Genetic basis of a cognitive complexity metric

Genome-wide association study of population-standardised cognitive performance phenotypes in a rural South African community

Cognitive function is an indicator for global physical and mental health, and cognitive impairment has been associated with poorer life outcomes and earlier mortality. A standard cognition test, adapted to a rural-dwelling African community, and the Oxford Cognition Screen-Plus were used to capture cognitive performance as five continuous traits (total cognition score, verbal episodic memory, executive function, language, and visuospatial ability) for 2,246 adults in this population of South Africans. A novel common variant, rs73485231, reached genome-wide significance for association with episodic memory using data for ~14 million markers imputed from the H3Africa genotyping array data. Window-based replication of previously implicated variants and regions of interest support the discovery of African-specific associated variants despite the small population size and low allele frequency. This African genome-wide association study identifies suggestive associations with general cognition and domain-specific cognitive pathways and lays the groundwork for further genomic studies on cognition in Africa.

Maternal genetic risk for depression and child human capital

We here address the causal relationship between the maternal genetic risk for depression and child human capital using UK birth-cohort data. We find that an increase of one standard deviation (SD) in the maternal polygenic risk score for depression reduces their children's cognitive and non-cognitive skill scores by 5 to 7% of a SD throughout adolescence. Our results are robust to a battery of sensitivity tests addressing, among others, concerns about pleiotropy and dynastic effects. Our Gelbach decomposition analysis suggests that the strongest mediator is genetic nurture (through maternal depression itself), with genetic inheritance playing only a marginal role.

Generating distant analogies facilitates relational integration: Intermediary role of relational mindset and cognitive load

Relational integration is essential for learning, working, and living, as we must encode enormous volumes of information and extract their relations to construct knowledge about the environment. Recent research hints that generating distant analogies can temporarily facilitate learners’ state-based relational integration. This study aimed to investigate the internal mechanism underlying the facilitation effect and preliminarily confirm its application in education. First, we adopted the classical n-term premise integration task (Experiment 1a) and the Latin Square Task (Experiment 1b) to explore the robustness of the facilitation effect. Then we employed an emerging multidimensional relational reasoning task to further explore the internal mechanism underlying this facilitation effect (Experiment 2). Finally, we verified the practical role of the facilitation effect in learning the interaction concept in statistics (Experiment 3). The results showed that generating distant analogies did facilitate students’ relational integration performance, both in classical cognitive tasks and in a practical learning task, and a relational mindset and cognitive load play an intermediary role in the facilitation, supporting the cognitive load theory. The results suggest that generating distant analogies can be a useful warm-up activity to assist educators in promoting students’ relational integration.

Individual differences in relational reasoning

Various forms of relational processing have been linked to cognitive capacity measures, such as working memory and fluid intelligence. However, previous work has not established the extent to which different forms of relational processing reflect common factors, nor whether individual differences in cognitive style also contribute to variations in relational reasoning. The current study took an individual-differences approach to investigate the prerequisites for relational processing. In two studies, college students completed a battery of standardized tests of individual differences related to fluid intelligence and cognitive style, as well as a series of experimental tasks that require relational reasoning. Moderate correlations were obtained between relational processing and measures of cognitive capacity. Questionnaire measures of cognitive style generally did not improve predictions of relational processing beyond the influence of measures of cognitive capacity.

Beyond Lipid Signaling: Pleiotropic Effects of Diacylglycerol Kinases in Cellular Signaling

The diacylglycerol kinase family, which can attenuate diacylglycerol signaling and activate phosphatidic acid signaling, regulates various signaling transductions in the mammalian cells. Studies on the regulation of diacylglycerol and phosphatidic acid levels by various enzymes, the identification and characterization of various diacylglycerol and phosphatidic acid-regulated proteins, and the overlap of different diacylglycerol and phosphatidic acid metabolic and signaling processes have revealed the complex and non-redundant roles of diacylglycerol kinases in regulating multiple biochemical and biological networks. In this review article, we summarized recent progress in the complex and non-redundant roles of diacylglycerol kinases, which is expected to aid in restoring dysregulated biochemical and biological networks in various pathological conditions at the bed side.

Genetic Variation of a DRD2 Co-expression Network is Associated with Changes in Prefrontal Function After D2 Receptors Stimulation

Dopamine D2 receptors (D2Rs) contribute to the inverted U-shaped relationship between dopamine signaling and prefrontal function. Genetic networks from post-mortem human brain revealed 84 partner genes co-expressed with DRD2. Moreover, eight functional single nucleotide polymorphisms combined into a polygenic co-expression index (PCI) predicted co-expression of this DRD2 network and were associated with prefrontal function in humans. Here, we investigated the non-linear association of the PCI with behavioral and Working Memory (WM) related brain response to pharmacological D2Rs stimulation. Fifty healthy volunteers took part in a double-blind, placebo-controlled, functional MRI (fMRI) study with bromocriptine and performed the N-Back task. The PCI by drug interaction was significant on both WM behavioral scores (P = 0.046) and related prefrontal activity (all corrected P < 0.05) using a polynomial PCI model. Non-linear responses under placebo were reversed by bromocriptine administration. fMRI results on placebo were replicated in an independent sample of 50 participants who did not receive drug administration (P = 0.034). These results match earlier evidence in non-human primates and confirm the physiological relevance of this DRD2 co-expression network. Results show that in healthy subjects, different alleles evaluated as an ensemble are associated with non-linear prefrontal responses. Therefore, brain response to a dopaminergic drug may depend on a complex system of allelic patterns associated with DRD2 co-expression.

Genetics and Learning: How the Genes Influence Educational Attainment

The brain is the organ of thought. The word thought is defined as the act of thinking about or considering something: an idea or opinion, or a set of ideas about a particular subject. It implicitly includes the processes of learning. Mental functions, including most if not all aspects of human behavior, such as those related to learning, arise from the activity of the brain. Neural connections that generate and support mental functions are formed throughout life, which enables lifelong learning of new concepts and skills. Both brain formation and function, as well as neural plasticity, are influenced by the activity of a variety of genes and also by epigenetic modifications, which contribute to the regulation of gene expression by adapting it to environmental conditions. In this review, aimed especially at education professionals, I discuss the genetic and epigenetic contributions to mental aspects related to learning processes in terms of heritability. I will argue that, despite most if not all aspects related to learning having a clear genetic background, innate abilities can be enhanced or diminished through educational processes. Thus, the importance of education, in the context of the inheritability of learning processes, will be discussed. The conclusion I draw is that, despite the relatively high genetic heritability shown in most brain processes associated with learning, educational practices are a key contributor to student development, allowing genetically based skills to be enhanced or alternatively diminished. Therefore one of the main goals of education in a changing an uncertain world should be to form adaptable and versatile people who can, and want to, make the most of their capabilities. Thus, knowledge derived from genetics and epigenetics, as well as from neuroscience, should be used to enhance education professionals’ understanding of the biological origins of differences in mental capabilities, thereby empowering them with the possibility to adopt more respectful and flexible educational practices to attain the goal mentioned above.

Diacylglycerol Kinase Malfunction in Human Disease and the Search for Specific Inhibitors

The diacylglycerol kinases (DGKs) are master regulator kinases that control the switch from diacylglycerol (DAG) to phosphatidic acid (PA), two lipids with important structural and signaling properties. Mammalian DGKs distribute into five subfamilies that regulate local availability of DAG and PA pools in a tissue- and subcellular-restricted manner. Pharmacological manipulation of DGK activity holds great promise, given the critical contribution of specific DGK subtypes to the control of membrane structure, signaling complexes, and cell-cell communication. The latest advances in the DGK field have unveiled the differential contribution of selected isoforms to human disease. Defects in the expression/activity of individual DGK isoforms contribute substantially to cognitive impairment, mental disorders, insulin resistance, and vascular pathologies. Abnormal DGK overexpression, on the other hand, confers the acquisition of malignant traits including invasion, chemotherapy resistance, and inhibition of immune attack on tumors. Translation of these findings into therapeutic approaches will require development of methods to pharmacologically modulate DGK functions. In particular, inhibitors that target the DGKα isoform hold particular promise in the fight against cancer, on their own or in combination with immune-targeting therapies.

Genetic underpinnings in Alzheimer's disease - a review

In this review, we discuss the genetic etiologies of Alzheimer's disease (AD). Furthermore, we review genetic links to protein signaling pathways as novel pharmacological targets to treat AD. Moreover, we also discuss the clumps of AD-m ediated genes according to their single nucleotide polymorphism mutations. Rigorous data mining approaches justified the significant role of genes in AD prevalence. Pedigree analysis and twin studies suggest that genetic components are part of the etiology, rather than only being risk factors for AD. The first autosomal dominant mutation in the amyloid precursor protein (APP) gene was described in 1991. Later, AD was also associated with mutated early-onset (presenilin 1/2, PSEN1/2 and APP) and late-onset (apolipoprotein E, ApoE) genes. Genome-wide association and linkage analysis studies with identified multiple genomic areas have implications for the treatment of AD. We conclude this review with future directions and clinical implications of genetic research in AD.

Transcriptomic context of DRD1 is associated with prefrontal activity and behavior during working memory

Dopamine D1 receptor (D1R) signaling shapes prefrontal cortex (PFC) activity during working memory (WM). Previous reports found higher WM performance associated with alleles linked to greater expression of the gene coding for D1Rs (DRD1). However, there is no evidence on the relationship between genetic modulation of DRD1 expression in PFC and patterns of prefrontal activity during WM. Furthermore, previous studies have not considered that D1Rs are part of a coregulated molecular environment, which may contribute to D1R-related prefrontal WM processing. Thus, we hypothesized a reciprocal link between a coregulated (i.e., coexpressed) molecular network including DRD1 and PFC activity. To explore this relationship, we used three independent postmortem prefrontal mRNA datasets (total n = 404) to characterize a coexpression network including DRD1 Then, we indexed network coexpression using a measure (polygenic coexpression index-DRD1-PCI) combining the effect of single nucleotide polymorphisms (SNPs) on coexpression. Finally, we associated the DRD1-PCI with WM performance and related brain activity in independent samples of healthy participants (total n = 371). We identified and replicated a coexpression network including DRD1, whose coexpression was correlated with DRD1-PCI. We also found that DRD1-PCI was associated with lower PFC activity and higher WM performance. Behavioral and imaging results were replicated in independent samples. These findings suggest that genetically predicted expression of DRD1 and of its coexpression partners stratifies healthy individuals in terms of WM performance and related prefrontal activity. They also highlight genes and SNPs potentially relevant to pharmacological trials aimed to test cognitive enhancers modulating DRD1 signaling.

Associations between maternal cytokine levels during gestation and measures of child cognitive abilities and executive functioning

Preclinical studies demonstrate that environmentally-induced alterations in inflammatory cytokines generated by the maternal and fetal immune system can significantly impact fetal brain development. Yet, the relationship between maternal cytokines during gestation and later cognitive ability and executive function remains understudied. Children (n = 246) were born of mothers enrolled in the Newborn Epigenetic Study - a prospective pre-birth cohort in the Southeastern US. We characterized seven cytokines [IL-1β, IL-4,IL-6, IL-12p70, IL-17A, tumor necrosis factor-α (TNFα), and interferon-γ (IFNγ)] and one chemokine (IL-8) from maternal plasma collected during pregnancy. We assessed children's cognitive abilities and executive functioning at a mean age of 4.5 (SD = 1.1) years. Children's DAS-II and NIH toolbox scores were regressed on cytokines and the chemokine, controlling for maternal age, race, education, body mass index, IQ, parity, smoking status, delivery type, gestational weeks, and child birth weight and sex. Higher IL-12p70 (β_IL-12p70 = 4.26, p = 0.023) and IL-17A (β_IL-17A = 3.70, p = 0.042) levels were related to higher DAS-II GCA score, whereas higher IL-1β (β_IL-1B = -6.07, p = 0.003) was related to lower GCA score. Higher IL-12p70 was related to higher performance on NIH toolbox measures of executive functions related to inhibitory control and attention (β_IL-12p70 = 5.20, p = 0.046) and cognitive flexibility (β_IL-12p70 = 5.10, p = 0.047). Results suggest that dysregulation in gestational immune activity are associated with child cognitive ability and executive functioning.

Resolving Conflicts Between Syntax and Plausibility in Sentence Comprehension

Comprehension of plausible and implausible object- and subject-relative clause sentences with and without prepositional phrases was examined. Undergraduates read each sentence then evaluated a statement as consistent or inconsistent with the sentence. Higher acceptance of consistent than inconsistent statements indicated reliance on syntactic analysis. Higher acceptance of plausible than implausible statements reflected reliance on semantic plausibility. There was greater reliance on semantic plausibility and lesser reliance on syntactic analysis for more complex object-relatives and sentences with prepositional phrases than for less complex subject-relatives and sentences without prepositional phrases. Comprehension accuracy and confidence were lower when syntactic analysis and semantic plausibility yielded conflicting interpretations. The conflict effect on comprehension was significant for complex sentences but not for less complex sentences. Working memory capacity predicted resolution of the syntax-plausibility conflict in more and less complex items only when sentences and statements were presented sequentially. Fluid intelligence predicted resolution of the conflict in more and less complex items under sequential and simultaneous presentation. Domain-general processes appear to be involved in resolving syntax-plausibility conflicts in sentence comprehension.

A method for integrating neuroimaging into genetic models of learning performance

Specific learning disorders (SLD) are an archetypal example of how clinical neuropsychological (NP) traits can differ from underlying genetic and neurobiological risk factors. Disparate environmental influences and pathologies impact learning performance assessed through cognitive examinations and clinical evaluations, the primary diagnostic tools for SLD. We propose a neurobiological risk for SLD with neuroimaging biomarkers, which is integrated into a genome-wide association study (GWAS) of learning performance in a cohort of 479 European individuals between 8 and 21 years of age. We first identified six regions of interest (ROIs) in temporal and anterior cingulate regions where the group diagnosed with learning disability has the least overall variation, relative to the other group, in thickness, area, and volume measurements. Although we used the three imaging measures, the thickness was the leading contributor. Hence, we calculated the Euclidean distances between any two individuals based on their thickness measures in the six ROIs. Then, we defined the relative similarity of one individual according to the averaged ranking of pairwise distances from the individuals to those in the SLD group. The inverse of this relative similarity is called the neurobiological risk for the individual. Single nucleotide polymorphisms in the AGBL1 gene on chromosome 15 had a significant association with learning performance at a genome-wide level. This finding was supported in an independent cohort of 2,327 individuals of the same demographic profile. Our statistical approach for integrating genetic and neuroimaging biomarkers can be extended into studying the biological basis of other NP traits.

Heritability of Children's Dietary Intakes: A Population-Based Twin Study in China

Background: Despite evidence for some genetic control of dietary intake in adults, there is little evidence of how genetic factors influence children's dietary patterns. Objective: To estimate heritability of dietary intake in twin children from China and test if genetic effects on dietary intakes vary by the children's socio-economic status (SES). Methods: A sample of 622 twins (162 monozygotic and 149 dizygotic pairs; 298 boys and 324 girls aged 7–15 years) was recruited in South China. Dietary intakes were assessed using a validated 145-item semi-quantitative food frequency questionnaire. Pooled and sex-specific dietary patterns were identified using factor analysis. Heritability was estimated using structural equation models. Results: Heritable components differed by gender and for nutrients and food groups; and estimated heritability of dietary patterns was generally greater in girls than boys. In boys, estimated heritabilities ranged from 18.8% (zinc) to 58.4% (fat) for nutrients; and for food group, 1.1% (Western fast foods) to 65.8% (soft drinks). In girls, these estimates ranged from 5.1% (total energy) to 38.7% (percentage of energy from fat) for nutrients, and 12.6% (eggs) to 94.6% (Western fast foods) for food groups. Factor analysis identified five food patterns: vegetables and fruits, fried and fast foods, beverages, snacks and meats. Maternal education and family income were positively associated with higher heritabilities for intake of meat, fried, and fast food. Conclusions: Genetic influence on dietary intakes differed by gender, nutrients, food groups, and dietary patterns among Chinese twins. Parental SES characteristics modified the estimated genetic influence.