Gene-Environment Interactions in Psychiatry: Recent Evidence and Clinical Implications

Polygenic risk scores for mood and related disorders and environmental factors: Interaction effects on wellbeing in the UK biobank

Mood disorders have a genetic and environmental component and interactions (GxE) on the risk of psychiatric diseases have been investigated. The same GxE interactions may affect wellbeing measures, which go beyond categorical diagnoses and reflect the health-disease continuum. We evaluated GxE effects in the UK Biobank, considering as outcomes subjective wellbeing (feeling good and functioning well) and objective measures (education and income). We estimated the polygenic risk scores (PRSs) of major depressive disorder, bipolar disorder, schizophrenia, and attention deficit hyperactivity disorder. Stressful/traumatic events during adulthood or childhood were considered as E variables, as well as social support. The addition of the PRSxE interaction to PRS and E variables was tested in linear or multinomial regression models, adjusting for confounders. We included 33 k-380 k participants, depending on the variables considered. Most PRSs and E factors showed additive effects on outcomes, with effect sizes generally 3-5 times larger for E variables than PRSs. We found some interaction effects, particularly when considering recent stress, history of a long illness/disability/infirmity, and social support. Higher PRSs increased the negative effects of stress on wellbeing, but they also increased the positive effects of social support, with interaction effects particularly for the outcomes health satisfaction, loneliness, and income (p < Bonferroni corrected threshold of 1.92e-4). PRSxE terms usually added ∼0.01-0.02% variance explained to the corresponding additive model. PRSxE effects on wellbeing involve both positive and negative E factors. Despite small variance explained at the population level, preventive/therapeutic interventions that modify E factors could be beneficial at the individual level.

Divorce, genetic risk, and suicidal thoughts and behaviors in a sample with recurrent major depressive disorder

BACKGROUND

Theories of risk for suicidal thoughts and behaviors (STB) implicate both interpersonal and biological factors. Divorce/separation and aggregate genetic liability are robustly associated with STB, but have seldom been evaluated in conjunction with one another. Furthermore, whether these factors are effective predictors in high-risk populations is not clear.

METHODS

Analyses were conducted in a sample of Han Chinese women with severe recurrent major depressive disorder (maximum N = 4380). Logistic regressions were used to evaluate the associations between divorce/separation and polygenic scores (PGS) for suicidal ideation or behavior with STB. Where appropriate, additive interactions between divorce and PGS were tested.

RESULTS

Divorce/separation was significantly associated with increased risk of suicidal ideation, plans, and attempts (odds ratios = 1.28-1.61). PGS for suicidal ideation were not associated with STB, while PGS for suicidal behavior were associated with ideation and plans (odds ratios = 1.08-1.09). There were no significant interactions between divorce/separation and PGS.

CONCLUSIONS

Consistent with theories of suicidality, the disruption or end of an important interpersonal relationship is an indicator of risk for STB. Aggregate genetic liability for suicidal behavior more modestly contributes to risk, but does not exacerbate the negative impact of divorce. Thus, even within a high-risk sample, interpersonal and biological exposures distinguish between those who do and do not experience STB, and could motivate targeted screening. Further research is necessary to evaluate whether and how the context of divorce contributes to variation in its effect on STB risk.

Physical activity and prevention of mental health complications: An umbrella review

The potential of physical activity in preventing mental health issues has garnered interest among health professionals. We conducted a systematic umbrella review of evidence supporting the relationship between physical activity and the prevention of mental health complications. Our findings revealed a significant association between higher physical activity levels and reduced risk of depression (OR = 0.77, 95% CI 0.72 - 0.82). This association was consistent across various age groups, sex, and geographical regions. Interestingly, low and moderate-intensity physical activity showed the most significant protective effects against depression (low-intensity: OR = 0.81, 95% CI: 0.75-0.56; moderate-intensity: OR = 0.79, 95% CI: 0.72-0.87). Our analysis also showed significant associations between higher physical activity levels and prevention of anxiety disorders (OR = 0.71, 95% CI: 0.61-0.82). However, the evidence regarding the association between physical activity and psychosis/schizophrenia risk was less clear. These findings underscore the physical activity's potential as a preventative measure against mental health complications, highlighting the importance of promoting physical activity in mental health interventions.

Exploring the similarities between risk factors triggering depression in humans and elevated in-cage "inactive but awake" behavior in laboratory mice

Introduction

Depression is a human mental disorder that can also be inferred in non-human animals. This study explored whether time spent inactive but awake ("IBA") in the home-cage in mice was further triggered by risk factors similar to those increasing vulnerability to depression in humans (early life stress, genetic predispositions, adulthood stress).

Methods

Eighteen DBA/2 J and 18 C57BL/6 J females were tested, of which half underwent as pups a daily maternal separation on post-natal days 2-14 (early-life stress "ELS") (other half left undisturbed). To assess the effect of the procedure, the time the dams from which the 18 subjects were born spent active in the nest (proxy for maternal behavior) was recorded on post-natal days 2, 6, 10 and 14 for 1 h before separation and following reunion (matched times for controls), using live instantaneous scan sampling (total: 96 scans/dam). For each ELS condition, about half of the pups were housed post-weaning (i.e., from 27 days old on average) in either barren (triggering IBA and depression-like symptoms) or larger, highly enriched cages (n = 4-5 per group). Time mice spent IBA post-weaning was observed blind to ELS treatment using live instantaneous scan sampling in two daily 90-min blocks, two days/week, for 6 weeks (total: 192 scans/mouse). Data were analyzed in R using generalized linear mixed models.

Results

The dams were significantly more active in the nest over time (p = 0.016), however with no significant difference between strains (p = 0.18), ELS conditions (p = 0.20) and before/after separation (p = 0.83). As predicted, post-weaning barren cages triggered significantly more time spent IBA in mice than enriched cages (p < 0.0001). However, neither ELS (p = 0.4) nor strain (p = 0.84) significantly influenced time mice spent IBA, with no significant interaction with environmental condition (ELS × environment: p = 0.2861; strain × environment: p = 0.5713).

Discussion

Our results therefore only partly support the hypothesis that greater time spent IBA in mice is triggered by risk factors for human depression. We discuss possible explanations for this and further research directions.

Temporal changes of gene expression in health, schizophrenia, bipolar disorder, and major depressive disorder

The molecular events underlying the development, manifestation, and course of schizophrenia, bipolar disorder, and major depressive disorder span from embryonic life to advanced age. However, little is known about the early dynamics of gene expression in these disorders due to their relatively late manifestation. To address this, we conducted a secondary analysis of post-mortem prefrontal cortex datasets using bioinformatics and machine learning techniques to identify differentially expressed gene modules associated with aging and the diseases, determine their time-perturbation points, and assess enrichment with expression quantitative trait loci (eQTL) genes. Our findings revealed early, mid, and late deregulation of expression of functional gene modules involved in neurodevelopment, plasticity, homeostasis, and immune response. This supports the hypothesis that multiple hits throughout life contribute to disease manifestation rather than a single early-life event. Moreover, the time-perturbed functional gene modules were associated with genetic loci affecting gene expression, highlighting the role of genetic factors in gene expression dynamics and the development of disease phenotypes. Our findings emphasize the importance of investigating time-dependent perturbations in gene expression before the age of onset in elucidating the molecular mechanisms of psychiatric disorders.

Role of polygenic risk scores in the association between chronotype and health risk behaviors

BACKGROUND

This study explores the association between chronotypes and adolescent health risk behaviors (HRBs) by testing how genetic background moderates these associations and clarifies the influence of chronotypes and polygenic risk score (PRS) on adolescent HRBs.

METHODS

Using VOS-viewer software to select the corresponding data, this study used knowledge domain mapping to identify and develop the research direction with respect to adolescent risk factor type. Next, DNA samples from 264 students were collected for low-depth whole-genome sequencing. The sequencing detected HRB risk loci, 49 single nucleotide polymorphisms based to significant SNP. Subsequently, PRSs were assessed and divided into low, moderate, and high genetic risk according to the tertiles and chronotypes and interaction models were constructed to evaluate the association of interaction effect and clustering of adolescent HRBs. The chronotypes and the association between CLOCK-PRS and HRBs were examined to explore the association between chronotypes and mental health and circadian CLOCK-PRS and HRBs.

RESULTS

Four prominent areas were displayed by clustering information fields in network and density visualization modes in VOS-viewer. The total score of evening chronotypes correlated with high-level clustering of HRBs in adolescents, co-occurrence, and mental health, and the difference was statistically significant. After controlling covariates, the results remained consistent. Three-way interactions between chronotype, age, and mental health were observed, and the differences were statistically significant. CLOCK-PRS was constructed to identify genetic susceptibility to the clustering of HRBs. The interaction of evening chronotypes and high genetic risk CLOCK-PRS was positively correlated with high-level clustering of HRBs and HRB co-occurrence in adolescents, and the difference was statistically significant. The interaction between the sub-dimensions of evening chronotypes and the high genetic CLOCK-PRS risk correlated with the outcome of the clustering of HRBs and HRB co-occurrence.

CONCLUSIONS

The interaction of PRS and chronotype and the HRBs in adolescents appear to have an association, and the three-way interaction between the CLOCK-PRS, chronotype, and mental health plays important roles for HRBs in adolescents.

Psychometric properties of the Hungarian childhood trauma questionnaire short form and its validity in patients with adult attention-deficit hyperactivity disorder or borderline personality disorder

BACKGROUND

Compelling evidence supports the role of childhood traumatization in the etiology of psychiatric disorders, including adult attention-deficit hyperactivity disorder (aADHD) and borderline personality disorder (BPD). The aim of this study was to examine the psychometric properties of the Hungarian version of the Childhood Trauma Questionnaire Short Form (H-CTQ-SF) and to investigate the differences between patients diagnosed with aADHD and BPD in terms of early traumatization.

METHODS

Altogether 765 (mean age = 32.8 years, 67.7% women) patients and control subjects were enrolled from different areas of Hungary. Principal component analysis and confirmatory factor analysis were carried out to explore the factor structure of H-CTQ-SF and test the validity of the five-factor structure. Discriminative validity was assessed by comparing clinical and non-clinical samples. Subsequently, aADHD and BPD subgroups were compared with healthy controls to test for the role of early trauma in aADHD without comorbid BPD. Convergent validity was explored by measuring correlations with subscales of the Personality Inventory for DSM-5 (PID-5).

RESULTS

The five scales of the H-CTQ-SF demonstrated adequate internal consistency and reliability values. The five-factor model fitted the Hungarian version well after exclusion of one item from the physical neglect scale because of its cross-loading onto the emotional neglect subscale. The H-CTQ-SF effectively differentiated between the clinical and non-clinical samples. The BPD, but not the aADHD group showed significant differences in each CTQ domain compared with the healthy control group. All CTQ domains, except for physical abuse, demonstrated medium to high correlations with PID-5 emotional lability, anxiousness, separation insecurity, withdrawal, intimacy avoidance, anhedonia, depressivity, suspiciousness, and hostility subscales.

CONCLUSIONS

Our study confirmed the psychometric properties of the H-CTQ-SF, an easy-to-administer, non-invasive, ethically sound questionnaire. In aADHD patients without comorbid BPD, low levels of traumatization in every CTQ domain were comparable to those of healthy control individuals. Thus, the increased level of traumatization found in previous studies of aADHD might be associated with the presence of comorbid BPD. Our findings also support the role of emotional neglect, emotional abuse and sexual abuse in the development of BPD.

Evaluating the interaction between 3'aQTL and alcohol consumption/smoking on anxiety and depression: 3'aQTL-by-environment interaction study in UK Biobank cohort

BACKGROUND

Smoking and alcohol consumption were associated with the development of depression and anxiety. 3'UTR APA quantitative trait loci (3'aQTLs) have been associated with multiple health states and conditions. Our aim is to evaluate the interactive effects of 3'aQTLs-alcohol consumption/tobacco smoking on the risk of anxiety and depression.

METHODS

The 3'aQTL data of 13 brain regions were extracted from the large-scale 3'aQTL atlas. The phenotype data (frequency of cigarette smoking and alcohol drinking, anxiety score, self-reported anxiety, depression score and self-reported depression) of 90,399-103,011 adults aged 40-69 years living in the UK and contributing to the UK Biobank during 2006-2010, were obtained from the UK Biobank cohort. The frequency of cigarette smoking and alcohol drinking of each subject were defined by the amount of smoking and alcohol drinking of self-reported, respectively. The continuous alcohol consumption/smoking terms were further categorized in tertiles. 3'aQTL-by-environmental interaction analysis was then performed to evaluate the associations of gene-smoking/alcohol consumption interactions with anxiety and depression using generalized linear model (GLM) of PLINK 2.0 with an additive mode of inheritance. Furthermore, GLM was also used to explore the relationship between alcohol consumption/smoking with hazard of anxiety/depression stratified by allele for the significant genotyped SNPs that modified the alcohol consumption/smoking-anxiety/depression association.

RESULTS

The interaction analysis identified several candidate 3'aQTLs-alcohol consumption interactions, such as rs7602638 located in PPP3R1 (β = 0.08, P = 6.50 × 10-6) for anxiety score; rs10925518 located in RYR2 (OR = 0.95, P = 3.06 × 10-5) for self-reported depression. Interestingly, we also observed that the interactions between TMOD1 (β = 0.18, P = 3.30 × 10-8 for anxiety score; β = 0.17, P = 1.42 × 10-6 for depression score), ZNF407 (β = 0.17, P = 2.11 × 10-6 for anxiety score; β = 0.15, P = 4.26 × 10-5 for depression score) and alcohol consumption was not only associated with anxiety, but related to depression. Besides, we found that relationship between alcohol consumption and hazard of anxiety/depression was significantly different for different SNPs genotypes, such as rs34505550 in TMOD1 (AA: OR = 1.03, P = 1.79 × 10-6; AG: OR = 1.00, P = 0.94; GG: OR = 1.00, P = 0.21) for self-reported anxiety.

LIMITATIONS

The identified 3'aQTLs-alcohol consumption/smoking interactions were associated with depression and anxiety, and its potential biological mechanisms need to be further revealed.

CONCLUSIONS

Our study identified important interactions between candidate 3'aQTL and alcohol consumption/smoking on depression and anxiety, and found that the 3'aQTL may modify the associations between consumption/smoking with depression and anxiety. These findings may help to further explore the pathogenesis of depression and anxiety.

Stress-mediated dysregulation of the Rap1 small GTPase impairs hippocampal structure and function

The effects of repeated stress on cognitive impairment are thought to be mediated, at least in part, by reductions in the stability of dendritic spines in brain regions critical for proper learning and memory, including the hippocampus. Small GTPases are particularly potent regulators of dendritic spine formation, stability, and morphology in hippocampal neurons. Through the use of small GTPase protein profiling in mice, we identify increased levels of synaptic Rap1 in the hippocampal CA3 region in response to escalating, intermittent stress. We then demonstrate that increased Rap1 in the CA3 is sufficient in and of itself to produce stress-relevant dendritic spine and cognitive phenotypes. Further, using super-resolution imaging, we investigate how the pattern of Rap1 trafficking to synapses likely underlies its effects on the stability of select dendritic spine subtypes. These findings illuminate the involvement of aberrant Rap1 regulation in the hippocampus in contributing to the psychobiological effects of stress.

Whole Person Modeling: a transdisciplinary approach to mental health research

The growing global burden of mental illness has prompted calls for innovative research strategies. Theoretical models of mental health include complex contributions of biological, psychosocial, experiential, and other environmental influences. Accordingly, neuropsychiatric research has self-organized into largely isolated disciplines working to decode each individual contribution. However, research directly modeling objective biological measurements in combination with cognitive, psychological, demographic, or other environmental measurements is only now beginning to proliferate. This review aims to (1) to describe the landscape of modern mental health research and current movement towards integrative study, (2) to provide a concrete framework for quantitative integrative research, which we call Whole Person Modeling, (3) to explore existing and emerging techniques and methods used in Whole Person Modeling, and (4) to discuss our observations about the scarcity, potential value, and untested aspects of highly transdisciplinary research in general. Whole Person Modeling studies have the potential to provide a better understanding of multilevel phenomena, deliver more accurate diagnostic and prognostic tests to aid in clinical decision making, and test long standing theoretical models of mental illness. Some current barriers to progress include challenges with interdisciplinary communication and collaboration, systemic cultural barriers to transdisciplinary career paths, technical challenges in model specification, bias, and data harmonization, and gaps in transdisciplinary educational programs. We hope to ease anxiety in the field surrounding the often mysterious and intimidating world of transdisciplinary, data-driven mental health research and provide a useful orientation for students or highly specialized researchers who are new to this area.

Brain-Derived Neurotrophic Factor Val66Met Genotype Modulates Latent Inhibition: Relevance for Schizophrenia

BACKGROUND AND HYPOTHESIS

Latent inhibition (LI) is a measure of selective attention and learning relevant to Schizophrenia (SZ), with 2 abnormality poles: Disrupted LI in acute SZ, thought to underlie positive symptoms, and persistent LI (PLI) in schizotypy and chronic SZ under conditions where normal participants fail to show LI. We hypothesized that Brain-Derived Neurotrophic Factor (BDNF)-Met genotype shifts LI toward the PLI pole.

STUDY DESIGN

We investigated the role of BDNF-Val66Met polymorphism and neural activation in regions involved in LI in mice, and the interaction between the BDNF and CHL1, a gene associated with SZ.

STUDY RESULTS

No LI differences occurred between BDNF-wild-type (WT) (Val/Val) and knock-in (KI) (Met/Met) mice after weak conditioning. Chronic stress or stronger conditioning disrupted LI in WT but not KI mice. Behavior correlated with activation in infralimbic and orbitofrontal cortices, and nucleus accumbens. Examination of LI in CHL1-KO mice revealed no LI with no Met alleles (BDNF-WTs), PLI in CHL1-WT mice with 1 Met allele (BDNF-HETs), and PLI in both CHL1-WTs and CHL1-KOs with 2 Met alleles (BDNF-KIs), suggesting a shift to LI persistence with the number of BDNF-Met alleles in the CHL1 model of acute SZ.

CONCLUSIONS

Results support a role for BDNF polymorphisms in gene-gene and gene-environment interactions relevant to SZ. BDNF-Met allele may reduce expression of some acute SZ symptoms, and may increase expression of negative symptoms in individuals with chronic SZ. Evaluation of (screening for) SZ phenotypes associated with mutations at a particular locus (eg, CHL1), may be masked by strong effects at different loci (eg, BDNF).

Validation and adaption of an Information-Motivation-Behavioral Skills model of medication adherence in older patients with multimorbidity

OBJECTIVE

To test and adapt the Information-Motivation-Behavioral Skills (IMB) model in explaining medication adherence for older patients with multimorbidity.

METHODS

Older patients with at least three chronic conditions (N = 254) were recruited from community health centers in Changsha, China. All participants completed a self-administrated questionnaire assessing adherence information, personal motivation, social motivation, behavioral skills, medication adherence, depressive symptoms, medication treatment satisfaction, treatment burden, and disease burden. Structural equation modeling was used to examine the hypothesized models and relationships between variables.

RESULTS

The final extended IMB model could explain 52.0% of the variance in adherence. Personal motivation (β = 0.29, p < 0.001), behavioral skills (β = 0.36, p < 0.001), and medication treatment satisfaction (β = 0.23, p = 0.001) had a positive direct effect on adherence. Information, social motivation, personal motivation, medication treatment satisfaction, and treatment burden could also affect adherence indirectly through multiple pathways.

CONCLUSION

This study demonstrated that an extended IMB model could be used to conceptualize determinants of medication adherence among older patients with multimorbidity.

PRACTICAL IMPLICATIONS

Adherence improvement programs might be more effective if targeting psychosocial factors, including adherence information, motivation, behavioral skills, treatment burden, and medication treatment satisfaction.

Canalization and plasticity in psychopathology

This theoretical article revives a classical bridging construct, canalization, to describe a new model of a general factor of psychopathology. To achieve this, we have distinguished between two types of plasticity, an early one that we call 'TEMP' for 'Temperature or Entropy Mediated Plasticity', and another, we call 'canalization', which is close to Hebbian plasticity. These two forms of plasticity can be most easily distinguished by their relationship to 'precision' or inverse variance; TEMP relates to increased model variance or decreased precision, whereas the opposite is true for canalization. TEMP also subsumes increased learning rate, (Ising) temperature and entropy. Dictionary definitions of 'plasticity' describe it as the property of being easily shaped or molded; TEMP is the better match for this. Importantly, we propose that 'pathological' phenotypes develop via mechanisms of canalization or increased model precision, as a defensive response to adversity and associated distress or dysphoria. Our model states that canalization entrenches in psychopathology, narrowing the phenotypic state-space as the agent develops expertise in their pathology. We suggest that TEMP - combined with gently guiding psychological support - can counter canalization. We address questions of whether and when canalization is adaptive versus maladaptive, furnish our model with references to basic and human neuroscience, and offer concrete experiments and measures to test its main hypotheses and implications. This article is part of the Special Issue on "National Institutes of Health Psilocybin Research Speaker Series".

Suicidal ideation during adolescence: The roles of aggregate genetic liability for suicide attempts and negative life events in the past year

BACKGROUND

Suicidal thoughts and behaviors (STB) constitute a central public health concern in adolescence. Previous studies emphasized the difficulty to cope with negative life events during adolescence as a risk factor for STB. Familial and genetic liability has also been documented to explain STB risk. Nevertheless, less is known about aggregate genetic liability and its possible interaction with negative life events. Moreover, information is needed to understand how these factors differently affect STB in boys and girls.

METHODS

We evaluated suicidal ideation at 17 years old and examined the role of aggregate genetic liability, negative life events, and their interaction in a sample of 2,571 adolescents. Aggregate genetic liability was measured using a polygenic score (PGS) for suicide attempts. Negative life events were assessed in the past year and included parental divorce and hospitalizations, death of friends and relatives, bullying, failure-related events, and involvement with drugs. We conducted univariable and multivariable general linear models stratified by sex and evaluated the interactions between PGS and negative life events in subsequent models.

RESULTS

Analyses showed that suicidal ideation in boys is associated with failure to achieve something important (estimate = 0.198), bullying (estimate = 0.285), drug use (estimate = 0.325), and parental death (estimate = 0.923). In girls, both aggregate genetic liability (estimate = 0.041) and negative life events (failure at school [estimate = 0.120], failure to achieve something important [estimate = 0.279], drug use [estimate = 0.395], and bullying [estimate = 0.472]) were associated with suicidal ideation. Interaction analyses suggested that PGS interacted with drug use and failures at school, though this would need additional support.

CONCLUSIONS

These findings represent significant contributions to the fundamental understanding of STB in adolescence, suggesting to monitor the impact of negative life events during adolescence to better prevent suicide risk. Genetic liability is also of importance in girls and might influence the way they respond to environmental threats.

Circulating miRNAs as Potential Biomarkers for Patient Stratification in Bipolar Disorder: A Combined Review and Data Mining Approach

Bipolar disorder is a debilitating psychiatric condition that is shaped in a concerted interplay between hereditary and triggering risk factors. Profound depression and mania define the disorder, but high clinical heterogeneity among patients complicates diagnosis as well as pharmacological intervention. Identification of peripheral biomarkers that capture the genomic response to the exposome may thus progress the development of personalized treatment. MicroRNAs (miRNAs) play a prominent role in of post-transcriptional gene regulation in the context of brain development and mental health. They are coordinately modulated by multifarious effectors, and alteration in their expression profile has been reported in a variety of psychiatric conditions. Intriguingly, miRNAs can be released from CNS cells and enter circulatory bio-fluids where they remain remarkably stable. Hence, peripheral circulatory miRNAs may act as bio-indicators for the combination of genetic risk, environmental exposure, and/or treatment response. Here we provide a comprehensive literature search and data mining approach that summarize current experimental evidence supporting the applicability of miRNAs for patient stratification in bipolar disorder.

Analysis of Gene-Environment Interactions Related to Developmental Disorders

Various genetic and environmental factors are associated with developmental disorders (DDs). It has been suggested that interaction between genetic and environmental factors (G × E) is involved in the etiology of DDs. There are two major approaches to analyze the interaction: genome-wide and candidate gene-based approaches. In this mini-review, we demonstrate how these approaches can be applied to reveal the G × E related to DDs focusing on zebrafish and mouse models. We also discuss novel approaches to analyze the G × E associated with DDs.

Genetic and environment effects on structural neuroimaging endophenotype for bipolar disorder: a novel molecular approach

We investigated gene-environment effects on structural brain endophenotype in bipolar disorder (BD) using a novel method of combining polygenic risk scores with epigenetic signatures since traditional methods of examining the family history and trauma effects have significant limitations. The study enrolled 119 subjects, including 55 BD spectrum (BDS) subjects diagnosed with BD or major depressive disorder (MDD) with subthreshold BD symptoms and 64 non-BDS subjects comprising 32 MDD subjects without BD symptoms and 32 healthy subjects. The blood samples underwent genome-wide genotyping and methylation quantification. We derived polygenic risk score (PRS) and methylation profile score (MPS) as weighted summations of risk single nucleotide polymorphisms and methylation probes, respectively, which were considered as molecular measures of genetic and environmental risks for BD. Linear regression was used to relate PRS, MPS, and their interaction to 44 brain structure measures quantified from magnetic resonance imaging (MRI) on 47 BDS subjects, and the results were compared with those based on family history and childhood trauma. After multiplicity corrections using false discovery rate (FDR), MPS was found to be negatively associated with the volume of the medial geniculate thalamus (FDR = 0.059, partial R² = 0.208). Family history, trauma scale, and PRS were not associated with any brain measures. PRS and MPS show significant interactions on whole putamen (FDR = 0.09, partial R² = 0.337). No significant gene-environment interactions were identified for the family history and trauma scale. PRS and MPS generally explained greater proportions of variances of the brain measures (range of partial R² = [0.008, 0.337]) than the clinical risk factors (range = [0.004, 0.228]).

A multi-environments-gene interaction study of anxiety, depression and self-harm in the UK Biobank cohort

The effects of gene-by-environment (G×E) interactions on complex diseases are significant, especially the superimposed effects of multiple environmental factors. However, research on the multi-environments-gene interactions of anxiety, depression, and self-harm is still limited. This study included white individuals (N = 66,041-74,482) from the UK Biobank. We fitted all environmental factors to a single environmental score (ES), and the estimated ES was used to calculate the multiplicative interaction effects between ES and genome-wide SNPs. Heritability was stratified by minor allele frequency (MAF) and linkage disequilibrium (LD). Our research found 10 loci with significant interaction effects, such as rs114830993 (PRICKLE2, P = 2.30 × 10^-8), rs151323364 (ASTN2, P = 2.71 × 10^-10) and rs536631793 (SYN3, P = 4.09 × 10^-8). In addition, we found that G×E heritability has a significant contribution to the depression of Patient Health Questionnaire-9 (PHQ-9) scores (h²_{G×E (female)} = 6.1%, h²_{G×E (male)} = 8.7%). Our research supported the important influence of multi-environments-gene interactions on anxiety, depression, and self-harm and provided clues for the prevention and etiological research of them.

Auditory mismatch negativity in bipolar disorder: a focused review

The auditory mismatch negativity, a component of the event-related potential elicited by an unexpected stimulus in a sequence of acoustic stimuli, provides an objective measure of the accuracy of the echoic information processing of the human brain in vivo. Auditory mismatch negativity is also a useful probe of cortical glutamatergic N-methyl-d-aspartate receptor activity and disturbance. Notably, auditory mismatch negativity is consistently impaired in schizophrenia. Because of the wide spectrum extending from bipolar affective illness and schizoaffective psychosis to typical schizophrenia, we examined the literature on auditory mismatch negativity in bipolar disorder with the aim to find any neurophysiological dysfunction concerning pre-attentive information processing shared by these clinical conditions. This focused review includes 26 original articles published in peer-reviewed journals and indexed in the National Institutes of Health National Library of Medicine (PubMed) search system. Overall, evidence is consistent with the finding that auditory mismatch negativity is impaired in bipolar disorder with psychotic features, even though to a lesser extent than in schizophrenia. It must be acknowledged that, in a few twin and family studies, mismatch negativity abnormalities were not specifically associated with bipolar disorder. In conclusion, auditory mismatch negativity research supports the involvement of the N-methyl-d-aspartate system in the pathophysiology of bipolar disorder, as previously assessed for schizophrenia, thus creating an intriguing trait d'union between these two mental illnesses and stimulating the development of novel therapeutic agents. With additional replication and validation, auditory mismatch negativity may be further considered as a correlate of a common psychopathology of schizophrenia and bipolar spectrum illnesses.

From genetics to systems biology of stress-related mental disorders

Many individuals will be exposed to some form of traumatic stress in their lifetime which, in turn, increases the likelihood of developing stress-related disorders such as post-traumatic stress disorder (PTSD), major depressive disorder (MDD) and anxiety disorders (ANX). The development of these disorders is also influenced by genetics and have heritability estimates ranging between ∼30 and 70%. In this review, we provide an overview of the findings of genome-wide association studies for PTSD, depression and ANX, and we observe a clear genetic overlap between these three diagnostic categories. We go on to highlight the results from transcriptomic and epigenomic studies, and, given the multifactorial nature of stress-related disorders, we provide an overview of the gene-environment studies that have been conducted to date. Finally, we discuss systems biology approaches that are now seeing wider utility in determining a more holistic view of these complex disorders.

Three-way interaction effects of early life stress, positive parenting and FKBP5 in the development of depressive symptoms in a general population

FKBP5 gene–environment interaction (cG × E) studies have shown diverse results, some indicating significant interaction effects between the gene and environmental stressors on depression, while others lack such results. Moreover, FKBP5 has a potential role in the diathesis stress and differential susceptibility theorem. The aim of the present study was to evaluate whether a cG × E interaction effect of FKBP5 single-nucleotide polymorphisms (SNPs) or haplotype and early life stress (ELS) on depressive symptoms among young adults was moderated by a positive parenting style (PASCQ^pos), through the frameworks of the diathesis stress and differential susceptibility theorem. Data were obtained from the Survey of Adolescent Life in Västmanland Cohort Study, including 1006 participants and their guardians. Data were collected during 2012, when the participants were 13 and 15 years old (Wave I: DNA), 2015, when participants were 16 and 18 years old (Wave II: PASCQ^pos, depressive symptomology and ELS) and 2018, when participants were 19 and 21 years old (Wave III: depressive symptomology). Significant three-way interactions were found for the FKBP5 SNPs rs1360780, rs4713916, rs7748266 and rs9394309, moderated by ELS and PASCQ^pos, on depressive symptoms among young adults. Diathesis stress patterns of interaction were observed for the FKBP5 SNPs rs1360780, rs4713916 and rs9394309, and differential susceptibility patterns of interaction were observed for the FKBP5 SNP rs7748266. Findings emphasize the possible role of FKBP5 in the development of depressive symptoms among young adults and contribute to the understanding of possible differential susceptibility effects of FKBP5.

Ankyrin-G Heterozygous Knockout Mice Display Increased Sensitivity to Social Defeat Stress

The <i>ANK3</i> locus has been repeatedly found to confer an increased risk for bipolar disorder. <i>ANK3</i> codes for Ankyrin-G (Ank-G), a scaffold protein concentrated at axon initial segments, nodes of Ranvier, and dendritic spines, where it organizes voltage-gated sodium and potassium channels and cytoskeletal proteins. Mice with homozygous conditional knockout of Ank-G in the adult forebrain display hyperactivity and reduced anxiety-like behaviors, responsive to mood stabilizers. Their behavior switches to a depression-like phenotype when exposed to chronic social defeat stress (SDS), and then spontaneously reverts to baseline hyperactivity. Ank-G heterozygous conditional knockouts (Ank-G Het cKO) have not previously been characterized. Here, we describe the behavior of Ank-G Het cKO mice compared to littermate controls in the open field, elevated plus maze, and forced swim test, under both unstressed and stressed conditions. We found that Ank-G Het cKO is not significantly different from controls at baseline or after chronic SDS. The chronic stress-induced “depression-like” behavioral phenotype is persistent for at least 28 days and is responsive to fluoxetine. Strikingly, Ank-G Het cKO mice display increased sensitivity to a short duration SDS, which does not affect controls. The heterozygous Ank-G genetic model may provide novel insights into the role of Ank-G in the pathophysiology of stress sensitivity and “depression-like” phenotypes and could be useful for studying Ank-G-related gene-environment interactions.

Borderline personality disorder (BPD) and attention deficit hyperactivity disorder (ADHD) revisited - a review-update on common grounds and subtle distinctions

BACKGROUND

Overlap in symptom domains particularly in the field of impulsivity and emotional dysregulation in attention deficit hyperactivity disorder (ADHD) and borderline personality disorder (BPD) have stimulated further research activities since our last review from 2014.

MAIN BODY

Disentangling features of impulsivity in ADHD and BPD revealed that impulsivity is a feature of both disorders with patients suffering from both ADHD and BPD having highest impulsivity ratings. BPD individuals have more problems using context cues for inhibiting responses and their impulsivity is stress-dependent, whereas ADHD patients have more motor impulsivity and therefore difficulties interrupting ongoing responses. For emotion regulation difficulties the ranking order ranges from ADHD to BPD to the comorbid condition, again with the patients suffering from both, ADHD and BPD, having the most pronounced emotion regulation problems. Environmental influences namely adverse childhood events were shown to be linked to both ADHD and BPD. Traumatic experiences seem independently linked to impulsivity features. Thus, some authors point to the risk of misdiagnosis during childhood and the necessity to screen for traumatic experiences in both patient groups. Genetic research confirmed genetic overlap of BPD with bipolar disorder (BD) and schizophrenic disorders, as well as genetic overlap of BD and ADHD. A population-based study confirmed the high co-occurrence and familial co-aggregation of ADHD and BPD. Interesting questions in the field of gene-environment-interactions are currently dealt with by genetic and epigenetic research. Few studies have investigated treatment strategies for the comorbid condition, though the issue is highly important for the management of patients suffering from both disorders and presenting with the highest symptom scores.

CONCLUSION

Research on the different impulsivity features might point to a necessity of disorder-specific treatment strategies in the field of impulse control. Future research is needed to base treatment decisions for the comorbid condition on an evidence basis.

Candidate risk genes for bipolar disorder are highly conserved during evolution and highly interconnected

OBJECTIVES

Bipolar disorder (BPD) is a highly heritable psychiatric disorder whose genetic complexity and pathogenetic mechanisms are still being unraveled. The main goal of this work was to characterize BPD risk-gene candidates (identified by Nurnberger et al., JAMA Psychiatry 71:657, 2014, and Stahl et al., Nat. Genet. 51:793, 2019) with respect to their evolutionary conservation, associated phenotypes, and extent of gene-gene interactions.

METHODS

Database searches and BLAST were used to identify homologous counterparts of human BPD risk genes in C. elegans, zebrafish, and Drosophila. Phenotypes associated with the C. elegans genes were annotated and searched. With GeneMANIA, we characterized and quantified gene-gene interactions among members of the BPD gene set in comparison to randomly chosen gene sets of the same size.

RESULTS

BPD risk genes are highly conserved across species and are enriched for essential genes and genes associated with lethality and altered life span. They are significantly more interactive with each other in comparison to random genes. We identified syntenic blocks of risk genes, which provided potential insights into molecular pathways and co-morbidities associated with BPD including coronary disease, obesity, and decreased life expectancy.

CONCLUSIONS

BPD risk genes appear to be special in terms of their degree of conservation, interconnectedness, and pleiotropic effects that extend beyond a role in brain function. Key hub genes or pleiotropic regulatory components may represent attractive targets for future drug discovery.

Greater genetic risk for adult psychiatric diseases increases vulnerability to adverse outcome after preterm birth

Preterm birth is an extreme environmental stress associated with an increased risk of later cognitive dysfunction and mental health problems. However, the extent to which preterm birth is modulated by genetic variation remains largely unclear. Here, we test for an interaction effect between psychiatric polygenic risk and gestational age at birth on cognition at age four. Our sample comprises 4934 unrelated individuals (2066 individuals born < 37 weeks, 918 born <  = 34 weeks). Genome-wide polygenic scores (GPS's) were calculated for each individual for five different psychiatric pathologies: Schizophrenia, Bipolar Disorder, Major Depressive Disorder, Attention Deficit Hyperactivity Disorder and Autism Spectrum Disorder. Linear regression modelling was used to estimate the interaction effect between psychiatric GPS and gestational age at birth (GA) on cognitive outcome for the five psychiatric disorders. We found a significant interaction effect between Schizophrenia GPS and GA (β = 0.038 ± 0.013, p = 6.85 × 10-3) and Bipolar Disorder GPS and GA (β = 0.038 ± 0.014, p = 6.61 × 10-3) on cognitive outcome. Individuals with greater genetic risk for Schizophrenia or Bipolar Disorder are more vulnerable to the adverse effects of birth at early gestational age on brain development, as assessed by cognition at age four. Better understanding of gene-environment interactions will inform more effective risk-reducing interventions for this vulnerable population.

Immunohistological Examination of AKT Isoforms in the Brain: Cell-Type Specificity That May Underlie AKT's Role in Complex Brain Disorders and Neurological Disease

Protein kinase B (PKB/AKT) is a central kinase involved in many neurobiological processes. AKT is expressed in the brain as three isoforms, AKT1, AKT2, and AKT3. Previous studies suggest isoform-specific roles in neural function, but very few studies have examined AKT isoform expression at the cellular level. In this study, we use a combination of histology, immunostaining, and genetics to characterize cell-type-specific expression of AKT isoforms in human and mouse brains. In mice, we find that AKT1 is the most broadly expressed isoform, with expression in excitatory neurons and the sole detectable AKT isoform in gamma-aminobutyric acid ergic interneurons and microglia. By contrast, we find that AKT2 is the sole isoform expressed in astroglia and is not detected in other neural cell types. We find that AKT3 is expressed in excitatory neurons with AKT1 but shows greater expression levels in dendritic compartments than AKT1. We extend our analysis to human brain tissues and find similar results. Using genetic deletion approaches, we also find that the cellular determinants restricting AKT isoform expression to specific cell types remain intact under Akt deficiency conditions. Because AKT signaling is linked to numerous neurological disorders, a greater understanding of cell-specific isoform expression could improve treatment strategies involving AKT.

The 5-HTTLPR-rs25531 S-A-S-A Haplotype and Chronic Stress Moderate the Association Between Acute Stress and Internalizing Mental Disorders Among HIV+ Children and Adolescents in Uganda

Background: Internalizing mental disorders (IMDs) among HIV-positive (HIV+) children and adolescents are associated with poor disease outcomes, such as faster HIV disease progression. Although it has been suggested that the development of IMDs is moderated by interaction of stressful life events and vulnerability factors, the underlying etiology is largely unknown. Serotonin transporter gene [solute carrier family 6 member A4 (SLC6A4)] and human tryptophan hydroxylase 2 gene (TPH2) polymorphisms have been implicated in the development of IMDs. This study investigated the association between acute stress and IMDs, and moderation by chronic stress and genetic variants in SLC6A4 and TPH2. Hypothesis: Acute stress acts through genetic and environmental vulnerability factors to increase the risk of developing IMDs. Methods: Polymorphisms in SLC6A4 (5-HTTLPR, rs25531, 5-HTTLPR-rs25531, and STin2 VNTR) and TPH2 (rs1843809, rs1386494, rs4570625, and rs34517220) were genotyped in 368 HIV+ children and adolescents (aged 5-17 years) with any internalizing mental disorder (depression, anxiety disorders, or posttraumatic stress disorder), and 368 age- and sex-matched controls, who were also HIV+. Chronic and acute stress categories were derived by hierarchical cluster analysis. Logistic regression analysis was used to assess the independent moderating effect of chronic stress and each selected polymorphism on the association between acute stress and IMDs. Results: We observed a statistically significant association between severe acute stress and IMDs (p = 0.001). Children and adolescents who experienced severe acute stress were twice as likely to develop IMDs, compared to children and adolescents who experienced mild acute stress (p = 0.001). Chronic stress interacted with severe acute stress to increase the risk of IMDs (p = 0.033). Acute stress was found to interact with 5-HTTLPR-rs25531 S-A-S-A haplotype to increase the risk for IMDs among Ugandan HIV+ children and adolescents (p = 0.049). We found no evidence for a combined interaction of acute stress, chronic stress, and 5-HTTLPR-rs25531 on IMDs. Conclusion: The odds of having an internalizing mental disorder (IMD) were higher among HIV+ children and adolescents who experienced severe acute stress compared to HIV+ children and adolescents who experienced mild acute stress. Chronic stress and 5-HTTLPR-rs25531 independently moderated the association between acute stress and IMDs.

The "missing heritability"-Problem in psychiatry: Is the interaction of genetics, epigenetics and transposable elements a potential solution?

Psychiatric disorders exhibit an enormous burden on the health care systems worldwide accounting for around one-third of years lost due to disability among adults. Their etiology is largely unknown and diagnostic classification is based on symptomatology and course of illness and not on objective biomarkers. Most psychiatric disorders are moderately to highly heritable. However, it is still unknown what mechanisms may explain the discrepancy between heritability estimates and the present data from genetic analysis. In addition to genetic differences also epigenetic modifications are considered as potentially relevant in the transfer of susceptibility to psychiatric diseases. Though, whether or not epigenetic alterations can be inherited for many generations is highly controversial. In the present article, we will critically summarize both the genetic findings and the results from epigenetic analyses, including also those of noncoding RNAs. We will argue that one possible solution to the "missing heritability" problem in psychiatry is a potential role of retrotransposons, the exploration of which is presently only in its beginnings.

Isoform-specific roles for AKT in affective behavior, spatial memory, and extinction related to psychiatric disorders

AKT is implicated in neurological disorders. AKT has three isoforms, AKT1/AKT2/AKT3, with brain cell type-specific expression that may differentially influence behavior. Therefore, we examined single Akt isoform, conditional brain-specific Akt1, and double Akt1/3 mutant mice in behaviors relevant to neuropsychiatric disorders. Because sex is a determinant of these disorders but poorly understood, sex was an experimental variable in our design. Our studies revealed AKT isoform- and sex-specific effects on anxiety, spatial and contextual memory, and fear extinction. In Akt1 mutant males, viral-mediated AKT1 restoration in the prefrontal cortex rescued extinction phenotypes. We identified a novel role for AKT2 and overlapping roles for AKT1 and AKT3 in long-term memory. Finally, we found that sex-specific behavior effects were not mediated by AKT expression or activation differences between sexes. These results highlight sex as a biological variable and isoform- or cell type-specific AKT signaling as potential targets for improving treatment of neuropsychiatric disorders.

Extending the vulnerability-stress model of mental disorders: three-dimensional NPSR1 × environment × coping interaction study in anxiety

BACKGROUND

The general understanding of the 'vulnerability-stress model' of mental disorders neglects the modifying impact of resilience-increasing factors such as coping ability.

AIMS

Probing a conceptual framework integrating both adverse events and coping factors in an extended 'vulnerability-stress-coping model' of mental disorders, the effects of functional neuropeptide S receptor gene (NPSR1) variation (G), early adversity (E) and coping factors (C) on anxiety were addressed in a three-dimensional G × E × C model.

METHOD

In two independent samples of healthy probands (discovery: n = 1403; replication: n = 630), the interaction of NPSR1 rs324981, childhood trauma (Childhood Trauma Questionnaire, CTQ) and general self-efficacy as a measure of coping ability (General Self-Efficacy Scale, GSE) on trait anxiety (State-Trait Anxiety Inventory) was investigated via hierarchical multiple regression analyses.

RESULTS

In both samples, trait anxiety differed as a function of NPSR1 genotype, CTQ and GSE score (discovery: β = 0.129, P = 3.938 × 10-8; replication: β = 0.102, P = 0.020). In A allele carriers, the relationship between childhood trauma and anxiety was moderated by general self-efficacy: higher self-efficacy and childhood trauma resulted in low anxiety scores, and lower self-efficacy and childhood trauma in higher anxiety levels. In turn, TT homozygotes displayed increased anxiety as a function of childhood adversity unaffected by general self-efficacy.

CONCLUSIONS

Functional NPSR1 variation and childhood trauma are suggested as prime moderators in the vulnerability-stress model of anxiety, further modified by the protective effect of self-efficacy. This G × E × C approach - introducing coping as an additional dimension further shaping a G × E risk constellation, thus suggesting a three-dimensional 'vulnerability-stress-coping model' of mental disorders - might inform targeted preventive or therapeutic interventions strengthening coping ability to promote resilient functioning.