it difficult to detect change in cognition and functioning. This study first assessed the range of raw intelligence scores and raw adaptive functioning of individuals with DS at the normative floor. Next, we assessed whether those raw intelligence scores were predictive of raw adaptive functioning scores, and by association, whether they may be meaningful when assessing change in individuals with a lower baseline of cognitive functioning.Participants and Methods:Participants were selected from a cohort of 117 adults with DS in a longitudinal study examining AD risk. Participants (n=96; M=40.9 years-old, SD=10.67; 57.3% female) were selected if they had both a completed measure of IQ (Kaufmann Brief Intelligence Test; KBIT2) and informant ratings of adaptive functioning (Vineland Adaptive Behavior Scales; VABS-II). Multiple regression was conducted predicting VABS-II total raw score using K-BIT2 total raw score, while controlling for age.Results:A slight majority (57.3%) of the sample had a standardized IQ score of 40 with the majority (95.7%) having a standardized score at or below 60. Additionally, 85.3% of the sample had a standard VABS-II score at or below 60. Within the normative floor for the KBIT2 (IQ=40), there was a normal distribution and substantial range of both KBIT2 raw scores (M = 31.19, SD = 13.19, range: 2 to 41) and VABS-II raw scores (M = 406.33, SD = 84.91, range: 198 to 569). Using the full sample, age significantly predicted raw VABS-II scores (ß = -.283, p = .008). When KBIT2 raw scores were included in the model, age was no longer an independently significant predictor. KBIT2 raw scores significantly predicted raw VABS-II scores (ß = .689, p < .001). Age alone accounted for 8.0% of variance in VABS-II raw scores and KBIT2 raw scores accounted for 43.8% additional variance in VABS-II raw scores. This relationship was maintained when the sample was reduced to individuals at the normative floor (n = 51) where KBIT2 raw scores accounted for 23.7% of the variance in raw VABS-II scores (ß = .549, p < .001).Conclusions:The results indicate that meaningful variability exists among raw intelligence test performances that may be masked by scores at the normative floor. Further, the variability in raw intelligence scores is associated with variability in adaptive functioning, such that lower intelligence scores are associated with lower ratings of adaptive functioning. Considering this relationship would be masked by a reduction of range due to norming, these findings indicate that raw test performances and adaptive functioning ratings may have value when monitoring change in adults with DS at risk for AD.

Selected Wechsler Memory Scale norms and aging: Implications for assessment

The Wechsler Memory Scale-I was published in 1945, although it had been used clinically since 1940. Since the original publication, there have been three major revisions. The Wechsler Memory Scale-Revised was published in 1987, the Wechsler Memory Scale-III in 1997, and the Wechsler Memory Scale-IV in 2009. It is significant to note that all official versions of the memory scale have remained in clinical and research use well into the second decade of the 20th century. Each version of the scale was designed to assess memory and attention dysfunction in various clinical populations by comparing the discrepancy between intelligence and memory test performance using age-corrected standard scores. It has long been known that intellectual and memory performance declines with age. Most psychologists, however, are likely unaware of the extent of the decline with age or how this decline is manifested in the various versions of the Wechsler Memory Scale. The purpose of this paper is to investigate what selected norms accompanying each official version of the Wechsler Memory Scale reveal about aging and memory performance and discuss the possible clinical implications of such.

Intelligence Polygenic Score Is More Predictive of Crystallized Measures: Evidence From the Adolescent Brain Cognitive Development (ABCD) Study

Findings in adults have shown that crystallized measures of intelligence, which are more culturally sensitive than fluid intelligence measures, have greater heritability; however, these results have not been found in children. The present study used data from 8,518 participants between 9 and 11 years old from the Adolescent Brain Cognitive Development (ABCD) Study. We found that polygenic predictors of intelligence test performance (based on genome-wide association meta-analyses of data from 269,867 individuals) and of educational attainment (based on data from 1.1 million individuals) predicted neurocognitive performance. We found that crystallized measures were more strongly associated with both polygenic predictors than were fluid measures. This mirrored heritability differences reported previously in adults and suggests similar associations in children. This may be consistent with a prominent role of gene–environment correlation in cognitive development measured by crystallized intelligence tests. Environmental and experiential mediators may represent malleable targets for improving cognitive outcomes.

Working memory load affects intelligence test performance by reducing the strength of relational item bindings and impairing the filtering of irrelevant information

There is a broad consensus that individual differences in working memory capacity (WMC) are strongly related to individual differences in intelligence. However, correlational studies do not allow conclusions about the causal nature of the relationship between WMC and fluid intelligence. While research on the cognitive basis of intelligence typically assumes that simpler lower-level cognitive processes contribute to individual differences in higher-order reasoning processes, a reversed causality or a third variable giving rise to two intrinsically uncorrelated variables may exist. In two studies (n1 = 65, n2 = 113), we investigated the causal nature of the relationship between WMC and intelligence by assessing the experimental effect of working memory load on intelligence test performance. Moreover, we tested if the effect of working memory load on intelligence test performance increased under time constraints, as previous studies have shown that the association between the two constructs increases if intelligence tests are administered with a strict time limit. We show that working memory load impaired intelligence test performance, but that this experimental effect was not affected by time constraints, which suggests that the experimental manipulations of working memory capacity and processing time did not affect the same underlying cognitive process. Using a computational modeling approach, we demonstrated that external memory load affected both the building and maintenance of relational item bindings and the filtering of irrelevant information in working memory. Our results confirm that WMC causally contributes to higher-order reasoning processes. Moreover, they support the hypothesis that working memory capacity in general and the abilities to maintain arbitrary bindings and to disengage from irrelevant information in particular are intrinsically related to intelligence.

Fluid Intelligence Is (Much) More than Working Memory Capacity: An Experimental Analysis.

Empirical evidence suggests a great positive association between measures of fluid intelligence and working memory capacity, which implied to some researchers that fluid intelligence is little more than working memory. Because this conclusion is mostly based on correlation analysis, a causal relationship between fluid intelligence and working memory has not yet been established. The aim of the present study was therefore to provide an experimental analysis of this relationship. In a first study, 60 participants worked on items of the Advanced Progressive Matrices (APM) while simultaneously engaging in one of four secondary tasks to load specific components of the working memory system. There was a diminishing effect of loading the central executive on the APM performance, which could explain 15% of the variance in the APM score. In a second study, we used the same experimental manipulations but replaced the dependent variable with complex working memory span tasks from three different domains. There was also a diminishing effect of the experimental manipulation on span task performance, which could now explain 40% of the variance. These findings suggest a causal effect of working memory functioning on fluid intelligence test performance, but they also imply that factors other than working memory functioning must contribute to fluid intelligence.

Students' intelligence test results after six and sixteen months of irregular schooling due to the COVID-19 pandemic.

The COVID-19 pandemic has affected schooling worldwide. In many places, schools closed for weeks or months, only part of the student body could be educated at any one time, or students were taught online. Previous research discloses the relevance of schooling for the development of cognitive abilities. We therefore compared the intelligence test performance of 424 German secondary school students in Grades 7 to 9 (42% female) tested after the first six months of the COVID-19 pandemic (i.e., 2020 sample) to the results of two highly comparable student samples tested in 2002 (n = 1506) and 2012 (n = 197). The results revealed substantially and significantly lower intelligence test scores in the 2020 sample than in both the 2002 and 2012 samples. We retested the 2020 sample after another full school year of COVID-19-affected schooling in 2021. We found mean-level changes of typical magnitude, with no signs of catching up to previous cohorts or further declines in cognitive performance. Perceived stress during the pandemic did not affect changes in intelligence test results between the two measurements.

The Associations between Results in Different Domains of Cognitive and Psychomotor Abilities Measured in Medical Students.

We aimed to investigate the associations between intelligence quotient test scores obtained using the Raven's Advanced Progressive Matrices (APM) and psychomotor testing using the Complex Reactionmeter Drenovac (CRD) test battery, while taking into account previous theoretical approaches recognizing intelligent behavior as the cumulative result of a general biological speed factor reflected in the reaction time for perceptual detections and motor decisions. A total of 224 medical students at the University of Split School of Medicine were recruited. Their IQ scores were assessed using Raven's APM, while the computerized tests of CRD-series were used for testing the reaction time of perception to visual stimulus (CRD311), psychomotor limbs coordination task (CRD411), and solving simple arithmetic operations (CRD11). The total test-solving (TTST) and the minimum single-task-solving (MinT) times were analyzed. On the CRD11 test, task-solving times were shorter in students with higher APM scores (r = -0.48 for TTST and r = -0.44 for MinT; p < 0.001 for both). Negative associations between task-solving times and APM scores were reported on CRD311 (r = -0.30 for TTST and r = -0.33 for MinT, p < 0.001 for both). Negative associations between task-solving times in CRD411 and APM scores (r = -0.40 for TTST and r = -0.30 for MinT, p < 0.001 for both) were found. Faster reaction time in psychomotor limbs coordination tasks, the reaction time of perception to visual stimulus, and the reaction time of solving simple arithmetic operations were associated with a higher APM score in medical students, indicating the importance of mental speed in intelligence test performance. However, executive system functions, such as attention, planning, and goal weighting, might also impact cognitive abilities and should be considered in future research.

Effects of Transcranial Direct Current Stimulation Over the Left Primary Motor Cortex on Verbal Intelligence.

Previous studies have shown that changes in gray matter density and volume in the left primary motor cortex are significantly associated with changes in individuals’ verbal intelligence quotient (VIQ), but not with their performance intelligence quotient (PIQ). In the present study, we examined the effects of transcranial direct current stimulation (tDCS) over the left primary motor cortex on performance in intelligence tests. We chose four subtests (two each for VIQ and PIQ) of the Wechsler Adult Intelligence Scale-Chinese Revised version and randomized participants into anodal, cathodal, and sham groups. We found that anodal stimulation significantly improved performance in verbal intelligence subtests compared to cathodal and sham stimulation, while performance intelligence subtest scores did not change in any stimulation condition. These findings suggest that the excitation level of the left primary motor cortex has a unique effect on verbal intelligence.

Effort impacts IQ test scores in a minor way: A multi-study investigation with healthy adult volunteers

Test motivation has been suggested to strongly influence low-stakes intelligence scores, with for instance, a recent meta-analysis of monetary incentive effects suggesting an average 9.6 IQ point impact (d = 0.64). Effects of such magnitude would have important implications for the predictive validity of intelligence tests. We report six studies (N = 4208) investigating the association and potential causal link of effort on cognitive performance. In three tests of the association of motivation with cognitive test scores we find a positive, but modest linear association of scores with reported effort (N = 3007: r ~ 0.28). In three randomized control tests of the effects of monetary incentive on test scores (total N = 1201), incentive effects were statistically non-significant in each study, showed no dose dependency, and jointly indicated an effect one quarter the size previously estimated (d = 0.166). These results suggest that, in neurotypical adults, individual differences in test motivation have, on average, a negligible influence on intelligence test performance. (≈ 2.5 IQ points). The association between test motivation and test performance likely partly reflects differences in ability, and subjective effort partly reflects outcome expectations.

Relationship between emotional intelligence and academic performance in peruvian university students

Emotional intelligence is the set of capacities that allow a student to properly manage their emotions and interpersonal relationships, when subjected to stressful situations, such as the educational environment; in which they have to deal with internal and external conflicts for good academic performance. The research aimed to relate emotional intelligence and academic performance in students of the National Autonomous University of Chota, Peru. The study was descriptive correlational, not cross-sectional experimental, and it worked with 325 university students who signed the informed consent, after knowing the purpose of the research; emotional intelligence was determined with the BarOn ICE Emotional Intelligence Test and academic performance with a data collection sheet. The results show a higher proportion of university students with high emotional intelligence (51.1%) and average academic performance of 12.59 ± 1.17 weighted score, results similar to those reported by various national and international studies. It is concluded that there is a statistically significant relationship between emotional intelligence, the adaptability dimension and the academic performance of university students (p = 0.043 and p = 0.021).

How Is Intelligence Test Performance Associated with Creative Achievement? A Meta-Analysis.

This paper presents a meta-analysis of the links between intelligence test scores and creative achievement. A three-level meta-analysis of 117 correlation coefficients from 30 studies found a correlation of r = .16 (95% CI: .12, .19), closely mirroring previous meta-analytic findings. The estimated effects were stronger for overall creative achievement and achievement in scientific domains than for correlations between intelligence scores and creative achievement in the arts and everyday creativity. No signs of publication bias were found. We discuss theoretical implications and provide recommendations for future studies.

Intelligence test items varying in capacity demands cannot be used to test the causality of working memory capacity for fluid intelligence

There is a strong relationship between fluid intelligence and working memory capacity (WMC). Yet, the cognitive mechanisms underlying this relationship remain elusive. The capacity hypothesis states that this relationship is due to limitations in the amount of information that can be stored and held active in working memory. Previous research aimed at testing the capacity hypothesis assumed that it implies stronger relationships of intelligence test performance with WMC for test items with higher capacity demands. The present article addresses this assumption through simulations of three theoretical models implementing the capacity hypothesis while systematically varying different psychometric variables. The results show that almost any relation between the capacity demands of items and their correlation with WMC can be obtained. Therefore, the assumption made by previous studies does not hold: The capacity hypothesis does not imply stronger correlations of WMC and intelligence test items with higher capacity demands. Items varying in capacity demands cannot be used to test the causality of WMC (or any other latent variable) for fluid intelligence.

Neuroimaging evidence for a network sampling theory of individual differences in human intelligence test performance

Despite a century of research, it remains unclear whether human intelligence should be studied as one dominant, several major, or many distinct abilities, and how such abilities relate to the functional organisation of the brain. Here, we combine psychometric and machine learning methods to examine in a data-driven manner how factor structure and individual variability in cognitive-task performance relate to dynamic-network connectomics. We report that 12 sub-tasks from an established intelligence test can be accurately multi-way classified (74%, chance 8.3%) based on the network states that they evoke. The proximities of the tasks in behavioural-psychometric space correlate with the similarities of their network states. Furthermore, the network states were more accurately classified for higher relative to lower performing individuals. These results suggest that the human brain uses a high-dimensional network-sampling mechanism to flexibly code for diverse cognitive tasks. Population variability in intelligence test performance relates to the fidelity of expression of these task-optimised network states.

Causal relationships between genetically determined metabolites and human intelligence: a Mendelian randomization study

Intelligence predicts important life and health outcomes, but the biological mechanisms underlying differences in intelligence are not yet understood. The use of genetically determined metabotypes (GDMs) to understand the role of genetic and environmental factors, and their interactions, in human complex traits has been recently proposed. However, this strategy has not been applied to human intelligence. Here we implemented a two-sample Mendelian randomization (MR) analysis using GDMs to assess the causal relationships between genetically determined metabolites and human intelligence. The standard inverse-variance weighted (IVW) method was used for the primary MR analysis and three additional MR methods (MR-Egger, weighted median, and MR-PRESSO) were used for sensitivity analyses. Using 25 genetic variants as instrumental variables (IVs), our study found that 5-oxoproline was associated with better performance in human intelligence tests (PIVW = 9.25 × 10–5). The causal relationship was robust when sensitivity analyses were applied (PMR-Egger = 0.0001, PWeighted median = 6.29 × 10–6, PMR-PRESSO = 0.0007), and repeated analysis yielded consistent result (PIVW = 0.0087). Similarly, also dihomo-linoleate (20:2n6) and p-acetamidophenylglucuronide showed robust association with intelligence. Our study provides novel insight by integrating genomics and metabolomics to estimate causal effects of genetically determined metabolites on human intelligence, which help to understanding of the biological mechanisms related to human intelligence.

Metacognitive Awareness Scale, Domain Specific (MCAS-DS): Assessing Metacognitive Awareness During Raven's Progressive Matrices.

Metacognition, the cognition about cognition, is closely linked to intelligence and therefore understanding the metacognitive processes underlying intelligence test performance, specifically on Raven’s Progressive Matrices, could help advance the knowledge about intelligence. The measurement of metacognition, is often done using domain-general offline questionnaires or domain-specific online think-aloud protocols. This study aimed to investigate the relationship between metacognitive awareness and intelligence via the design and use of a novel Meta-Cognitive Awareness Scale – Domain Specific (MCAS-DS) that encourages reflection of task strategy processes. This domain-specific scale was first constructed to measure participants’ awareness of their own metacognition linked to Raven’s Progressive Matrices (SPM). Following discriminatory index and Exploratory Factor Analysis, a 15-item scale was derived. Exploratory Factor Analysis showed five factors: Awareness of Engagement in Self-Monitoring, Awareness of Own Ability, Awareness of Responding Speed/Time, Awareness of Alternative Solutions and Awareness of Requisite Problem-Solving Resources. The intelligence level of ninety-eight adults was then estimated using Raven’s Standard Progressive Matrices. Participants also completed the MCAS-DS, and further items that examined their test-taking behavior and Confidence level. Metacognitive awareness was positively correlated to standardized IQ scores derived from the SPM whilst Over-Confidence derived using the Confidence level measure was negatively correlated to SPM. Despite some limitations, this study shows promise for elucidating the relationship between metacognitive awareness and intelligence using the task-specific scale.

Association between cesarean section and human capital in adulthood: 1982 and 1993 Pelotas birth cohorts, Rio Grande do Sul State, Brazil.

This study aims to assess the association between mode of delivery and human capital among young adults enrolled in the 1982 and 1993 Pelotas birth cohorts, Rio Grande do Sul State, Brasil. In 1982 and 1993, the maternity hospitals of the municipality were daily visited, the births identified, and those live births, whose family lived in the urban area of Pelotas, were examined and their mothers interviewed. Information on mode of delivery, vaginal or cesarean, was provided by the mother in the perinatal study. Performance in intelligence tests achieved schooling and income were evaluated in the 30 years visit at the 1982 cohort. At the 1993 cohort, schooling and income were assessed at the 22 years visit, whereas IQ was evaluated at 18 years. Tobacco smoking in adulthood and type of school was used as negative outcomes to strength causal inference. Initially, cesarean section was positively associated with human capital at adulthood, with the exception of income in the 1993 cohort. After controlling for confounders, the magnitude of the associations was strongly reduced, and the regression coefficients were close to the null value. The negative outcome analysis showed that, after controlling for confounding variables, the mode of delivery was not associated with tobacco smoking and type of school. Suggesting that the variables included in the regression model to control for confounding, provided an adequate adjustment and it is unlikely that the results are due to residual confounding by socioeconomic status. On the other hand, considering the short- and long-term risks and the epidemic of cesarean sections, measures should be implemented to reduce its prevalence.

Determinants of early childhood stimulation: Evidence using panel data from Chile

This paper examines the determinants of early childhood stimulation provided by caregivers using an ecological approach. The focus of our inquiry is on Chile, one of the most economically unequal countries in the world. We use data from the Longitudinal Early Childhood Survey conducted in 2010 and 2012, which contains information regarding infants aged 30 months on average (n = 8,251). Early childhood stimulation is examined using a multidimensional index that comprises three domains: caregivers’ stimulation of cognitive-language, sensorimotor, and socio-emotional development. Our dynamic models show that the main factors that lead to less stimulation are low caregiver education, low-income households, and large families. Specifically, it was found that an additional child being born within a two-year period decreases stimulation, indicating possible competition between siblings due to time and resource restrictions in the household. Furthermore, caregivers’ performance in personality (BFI) and linguistic intelligence (WAIS language) tests was found to be a more significant factor than operational memory. Taken together, these findings suggest the need for initiatives aimed at increasing equality in early childhood stimulation.

Genetic predictors of educational attainment and intelligence test performance predict voter turnout.

Although the genetic influence on voter turnout is substantial (typically 40-50%), the underlying mechanisms remain unclear. Across the social sciences, research suggests that 'resources for politics' (as indexed notably by educational attainment and intelligence test performance) constitute a central cluster of factors that predict electoral participation. Educational attainment and intelligence test performance are heritable. This suggests that the genotypes that enhance these phenotypes could positively predict turnout. To test this, we conduct a genome-wide complex trait analysis of individual-level turnout. We use two samples from the Danish iPSYCH case-cohort study, including a nationally representative sample as well as a sample of individuals who are particularly vulnerable to political alienation due to psychiatric conditions (n = 13,884 and n = 33,062, respectively). Using validated individual-level turnout data from the administrative records at the polling station, genetic correlations and Mendelian randomization, we show that there is a substantial genetic overlap between voter turnout and both educational attainment and intelligence test performance.