Understanding risk for psychopathology through imaging gene-environment interactions

Impact of sleep quality on amygdala reactivity, negative affect, and perceived stress

OBJECTIVE

Research demonstrates a negative impact of sleep disturbance on mood and affect; however, the biological mechanisms mediating these links are poorly understood. Amygdala reactivity to negative stimuli has emerged as one potential pathway. Here, we investigate the influence of self-reported sleep quality on associations between threat-related amygdala reactivity and measures of negative affect and perceived stress.

METHODS

Analyses on data from 299 participants (125 men, 50.5% white, mean [standard deviation] age = 19.6 [1.3] years) who completed the Duke Neurogenetics Study were conducted. Participants completed several self-report measures of negative affect and perceived stress. Threat-related (i.e., angry and fearful facial expressions) amygdala reactivity was assayed using blood oxygen level-dependent functional magnetic resonance imaging. Global sleep quality was assessed using the Pittsburgh Sleep Quality Index.

RESULTS

Amygdala reactivity to fearful facial expressions predicted greater depressive symptoms and higher perceived stress in poor (β values = 0.18-1.86, p values < .05) but not good sleepers (β values = -0.13 to -0.01, p values > .05). In sex-specific analyses, men reporting poorer global sleep quality showed a significant association between amygdala reactivity and levels of depression and perceived stress (β values = 0.29-0.44, p values < .05). In contrast, no significant associations were observed in men reporting good global sleep quality or in women, irrespective of sleep quality.

CONCLUSIONS

This study provides novel evidence that self-reported sleep quality moderates the relationships between amygdala reactivity, negative affect, and perceived stress, particularly among men.

A neurogenetics approach to understanding individual differences in brain, behavior, and risk for psychopathology

Neurogenetics research has begun to advance our understanding of how genetic variation gives rise to individual differences in brain function, which, in turn, shapes behavior and risk for psychopathology. Despite these advancements, neurogenetics research is currently confronted by three major challenges: (1) conducting research on individual variables with small effects, (2) absence of detailed mechanisms, and (3) a need to translate findings toward greater clinical relevance. In this review, we showcase techniques and developments that address these challenges and highlight the benefits of a neurogenetics approach to understanding brain, behavior and psychopathology. To address the challenge of small effects, we explore approaches including incorporating the environment, modeling epistatic relationships and using multilocus profiles. To address the challenge of mechanism, we explore how non-human animal research, epigenetics research and genome-wide association studies can inform our mechanistic understanding of behaviorally relevant brain function. Finally, to address the challenge of clinical relevance, we examine how neurogenetics research can identify novel therapeutic targets and for whom treatments work best. By addressing these challenges, neurogenetics research is poised to exponentially increase our understanding of how genetic variation interacts with the environment to shape the brain, behavior and risk for psychopathology.

Gene-environment interactions in the etiology of human violence

This chapter reviews the current research on gene-environment interactions (G × E) with regard to human violence. Findings are summarized from both behavioral and molecular genetic studies that have investigated the interplay of genetic and environmental factors in terms of influencing violence-related behavior. Together, these studies reveal promising evidence that genetic factors combine with environmental influences to impact on the development of violent behavior and related phenotypes. G × E have been identified for a number of candidate genes implicated in violence. Moreover, the reviewed G × E were found to extend to a broad range of environmental characteristics, including both adverse and favorable conditions. As has been the case with other G × E research, findings have been mixed, with considerable heterogeneity between studies. Lack of replication together with serious methodological limitations remains a major challenge for drawing definitive conclusions about the nature of violence-related G × E. In order to fulfill its potential, it is recommended that future G × E research needs to shift its focus to dissecting the neural mechanisms and the underlying pathophysiological pathways by which genetic variation may influence differential susceptibility to environmental exposures.

Variation in key genes of serotonin and norepinephrine function predicts gamma-band activity during goal-directed attention

Recent evidence shows that genetic variations in key regulators of serotonergic (5-HT) signaling explain variance in executive tasks, which suggests modulatory actions of 5-HT on goal-directed selective attention as one possible underlying mechanism. To investigate this link, 130 volunteers were genotyped for the 5-HT transporter gene-linked polymorphic region (5-HTTLPR) and for a variation (TPH2-703 G/T) of the TPH2 gene coding for the rate-limiting enzyme of 5-HT synthesis in the brain. Additionally, a functional polymorphism of the norepinephrine transporter gene (NET -3081 A/T) was considered, which was recently found to predict attention and working memory processes in interaction with serotonergic genes. The flanker-based Attention Network Test was used to assess goal-directed attention and the efficiency of attentional networks. Event-related gamma-band activity served to indicate selective attention at the intermediate phenotype level. The main findings were that 5-HTTLPR s allele and TPH2 G-allele homozygotes showed increased induced gamma-band activity during target processing when combined with the NET A/A genotype compared with other genotype combinations, and that gamma activity mediates the genotype-specific effects on task performance. The results further support a modulatory role of 5-HT and NE function in the top-down attentional selection of motivationally relevant over competing or irrelevant sensory input.

Classification issues and challenges in child and adolescent psychopathology

The major advances that have taken place over the last half century are reviewed with a focus on those that are particularly important with respect to classification issues in the field of child and adolescent psychopathology. Attention is paid to the conceptual issues in DSM and ICD development and differences between the two classifications. Specific recommendations for changes in ICD-11 are presented and an online supplement provides specific details with respect to diagnostic categories that are in need of further testing.

Fkbp52 heterozygosity alters behavioral, endocrine and neurogenetic parameters under basal and chronic stress conditions in mice

Aversive life events represent one of the main risk factors for the development of many psychiatric diseases, but the interplay between environmental factors and genetic predispositions is still poorly understood. One major finding in many depressed patients is an impaired regulation of the hypothalamic-pituitary-adrenal (HPA) axis. The negative feedback loop of the HPA axis is mediated via the glucocorticoid receptor (GR) and the mineralocorticoid receptor. The co-chaperones FK506-binding protein 51 (FKBP51) and FK506-binding protein 52 (FKBP52) are components of the heat shock protein 90-receptor-heterocomplex and are functionally divergent regulators of both receptors. Here, we characterized heterozygous Fkbp52 knockout (Fkbp52(+/-)) mice under basal or chronic social defeat stress (CSDS) conditions with regard to physiological, neuroendocrine, behavioral and mRNA expression alterations. Fkbp52(+/-) mice displayed symptoms of increased stress sensitivity in a subset of behavioral and neuroendocrine parameters. These included increased anxiety-related behavior in the elevated plus-maze and an enhanced neuroendocrine response to a forced swim test (FST), possibly mediated by reduced GR sensitivity. At the same time, Fkbp52(+/-) mice also demonstrated signs of stress resilience in other behavioral and neuroendocrine aspects, such as reduced basal corticosterone levels and more active stress-coping behavior in the FST following CSDS. These contrasting results are in line with previous reports showing that FKBP52 is not involved in all branches of GR signaling, but rather acts in a gene-specific manner to regulate GR transcriptional activation.

Contemporary Genetics for Gender Researchers

Over the past century, much of genetics was deterministic, and feminist researchers framed justified criticisms of genetics research. However, over the past two decades, genetics research has evolved remarkably and has moved far from earlier deterministic approaches. Our article provides a brief primer on modern genetics, emphasizing contemporary evidence for the complex interplay between genes and environment. We focus particularly on the role of gene–environment interactions for gender-imbalanced disorders such as depression. We review research on epigenetics, which is one mechanism by which environment influences gene expression. Modern genetics is not based on a model of genetic determinism; instead, it recognizes the complexity of genetic influences and the nuanced interplay between genes and environment across life span development. Even with the modern genetics approaches, of course, there is still room for criticism and input from gender researchers. We outline methodological and conceptual issues more generally and from a gender researcher’s perspective. We argue that, with interdisciplinary collaborations, modern genetics can be integrated into gender research and vice versa in ways that will create progress in both fields.

MK4MDD: a multi-level knowledge base and analysis platform for major depressive disorder

Background

Major depressive disorder (MDD) is a complex neuropsychiatric syndrome with high heterogeneity. There are different levels of biological components that underlie MDD and interact with each other. To uncover the disease mechanism, large numbers of studies at different levels have been conducted. There is a growing need to integrate data from multiple levels of research into a database to provide a systematic review of current research results. The cross level integration will also help bridge gaps of different research levels for further understanding on MDD. So far, there has been no such effort for MDD.

Descriptions

We offer researchers a Multi-level Knowledge base for MDD (MK4MDD) to study the interesting interplay of components in the pathophysiological cascade of MDD from genetic variations to diagnostic syndrome. MK4MDD contains 2,341 components and 5,206 relationships between components based on reported experimental results obtained by diligent literature reading with manual curation. All components were well classified with careful curation and supplementary annotation. The powerful search and visualization tools make all data in MK4MDD form a cross-linked network to be applied to a broad range of both basic and applied research.

Conclusions

MK4MDD aims to provide researchers with a central knowledge base and analysis platform for MDD etiological and pathophysiological mechanisms research. MK4MDD is freely available at http://mdd.psych.ac.cn.

Epigenetik–Revolution der Entwicklungspsychopathologie?

Die Epigenetik, die sich mit der Bedeutung der Gene im Kontext der menschlichen Entwicklung beschäftigt, konnte zeigen, dass genetische Wirkungen auf die Entwicklung immer auf einer Wechselwirkung zwischen Genom und Umwelt basieren. Die Annahme, der genetische Einfluss auf die (psychische) Entwicklung sei konstant und nur durch gentechnologische Maßnahmen veränderbar, ist demnach offenbar ein Fehlschluss. Es werden Grundbegriffe der Epigenetik und aktuelle Forschungsergebnisse erörtert. Desweiteren wird diskutiert, ob epigenetische Prozesse die Pathogenese psychischer Störungen beeinflussen und ob diese Prozesse an bestimmte Entwicklungsphasen gebunden sind. Anschließend wird die Epigenetik im Kontext der Klinischen Kinderpsychologie betrachtet. Es wird diskutiert, ob die Epigenetik die Entwicklungspsychopathologie grundlegend verändert und welche Konsequenzen die neuen epigenetischen Erkenntnisse für die Klinische Kinderpsychologie bereithalten.

Gene, brains, and environment-genetic neuroimaging of depression

Depression, conceptualized as major depressive disorder (MDD), is a complex psychiatric disorder with multiple behavioral changes and alterations in various brain regions. Biochemically, serotonin and others substances like GABA, glutamate, norepinephrin, adrenaline/noradrenaline play an essential role in the pathogenesis of MDD. The paper reviews recent human neuroimaging findings on how the genes underlying these biochemical substances modulate neural activity, behavior, and ultimately clinical symptoms. Current data provide solid evidence that genes related to serotonin impact emotion-related neural activity in the amygdala and the anterior cingulate cortex. By contrast, evidence is not as strong for genes related to biochemical substances other than serotonin and other regions of the brain. The review concludes with discussing future genetic, neural, and clinical challenges that point out the central role of gene × environment and brain × environment interactions as genetic and neural predispositions of depression.

Future directions in vulnerability to depression among youth: integrating risk factors and processes across multiple levels of analysis

Depression is a developmental phenomenon. Considerable progress has been made in describing the syndrome, establishing its prevalence and features, providing clues as to its etiology, and developing evidence-based treatment and prevention options. Despite considerable headway in distinct lines of vulnerability research, there is an explanatory gap in the field's ability to more comprehensively explain and predict who is likely to become depressed, when, and why. Still, despite clear success in predicting moderate variance for future depression, especially with empirically rigorous methods and designs, the heterogeneous and multi-determined nature of depression suggests that additional etiologies need to be included to advance knowledge on developmental pathways to depression. This paper advocates for a multiple levels of analysis approach to investigating vulnerability to depression across the lifespan and providing a more comprehensive understanding of its etiology. One example of a multiple levels of analysis model of vulnerabilities to depression is provided that integrates the most accessible, observable factors (e.g., cognitive and temperament risks), intermediate processes and endophenotypes (e.g., information-processing biases, biological stress physiology, and neural activation and connectivity), and genetic influences (e.g., candidate genes and epigenetics). Evidence for each of these factors as well as their cross-level integration is provided. Methodological and conceptual considerations important for conducting integrative, multiple levels of depression vulnerability research are discussed. Finally, translational implications for how a multiple levels of analysis perspective may confer additional leverage to reduce the global burden of depression and improve care are considered.

Early predictors of boys' antisocial trajectories

Despite the large number of studies tracing patterns of youth antisocial behavior (AB) during adolescence, few have prospective data on the developmental precursors of AB beginning during infancy. Using a cohort of 268 low-income boys first assessed at 18 months, the current study examined predictors of early- and late-starting trajectories of AB assessed during early childhood and early adolescence. Four trajectory groups were identified, including early- and late-starting groups, a low stable group, and a high decreasing group, characterized by multiple risk factors during early childhood and early adolescence. During early childhood, parenting and maternal depression discriminated two AB trajectory groups, an early-starting and a high decreasing group, who would go on to demonstrate a high preponderance of juvenile court involvement (60% to 79%) and elevated rates of clinical depression 13 to 15 years later. The results were discussed in reference to targeting malleable family risk factors during early childhood associated with patterns of AB and mental health disorders during adolescence.

Mineralocorticoid receptor Iso/Val (rs5522) genotype moderates the association between previous childhood emotional neglect and amygdala reactivity

OBJECTIVE

The amygdala is especially reactive to threatening stimuli, and the degree of reactivity predicts individual differences in the expression of depression and anxiety. Emerging research suggests that emotional neglect during childhood as well as hypercortisolemia may lead to heightened threat-related amygdala reactivity. This raises the possibility that genetic variation affecting hypothalamic-pituitary-adrenal (HPA) axis function contributes to individual differences in amygdala reactivity, both independently and as a function of childhood emotional neglect.

METHOD

This study assessed whether the mineralocorticoid receptor iso/val polymorphism (rs5522), a functional genetic variant affecting HPA axis function, influenced threat-related amygdala reactivity in 279 individuals in late childhood and early adolescence. The study also explored the extent to which any effects of the genotype on amygdala reactivity were contingent upon previous childhood emotional neglect.

RESULTS

Prior childhood emotional neglect and the val allele were associated with greater amygdala reactivity. Moreover, a significant genotype-by-emotional neglect interaction was observed whereby greater amygdala reactivity in val allele carriers was independent of previous childhood emotional neglect, while greater reactivity in iso homozygotes was revealed only in the context of a history of elevated emotional neglect. At relatively low levels of previous emotional neglect, val carriers had heightened amygdala reactivity relative to iso homozygotes.

CONCLUSIONS

These results suggest that relatively greater amygdala reactivity may represent a biological mechanism through which childhood adversity and functional genetic variation in HPA axis responsiveness to stress may mediate risk for psychopathology.

Linking variability in brain chemistry and circuit function through multimodal human neuroimaging

Identifying neurobiological mechanisms mediating the emergence of individual differences in behavior is critical for advancing our understanding of relative risk for psychopathology. Neuroreceptor positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) can be used to assay in vivo regional brain chemistry and function, respectively. Typically, these neuroimaging modalities are implemented independently despite the capacity for integrated data sets to offer unique insight into molecular mechanisms associated with brain function. Through examples from the serotonin and dopamine system and its effects on threat- and reward-related brain function, we review evidence for how such a multimodal neuroimaging strategy can be successfully implemented. Furthermore, we discuss how multimodal PET-fMRI can be integrated with techniques such as imaging genetics, pharmacological challenge paradigms and gene-environment interaction models to more completely map biological pathways mediating individual differences in behavior and related risk for psychopathology and inform the development of novel therapeutic targets.

What does it mean to be musical?

Music can be seen as a model system for understanding gene × environment interactions and how these can influence neurocognitive development. The concept of musicality, however, is underspecified and not well understood. Here, I propose a framework for defining musicality to provide a foundation for studying the contributions of biological and environmental factors.