Meta-analysis of Genome-wide Association Studies for Neuroticism, and the Polygenic Association With Major Depressive Disorder

Polygenic risk scoring and prediction of mental health outcomes

Psychiatric conditions are highly polygenic, meaning that genetic risk arises from many hundreds or thousands of genetic variants. Psychiatric genomics and psychological science are increasingly using polygenic risk scoring-the integration of all common genetic variant effects into a single risk metric-to model latent risk and to predict mental health outcomes. This review discusses the use of these scores in psychology and psychiatry to date, important methodological considerations, and potential of scoring methods for informing psychological science. Polygenic risk scores can easily be added to environmental and behavioral genetic models of latent risk, making them desirable metrics for use in psychological research.

A DNA Methylation Signature of Addiction in T Cells and Its Reversal With DHEA Intervention

Previous studies in animal models of cocaine craving have delineated broad changes in DNA methylation profiles in the nucleus accumbens. A crucial factor for progress in behavioral and mental health epigenetics is the discovery of epigenetic markers in peripheral tissues. Several studies in primates and humans have associated differences in behavioral phenotypes with changes in DNA methylation in T cells and brain. Herein, we present a pilot study (n = 27) showing that the T cell DNA methylation profile differentiates persons with a substance use disorder from controls. Intervention with dehydroepiandrosterone (DHEA), previously shown to have a long-term therapeutic effect on human addicts herein resulted in reversal of DNA methylation changes in genes related to pathways associated with the addictive state.

Psychometric Properties of the Chinese Version of the Neuroticism Subscale of the NEO-PI

Neuroticism is an important concept in psychology, self-report measures of neuroticism are important for both research and clinical practice. The neuroticism subscale of the Neuroticism-Extraversion-Openness Personality Inventory (NEO-PI) is a brief measure of neuroticism, and it was widely used in the world. This study was aimed to examine the psychometric properties of the Chinese version of the neuroticism subscale of the NEO-PI. A total of 5,494 undergraduates from three universities and 551 clinical patients with mental disorders from a psychological clinic had completed the Chinese version of the neuroticism subscale of the NEO-PI. Confirmatory factor analysis was performed to examine how well the three hypothetical models fit the data and the measurement equivalence of neuroticism subscale across gender. The internal consistency and test-retest reliability were also evaluated. Both the six-facet model and the bi-factor model (six-facet model with one general factor) achieved satisfactory fit, while the six-facet model had best fit (Undergraduate sample: TLI = 0.919, CFI = 0.933, RMSEA = 0.044, SRMR = 0.033; Clinical sample: TLI = 0.921, CFI = 0.935, RMSEA = 0.047, SRMR = 0.041), and it had measurement equivalence across gender. The neuroticism subscale also showed acceptable internal consistency and good stability. Within the undergraduate sample, there were statistically significant gender differences in neuroticism total scores and scores of six facets, while there were no significant gender differences in the neuroticism scores in the clinical sample. Both in the undergraduate sample and the clinical sample, anxiety facet, depression facet and vulnerability facet of the neuroticism subscale significantly predicted the depression level, while anxiety facet, angry-hostility facet and vulnerability facet significantly predicted the anxiety level. In conclusion, the Chinese version of the neuroticism subscale is a reliable and valid measurement of neuroticism in both undergraduate and clinical population.

Associations between loneliness and personality are mostly driven by a genetic association with Neuroticism

OBJECTIVE

Loneliness is an aversive response to a discrepancy between desired and actual social relationships and correlates with personality. We investigate the relationship of loneliness and personality in twin family and molecular genetic data.

METHOD

Phenotypic correlations between loneliness and the Big Five personality traits were estimated in 29,625 adults, and in a group with genome-wide genotype data (N = 4,222), genetic correlations were obtained. We explored whether genetic correlations may reflect causal relationships by investigating within monozygotic twin pair differences (N_pairs  = 2,662), by longitudinal within-subject changes in personality and loneliness (N = 4,260-9,238 longitudinal comparisons), and by longitudinal cross-lagged panel analyses (N = 15,628). Finally, we tested whether genetic correlations were due to cross-trait assortative mating (N_{spouse pairs}  = 4,436).

RESULTS

The strongest correlations with loneliness were observed for Neuroticism (r = .55) and Extraversion (r = -.33). Only Neuroticism showed a high correlation with loneliness independent of other personality traits (r = .50), so follow-up analyses focused on Neuroticism. The genetic correlation between loneliness and Neuroticism from genotyped variants was .71; a significant reciprocal causal relationship and nonsignificant cross-trait assortative mating imply that this is at least partly due to mediated pleiotropy.

CONCLUSIONS

We show that the relationship between loneliness and personality is largely explained by its relationship with Neuroticism, which is substantially genetic in nature.

Genetic risk of major depressive disorder: the moderating and mediating effects of neuroticism and psychological resilience on clinical and self-reported depression

BACKGROUND

Polygenic risk scores (PRS) for depression correlate with depression status and chronicity, and provide causal anchors to identify depressive mechanisms. Neuroticism is phenotypically and genetically positively associated with depression, whereas psychological resilience demonstrates negative phenotypic associations. Whether increased neuroticism and reduced resilience are downstream mediators of genetic risk for depression, and whether they contribute independently to risk remains unknown.

METHODS

Moderating and mediating relationships between depression PRS, neuroticism, resilience and both clinical and self-reported depression were examined in a large, population-based cohort, Generation Scotland: Scottish Family Health Study (N = 4166), using linear regression and structural equation modelling. Neuroticism and resilience were measured by the Eysenck Personality Scale Short Form Revised and the Brief Resilience Scale, respectively.

RESULTS

PRS for depression was associated with increased likelihood of self-reported and clinical depression. No interaction was found between PRS and neuroticism, or between PRS and resilience. Neuroticism was associated with increased likelihood of self-reported and clinical depression, whereas resilience was associated with reduced risk. Structural equation modelling suggested the association between PRS and self-reported and clinical depression was mediated by neuroticism (43-57%), while resilience mediated the association in the opposite direction (37-40%). For both self-reported and clinical diagnoses, the genetic risk for depression was independently mediated by neuroticism and resilience.

CONCLUSIONS

Findings suggest polygenic risk for depression increases vulnerability for self-reported and clinical depression through independent effects on increased neuroticism and reduced psychological resilience. In addition, two partially independent mechanisms - neuroticism and resilience - may form part of the pathway of vulnerability to depression.

Incorporating epigenetic mechanisms to advance fetal programming theories

Decades of fetal programming research indicates that we may be able to map the origins of many physical, psychological, and medical variations and morbidities before the birth of the child. While great strides have been made in identifying associations between prenatal insults, such as undernutrition or psychosocial stress, and negative developmental outcomes, far less is known about how adaptive responses to adversity regulate the developing phenotype to match stressful conditions. As the application of epigenetic methods to human behavior has exploded in the last decade, research has begun to shed light on the role of epigenetic mechanisms in explaining how prenatal conditions shape later susceptibilities to mental and physical health problems. In this review, we describe and attempt to integrate two dominant fetal programming models: the cumulative stress model (a disease-focused approach) and the match-mismatch model (an evolutionary-developmental approach). In conjunction with biological sensitivity to context theory, we employ these two models to generate new hypotheses regarding epigenetic mechanisms through which prenatal and postnatal experiences program child stress reactivity and, in turn, promote development of adaptive versus maladaptive phenotypic outcomes. We conclude by outlining priority questions and future directions for the fetal programming field.

Polygenic prediction of the phenome, across ancestry, in emerging adulthood

BACKGROUND

Identifying genetic relationships between complex traits in emerging adulthood can provide useful etiological insights into risk for psychopathology. College-age individuals are under-represented in genomic analyses thus far, and the majority of work has focused on the clinical disorder or cognitive abilities rather than normal-range behavioral outcomes.

METHODS

This study examined a sample of emerging adults 18-22 years of age (N = 5947) to construct an atlas of polygenic risk for 33 traits predicting relevant phenotypic outcomes. Twenty-eight hypotheses were tested based on the previous literature on samples of European ancestry, and the availability of rich assessment data allowed for polygenic predictions across 55 psychological and medical phenotypes.

RESULTS

Polygenic risk for schizophrenia (SZ) in emerging adults predicted anxiety, depression, nicotine use, trauma, and family history of psychological disorders. Polygenic risk for neuroticism predicted anxiety, depression, phobia, panic, neuroticism, and was correlated with polygenic risk for cardiovascular disease.

CONCLUSIONS

These results demonstrate the extensive impact of genetic risk for SZ, neuroticism, and major depression on a range of health outcomes in early adulthood. Minimal cross-ancestry replication of these phenomic patterns of polygenic influence underscores the need for more genome-wide association studies of non-European populations.

Maternal smoking during pregnancy and offspring personality in childhood and adulthood

OBJECTIVE

Maternal smoking during pregnancy (MSDP) has been associated with offspring internalizing and externalizing disorders. The purpose of this research is to examine whether MSDP is also associated with variations in normal personality traits in childhood and adulthood.

METHOD

This study uses four independent samples (total N = 16,323) to examine whether there are mean-level differences in offspring personality traits by MSDP, controlling for relevant sociodemographic factors. Two samples are of children (Ns = 3,782 and 3,841) and two samples are of adults (Ns = 1,786 and 6,914).

RESULTS

A meta-analysis across the four samples indicated that offspring of mothers who did smoke during pregnancy scored higher in Neuroticism (p = .000) and Extraversion (p = .003) and lower in Conscientiousness (p = .002) than offspring of mothers who did not smoke during pregnancy. The association between MSDP and Neuroticism and Conscientiousness held across both childhood and adulthood and when propensity score matching was used, whereas the association with Extraversion was only apparent in adulthood and did not hold with propensity scores.

CONCLUSIONS

These results suggest that MSDP is associated with individual differences in psychological traits in childhood and adulthood and may be one prenatal factor that contributes to trait Neuroticism and Conscientiousness.

Genetic influences on creativity: an exploration of convergent and divergent thinking

Previous studies on the genetic basis of creativity have mainly focused on the biological mechanisms of divergent thinking, possibly limiting the exploration of possible candidate genes. Taking a cognition-based perspective, the present study investigated the genetic basis for both the divergent and the convergent thinking components of creativity. A total of 321 Chinese university students were recruited to complete the Guildford Unusual Using Test (UUT) for divergent thinking capability and the Remote Associates Test (RAT) for convergent thinking capability. The polymorphism of rs2576037 in KATNAL2 was related to the fluency and originality component scores of UUT, and the polymorphism of rs5993883 in COMT, rs362584 in SNAP25 was related to the RAT performance. These effects remained significant after considering the influence of age, gender and intelligence. Our results provide new evidence for the genetic basis of creativity and reveal the important role of gene polymorphisms in divergent and convergent thinking.

Associations between genetic risk, functional brain network organization and neuroticism

Neuroticism and genetic variation in the serotonin-transporter (SLC6A4) and catechol-O-methyltransferase (COMT) gene are risk factors for psychopathology. Alterations in the functional integration and segregation of neural circuits have recently been found in individuals scoring higher on neuroticism. The aim of the current study was to investigate how genetic risk factors impact functional network organization and whether genetic risk factors moderate the association between neuroticism and functional network organization. We applied graph theory analysis on resting-state fMRI data in a sample of 120 women selected based on their neuroticism score, and genotyped two polymorphisms: 5-HTTLPR (S-carriers and L-homozygotes) and COMT (rs4680-rs165599; COMT risk group and COMT non-risk group). For the 5-HTTLPR polymorphism, we found that subnetworks related to cognitive control show less connections with other subnetworks in S-carriers compared to L-homozygotes. The COMT polymorphism moderated the association between neuroticism and functional network organization. We found that neuroticism was associated with lower efficiency coefficients in visual and somatosensory-motor subnetworks in the COMT risk group compared to the COMT non-risk group. The findings of altered topology of specific subnetworks point to different cognitive-emotional processes that may be affected in relation to the genetic risk factors, concerning emotion regulation in S-carriers (5-HTTLPR) and emotional salience processing in COMT risk carriers.

Intellectual Investment, Dopaminergic Gene Variation, and Life Events: A Critical Examination

Need for Cognition (NFC) and Openness to Ideas are intellectual investment traits that are characterized by a tendency to seek out, engage in and enjoy effortful cognitive activity. Little, however, is known about the extent to which they are influenced by genetic and environmental factors. With the present contribution, we aim at furthering our knowledge on the mechanisms underlying intellectual investment traits by following-up on a recent investigation of the role of dopaminergic gene variation in intellectual investment. Employing a standard approach that relied on null-hypothesis significance testing, we found that, first, two dopaminergic genetic variants interacted in modulating individual differences in NFC, but not in Openness to Ideas; that, second, negative life events played a role in the modulation of Openness to Ideas, but not of NFC; and that, third, negative life events as assessed using another measure were only marginally related to Openness to Ideas while positive life events were associated with both Openness to Ideas and NFC, with the latter effect being also dependent on DRD4 exon III genotype. However, employing a Bayesian approach, the assumption of a genetic effect on investment traits was overall not supported, while the assumption of a role of positive life events in the modulation of investment traits could be confirmed, with a tentative increment in the prediction of NFC by adding an interaction of positive life events and DRD4 variation to the main effect of positive life events. Our findings underscore the importance to use different approaches in the field of personality neuroscience. To gain deeper insight into the basis of personality traits does not only require to consider genetic as well as environmental influences and their interplay, but also requires more differentiated statistical analyses that can at least in part tackle the often inconsistent findings in this field.

Analysis of shared heritability in common disorders of the brain

Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.

Detection of Significant Association Between Variants in Cannabinoid Receptor 1 Gene (CNR1) and Personality in African-American Population

Background: Several studies have revealed significant associations between single nucleotide polymorphisms (SNPs) in the cannabinoid receptor 1 (CNR1) gene and a broad spectrum of psychiatric disorders such as major depressive disorder (MDD), attention deficit hyperactivity disorder (ADHD), and schizophrenia. Personality traits that are highly related to susceptibility to these conditions have been associated with the CNR1 variants in subjects of Caucasian origin. However, there are no reported studies regarding the effects of CNR1 polymorphisms on personality traits in the African-American (AA) population. Methods: We performed an imputation-based association analysis for 26 CNR1 variants with five dimensions of personality in 3,046 AAs. Results: SNPs rs806372 and rs2180619 showed a significant association with extraversion after Bonferroni correction for multiple testing (p < 0.0019). Further, several extraversion-associated SNPs were significantly associated with conscientiousness, agreeableness, and openness. SNP priority score analysis indicated that SNPs rs806368, rs806371, and rs2180619 play a role in the modulation of personality and psychiatric conditions. Conclusion:CNR1 is important in determining personality traits in the AA population.

Stress-Induced Depression: Is Social Rank a Predictive Risk Factor?

An intriguing question in the field of stress is what makes an individual more likely to be susceptible or resilient to stress-induced depression. Predisposition to stress susceptibility is believed to be influenced by genetic factors and early adversity. However, beyond genetics and life experiences, recent evidence has highlighted social rank as a key determinant of susceptibility to stress, underscoring dominant individuals as the vulnerable ones. This evidence is in conflict with epidemiological, clinical, and animal work pointing at a link between social subordination and depression. Here, we review and analyze rodent protocols addressing the relevance of social rank to predict vulnerability to chronic social stress. We also discuss whether a specific social status (i.e., dominance or subordination) is the appropriate predictor of vulnerability to develop stress-induced depression or rather, the loss of social rank and resources.

[A Patient´s Personality: A Frequently Ignored but Important Component in General Medical Practice]

A Patient´s Personality: A Frequently Ignored but Important Component in General Medical Practice Abstract. In general medical practice, a patient's personality is hardly considered and assessed. In this mini-review the author summarises how a comprehensive personality assessment may provide valuable patient information. Prospective effects of personality traits on general lifestyle as well as mental and physical health are presented. In addition, original research is introduced that shows meaningful associations between personality traits, clinical disease markers, and all-cause mortality. These findings are discussed with respect to selected etiological models. The studies illustrate that a personality assessment could be a useful aid for diagnosis, prognosis, and treatment planning.

Signatures of negative selection in the genetic architecture of human complex traits

We develop a Bayesian mixed linear model that simultaneously estimates single-nucleotide polymorphism (SNP)-based heritability, polygenicity (proportion of SNPs with nonzero effects), and the relationship between SNP effect size and minor allele frequency for complex traits in conventionally unrelated individuals using genome-wide SNP data. We apply the method to 28 complex traits in the UK Biobank data (N = 126,752) and show that on average, 6% of SNPs have nonzero effects, which in total explain 22% of phenotypic variance. We detect significant (P < 0.05/28) signatures of natural selection in the genetic architecture of 23 traits, including reproductive, cardiovascular, and anthropometric traits, as well as educational attainment. The significant estimates of the relationship between effect size and minor allele frequency in complex traits are consistent with a model of negative (or purifying) selection, as confirmed by forward simulation. We conclude that negative selection acts pervasively on the genetic variants associated with human complex traits.

Local adaptation in European populations affected the genetics of psychiatric disorders and behavioral traits

Background

Recent studies have used genome-wide data to investigate evolutionary mechanisms related to behavioral phenotypes, identifying widespread signals of positive selection. Here, we conducted a genome-wide investigation to study whether the molecular mechanisms involved in these traits were affected by local adaptation.

Methods

We performed a polygenic risk score analysis in a sample of 2455 individuals from 23 European populations with respect to variables related to geo-climate diversity, pathogen diversity, and language phonological complexity. The analysis was adjusted for the genetic diversity of European populations to ensure that the differences detected would reflect differences in environmental exposures.

Results

The top finding was related to the association between winter minimum temperature and schizophrenia. Additional significant geo-climate results were also observed with respect to bipolar disorder (sunny daylight), depressive symptoms (precipitation rate), major depressive disorder (precipitation rate), and subjective well-being (relative humidity). Beyond geo-climate variables, we also observed findings related to pathogen diversity and language phonological complexity: openness to experience was associated with protozoan diversity; conscientiousness and extraversion were associated with language consonants.

Conclusions

We report that common variation associated with psychiatric disorders and behavioral traits was affected by processes related to local adaptation in European populations.

Electronic supplementary material

The online version of this article (10.1186/s13073-018-0532-7) contains supplementary material, which is available to authorized users.

Genome-wide analyses of self-reported empathy: correlations with autism, schizophrenia, and anorexia nervosa

Empathy is the ability to recognize and respond to the emotional states of other individuals. It is an important psychological process that facilitates navigating social interactions and maintaining relationships, which are important for well-being. Several psychological studies have identified difficulties in both self-report and performance-based measures of empathy in a range of psychiatric conditions. To date, no study has systematically investigated the genetic architecture of empathy using genome-wide association studies (GWAS). Here we report the results of the largest GWAS of empathy to date using a well-validated self-report measure of empathy, the Empathy Quotient (EQ), in 46,861 research participants from 23andMe, Inc. We identify 11 suggestive loci (P < 1 × 10^-6), though none were significant at P < 2.5 × 10^-8 after correcting for multiple testing. The most significant SNP was identified in the non-stratified analysis (rs4882760; P = 4.29 × 10^-8), and is an intronic SNP in TMEM132C. The EQ had a modest but significant narrow-sense heritability (0.11 ± 0.014; P = 1.7 × 10^-14). As predicted, based on earlier work, we confirmed a significant female advantage on the EQ (P < 2 × 10^-16, Cohen's d = 0.65). We identified similar SNP heritability and high genetic correlation between the sexes. Also, as predicted, we identified a significant negative genetic correlation between autism and the EQ (r_g = -0.27 ± 0.07, P = 1.63 × 10^-4). We also identified a significant positive genetic correlation between the EQ and risk for schizophrenia (r_g = 0.19 ± 0.04; P = 1.36 × 10^-5), risk for anorexia nervosa (r_g = 0.32 ± 0.09; P = 6 × 10^-4), and extraversion (r_g = 0.45 ± 0.08; 5.7 × 10^-8). This is the first GWAS of self-reported empathy. The results suggest that the genetic variations associated with empathy also play a role in psychiatric conditions and psychological traits.

Item-level analyses reveal genetic heterogeneity in neuroticism

Genome-wide association studies (GWAS) of psychological traits are generally conducted on (dichotomized) sums of items or symptoms (e.g., case-control status), and not on the individual items or symptoms themselves. We conduct large-scale GWAS on 12 neuroticism items and observe notable and replicable variation in genetic signal between items. Within samples, genetic correlations among the items range between 0.38 and 0.91 (mean rg = .63), indicating genetic heterogeneity in the full item set. Meta-analyzing the two samples, we identify 255 genome-wide significant independent genomic regions, of which 138 are item-specific. Genetic analyses and genetic correlations with 33 external traits support genetic differences between the items. Hierarchical clustering analysis identifies two genetically homogeneous item clusters denoted depressed affect and worry. We conclude that the items used to measure neuroticism are genetically heterogeneous, and that biological understanding can be gained by studying them in genetically more homogeneous clusters.

The genetics of human personality

Personality traits are the relatively enduring patterns of thoughts, feelings and behaviors that reflect the tendency to respond in certain ways under certain circumstances. Twin and family studies have showed that personality traits are moderately heritable, and can predict various lifetime outcomes, including psychopathology. The Research Domain Criteria characterizes psychiatric diseases as extremes of normal tendencies, including specific personality traits. This implies that heritable variation in personality traits, such as neuroticism, would share a common genetic basis with psychiatric diseases, such as major depressive disorder. Despite considerable efforts over the past several decades, the genetic variants that influence personality are only beginning to be identified. We review these recent and increasingly rapid developments, which focus on the assessment of personality via several commonly used personality questionnaires in healthy human subjects. Study designs covered include twin, linkage, candidate gene association studies, genome-wide association studies and polygenic analyses. Findings from genetic studies of personality have furthered our understanding about the genetic etiology of personality, which, like neuropsychiatric diseases themselves, is highly polygenic. Polygenic analyses have showed genetic correlations between personality and psychopathology, confirming that genetic studies of personality can help to elucidate the etiology of several neuropsychiatric diseases.

Ethical Application of Precision Medicine to Schizophrenia Management

A recent effort has been made to better characterize the genetic architecture of schizophrenia, and apply a precision medicine model to its treatment. In pursuing this approach, it is likely that ethical concerns regarding cost-benefit uncertainties, the duty to inform and confidentiality will arise. Due to the complexity of schizophrenia's genetic profile, research efforts must be weighed against the risk to human subjects and the required consumption of valuable healthcare resources. Genetic risk profiles must be judged in conjunction with actionability and must be fully explained to patients and others potentially affected. However, confidentiality should be of paramount importance due to the presence of a risk-state phenotype, meaning the associated presence of clinically detectable neurocognitive deficiencies in those with elevated schizophrenia risk profiles.

Multi-trait analysis of genome-wide association summary statistics using MTAG

We introduce multi-trait analysis of GWAS (MTAG), a method for joint analysis of summary statistics from genome-wide association studies (GWAS) of different traits, possibly from overlapping samples. We apply MTAG to summary statistics for depressive symptoms (N eff = 354,862), neuroticism (N = 168,105), and subjective well-being (N = 388,538). As compared to the 32, 9, and 13 genome-wide significant loci identified in the single-trait GWAS (most of which are themselves novel), MTAG increases the number of associated loci to 64, 37, and 49, respectively. Moreover, association statistics from MTAG yield more informative bioinformatics analyses and increase the variance explained by polygenic scores by approximately 25%, matching theoretical expectations.

The protocadherin 17 gene affects cognition, personality, amygdala structure and function, synapse development and risk of major mood disorders

Major mood disorders, which primarily include bipolar disorder and major depressive disorder, are the leading cause of disability worldwide and pose a major challenge in identifying robust risk genes. Here, we present data from independent large-scale clinical data sets (including 29 557 cases and 32 056 controls) revealing brain expressed protocadherin 17 (PCDH17) as a susceptibility gene for major mood disorders. Single-nucleotide polymorphisms (SNPs) spanning the PCDH17 region are significantly associated with major mood disorders; subjects carrying the risk allele showed impaired cognitive abilities, increased vulnerable personality features, decreased amygdala volume and altered amygdala function as compared with non-carriers. The risk allele predicted higher transcriptional levels of PCDH17 mRNA in postmortem brain samples, which is consistent with increased gene expression in patients with bipolar disorder compared with healthy subjects. Further, overexpression of PCDH17 in primary cortical neurons revealed significantly decreased spine density and abnormal dendritic morphology compared with control groups, which again is consistent with the clinical observations of reduced numbers of dendritic spines in the brains of patients with major mood disorders. Given that synaptic spines are dynamic structures which regulate neuronal plasticity and have crucial roles in myriad brain functions, this study reveals a potential underlying biological mechanism of a novel risk gene for major mood disorders involved in synaptic function and related intermediate phenotypes.

Genetics of generalized anxiety disorder and related traits

This review serves as a systematic guide to the genetics of generalized anxiety disorder (GAD) and further focuses on anxiety-relevant endophenotypes, such as pathological worry fear of uncertainty, and neuroticism. We inspect clinical genetic evidence for the familialityl heritability of GAD and cross-disorder phenotypes based on family and twin studies. Recent advances of linkage studies, genome-wide association studies, and candidate gene studies (eg, 5-HTT, 5-HT1A, MAOA, BDNF) are outlined. Functional and structural neuroimaging and neurophysiological readouts relating to peripheral stress markers and psychophysiology are further integrated, building a multilevel disease framework. We explore etiologic factors in gene-environment interaction approaches investigating childhood trauma, environmental adversity, and stressful life events in relation to selected candidate genes (5-HTT, NPSR1, COMT, MAOA, CRHR1, RGS2), Additionally, the pharmacogenetics of selective serotonin reuptake inhibitor/serotonin-norepinephrine reuptake inhibitor treatment are summarized (5-HTT, 5-HT2A, COMT, CRHR1). Finally, GAD and trait anxiety research challenges and perspectives in the field of genetics, including epigenetics, are discussed.

Updates on Genome-Wide Association Findings in Eating Disorders and Future Application to Precision Medicine

Heterogeneity, frequent diagnostic fluctuation across presentations, and global concerns with the absence of effective treatments all encourage science that moves the field toward individualized or precision medicine in eating disorders. We review recent advances in psychiatric genetics focusing on genome-wide association studies (GWAS) in eating disorders. Given that the only eating disorder to be the subject of GWAS to date is anorexia nervosa, we review anorexia GWAS and enumerate the prospects and challenges of a genomics-driven approach towards personalized intervention in eating disorders.

Association of the Polygenic Scores for Personality Traits and Response to Selective Serotonin Reuptake Inhibitors in Patients with Major Depressive Disorder

Studies reported a strong genetic correlation between the Big Five personality traits and major depressive disorder (MDD). Moreover, personality traits are thought to be associated with response to antidepressants treatment that might partly be mediated by genetic factors. In this study, we examined whether polygenic scores (PGSs) derived from the Big Five personality traits predict treatment response and remission in patients with MDD who were prescribed selective serotonin reuptake inhibitors (SSRIs). In addition, we performed meta-analyses of genome-wide association studies (GWASs) on these traits to identify genetic variants underpinning the cross-trait polygenic association. The PGS analysis was performed using data from two cohorts: the Pharmacogenomics Research Network Antidepressant Medication Pharmacogenomic Study (PGRN-AMPS, n = 529) and the International SSRI Pharmacogenomics Consortium (ISPC, n = 865). The cross-trait GWAS meta-analyses were conducted by combining GWAS summary statistics on SSRIs treatment outcome and on the personality traits. The results showed that the PGS for openness and neuroticism were associated with SSRIs treatment outcomes at p < 0.05 across P_T thresholds in both cohorts. A significant association was also found between the PGS for conscientiousness and SSRIs treatment response in the PGRN-AMPS sample. In the cross-trait GWAS meta-analyses, we identified eight loci associated with (a) SSRIs response and conscientiousness near YEATS4 gene and (b) SSRI remission and neuroticism eight loci near PRAG1, MSRA, XKR6, ELAVL2, PLXNC1, PLEKHM1, and BRUNOL4 genes. An assessment of a polygenic load for personality traits may assist in conjunction with clinical data to predict whether MDD patients might respond favorably to SSRIs.

Association analysis in over 329,000 individuals identifies 116 independent variants influencing neuroticism

Neuroticism is a relatively stable personality trait characterized by negative emotionality (for example, worry and guilt) 1 ; heritability estimated from twin studies ranges from 30 to 50% 2 , and SNP-based heritability ranges from 6 to 15% 3-6 . Increased neuroticism is associated with poorer mental and physical health 7,8 , translating to high economic burden 9 . Genome-wide association studies (GWAS) of neuroticism have identified up to 11 associated genetic loci 3,4 . Here we report 116 significant independent loci from a GWAS of neuroticism in 329,821 UK Biobank participants; 15 of these loci replicated at P < 0.00045 in an unrelated cohort (N = 122,867). Genetic signals were enriched in neuronal genesis and differentiation pathways, and substantial genetic correlations were found between neuroticism and depressive symptoms (r g = 0.82, standard error (s.e.) = 0.03), major depressive disorder (MDD; r g = 0.69, s.e. = 0.07) and subjective well-being (r g = -0.68, s.e. = 0.03) alongside other mental health traits. These discoveries significantly advance understanding of neuroticism and its association with MDD.

Clinical Characteristics, Life Adversities and Personality Traits in Monozygotic Twins With, at Risk of and Without Affective Disorders

Background: Affective disorders have a long-term impact on psychiatric health and are caused by multiple interacting factors including familial risk, childhood adversity, life events and personality traits. Methods: In this study, monozygotic twins (MZ) at familial risk (indexed by affective disorder in their co-twin; high-risk group), affected MZ twins (indexed by a diagnosis with affective disorder) and MZ twins with no family history of affective disorder (low-risk group) were identified through cross-linking of nation-wide Danish registers. In total, 204 MZ twins were included and psychopathology, personality traits and life adversity were evaluated by semi-structured interviews and questionnaires. Results: Affected MZ twins presented with more subclinical affective symptoms and were functionally impaired as evidenced by higher unemployment rates and reduced functional status. The affected and the high-risk groups reported more childhood adversity and had experienced more stressful life events than the low-risk group. A direct comparison within the discordant twin pairs showed that the high-risk twins presented fewer affective symptoms, better functional status, more extraversion and lower neuroticism scores than their affected co-twins although they had equal levels of life adversity as their affected co-twins. Conclusion: These findings add to the evidence indicating that patients experience higher neuroticism, persistent subclinical symptoms and reduced socio-occupational function after affective episodes. Additionally, neuroticism and extraversion seem capable of moderating the sensitivity to exposure from the environment.

A Powerful Approach to Estimating Annotation-Stratified Genetic Covariance via GWAS Summary Statistics

Despite the success of large-scale genome-wide association studies (GWASs) on complex traits, our understanding of their genetic architecture is far from complete. Jointly modeling multiple traits' genetic profiles has provided insights into the shared genetic basis of many complex traits. However, large-scale inference sets a high bar for both statistical power and biological interpretability. Here we introduce a principled framework to estimate annotation-stratified genetic covariance between traits using GWAS summary statistics. Through theoretical and numerical analyses, we demonstrate that our method provides accurate covariance estimates, thereby enabling researchers to dissect both the shared and distinct genetic architecture across traits to better understand their etiologies. Among 50 complex traits with publicly accessible GWAS summary statistics (Ntotal≈ 4.5 million), we identified more than 170 pairs with statistically significant genetic covariance. In particular, we found strong genetic covariance between late-onset Alzheimer disease (LOAD) and amyotrophic lateral sclerosis (ALS), two major neurodegenerative diseases, in single-nucleotide polymorphisms (SNPs) with high minor allele frequencies and in SNPs located in the predicted functional genome. Joint analysis of LOAD, ALS, and other traits highlights LOAD's correlation with cognitive traits and hints at an autoimmune component for ALS.

Genetic Risk Variants Associated With Comorbid Alcohol Dependence and Major Depression

Importance

Alcohol dependence (AD) and major depression (MD) are leading causes of disability that often co-occur. Genetic epidemiologic data have shown that AD and MD share a common possible genetic cause. The molecular nature of this shared genetic basis is poorly understood.

Objectives

To detect genetic risk variants for comorbid AD and MD and to determine whether polygenic risk alleles are shared with neuropsychiatric traits or subcortical brain volumes.

Design, Setting, and Participants

This genome-wide association study analyzed criterion counts of comorbid AD and MD in African American and European American data sets collected as part of the Yale-Penn study of the genetics of drug and alcohol dependence from February 14, 1999, to January 13, 2015. After excluding participants never exposed to alcohol or with missing information for any diagnostic criterion, genome-wide association studies were performed on 2 samples (the Yale-Penn 1 and Yale-Penn 2 samples) totaling 4653 African American participants and 3169 European American participants (analyzed separately). Tests were performed to determine whether polygenic risk scores derived from potentially related traits in European American participants could be used to estimate comorbid AD and MD.

Main Outcomes and Measures

Comorbid criterion counts (ranging from 0 to 14) for AD (7 criteria) and MD (9 criteria, scaled to 7) as defined by the DSM-IV.

Results

Of the 7822 participants (3342 women and 4480 men; mean [SD] age, 40.1 [10.7] years), the median comorbid criterion count was 6.2 (interquartile range, 2.3-10.9). Under the linear regression model, rs139438618 at the semaphorin 3A (SEMA3A [OMIM 603961]) locus was significantly associated with AD and MD comorbidity in African American participants in the Yale-Penn 1 sample (β = 0.89; 95% CI, 0.57-1.20; P = 2.76 × 10-8). In the independent Yale-Penn 2 sample, the association was also significant (β = 0.83; 95% CI, 0.39-1.28; P = 2.06 × 10-4). Meta-analysis of the 2 samples yielded a more robust association (β = 0.87; 95% CI, 0.61-1.12; P = 2.41 × 10-11). There was no significant association identified in European American participants. Analyses of polygenic risk scores showed that individuals with a higher risk of neuroticism (β = 1.01; 95% CI, 0.50-1.52) or depressive symptoms (β = 0.87; 95% CI, 0.32-1.42) and a lower level of subjective well-being (β = -0.94; 95% CI, -1.46 to -0.42) and educational attainment (β = -1.00, 95% CI, -1.57 to -0.44) had a higher level of AD and MD comorbidity, while larger intracranial (β = 1.07; 95% CI, 0.50 to 1.64) and smaller putamen volumes (β = -1.16; 95% CI, -1.86 to -0.46) were associated with higher risks of AD and MD comorbidity.

Conclusions and Relevance

SEMA3A variation is significantly and replicably associated with comorbid AD and MD in African American participants. Analyses of polygenic risk scores identified pleiotropy with neuropsychiatric traits and brain volumes. Further studies are warranted to understand the biological and genetic mechanisms of this comorbidity, which could facilitate development of medications and other treatments for comorbid AD and MD.

Modeling prior information of common genetic variants improves gene discovery for neuroticism

Neuroticism reflects emotional instability, and is related to various mental and physical health issues. However, the majority of genetic variants associated with neuroticism remain unclear. Inconsistent genetic variants identified by different genome-wide association studies (GWAS) may be attributable to low statistical power. We proposed a novel framework to improve the power for gene discovery by incorporating prior information of single nucleotide polymorphisms (SNPs) and combining two relevant existing tools, relative enrichment score (RES) and conditional false discovery rate (FDR). Here, SNP's conditional FDR was estimated given its RES based on SNP prior information including linkage disequilibrium (LD)-weighted genic annotation scores, total LD scores and heterozygosity. A known significant locus in chromosome 8p was excluded before estimating FDR due to long-range LD structure. Only one significant LD-independent SNP was detected by analyses of unconditional FDR and traditional GWAS in the discovery sample (N = 59 225), and notably four additional SNPs by conditional FDR. Three of the five SNPs, all identified by conditional FDR, were replicated (P < 0.05) in an independent sample (N = 170 911). These three SNPs are located in intronic regions of CADM2, LINGO2 and EP300 which have been reported to be associated with autism, Parkinson's disease and schizophrenia, respectively. Our approach using a combination of RES and conditional FDR improved power of traditional GWAS for gene discovery providing a useful framework for the analysis of GWAS summary statistics by utilizing SNP prior information, and helping to elucidate the links between neuroticism and complex diseases from a genetic perspective.

Monoamine Oxidase A (MAOA) Gene and Personality Traits from Late Adolescence through Early Adulthood: A Latent Variable Investigation

Very few molecular genetic studies of personality traits have used longitudinal phenotypic data, therefore molecular basis for developmental change and stability of personality remains to be explored. We examined the role of the monoamine oxidase A gene (MAOA) on extraversion and neuroticism from adolescence to adulthood, using modern latent variable methods. A sample of 1,160 male and 1,180 female participants with complete genotyping data was drawn from a British national birth cohort, the MRC National Survey of Health and Development (NSHD). The predictor variable was based on a latent variable representing genetic variations of the MAOA gene measured by three SNPs (rs3788862, rs5906957, and rs979606). Latent phenotype variables were constructed using psychometric methods to represent cross-sectional and longitudinal phenotypes of extraversion and neuroticism measured at ages 16 and 26. In males, the MAOA genetic latent variable (AAG) was associated with lower extraversion score at age 16 (β = −0.167; CI: −0.289, −0.045; p = 0.007, FDRp = 0.042), as well as greater increase in extraversion score from 16 to 26 years (β = 0.197; CI: 0.067, 0.328; p = 0.003, FDRp = 0.036). No genetic association was found for neuroticism after adjustment for multiple testing. Although, we did not find statistically significant associations after multiple testing correction in females, this result needs to be interpreted with caution due to issues related to x-inactivation in females. The latent variable method is an effective way of modeling phenotype- and genetic-based variances and may therefore improve the methodology of molecular genetic studies of complex psychological traits.

Opportunities for an enhanced integration of neuroscience and genomics

Neuroimaging and genetics are two rapidly expanding fields of research. Thoughtful integration of these areas is critical for ongoing large-scale research into the genetic mechanisms underlying brain structure, function, and development. Neuroimaging genetics has been slow to evolve relative to psychiatric genetics research, and some may be unaware that new statistical methods allow for the genomic analysis of more modestly-sized imaging samples. We present a broad overview of the extant imaging genetics literature, provide an interpretation of the major problems surrounding the integration of neuroimaging and genetics, discuss the influence and impact of genetics consortia, and suggest statistical genetic analyses that expand the repertoire of imaging researchers amassing rich behavioral data in modestly-sized samples. Specific attention is paid to the creative use of polygenic risk scoring in imaging genetic analyses, with primers on the most current risk scoring applications.

An Extended Twin-Pedigree Study of Neuroticism in the Netherlands Twin Register

For the participants in the Netherlands Twin Register (NTR) we constructed the extended pedigrees which specify all relations among nuclear and larger twin families in the register. A total of 253,015 subjects from 58,645 families were linked to each other, to the degree that we had information on the relations among participants. We describe the algorithm that was applied to construct the pedigrees. For > 30,000 adolescent and adult NTR participants data were available on harmonized neuroticism scores. We analyzed these data in the Mendel software package (Lange et al., Bioinformatics 29(12):1568-1570, 2013) to estimate the contributions of additive and non-additive genetic factors. In contrast to much of the earlier work based on twin data rather than on extended pedigrees, we could also estimate the contribution of shared household effects in the presence of non-additive genetic factors. The estimated broad-sense heritability of neuroticism was 47%, with almost equal contributions of additive and non-additive (dominance) genetic factors. A shared household effect explained 13% and unique environmental factors explained the remaining 40% of the variance in neuroticism.

The schizophrenia susceptibility gene ZNF804A confers risk of major mood disorders

OBJECTIVES

Genome-wide association studies (GWAS) followed by independent replications suggest that ZNF804A is a risk gene for schizophrenia (SCZ), considering the substantial genetic overlap between SCZ and major mood disorders (e.g., bipolar disorder (BPD) and major depressive disorder (MDD)).

METHODS

We collected the data of two ZNF804A single-nucleotide polymorphisms (SNPs rs1344706 and rs7597593) from European and Asian populations to perform systematic meta-analyses with major mood disorders in a total of 65,240 subjects.

RESULTS

Meta-analysis showed that rs1344706 and rs7597593 were both associated with major mood disorders as well as diagnosis of either BPD or MDD, although neither of the analyses achieved a genome-wide level of statistical significance.

CONCLUSIONS

Our data provide evidence for the genetic involvement of ZNF804A SNPs in the susceptibility of major mood disorders, but further replication analyses in larger samples are necessary.

High levels of neuroticism are associated with decreased cortical folding of the dorsolateral prefrontal cortex

The personality trait neuroticism has been identified as a vulnerability factor for common psychiatric diseases and defining potential neuroanatomical markers for early recognition and prevention strategies is mandatory. Because both personality traits and cortical folding patterns are early imprinted and timely stable there is reason to hypothesize an association between neuroticism and cortical folding. Thus, to identify a putative linkage, we tested whether the degree of neuroticism is associated with local cortical folding in a sample of 109 healthy individuals using a surface-based MRI approach. Based on previous findings we additionally tested for a potential association with cortical thickness. We found a highly significant negative correlation between the degree of neuroticism and local cortical folding of the left dorsolateral prefrontal cortex (DLPFC), i.e., high levels of neuroticism were associated with low cortical folding of the left DLPFC. No association was found with cortical thickness. The present study is the first to describe a linkage between the extent of local cortical folding and the individual degree of neuroticism in healthy subjects. Because neuroticism is a vulnerability factor for common psychiatric diseases such as depression our finding indicates that alterations of DLPFC might constitute a neurobiological marker elevating risk for psychiatric burden.

A comprehensive regional analysis of genome-wide expression profiles for major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a global health challenge. In recent years, a large number of genome-wide expression studies (GWES) have been carried out to identify the transcriptomic profiles for MDD. The objective of this work was to carry out a comprehensive meta-analysis of available GWES for MDD.

METHODS

GWES for MDD with available raw data were searched in NCBI GEO, Array Express and Stanley databases. Raw GWES data were preprocessed and normalized and meta-analytical procedures were carried out with the Network Analyst program. 743 samples from 24 primary studies were included in our meta-analyses for blood (Blo), amygdala (Amy), cerebellum (Cer), anterior cingulate cortex (ACC) and prefrontal cortex (PFC) regions. A functional enrichment analysis was carried out.

RESULTS

We identified 35, 793, 231, 668 and 252 differentially expressed (DE) genes for Blo, Amy, Cer, ACC and PFC regions. A region-dependent significant enrichment for several functional categories, such as gene ontologies, signaling pathways and topographic parameters, was identified. There was convergence with other available genome-wide studies, such as GWAS, DNA methylation analyses and miRNA expression studies.

LIMITATIONS

Raw data were not available for several primary studies that have been published previously.

CONCLUSIONS

This is the largest meta-analysis for GWES in MDD. The examination of convergence of genome-wide evidence and of the functional enrichment analysis provides a global overview of potential neural signaling mechanisms dysregulated in MDD. Our comprehensive analysis of several brain regions identified lists of DE genes for MDD that are interesting candidates for further studies.

The influence of parental care and overprotection, neuroticism and adult stressful life events on depressive symptoms in the general adult population

BACKGROUND

The quality of parenting, neuroticism, and adult stressful life events are reportedly associated with depressive symptoms. However, previous studies have not examined the complex interaction between these three factors. In this study, we hypothesized that the quality of parenting (care and overprotection) acts on depressive symptoms through 'neuroticism' and the appraisal of adult stressful life events, and this hypothesis was verified by structural equation modeling.

METHODS

Four hundred one participants from the general adult population were studied using the following self-administered questionnaire surveys: Patient Health Questionnaire-9 (PHQ-9), Parental Bonding Instrument (PBI), neuroticism subscale of the short version of the Eysenck Personality Questionnaire-revised (EPQ-R), and Life Experiences Survey (LES). The data were analyzed with single and multiple regression analyses and covariance structure analyses.

RESULTS

In the covariance structure analysis, neuroticism scores and negative change scores on the LES acted on the depressive symptoms (PHQ-9 scores) directly, but care or overprotection in childhood on the PBI did not act on them directly. Low care and high overprotection of the PBI increased depressive symptoms and negative change scores on the LES through enhanced neuroticism, which is regarded as a mediator in these effects.

LIMITATIONS

The subjects of this study were nonclinical volunteers; the findings might not be generalizable to psychiatric patients.

CONCLUSIONS

This research showed that low care and high overprotection of maternal and paternal parenting in childhood influence depressive symptoms indirectly through enhanced neuroticism in general adults. These findings suggest that neuroticism mediates the long-term effect of the quality of parenting on depression in adulthood.

Integrating genome-wide association study and expression quantitative trait loci data identifies multiple genes and gene set associated with neuroticism

Neuroticism is a fundamental personality trait with significant genetic determinant. To identify novel susceptibility genes for neuroticism, we conducted an integrative analysis of genomic and transcriptomic data of genome wide association study (GWAS) and expression quantitative trait locus (eQTL) study. GWAS summary data was driven from published studies of neuroticism, totally involving 170,906 subjects. eQTL dataset containing 927,753 eQTLs were obtained from an eQTL meta-analysis of 5311 samples. Integrative analysis of GWAS and eQTL data was conducted by summary data-based Mendelian randomization (SMR) analysis software. To identify neuroticism associated gene sets, the SMR analysis results were further subjected to gene set enrichment analysis (GSEA). The gene set annotation dataset (containing 13,311 annotated gene sets) of GSEA Molecular Signatures Database was used. SMR single gene analysis identified 6 significant genes for neuroticism, including MSRA (p value=2.27×10^-10), MGC57346 (p value=6.92×10^-7), BLK (p value=1.01×10^-6), XKR6 (p value=1.11×10^-6), C17ORF69 (p value=1.12×10^-6) and KIAA1267 (p value=4.00×10^-6). Gene set enrichment analysis observed significant association for Chr8p23 gene set (false discovery rate=0.033). Our results provide novel clues for the genetic mechanism studies of neuroticism.

Spatial and temporal expression patterns of genes around nine neuroticism-associated loci

Neuroticism is a high-order personality trait. Individuals with higher neuroticism have increased risks of various psychiatric disorders and physical health outcomes. Neuroticism is related to physiological differences in the brain. A recent genome-wide association study identified nine distinct genomic loci that contribute to neuroticism. Brain development and function depend on the precise regulation of gene expression, which is differentially regulated across brain regions and developmental stages. Using multiple publicly available human post-mortem databases, we investigated, in brain and non-brain tissues and across several developmental life stages, the spatial and temporal expression patterns of genes arising from nine neuroticism-associated loci. Functional gene-network analysis for neuroticism-associated genes was performed. The spatial expression analysis revealed that the nearest genes (GRIK3, SRP9, KLHL2, PTPRD, ELAVL2, CRHR1 and CELF4) from index single-nucleotide polymorphisms (SNPs) at the nine loci were intensively enriched in the brain compared with their representation in non-brain tissues (p<1.56×10^-3). The nearest genes associated with the glutamate receptor activity network consisted mainly of GRIK3 (FDR q=4.25×10^-2). The temporal expression analysis revealed that the neuroticism-associated genes were divided into three expression patterns: KLHL2, CELF4 and CRHR1 were preferentially expressed during postnatal stages; PTPRD, ELAVL2 and MFHAS1 were expressed during prenatal stages; and the other three genes were not expressed during specific life stages. These findings suggest that the glutamate network might be a target for investigating the neurobiological mechanisms underlying susceptibilities to higher neuroticism and several psychiatric disorders and that neuroticism is mediated by genes specifically expressed in the brain during several developmental stages.

Parental educational attainment and adult offspring personality: An intergenerational life span approach to the origin of adult personality traits

Why do some individuals have more self-control or are more vulnerable to stress than others? Where do these basic personality traits come from? Although a fundamental question in personality, more is known about how traits are related to important life outcomes than their developmental origins. The present research took an intergenerational life span approach to address whether a significant aspect of the childhood environment-parental educational attainment-was associated with offspring personality traits in adulthood. We tested the association between parents' educational levels and adult offspring personality traits in 7 samples (overall age range 14-95) and meta-analytically combined the results (total N > 60,000). Parents with more years of education had children who were more open, extraverted, and emotionally stable as adults. These associations were small but consistent, of similar modest magnitude to the association between life events and change in personality in adulthood, and were also supported by longitudinal analyses. Contrary to expectations, parental educational attainment was unrelated to offspring Conscientiousness, except for a surprisingly negative association in the younger cohorts. The results were similar in a subsample of participants who were adopted, which suggested that environmental mechanisms were as relevant as shared genetic variants. Participant levels of education were associated with greater conscientiousness, emotional stability, extraversion, and openness and partially mediated the relation between parent education and personality. Child IQ and family income were also partial mediators. The results of this research suggest that parental educational attainment is 1 intergenerational factor associated with offspring personality development in adulthood. (PsycINFO Database Record

Using a Systems-Based Risk Score Approach to Examine Genetic Predisposition to Novelty Seeking

Abstract. Previous research is mixed regarding the relation between dopamine and Novelty Seeking. The goals of the current study were to support the hypotheses that Novelty Seeking is associated with dopamine genes and that modeling genetic risk score increases the utility of genetic information in hypothesis-driven research. The results showed that higher hypodopaminergic genetic risk score positively predicted higher Novelty Seeking score, F(1, 115) = 5.76, p < .01, R2 = 0.06. The findings support study hypotheses and, in combination with previous studies, show the utility of empirically validated system-based risk scores as a means of modeling genetic predisposition in neurobiological systems. This approach provides a mechanism for incorporating genetic predisposition into theory-driven multivariate etiological models of psychological constructs such as personality and mental illness.

Association of Late Adolescent Personality With Risk for Subsequent Serious Mental Illness Among Men in a Swedish Nationwide Cohort Study

IMPORTANCE

Understanding of personality as an independent risk factor for serious mental illness (SMI) remains limited. Recently, overlap between the polygenic basis for specific personality traits and specific SMIs has been identified.

OBJECTIVE

To determine the association of the adolescent personality domains of social maturity, mental energy, and emotional stability with later diagnosis of SMI.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal cohort study enrolled Swedish male military conscripts aged 18 or 19 years from January 1, 1974, through December 31, 1997. The diagnosis of an SMI was extracted from the National Patient Register for all inpatient treatment episodes in Sweden from January 1, 1974, through December 31, 2011. Data were analyzed from May 3 to September 16, 2016.

EXPOSURES

Social maturity, mental energy, and emotional stability assessed at conscription interview.

MAIN OUTCOMES AND MEASURES

Inpatient diagnoses of bipolar disorder, schizoaffective disorder, schizophrenia, and other nonaffective psychoses occurring until December 31, 2011.

RESULTS

Of the 1 017 691 men included in the cohort, 4310 developed bipolar disorder; 784, schizoaffective disorder; 4823, schizophrenia; and 5013, other nonaffective psychoses. After adjustment, with use of mean scores as a reference, low social maturity (hazard ratio [HR], 1.61; 95% CI, 1.48-1.74), low mental energy (HR, 1.34; 95% CI, 1.24-1.44), and low emotional stability (HR, 1.51; 95% CI, 1.40-1.63) were inversely associated with schizophrenia in a dose-dependent fashion. Other nonaffective psychoses displayed a similar pattern. Bipolar disorder was associated with high (HR, 1.21; 95% CI, 1.09-1.35) and low (HR, 1.12; 95% CI, 1.01-1.25) social maturity and low emotional stability (HR, 1.62; 95% CI, 1.46-1.78). Schizoaffective disorder was associated with low emotional stability (HR, 1.53; 95% CI, 1.26-1.85).

CONCLUSIONS AND RELEVANCE

Emotional stability is inversely associated with all SMI. Bipolar disorder has a unique U-shaped association with social maturity. Premorbid personality may reflect subtle changes in cerebral function, may combine with symptoms and other neurocognitive deficits to influence illness presentation, and/or may be owing to shared genetic architecture.

Posttraumatic stress disorder symptom severity is associated with reduced default mode network connectivity in individuals with elevated genetic risk for psychopathology

BACKGROUND

Accumulating evidence suggests that posttraumatic stress disorder (PTSD) is associated with disrupted default mode network (DMN) connectivity, but findings across studies have not been uniform. Individual differences in relevant genes may account for some of the reported variability in the relationship between DMN connectivity and PTSD. In this study, we investigated this possibility using genome-wide association study (GWAS) derived polygenic risk scores (PRSs) for relevant psychiatric traits. We hypothesized that the association between PTSD and DMN connectivity would be moderated by genetic risk for one or more psychiatric traits such that individuals with elevated polygenic risk for psychopathology and severe PTSD would exhibit disrupted DMN connectivity.

METHODS

Participants were 156 white, non-Hispanic veterans of the wars in Iraq and Afghanistan who were genotyped and underwent resting state functional magnetic resonance imaging and clinical assessment. PRSs for neuroticism, anxiety, major depressive disorder, and cross-disorder risk (based on five psychiatric disorders) were calculated using summary statistics from published large-scale consortia-based GWASs.

RESULTS

Cross-disorder polygenic risk influenced the relationship between DMN connectivity and PTSD symptom severity such that individuals at greater genetic risk showed a significant negative association between PTSD symptom severity and connectivity between the posterior cingulate cortex and right middle temporal gyrus. Polygenic risk for neuroticism, anxiety, and major depressive disorder did not influence DMN connectivity directly or through an interaction with PTSD.

CONCLUSIONS

Findings illustrate the potential power of genome-wide PRSs to advance understanding of the relationship between PTSD and DMN connectivity, a putative neural endophenotype of the disorder.

Meta-analysis of genome-wide SNP- and pathway-based associations for facets of neuroticism

Neuroticism is a heritable personality trait that is comprised of distinct sub-factors, or facets. Sub-factors of neuroticism are linked to different emotional states or psychiatric symptoms and studying the genetic variants associated with these facets may help reveal the biological mechanisms underlying psychiatric disorders. In the present study, a meta-analysis of genome-wide association studies for six facets of neuroticism was performed in 5584 participants from three cohorts. Additionally, a Gene Set Enrichment Analysis was conducted to find biological pathways associated with each facet. Six neuroticism facets (N1: anxiety, N2: angry hostility, N3: depression, N4: self-consciousness, N5: impulsivity and N6: vulnerability) were assessed using the Korean version of the Revised NEO Personality Inventory. In the single-nucleotide polymorphism-based analysis, results showed genome-wide significance for N2 within the MIR548H3 gene (rs1360001, P=4.14 × 10^-9). Notable genes with suggestive associations (P<1.0 × 10^-6) were ITPR1 for N1, WNT7A for N2, FGF10 and FHIT for N3, DDR1 for N4, VGLL4 for N5 and PTPRD for N6. In the pathway-based analysis, the axon guidance pathway was identified to be associated with multiple facets of neuroticism (N2, N4 and N6). The focal adhesion and extracellular matrix receptor interaction pathways were significantly associated with N2 and N3. Our findings revealed genetic influences and biological pathways that are associated with facets of neuroticism.

Identification of genetic loci shared between schizophrenia and the Big Five personality traits

Schizophrenia is associated with differences in personality traits, and recent studies suggest that personality traits and schizophrenia share a genetic basis. Here we aimed to identify specific genetic loci shared between schizophrenia and the Big Five personality traits using a Bayesian statistical framework. Using summary statistics from genome-wide association studies (GWAS) on personality traits in the 23andMe cohort (n = 59,225) and schizophrenia in the Psychiatric Genomics Consortium cohort (n = 82,315), we evaluated overlap in common genetic variants. The Big Five personality traits neuroticism, extraversion, openness, agreeableness and conscientiousness were measured using a web implementation of the Big Five Inventory. Applying the conditional false discovery rate approach, we increased discovery of genetic loci and identified two loci shared between neuroticism and schizophrenia and six loci shared between openness and schizophrenia. The study provides new insights into the relationship between personality traits and schizophrenia by highlighting genetic loci involved in their common genetic etiology.