Nature, nurture and mental disorder: old concepts in the new millennium

Interaction between HTR2A rs3125 and negative life events in suicide attempts among patients with major depressive disorder: a cross-sectional study

BACKGROUND

Both genetic and environmental factors play crucial roles in the development of major depressive disorder (MDD) and suicide attempts (SA). However, the interaction between both items remains unknown. This study aims to explore the interactions between the genetic variants of the serotonin 2 A receptor (HTR2A) and the nitric oxide synthase 1 (NOS1) and environmental factors in patients who experience MDD and SA.

METHODS

A total of 334 patients with MDD and a history of SA (MDD-SA) were recruited alongside 518 patients with MDD with no history of SA (MDD-NSA), and 716 healthy controls (HC). The demographic data and clinical characteristics were collected. Sequenom mass spectrometry was used to detect eight tag-single nucleotide polymorphisms (tagSNPs) in HTR2A (rs1328683, rs17068986, and rs3125) and NOS1 (rs1123425, rs2682826, rs3741476, rs527590, and rs7959232). Generalized multifactor dimensionality reduction (GMDR) was used to analyze the gene-environment interactions.

RESULTS

Four tagSNPs (rs17068986, rs3125, rs527590, and rs7959232) exhibited significant differences between the three groups. However, these differences were not significant between the MDD-SA and MDD-NSA groups after Bonferroni correction. A logistic regression analysis revealed that negative life events (OR = 1.495, 95%CI: 1.071-2.087, P = 0.018), self-guilt (OR = 2.263, 95%CI: 1.515-3.379, P < 0.001), and negative cognition (OR = 2.252, 95%CI: 1.264-4.013, P = 0.006) were all independently associated with SA in patients with MDD. Furthermore, GMDR analysis indicated a significant interaction between HTR2A rs3125 and negative life events. Negative life events in conjunction with the HTR2A rs3125 CG + GG genotype were associated with a higher SA risk in patients with MDD when compared to the absence of negative life events in conjunction with the CC genotype (OR = 2.547, 95% CI: 1.264-5.131, P = 0.009).

CONCLUSION

Several risk factors and a potential interaction between HTR2A rs3125 and negative life events were identified in patients with SA and MDD. The observed interaction likely modulates the risk of MDD and SA, shedding light on the pathogenesis of SA in patients with MDD.

The estimation of environmental and genetic parental influences

Parents share half of their genes with their children, but they also share background social factors and actively help shape their child's environment - making it difficult to disentangle genetic and environmental causes of parent-offspring similarity. While adoption and extended twin family designs have been extremely useful for distinguishing genetic and nongenetic parental influences, these designs entail stringent assumptions about phenotypic similarity between relatives and require samples that are difficult to collect and therefore are typically small and not publicly shared. Here, we describe these traditional designs, as well as modern approaches that use large, publicly available genome-wide data sets to estimate parental effects. We focus in particular on an approach we recently developed, structural equation modeling (SEM)-polygenic score (PGS), that instantiates the logic of modern PGS-based methods within the flexible SEM framework used in traditional designs. Genetically informative designs such as SEM-PGS rely on different and, in some cases, less rigid assumptions than traditional approaches; thus, they allow researchers to capitalize on new data sources and answer questions that could not previously be investigated. We believe that SEM-PGS and similar approaches can lead to improved insight into how nature and nurture combine to create the incredible diversity underlying human behavior.

The Alzheimer's Disease Exposome

INTRODUCTION

Environmental factors are poorly understood in the etiology of Alzheimer's disease (AD) and related dementias. The importance of environmental factors in gene environment interactions (GxE) is suggested by wide individual differences in cognitive loss, even for carriers of AD-risk genetic variants.

RESULTS AND DISCUSSION

We propose the "AD exposome" to comprehensively assess the modifiable environmental factors relevant to genetic underpinnings of cognitive aging and AD. Analysis of endogenous and exogenous environmental factors requires multi-generational consideration of these interactions over age and time (GxExT). New computational approaches to the multi-level complexities may identify accessible interventions for individual brain aging. International collaborations on diverse populations are needed to identify the most relevant exposures over the life course for GxE interactions.

Violence against women and mental disorder: a qualitative study in Bangladesh

Background

Violence affects 15-75% of women across the globe and has a significant impact on their health, well-being, and rights. While quantitative research links it to poor mental health, there is a lack of qualitative enquiry in how women experience it, and how it is related to the mental disorders in Bangladesh. This information is important in understanding the situation and structuring a locally appropriate and culturally sensitive program.

Methods

We adopted a phenomenological approach and conducted 16 in-depth interviews, three informal interviews, one focus group discussion, and one key informant interview. We also reviewed published reports and documents. We followed criterion sampling in selecting women with mental disorders who experienced violence. We explored their experiences and understanding of the issues and described the phenomenon.

Results

We found that Bangladesh society was largely controlled by men, and marriage was often forced on women. Women often were blamed for any mishap in the family and married women were under social and emotional pressure to keep the marital relationship going even when painful. We found all forms of violence (physical, emotional, sexual etc.) and most of the time found more than one type in women with mental disorders. Sexual violence is a reality for some women but rarely discussed. We found the society very tolerant with mental disorder patients and those who resorted to violence against them.We identified four theoretical understandings about the role of violence in mental disorders. Sometimes the violence predisposed the mental illness, sometimes it precipitated it, while other times it maintained and was a consequence of it. Sometimes the violence may be unrelated to the mental illness. The relationships were complex and depended on both the type of mental disorder and the nature and intensity of the violence. We found most of the time that more than one type of violence was involved and played more than one role, which varied across different types of mental disorders. Interestingly, not all violence that mentally disordered women faced was because they were women, but because of mental disorders, which brought violence to them as a consequence.

Conclusions

The findings of this first ever qualitative study into the experiences of violence by women with mental disorder in Bangladesh can be used in developing a culturally specific intervention to reduce both violence and mental disorders in women.

Gene environment interaction studies in depression and suicidal behavior: An update

Increasing evidence supports the involvement of both heritable and environmental risk factors in major depression (MD) and suicidal behavior (SB). Studies investigating gene-environment interaction (G × E) may be useful for elucidating the role of biological mechanisms in the risk for mental disorders. In the present paper, we review the literature regarding the interaction between genes modulating brain functions and stressful life events in the etiology of MD and SB and discuss their potential added benefit compared to genetic studies only. Within the context of G × E investigation, thus far, only a few reliable results have been obtained, although some genes have consistently shown interactive effects with environmental risk in MD and, to a lesser extent, in SB. Further investigation is required to disentangle the direct and mediated effects that are common or specific to MD and SB. Since traditional G × E studies overall suffer from important methodological limitations, further effort is required to develop novel methodological strategies with an interdisciplinary approach.

Toward developmental models of psychiatric disorders in zebrafish

Psychiatric disorders are a diverse set of diseases that affect all aspects of mental function including social interaction, thinking, feeling, and mood. Although psychiatric disorders place a large economic burden on society, the drugs available to treat them are often palliative with variable efficacy and intolerable side-effects. The development of novel drugs has been hindered by a lack of knowledge about the etiology of these diseases. It is thus necessary to further investigate psychiatric disorders using a combination of human molecular genetics, gene-by-environment studies, in vitro pharmacological and biochemistry experiments, animal models, and investigation of the non-biological basis of these diseases, such as environmental effects. Many psychiatric disorders, including autism spectrum disorder, attention-deficit/hyperactivity disorder, mental retardation, and schizophrenia can be triggered by alterations to neural development. The zebrafish is a popular model for developmental biology that is increasingly used to study human disease. Recent work has extended this approach to examine psychiatric disorders as well. However, since psychiatric disorders affect complex mental functions that might be human specific, it is not possible to fully model them in fish. In this review, I will propose that the suitability of zebrafish for developmental studies, and the genetic tools available to manipulate them, provide a powerful model to study the roles of genes that are linked to psychiatric disorders during neural development. The relative speed and ease of conducting experiments in zebrafish can be used to address two areas of future research: the contribution of environmental factors to disease onset, and screening for novel therapeutic compounds.

Coping skills, mental disorders, and suicide among rural youths in China

The strain theory of suicide postulates that psychological strains usually precede mental disorders including suicidal behavior. Lack of coping skills is one of the four strains. This article focuses on the effect of lack of coping skills on individual mental disorders and suicide. Data including 392 suicide cases and 416 community-living controls were from a large psychological autopsy study conducted in rural China. The Hamilton Depression Rating Scale and the Structured Clinical Interview for DSM-III-R were used for the diagnosis of mental disorders. Coping skills were measured by the Coping Response Inventory. The logical analysis and cognitive avoidance coping skills were negatively associated with mental disorders, whereas the taking problem-solving action and acceptance/resignation coping skills were positively associated with mental disorders. This study supports the hypothesis that lack of coping skills to certain strains is likely to lead to mental disorders and suicidal behavior. Improving people's coping strategies may be an effective way to lower the prevalence of mental disorders and suicide.

Can positive family factors be protective against the development of psychosis?

Genetic and environmental factors are both involved in the aetiology of psychotic disorders. The aim of this study was to assess if positive and negative environmental factors, together with psychotic family antecedents, are associated with the recent development of psychosis. We also investigated the interactions between family history of psychosis and positive and negative family environment. The sample comprised 110 children and adolescents, who had suffered a first psychotic episode and 98 healthy controls. All subjects were interviewed about their socioeconomic status, family history of psychosis and family environment (Family Environment Scale, FES). Early onset psychosis was significantly associated with a family history of psychosis. Family environment was perceived as more negative and less positive among patients than among controls. A negative family environment increased the risk of psychosis independently of the family history of psychosis. However, there was a significant protective effect of a positive family environment for persons with a family history of psychosis. This effect was not seen in subjects without a family history of psychosis. Therefore, our results support the importance of considering both family history of psychosis and family environment in the early stages of psychosis.

Early life experiences and their impact on our understanding of depression

This paper presents part of a larger Grounded Theory study, which was designed to capture a sample of people's perceptions of living with or, caring for, individuals with depression. Data were collected from a focus group consisting of people with depression (n = 7). In-depth one-to-one interviews were undertaken with eight further respondents (n = 8). Purposeful sampling was used initially. Thereafter, in keeping with one of the key tenets of grounded theory, theoretical sampling was used. The emergent concepts were pursued until saturation occurred. The constant comparative approach was used to analyse the data together with the NVivo qualitative analysis software package. This paper focuses on the respondents' perceptions of the pre-diagnosis, depression encounter. The key category that emerged was 'the pre-diagnosis phase of depression and the now experience'. Five key themes surfaced within this category: (1) negative impact significant life events; (2) self-blame; (3) personal characteristics; (4) pre-diagnosis, depression unknowingness; and (5) pre-help seeking. The findings suggest that those in the field of human services need to better understand the lived experience of people with depression, in order to provide holistic treatment and care.

Systemic administration of the benzodiazepine receptor partial inverse agonist FG-7142 disrupts corticolimbic network interactions

The medial prefrontal cortex (mPFC) and basolateral amygdala (BLA) coordinate various stress responses. Although the effects of stressors on mPFC and BLA activity have been previously examined, it remains unclear to what extent stressors affect functional interactions between these regions. In vivo electrophysiology in the anesthetized rat was used to examine mPFC and BLA activity simultaneously in response to FG-7142, a benzodiazepine receptor partial inverse agonist that mimics various stress responses, in an attempt to model the effects of stressors on corticolimbic functional connectivity. Extracellular unit and local field potential (LFP) recordings, using multielectrode arrays positioned in mPFC and BLA, were conducted under basal conditions and in response to systemic FG-7142 administration. This drug increased mPFC and BLA unit firing at the lowest dose tested, whereas higher doses of FG-7142 decreased various burst firing parameters in both regions. Moreover, LFP power was attenuated at lower (<1 Hz) and potentiated at higher frequencies in mPFC (1-12 Hz) and BLA (4-8 Hz). Interestingly, FG-7142 diminished synchronized unit firing, both within and between mPFC and BLA. Finally, FG-7142 decreased LFP synchronization between these regions. In a separate group of animals, pretreatment with the selective benzodiazepine receptor antagonist flumazenil blocked the changes in burst firing, LFP power and synchronized activity induced by FG-7142, confirming direct benzodiazepine receptor-mediated effects. These results indicate that FG-7142 disrupts corticolimbic network interactions via benzodiazepine receptor partial inverse agonism. Perturbation of mPFC-BLA functional connectivity induced by FG-7142 may provide a useful model of corticolimbic dysfunction induced by stressors.

Suicide attempts and severe psychiatric morbidity among former child welfare clients--a national cohort study

BACKGROUND

Few large sample studies have examined psychiatric morbidity among former child welfare/protection clients. In this study, risks for suicide attempts and severe psychiatric morbidity in younger years were assessed for former child welfare clients in ten national birth cohorts, comparing them with general population peers and inter-country adoptees.

METHODS

We used national register data for almost one million people: 22,305 former child welfare clients who had experienced interventions before their teens, 955,326 general population cohort peers and 12,240 inter-country adoptees. Multivariate Cox regression models were used to estimate risks of hospitalisation for suicide attempts and psychiatric disorders from age 13 to age 18-27.

RESULTS

Former child welfare clients were in year of birth and sex standardised risk ratios (RRs) four to five times more likely than peers in the general population to have been hospitalised for suicide attempts. They were five to eight times more likely to have been hospitalised for serious psychiatric disorders in their teens, four to six times in young adulthood. High excess risks were also found for psychoses and depression. Individuals who had been in long-term foster care tended to have the most dismal outcome. Adjusting for birth parents' hospitalisations with a psychiatric diagnosis or for substance abuse, and for birth-home-related socio-economic factors, reduced excess risks to around twofold.

CONCLUSIONS

Irrespective of issues of causality, findings suggest that former child welfare/protection clients should be considered a high-risk group for suicide attempts and severe psychiatric morbidity. Results have substantial practice implications for mental health and social agencies serving this group in adolescence and/or young adulthood.

Expanding the 'central dogma': the regulatory role of nonprotein coding genes and implications for the genetic liability to schizophrenia

It is now evident that nonprotein coding RNA (ncRNA) plays a critical role in regulating the timing and rate of protein translation. The potential importance of ncRNAs is suggested by the observation that the complexity of an organism is poorly correlated with its number of protein coding genes, yet highly correlated with its number of ncRNA genes, and that in the human genome only a small fraction (2-3%) of genetic transcripts are actually translated into proteins. In this review, we discuss several examples of known RNA mechanisms for the regulation of protein synthesis. We then discuss the possibility that ncRNA regulation of schizophrenia risk genes may underlie the diverse findings of genetic linkage studies including that protein-altering gene polymorphisms are not generally found in schizophrenia. Thus, inadequate or mistimed expression of a functional protein may occur either due to mutation or other dysfunction of the DNA coding base pair sequence, leading to a dysfunctional protein, or due to post-transcriptional events such as abnormal ncRNA regulation of a normal gene. One or more 'schizophrenia disease genes' may turn out to include abnormal transcriptional units that code for RNA regulators of protein coding gene expression or to be proximal to such units, rather than to be abnormalities in the protein coding gene itself. Understanding the genetics of schizophrenia and other complex neuropsychiatric disorders might very well include consideration of RNA and epigenetic regulation of protein expression in addition to polymorphisms of the protein coding gene.

Modification of brain aging and neurodegenerative disorders by genes, diet, and behavior

Multiple molecular, cellular, structural, and functional changes occur in the brain during aging. Neural cells may respond to these changes adaptively, or they may succumb to neurodegenerative cascades that result in disorders such as Alzheimer's and Parkinson's diseases. Multiple mechanisms are employed to maintain the integrity of nerve cell circuits and to facilitate responses to environmental demands and promote recovery of function after injury. The mechanisms include production of neurotrophic factors and cytokines, expression of various cell survival-promoting proteins (e.g., protein chaperones, antioxidant enzymes, Bcl-2 and inhibitor of apoptosis proteins), preservation of genomic integrity by telomerase and DNA repair proteins, and mobilization of neural stem cells to replace damaged neurons and glia. The aging process challenges such neuroprotective and neurorestorative mechanisms. Genetic and environmental factors superimposed upon the aging process can determine whether brain aging is successful or unsuccessful. Mutations in genes that cause inherited forms of Alzheimer's disease (amyloid precursor protein and presenilins), Parkinson's disease (alpha-synuclein and Parkin), and trinucleotide repeat disorders (huntingtin, androgen receptor, ataxin, and others) overwhelm endogenous neuroprotective mechanisms; other genes, such as those encoding apolipoprotein E(4), have more subtle effects on brain aging. On the other hand, neuroprotective mechanisms can be bolstered by dietary (caloric restriction and folate and antioxidant supplementation) and behavioral (intellectual and physical activities) modifications. At the cellular and molecular levels, successful brain aging can be facilitated by activating a hormesis response in which neurons increase production of neurotrophic factors and stress proteins. Neural stem cells that reside in the adult brain are also responsive to environmental demands and appear capable of replacing lost or dysfunctional neurons and glial cells, perhaps even in the aging brain. The recent application of modern methods of molecular and cellular biology to the problem of brain aging is revealing a remarkable capacity within brain cells for adaptation to aging and resistance to disease.

Stress activation of glutamate neurotransmission in the prefrontal cortex: implications for dopamine-associated psychiatric disorders

In most psychiatric disorders, stress is the major nongenomic factor that contributes to the expression or exacerbation of acute symptoms, recurrence or relapse after a period of remission, and treatment outcome. Delineation of mechanisms by which stress contributes to these processes is fundamental to understanding the disease process and for improving outcome. In this article, evidence is reviewed to indicate that many central aspects of stress response, including activation of the hypothalmic-pituitary-adrenal (HPA) axis and dopamine neurotransmission, are modulated, and in some cases mediated, by glutamate neurotransmission in the prefrontal cortex (PFC). It is suggested that activation of glutamatergic neurotransmission in the PFC presents a common mechanism by which stress influences normal and abnormal processes that sustain affect and cognition. Although monoamines, in particular dopamine, have been considered the major culprits in the adverse effects of stress in disorders such as addiction and schizophrenia, it is likely that in a vulnerable brain with an underlying PFC pathophysiology, abnormal stress-activated monoaminergic neurotransmission is secondary to anomalies in cortical glutamate neurotransmission. Thus, understanding the contribution of glutamate-mediated processes to stress response through the use of experimental models that involve disrupted PFC function can provide insights to the fundamental pathophysiology of stress-sensitive psychiatric disorders and lead to novel strategies for treatment and prevention.