The genetic relationship between educational attainment and cognitive performance in major psychiatric disorders

Shared deficits of education, marital and occupational functioning in unaffected siblings of multiple affected families with major psychiatric illness

BACKGROUND

Major psychiatric illnesses often cluster in families, and their impact on affected and unaffected members within families may reflect the consequence of both genetic and social liability.

METHODS

Data was derived from 202 families with multiple affected individuals. Affected individuals (N = 259) had a diagnosis of schizophrenia, bipolar disorder, obsessive-compulsive disorder or substance use disorder. For comparison, we used the unaffected siblings from the same families (N = 229) and a matched random subset of healthy control (HC) data (N = 229) from India's National Mental Health Survey, 2016 (NMHS). We compared the three groups' educational attainment, functional marital status, and occupational status.

RESULTS

The highest educational attainment was significantly different between the groups. The affected and unaffected siblings had poorer educational attainment compared to HC. Similarly, the affected and unaffected siblings more often remained single, in contrast to HC. Moreover, employment rates were significantly higher in the unaffected siblings, especially female siblings. Overall, females had spent fewer years at school, were primarily married, and were majority homemakers across the three groups compared to males.

DISCUSSION

Affected and unaffected siblings had lower education and marriage rates than HC. The unaffected siblings were more likely to be employed than HC. Whether the poor educational attainment and lower marriage rates in unaffected siblings is a biological marker of shared endophenotype or the effect of the social burden of having an affected family member requires further systematic evaluation.

Cognitive performance's critical role in the progression from educational attainment to moderate to vigorous physical activity: insights from a Mendelian randomization study

Introduction

In individuals with high educational levels, moderate to vigorous physical activity (MVPA) is often elevated, yet the causal direction and the role of cognitive performance in this association remain ambiguous. Herein, Mendel randomization (MR) was employed to measure the causal relationship between education, cognitive performance, and moderate to vigorous physical activity. The purpose of this study was to analyze the causal effects of educational attainment on moderate-to-vigorous physical activity (MVPA) levels and to explore potential mediating factors.

Methods

Two-sample univariate MR analysis was conducted to assess the overall effect of education on moderate to severe physical activity. Besides, a two-step MR analysis was carried out to evaluate the mediating effect of cognitive performance on the impact of education on moderate to severe physical activity. Individuals included were exclusively of European ancestry, with data gathered from extensive genome-wide association studies (GWAS) on education (n = 470,941), cognitive performance (n = 257,841), and moderate-to-vigorous physical activity (MVPA) (n = 377,234). Educational attainment was measured by college graduation status. Cognitive performance encompasses not only psycho-motor speed, memory, and abstract reasoning abilities but also knowledge and skills acquired in professional domains. MVPA is defined as any physical activity that produces a metabolic equivalent (MET) of ≥3.0.

Results

The positive two-sample MR analysis showed that education level had a significant protective effect on MVPA deficiency (β = -0.276, 95% CI = -0.354 to -0.199, p = 2.866 × 10-12). However, the reverse two-sample MR analysis showed that MVPA had no significant causal relationship with education level (p = 0.165). Subsequently, the two-step MR analysis indicated that the potential causal protective effect of education on the risk of MVPA deficiency was mostly mediated by cognitive performance (mediating effect β = -0.235, 95% CI = -0.434 to -0.036, and the intermediary ratio was 85.061%).

Discussion

Cognitive performance holds considerable significance in the relationship between education level and MVPA. Consequently, the intervention of cognitive performance may greatly improve the risk of physical inactivity caused by education, thereby promoting individual health.

Impact of low birth weight on academic attainment during adolescence: A comprehensive retrospective cohort study using linked data

BACKGROUND

This study addresses a critical knowledge gap by exploring the intricate relationship between low birth weight (LBW) and the heightened risk of suboptimal academic achievement during adolescence through a comprehensive retrospective cohort design.

METHODS

In this registry-based cohort study, meticulously linked health and curriculum-based test data for individuals born in New South Wales (NSW), Australia, between 2003 and 2005 were employed. Birth weight data were carefully sourced from the NSW perinatal data collection (PDC). The educational performance of offspring was thoroughly evaluated using the National Assessment Program for Literacy and Numeracy (NAPLAN) during grade 9, approximately at 14 years of age.

RESULTS

After rigorous adjustments for potential confounders, findings revealed a compelling narrative: LBW adolescents demonstrated an elevated susceptibility to not meeting national minimum standards across all domains, encompassing spelling [OR, 1.59 (95%CI 1.48-1.69)], writing [OR, 1.51 (95%CI 1.41-1.61)], reading [OR, 1.38 (95%CI 1.29-1.48)], and numeracy [OR, 1.52 (95%CI 1.40-1.63)]. Notably, LBW boys exhibited a more pronounced inclination towards diminished academic performance compared to their female counterparts.

CONCLUSIONS

This comprehensive retrospective cohort study, based on linked data, unequivocally establishes LBW as significantly associated with an increased vulnerability to substandard educational achievement during adolescence. Particularly robust effects were observed in females across all outcomes. Aimed at investigating whether LBW serves as a predictive factor for later academic difficulties, this study underscores the imperative for the adoption and fortification of preventative and early intervention strategies to curtail the prevalence of LBW-associated academic underachievement in later adolescence.

Evolutionary Trends of Polygenic Scores in European Populations From the Paleolithic to Modern Times

This study examines the temporal and geographical evolution of polygenic scores (PGSs) across cognitive measures (Educational Attainment [EA], Intelligence Quotient [IQ]), Socioeconomic Status (SES), and psychiatric conditions (Autism Spectrum Disorder [ASD], schizophrenia [SCZ]) in various populations. Our findings indicate positive directional selection for EA, IQ, and SES traits over the past 12,000 years. Schizophrenia and autism, while similar, showed different temporal patterns, aligning with theories suggesting they are psychological opposites. We observed a decline in PGS for neuroticism and depression, likely due to their genetic correlations and pleiotropic effects on intelligence. Significant PGS shifts from the Upper Paleolithic to the Neolithic periods suggest lifestyle and cognitive demand changes, particularly during the Neolithic Revolution. The study supports a mild hypothesis of Gregory Clark's model, showing a noticeable rise in genetic propensities for intelligence, academic achievement and professional status across Europe from the Middle Ages to the present. While latitude strongly influenced height, its impact on schizophrenia and autism was smaller and varied. Contrary to the cold winters theory, the study found no significant correlation between latitude and intelligence.

Dissecting Schizotypy and Its Association With Cognition and Polygenic Risk for Schizophrenia in a Nonclinical Sample

Schizotypy is a multidimensional construct that captures a continuum of risk for developing schizophrenia-spectrum psychopathology. Existing 3-factor models of schizotypy, consisting of positive, negative, and disorganized dimensions have yielded mixed evidence of genetic continuity with schizophrenia using polygenic risk scores. Here, we propose an approach that involves splitting positive and negative schizotypy into more specific subdimensions that are phenotypically continuous with distinct positive symptoms and negative symptoms recognized in clinical schizophrenia. We used item response theory to derive high-precision estimates of psychometric schizotypy using 251 self-report items obtained from a non-clinical sample of 727 (424 females) adults. These subdimensions were organized hierarchically using structural equation modeling into 3 empirically independent higher-order dimensions enabling associations with polygenic risk for schizophrenia to be examined at different levels of phenotypic generality and specificity. Results revealed that polygenic risk for schizophrenia was associated with variance specific to delusional experiences (γ = 0.093, P = .001) and reduced social interest and engagement (γ = 0.076, P = .020), and these effects were not mediated via the higher-order general, positive, or negative schizotypy factors. We further fractionated general intellectual functioning into fluid and crystallized intelligence in 446 (246 females) participants that underwent onsite cognitive assessment. Polygenic risk scores explained 3.6% of the variance in crystallized intelligence. Our precision phenotyping approach could be used to enhance the etiologic signal in future genetic association studies and improve the detection and prevention of schizophrenia-spectrum psychopathology.

Cognitive performances across individuals at high genetic risk for schizophrenia, high genetic risk for bipolar disorder, and low genetic risks: a combined polygenic risk score approach

BACKGROUND

Individuals with schizophrenia (SCZ) and bipolar disorder (BD) display cognitive impairments, but the impairments in those with SCZ are more prominent, supported by genetic overlap between SCZ and cognitive impairments. However, it remains unclear whether cognitive performances differ between individuals at high and low genetic risks for SCZ or BD.

METHODS

Using the latest Psychiatric Genomics Consortium (PGC) data, we calculated PGC3 SCZ-, PGC3 BD-, and SCZ v. BD polygenic risk scores (PRSs) in 173 SCZ patients, 70 unaffected first-degree relatives (FRs) and 196 healthy controls (HCs). Based on combinations of three PRS deciles, individuals in the genetic SCZ, genetic BD and low genetic risk groups were extracted. Cognitive performance was assessed by the Brief Assessment of Cognition in Schizophrenia.

RESULTS

SCZ-, BD-, SCZ v. BD-PRSs were associated with case-control status (R2 = 0.020-0.061), and SCZ-PRS was associated with relative-control status (R2 = 0.023). Furthermore, individuals in the highest decile for SCZ PRSs had elevated BD-PRSs [odds ratio (OR) = 6.33] and SCZ v. BD-PRSs (OR = 1.86) compared with those in the lowest decile. Of the three genetic risk groups, the low genetic risk group contained more HCs, whereas the genetic BD and SCZ groups contained more SCZ patients (p < 0.05). SCZ patients had widespread cognitive impairments, and FRs had cognitive impairments that were between those of SCZ patients and HCs (p < 0.05). Cognitive differences between HCs in the low genetic risk group and SCZ patients in the genetic BD or genetic SCZ groups were more prominent (Cohen's d > -0.20) than those between HCs and SCZ patients in the no genetic risk group. Furthermore, SCZ patients in the genetic SCZ group displayed lower scores in verbal fluency and attention than those in the genetic BD group (d > -0.20).

CONCLUSIONS

Our findings suggest that cognitive impairments in SCZ are partially mediated through genetic loadings for SCZ but not BD.

Analysis of Educational Attainment in a Mexican Psychiatric Patient Population with Bipolar or Psychotic Disorders

Schizophrenia has been associated with premorbid poor educational performance and low educational attainment (EA). However, some studies have found positive associations between psychotic disorders and excellent scholastic performance. In the present study, we examined the association between EA and several clinical and nonclinical characteristics in psychiatric patients diagnosed with psychotic or bipolar disorders. Data were obtained from the files of 1132 patients who entered a major Mexico City psychiatric hospital during the years 2009-2010 for the treatment of psychotic symptoms and who were subsequently diagnosed with schizophrenia, bipolar, schizoaffective, or another psychotic disorder. Chi-squared tests, t-tests, and Cox regression analysis were applied to explore associations between EA and factors including gender, familial history of mental illness, premorbid personality characteristics, age of symptom onset, diagnosis, civil status, and current employment. Family history of mental illness decreased the hazard of having lower EA (B = -0.137, p = 0.025, ExpB = 0.872, 95% CI = 0.774-0.983), while a schizophrenia diagnosis independently increased it (B = 0.201, p = 0.004, ExpB = 1.223, 95% CI = 1.068-1.401). In male patients (but not in females), family history of mental illness was significantly associated with higher EA, while in female patients, premorbid schizoid-like personality characteristics were associated with lower EA. For both genders, lower EA was associated with having more children and being employed in manual labor, while higher EA was associated with professional employment. Conclusions: Compared with bipolar disorder, a schizophrenia diagnosis is associated with lower EA; however, familial history of mental illness and premorbid schizoid-like characteristics independently favor higher and lower EA in males and females, respectively. Since lower EA is generally associated with a lower economic status, special preventative attention should be given to students at high risk for schizophrenia, particularly those displaying a schizoid-like personality.

Association between mitochondria-related genes and cognitive performance in the PsyCourse Study

BACKGROUND

Mitochondria generate energy through oxidative phosphorylation (OXPHOS). The function of key OXPHOS proteins can be altered by variation in mitochondria-related genes, which may increase the risk of mental illness. We investigated the association of mitochondria-related genes and their genetic risk burden with cognitive performance.

METHODS

We leveraged cross-sectional data from 1320 individuals with a severe psychiatric disorder and 466 neurotypical individuals from the PsyCourse Study. The cognitive tests analyzed were the Trail-Making Test, Verbal Digit Span Test, Digit-Symbol Test, and Multiple Choice Vocabulary Intelligence Test. Association analyses between the cognitive tests, and single-nucleotide polymorphisms (SNPs) mapped to mitochondria-related genes, and their polygenic risk score (PRS) for schizophrenia (SCZ) were performed with PLINK 1.9 and R program.

RESULTS

We found a significant association (FDR-adjusted p < 0.05) in the Cytochrome C Oxidase Assembly Factor 8 (COA8) gene locus of the OXPHOS pathway with the Verbal Digit Span (forward) test. Mitochondrial PRS was not significantly associated with any of the cognitive tests.

LIMITATIONS

Moderate statistical power due to relatively small sample size.

CONCLUSIONS

COA8 encodes a poorly characterized mitochondrial protein involved in apoptosis. Here, this gene was associated with the Verbal Digit Span (forward) test, which evaluates short-term memory. Our results warrant replication and may lead to better understanding of cognitive impairment in mental disorders.

Association of early life stress and cognitive performance in patients with schizophrenia and healthy controls

As core symptoms of schizophrenia, cognitive deficits contribute substantially to poor outcomes. Early life stress (ELS) can negatively affect cognition in patients with schizophrenia and healthy controls, but the exact nature of the mediating factors is unclear. Therefore, we investigated how ELS, education, and symptom burden are related to cognitive performance. The sample comprised 215 patients with schizophrenia (age, 42.9 ± 12.0 years; 66.0 % male) and 197 healthy controls (age, 38.5 ± 16.4 years; 39.3 % male) from the PsyCourse Study. ELS was assessed with the Childhood Trauma Screener (CTS). We used analyses of covariance and correlation analyses to investigate the association of total ELS load and ELS subtypes with cognitive performance. ELS was reported by 52.1 % of patients and 24.9 % of controls. Independent of ELS, cognitive performance on neuropsychological tests was lower in patients than controls (p < 0.001). ELS load was more closely associated with neurocognitive deficits (cognitive composite score) in controls (r = -0.305, p < 0.001) than in patients (r = -0.163, p = 0.033). Moreover, the higher the ELS load, the more cognitive deficits were found in controls (r = -0.200, p = 0.006), while in patients, this correlation was not significant after adjusting for PANSS. ELS load was more strongly associated with cognitive deficits in healthy controls than in patients. In patients, disease-related positive and negative symptoms may mask the effects of ELS-related cognitive deficits. ELS subtypes were associated with impairments in various cognitive domains. Cognitive deficits appear to be mediated through higher symptom burden and lower educational level.

The shared genetic landscape of blood cell traits and risk of neurological and psychiatric disorders

Phenotypic associations have been reported between blood cell traits (BCTs) and a range of neurological and psychiatric disorders (NPDs), but in most cases, it remains unclear whether these associations have a genetic basis and, if so, to what extent genetic correlations reflect causality. Here, we report genetic correlations and Mendelian randomization analyses between 11 NPDs and 29 BCTs, using genome-wide association study summary statistics. We found significant genetic correlations for four BCT-NPD pairs, all of which have prior evidence for a phenotypic correlation. We identified a previously unreported causal effect of increased platelet distribution width on susceptibility to Parkinson's disease. We identified multiple functional genes and regulatory elements for specific BCT-NPD pairs, some of which are targets of known drugs. These results enrich our understanding of the shared genetic landscape underlying BCTs and NPDs and provide a robust foundation for future work to improve prognosis and treatment of common NPDs.

Academic performance in adolescent offspring of mothers with prenatal and perinatal psychiatric hospitalizations: A register-based, data linkage, cohort study

BACKGROUND

This is the first study to investigate the longitudinal association between prenatal and perinatal psychiatric hospitalizations and academic achievements in adolescent offspring.

METHODS

We conducted an administrative health data-based cohort study of 168, 528 mother-offspring pairs using linked data obtained from health and educational registries in New South Wales, Australia. Prenatal and perinatal maternal psychiatric diagnosis was measured by using ICD-10. The National Assessment Program for Literacy and Numeracy (NAPLAN) was used to assess the educational performance of the offspring. Logistic regression model was used to explore the association. Multivariate models were adjusted for maternal sociodemographic characteristics such as age at birth, marital status, educational status, and occupational status, maternal diabetes and chronic hypertension, maternal smoking during pregnancy, birth weight, and language spoken at home.

RESULTS

The findings show that after adjusting for important covariates adolescent offspring of mothers with prenatal and perinatal psychiatric hospitalizations were more likely to perform below the national minimum standard in all domains of academic performance at age 14 years, when compared with the offspring of mothers without such hospitalizations, with the highest odds for numeracy (OR = 2.88; 95% CI: 2.50-3.31) followed by reading (OR = 2.08; 95% CI: 1.81-2.38), spelling (OR = 1.74; 95% CI: 1.51-2.01), and writing (OR = 1.56; 95% CI: 1.34-1.80). There was significant gender interaction such that males were more likely to experience lower rates of academic performance than females in all academic domains. Lower academic achievements were observed among offspring of mothers with all major groupings of psychiatric disorders, with a higher risk for severe psychiatric disorders followed by mental disorders due to substance use or medical conditions.

CONCLUSION

In sum, maternal prenatal and perinatal psychiatric hospitalizations are associated with lower academic achievements in adolescent offspring, with a stronger effect on the academic performance of male offspring. Early intervention strategies that aim to enhance educational performance in the exposed offspring are needed.

Comparative serum proteomic analysis of a selected protein panel in individuals with schizophrenia and bipolar disorder and the impact of genetic risk burden on serum proteomic profiles

The diagnostic criteria for schizophrenia (SCZ) and bipolar disorder (BD) are based on clinical assessments of symptoms. In this pilot study, we applied high-throughput antibody-based protein profiling to serum samples of healthy controls and individuals with SCZ and BD with the aim of identifying differentially expressed proteins in these disorders. Moreover, we explored the influence of polygenic burden for SCZ and BD on the serum levels of these proteins. Serum samples from 113 individuals with SCZ and 125 with BD from the PsyCourse Study and from 44 healthy controls were analyzed by using a set of 155 antibodies in an antibody-based assay targeting a selected panel of 95 proteins. For the cases, genotyping and imputation were conducted for DNA samples and SCZ and BD polygenic risk scores (PRS) were calculated. Univariate linear and logistic models were used for association analyses. The comparison between SCZ and BD revealed two serum proteins that were significantly elevated in BD after multiple testing adjustment: "complement C9" and "Interleukin 1 Receptor Accessory Protein". Moreover, the first principal component of variance in the proteomics dataset differed significantly between SCZ and BD. After multiple testing correction, SCZ-PRS, BD-PRS, and SCZ-vs-BD-PRS were not significantly associated with the levels of the individual proteins or the values of the proteome principal components indicating no detectable genetic effects. Overall, our findings contribute to the evidence suggesting that the analysis of circulating proteins could lead to the identification of distinctive biomarkers for SCZ and BD. Our investigation warrants replication in large-scale studies to confirm these findings.

Genetic variations in evolutionary accelerated regions disrupt cognition in schizophrenia

Cognition is believed to be a product of human evolution, while schizophrenia is ascribed as the by-product with cognitive impairment as it's genetically mediated endophenotype. Genomic loci associated with these traits are enriched with recent evolutionary markers such as Human accelerated regions (HARs). HARs are markedly different in humans since their divergence with chimpanzees and mostly regulate gene expression by binding to transcription factors and/or modulating chromatin interactions. We hypothesize that variants within HARs may alter such functions and thus contribute to disease pathogenesis. 49 systematically prioritized variants from 2737 genome-wide HARs were genotyped in a north-Indian schizophrenia cohort (331 cases, 235 controls). Six variants were significantly associated with cognitive impairment in schizophrenia, thirteen with general cognition in healthy individuals. These variants were mapped to 122 genes; predicted to alter 79 transcription factors binding sites and overlapped with promoters, enhancers and/or repressors. These genes and TFs are implicated in neurocognitive phenotypes, autism, schizophrenia and bipolar disorders; a few are targets of common or repurposable antipsychotics suggesting their draggability; and enriched for immune response and brain developmental pathways. Immune response has been more strongly targeted by natural selection during human evolution and has a prominent role in neurodevelopment. Thus, its disruption may have deleterious consequences for neuronal and cognitive functions. Importantly, among the 15 associated SNPs, 12 showed association in several independent GWASs of different neurocognitive functions. Further analysis of HARs may be valuable to understand their role in cognition biology and identify improved therapeutics for schizophrenia.

The impact of parental mental health problems on the educational outcomes of their offspring: Findings from the Raine Study

OBJECTIVES

There is limited evidence on the impact of parental mental health problems on offspring's educational outcomes. We investigated the impact of maternal anxiety and depressive symptoms, as well as paternal emotional problems on the educational outcomes of their adolescent and young adult offspring.

METHODS

We used data from a longitudinal birth cohort recruited between 1989 and 1991 in Australia (the Raine Study). The Depression, Anxiety and Stress Scale was used to assess maternal depressive and anxiety symptoms, and a self-reported question was used to measure paternal mental health problems. Both were assessed when the offspring was aged 10 years. Outcomes included offspring's self-reported education attainment-not completing year 10 at age 17, not attending tertiary education at ages 17 and 22 and primary caregiver's reports of offspring's academic performance at age 17.

RESULTS

A total of 1033, 1307 and 1364 parent-offspring pairs were included in the final analysis exploring the association between parental mental health problems and offspring's academic performance at school, completing year 10 and attending tertiary education, respectively. After adjusting for potential confounders, the offspring of mothers with anxiety symptoms were 3.42 times more likely than the offspring of mothers without anxiety symptoms to have poor or below-average academic performance (odds ratio = 3.42; 95% confidence interval = [1.31, 8.92]) and more than 2 times more likely to not attend tertiary education (odds ratio = 2.55; 95% confidence interval = [1.10, 5.5.88]) and not to have completed year 10 (odds ratio = 2.13; 95% confidence interval = [1.04, 4.33]). We found no significant associations between maternal depressive symptoms or paternal emotional problems and offspring educational attainment.

CONCLUSION

Maternal anxiety symptoms, but not depression and paternal emotional problems, are associated with poor educational attainment and achievement in adolescent offspring. The findings highlight that efforts to improve the outcomes of offspring of mothers with anxiety could focus on educational attainment.

Immune marker levels in severe mental disorders: associations with polygenic risk scores of related mental phenotypes and psoriasis

Several lines of evidence implicate immune abnormalities in the pathophysiology of severe mental disorders (SMD) and comorbid mental disorders. Here, we use the data from genome-wide association studies (GWAS) of autoimmune diseases and mental phenotypes associated with SMD to disentangle genetic susceptibilities of immune abnormalities in SMD. We included 1004 patients with SMD and 947 healthy controls (HC) and measured plasma levels of IL-1Ra, sIL-2R, gp130, sTNFR-1, IL-18, APRIL, and ICAM-1. Polygenic risk scores (PRS) of six autoimmune disorders, CRP, and 10 SMD-related mental phenotypes were calculated from GWAS. General linear models were applied to assess the association of PRS with immune marker abnormalities. We found negative associations between PRS of educational attainment and IL-1Ra (P = 0.01) and IL-18 (P = 0.01). There were nominal positive associations between PRS of psoriasis and sgp130 (P = 0.02) and PRS of anxiety and IL-18 (P = 0.03), and nominal negative associations between PRS of anxiety and sIL-2R (P = 0.02) and PRS of educational attainment and sIL-2R (P = 0.03). Associations explained minor amounts of the immune marker plasma-level difference between SMD and HC. Different PRS and immune marker associations in the SMD group compared to HC were shown for PRS of extraversion and IL-1Ra ([interaction effect (IE), P = 0.002), and nominally for PRS of openness and IL-1Ra (IE, P = 0.02) and sTNFR-1 (IE, P = 0.04). Our findings indicate polygenic susceptibilities to immune abnormalities in SMD involving genetic overlap with SMD-related mental phenotypes and psoriasis. Associations might suggest immune genetic factors of SMD subgroups characterized by autoimmune or specific mental features.

Maternal smoking during pregnancy and poor academic performance in adolescent offspring: A registry data-based cohort study

BACKGROUND

Previous studies have suggested associations between maternal smoking during pregnancy (MSDP) and a range of adverse outcomes in offspring. However, evidence reporting adverse effects on poor academic performance in adolescence is scant.

METHODS

This register-based cohort study used linked data obtained from New South Wales (NSW) educational and health registries in Australia. MSDP was assessed using self-reports of smoking during pregnancy. Offspring's educational performance was assessed using the National Assessment Program for Literacy and numeracy (NAPLAN), when students were in grade 9 and approximately aged 14 years. We used multivariable logistic regression models to explore associations.

RESULTS

Adolescent offspring exposed to MSDP were at an increased risk of substandard academic performance in all domains, with the highest odds for spelling [OR, 3.12 (95%CI 2.98-3.26)] followed by writing [OR, 2.97 (95%CI 2.84-3.11)], reading [OR, 2.49 (95%CI 2.37-2.62)], and numeracy [OR, 2.43 (95%CI 2.30-2.58)]. In our sex-stratified analysis, MSDP displayed stronger effects on the academic performance of female offspring in all domains.

CONCLUSIONS

Our findings showed that MSDP was associated with an increased risk of reduced academic performance in adolescent offspring. The different effects of MSDP on the academic performance of male and female offspring is a new finding, which needs further investigation.

Genetic Overlap Profiles of Cognitive Ability in Psychotic and Affective Illnesses: A Multisite Study of Multiplex Pedigrees

BACKGROUND

Cognitive impairment is a key feature of psychiatric illness, making cognition an important tool for exploring of the genetics of illness risk. It remains unclear which measures should be prioritized in pleiotropy-guided research. Here, we generate profiles of genetic overlap between psychotic and affective disorders and cognitive measures in Caucasian and Hispanic groups.

METHODS

Data were from 4 samples of extended pedigrees (N = 3046). Coefficient of relationship analyses were used to estimate genetic overlap between illness risk and cognitive ability. Results were meta-analyzed.

RESULTS

Psychosis was characterized by cognitive impairments on all measures with a generalized profile of genetic overlap. General cognitive ability shared greatest genetic overlap with psychosis risk (average endophenotype ranking value [ERV] across samples from a random-effects meta-analysis = 0.32), followed by verbal memory (ERV = 0.24), executive function (ERV = 0.22), and working memory (ERV = 0.21). For bipolar disorder, there was genetic overlap with processing speed (ERV = 0.05) and verbal memory (ERV = 0.11), but these were confined to select samples. Major depressive disorder was characterized by enhanced working and face memory performance, as reflected in significant genetic overlap in 2 samples.

CONCLUSIONS

There is substantial genetic overlap between risk for psychosis and a range of cognitive abilities (including general intelligence). Most of these effects are largely stable across of ascertainment strategy and ethnicity. Genetic overlap between affective disorders and cognition, on the other hand, tends to be specific to ascertainment strategy, ethnicity, and cognitive test battery.

Polygenic Risk Scores Differentiating Schizophrenia From Bipolar Disorder Are Associated With Premorbid Intelligence in Schizophrenia Patients and Healthy Subjects

BACKGROUND

Impairments in intelligence are more severe in patients with schizophrenia (SCZ) than in patients with bipolar disorder (BD) despite clinical and genetic similarities between the disorders. Genetic loci differentiating SCZ from BD, that is, SCZ-specific risk, have been identified. Polygenetic [risk] scores (PGSs) for SCZ-specific risk are higher in SCZ patients than in healthy controls (HCs). However, the influence of genetic risk on impaired intelligence is poorly understood. Here, we investigated whether SCZ-specific risk could predict impairments in intelligence in SCZ patients and HCs.

METHODS

Large-scale genome-wide association study datasets related to SCZ vs BD, childhood intelligence (CHI), and adulthood intelligence (n = 12 441-282 014) were utilized to compute PGSs. PGSs derived from the genome-wide association studies were calculated for 130 patients with SCZ and 146 HCs. Premorbid and current intelligence and the decline were measured in SCZ patients and HCs. Correlations between PGSs and intelligence functions were investigated.

RESULTS

High PGSs for SCZ-specific risk were correlated with low premorbid intelligence in SCZ patients and HCs (β = -0.17, P = 4.12 × 10-3). The correlation was still significant after adjusting for diagnostic status (β = -0.13, P = .024). There were no significant correlations between PGSs for SCZ-specific risk and current intelligence or intelligence decline (P > .05). PGSs for CHI were lower in SCZ patients than in HCs (R2 = 0.025, P = .025), while the PGSs for CHI were not significantly correlated with premorbid and current intelligence, the decline, or the PGSs for SCZ-specific risk (P > .05).

CONCLUSIONS

These findings suggest that genetic factors differentiating SCZ from BD might affect the pathogenesis of SCZ and/or pathological differences between SCZ and BD via the impairment of premorbid intelligence, that is, crystallized intelligence, while genetic factors for CHI might affect the pathogenesis of SCZ but not via impairments in intelligence.

[Neurogenetics of schizophrenia: findings from studies based on data sharing and global partnerships]

Schizophrenic psychoses are the result of a multifactorial process in which not only environmental influences but also genetic factors play an important role. These factors are based on a complex mode of inheritance that involves a large number of genetic variants. In the last three decades, biological psychiatric research has focused closely on molecular genetic aspects of the hereditary basis of schizophrenic psychoses. In particular, international consortia are combining cohorts from individual researchers, creating continuously increasing sample sizes and thus increased statistical power. As part of the Psychiatric Genomics Consortium (PGC), genome-wide association studies with tens of thousands of patients and controls have for the first time found robustly replicable markers for schizophrenic psychoses. Through intensive phenotyping, first approaches to a transdiagnostic clinical reclassification of severe mental illnesses have been established in the longitudinal PsyCourse study of the UMG Göttingen and the LMU Munich, allowing new biologically validated disease subgroups with prognostic value to be identified. For the first time environmental factors could even be examined in an African cohort that contribute to the development of the psychosis. In the coming years, the enormous technical progress in the area of genomic high-throughput technologies (next-generation sequencing) is expected to provide new knowledge not only about the influence of frequently occurring single nucleotide polymorphisms but also about rare variants. For the successful use of this technological revolution an exchange of data between research groups is essential.

Polygenic scores for schizophrenia and general cognitive ability: associations with six cognitive domains, premorbid intelligence, and cognitive composite score in individuals with a psychotic disorder and in healthy controls

Cognitive impairments are considered core features in schizophrenia and other psychotic disorders. Cognitive impairments are, to a lesser degree, also documented in healthy first-degree relatives. Although recent studies have shown (negative) genetic correlations between schizophrenia and general cognitive ability, the association between polygenic risk for schizophrenia and individual cognitive phenotypes remains unclear. We here investigated the association between a polygenic score for schizophrenia (SCZ_PGS) and six well-defined cognitive domains, in addition to a composite measure of cognitive ability and a measure of premorbid intellectual ability in 731 participants with a psychotic disorder and 851 healthy controls. We also investigated the association between a PGS for general cognitive ability (COG_PGS) and the same cognitive domains in the same sample. We found no significant associations between the SCZ_PGS and any cognitive phenotypes, in either patients with a psychotic disorder or healthy controls. For COG_PGS we observed stronger associations with cognitive phenotypes in healthy controls than in participants with psychotic disorders. In healthy controls, the association between COG_PGS (at the p value threshold of ≥0.01) and working memory remained significant after Bonferroni correction (β = 0.12, p = 8.6 × 10^-5). Altogether, the lack of associations between SCZ_PGS and COG_PGS with cognitive performance in participants with psychotic disorders suggests that either environmental factors or unassessed genetic factors play a role in the development of cognitive impairments in psychotic disorders. Working memory should be further studied as an important cognitive phenotype.