The genetics of suicide: a critical review of molecular studies

Risk and Protective Factors for Childhood Physical Abuse and Suicidal Ideation: The Effect of Brain-Derived Neurotrophic Factor Polymorphism and Social Support

OBJECTIVE

This study aimed to explore the relationship between childhood physical abuse and suicidal ideation considering the effects of genetic and environmental factors in patients with post-traumatic stress disorder (PTSD) by focusing on brain-derived neurotrophic factor (BDNF) polymorphism and social support, respectively.

METHODS

One-hundred fourteen patients with PTSD and 94 healthy controls (HCs) were genotyped with respect to BDNF Val66Met polymorphism. All participants underwent psychological assessments. The hierarchical regression analysis and the simple slope analysis were conducted.

RESULTS

As for patients with PTSD, the moderation effect of BDNF polymorphism was significant but not for social support. Specifically, the BDNF Val/Val genotype worked as a risk factor and strengthens the relationship between childhood physical abuse and suicidal ideation. As for the HCs, the significant moderation effect was found only in social support, but not for BDNF polymorphism. The relationship between childhood physical abuse and suicidal ideation was weakened for the HCs with high social support.

CONCLUSION

This study demonstrated a significant BDNF genetic vulnerability for suicide in patients with PTSD who experienced childhood physical abuse. Our results suggested that social support provided a mitigating effect on the relationship between childhood physical abuse and suicidal ideation only in the HCs.

Gene-environment interactions between CREB1 and childhood maltreatment on aggression among male Chinese adolescents

Both the genetic and environmental factors may affect aggression susceptibility. However, the conclusions of these associations remain discrepant. In addition, studies that explored the association between CREB1 and aggression were meager. The aim of our present study was to assess whether CREB1 polymorphisms were related to aggression and also to explore the interactive effects of CREB1 variants and childhood maltreatment on aggression. A total of 488 individuals with aggressive behavior and 488 controls were recruited. Aggression and childhood maltreatment were surveyed by standardized self-administered questionnaires. Buccal cells were also obtained and genotyping was conducted using SNPscan. Logistic regressions were applied to investigate both individual effects of CREB1 polymorphisms and the interactive influences with childhood maltreatment on aggression. We found that adolescents who carried the rs4675690 T allele in CREB1 showed a higher level of aggression compared with those who carried wildtype genotypes (CC) under the dominant model (OR = 1.67, 95% CI, 1.16–2.40) after controlling for age and childhood maltreatment. Moreover, we also found that rs4675690 T allele had a synergic additive interaction with childhood sexual abuse and emotional neglect on aggression. The significant interactive effects of CREB1 polymorphisms and childhood maltreatment on aggression were reported for the first time.

Anhedonia and Suicide

Suicide is a leading cause of death, and presently, there is no definitive clinical indicator of future suicide behaviors. Anhedonia, a transdiagnostic symptom reflecting diminished ability to experience pleasure, has recently emerged as a risk factor for suicidal thoughts and behaviors (STBs). This overview, therefore, has the following aims. First, prior research relating anhedonia to STBs will be reviewed, with a particular focus on clarifying whether anhedonia is more closely associated with suicidal thoughts versus behaviors. Second, the National Institute of Mental Health's Research Domain Criteria Positive Valence Systems provide a useful heuristic to probe anhedonia across different units of analysis, including clinical symptoms, behaviors, neural mechanisms, and molecular targets. Accordingly, anhedonia-related constructs linked to STBs will be detailed as well as promising next steps for future research. Third, although anhedonia is not directly addressed in leading suicide theories, this review will provide potential inroads to explore anhedonia within diathesis-stress and interpersonal suicide frameworks. Last, novel approaches to treat anhedonia as a means of reducing STBs will be examined.

Suicide cases in developed and emerging countries: an analysis using wavelets

ABSTRACT Objective The aim of this study was to use a wavelet technique to determine whether the number of suicides is similar between developed and emerging countries. Methods Annual data were obtained from World Health Organization (WHO) reports from 1986 to 2015. Discrete nondecimated wavelet transform was used for the analysis, and the Daubechies wavelet function was applied with five-level decomposition. Regarding clustering, energy (variance) was used to analyze the clusters and visualize the clustering process. We constructed a dendrogram using the Mahalanobis distance. The number of groups was set using a specific function in the R program. Results The cluster analysis verified the formation of four groups as follows: Japan, the United States and Brazil were distinct and isolated groups, and other countries (Austria, Belgium, Chile, Israel, Mexico, Italy and the Netherlands) constituted a single group. Conclusion The methods utilized in this paper enabled a detailed verification of countries with similar behaviors despite very distinct socioeconomic, geographic and climate characteristics.

Suicide and suicide risk

Although recent years have seen large decreases in the overall global rate of suicide fatalities, this trend is not reflected everywhere. Suicide and suicidal behaviour continue to present key challenges for public policy and health services, with increasing suicide deaths in some countries such as the USA. The development of suicide risk is complex, involving contributions from biological (including genetics), psychological (such as certain personality traits), clinical (such as comorbid psychiatric illness), social and environmental factors. The involvement of multiple risk factors in conveying risk of suicide means that determining an individual's risk of suicide is challenging. Improving risk assessment, for example, by using computer testing and genetic screening, is an area of ongoing research. Prevention is key to reduce the number of suicide deaths and prevention efforts include universal, selective and indicated interventions, although these interventions are often delivered in combination. These interventions, combined with psychological (such as cognitive behavioural therapy, caring contacts and safety planning) and pharmacological treatments (for example, clozapine and ketamine) along with coordinated social and public health initiatives, should continue to improve the management of individuals who are suicidal and decrease suicide-associated morbidity.

Association between completed suicide and bipolar disorder: A systematic review of the literature

BACKGROUND

Completed suicide is a major cause of death in bipolar disorder (BD) patients.

OBJECTIVE

The aim of this paper is to provide an overall review of the existing literature of completed suicide in BD patients, including clinical and genetic data DATA SOURCES: We performed a systematic review of English and non-English articles published on MEDLINE/PubMed, PsycInfo and Cochrane database (1970-2017). Additional studies were identified by contacting clinical experts, searching bibliographies, major textbooks and website of World Health Organization. Initially we did a broad search for the association of bipolar disorder and suicide and we were narrowing the search in terms included "bipolar disorder" and "completed suicide".

STUDY SELECTION

Inclusion criteria were articles about completed suicide in patients with BD. Articles exclusively focusing on suicide attempts and suicidal behaviour have been excluded. We used PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) consensus for drafting this systematic review.

RESULTS

The initial search generated 2806 articles and a total of 61 meeting our inclusion criteria. We reviewed epidemiological data, genetic factors, risk factors and treatment of completed suicide in BD. Suicide rates in BD vary between studies but our analyses show that they are approximately 20-30-fold greater than in general population. The highest risk of successful suicide was observed in BD-II subjects. The heritability of completed suicide is about 40% and some genes related to major neurotransmitter systems have been associated with suicide. Lithium is the only treatment that has shown anti-suicide potential.

LIMITATIONS

The most important limitation of the present review is the limited existing literature on completed suicide in BD.

CONCLUSIONS

BD patients are at high risk for suicide. It is possible to identify some factors related to completed suicide, such as early onset, family history of suicide among first-degree relatives, previous attempted suicides, comorbidities and treatment. However it is necessary to promote research on this serious health problem.

Individual, programmatic and systemic indicators of the quality of mental health care using a large health administrative database: an avenue for preventing suicide mortality

Suicide is a major public health issue in Canada. The quality of health care services, in addition to other individual and population factors, has been shown to affect suicide rates. In publicly managed care systems, such as systems in Canada and the United Kingdom, the quality of health care is manifested at the individual, program and system levels. Suicide audits are used to assess health care services in relation to the deaths by suicide at individual level and when aggregated at the program and system levels. Large health administrative databases comprise another data source used to inform population-based decisions at the system, program and individual levels regarding mental health services that may affect the risk of suicide. This status report paper describes a project we are conducting at the Institut national de santé publique du Québec (INSPQ) with the Quebec Integrated Chronic Disease Surveillance System (QICDSS) in collaboration with colleagues from Wales (United Kingdom) and the Norwegian Institute of Public Health. This study describes the development of quality of care indicators at three levels and the corresponding statistical analysis strategies designed. We propose 13 quality of care indicators, including system-level and several population-level determinants, primary care treatment, specialist care, the balance between care sectors, emergency room utilization, and mental health and addiction budgets, that may be drawn from a chronic disease surveillance system.

The role of COMT gene Val108/158Met polymorphism in suicidal behavior: systematic review and updated meta-analysis

BACKGROUND

It is accepted that there is a genetic factor that influences the risk of suicidal behavior. The catechol-O-methyltransferase (COMT) gene, especially the Val108/158Met polymorphism, has been associated with suicide; however, no conclusive outcome has been attained. Therefore, the aim of the present study was to assess the role of COMT Val108/158Met in suicidal behavior throughout an updated meta-analysis.

METHODS

We performed an online search using PubMed and Web of Science (up to March 2017). Our systematic review included case-control studies of individuals who attempted suicide and completed suicide. We tested allelic, homozygous, heterozygous, dominant, and recessive inheritance models. The meta-analysis was performed in accordance with the statement of Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

RESULTS

The meta-analysis comprised 17 studies, which included 3,282 cases and 3,774 controls, and showed that when evaluating the overall population, the Val108/158Met polymorphism of COMT was not associated with suicidal behavior in any of the inheritance models; however, the subanalyses showed that this polymorphism exhibits a risk factor in males and a protective effect in females. Additionally, it conveyed a risk factor in Asian populations when using the allelic (OR 1.25; CI: 1.04-1.51) and recessive models (OR 1.32; CI: 1.03-1.68).

CONCLUSION

Our updated meta-analysis suggests a possible association between COMT Val108/158Met and suicidal behavior in Asian populations. However, in view of the small number of studies, these results should be considered exploratory. We recommend that more studies be performed with larger samples.

Neuropathology of suicide: recent findings and future directions

Suicide is a major public health concern and a leading cause of death in most societies. Suicidal behaviour is complex and heterogeneous, likely resulting from several causes. It associates with multiple factors, including psychopathology, personality traits, early-life adversity and stressful life events, among others. Over the past decades, studies in fields ranging from neuroanatomy, genetics and molecular psychiatry have led to a model whereby behavioural dysregulation, including suicidal behaviour (SB), develops as a function of biological adaptations in key brain systems. More recently, the unravelling of the unique epigenetic processes that occur in the brain has opened promising avenues in suicide research. The present review explores the various facets of the current knowledge on suicidality and discusses how the rapidly evolving field of neurobehavioural epigenetics may fuel our ability to understand, and potentially prevent, SB.

A case-control association study of 12 candidate genes and attempted suicide in French adolescents

Background Suicide is the second leading cause of death for 10-19-year-olds. Evidence has shown that attempted suicide is a complex interplay of genes and environmental factors. In the adult population, possible associations between genetic polymorphisms and suicidal behaviors have been investigated for several genes, most often with inconsistent findings and poor replicability of significant associations. This study aimed to identify gene variants conferring risk for adolescent suicide attempt. Methods We selected the genes and variants after an analysis of the literature and a selection of the most significant associations identified. We performed analysis on 22 single nucleotide polymorphisms (SNPs) in 12 genes (COMT, CRHR1, FKBP5, SLC6A4, HTR1B, HTR2A, TPH1, TPH2, BDNF, NTRK2, NOS1 and IL28RA) for association with suicide attempt, hopelessness and impulsivity in an independent sample, composed of 98 adolescent suicide attempters who required hospitalization based on emergency assessments, and 150 healthy volunteers. Quality controls, deviations from the Hardy-Weinberg disequilibrium and statistical tests of association (case/control) were calculated using PLINK. Asymptotic p-values were corrected with the Benjamini-Hochberg method. The level of significance was set to 0.05. Results We identified four polymorphisms of interest, rs10868235 (NTRK2), rs1659400 (NTRK2), rs2682826 (NOS1) and rs7305115 (TPH2), with significant associations for suicide attempts or for the quantitative hopelessness or impulsivity phenotypes. However, none of the associations withstand statistical correction tests. Conclusion Our results do not support the role of the 22 SNPs selected in suicide attempt or hopelessness and impulsivity in adolescent population. However, the relatively small sample size and the probable effect of gene-gene interaction or gene-environment interaction on suicidal behavior could not be ruled out.

Trait liabilities and specific promotive processes in psychopathology: The example of suicidal behavior

BACKGROUND

The RDoC matrix framework calls for investigation of mental health problems through analysis of core biobehavioral processes quantified and studied across multiple domains of measurement. Critics have raised concerns about RDoC, including overemphasis on biological concepts/measures and disregard for the principle of multifinality, which holds that identical biological predispositions can give rise to differing behavioral outcomes. The current work illustrates an ontogenetic process approach to addressing these concerns, focusing on biobehavioral traits corresponding to RDoC constructs as predictors, and suicidal behavior as the outcome variable.

METHOD

Data were collected from a young adult sample (N=105), preselected to enhance rates of suicidality. Participants completed self-report measures of traits (threat sensitivity, response inhibition) and suicide-specific processes.

RESULTS

We show that previously reported associations for traits of threat sensitivity and weak inhibitory control with suicidal behavior are mediated by more specific suicide-promoting processes-namely, thwarted belongingness, perceived burdensomeness, and capability for suicide.

LIMITATIONS

The sample was relatively small and the data were cross-sectional, limiting conclusions that can be drawn from the mediation analyses.

CONCLUSIONS

Given prior research documenting neurophysiological as well as psychological bases to these trait dispositions, the current work sets the stage for an intensive RDoC-oriented investigation of suicidal tendencies in which both traits and suicide-promoting processes are quantified using indicators from different domains of measurement. More broadly, this work illustrates how an RDoC research approach can contribute to a nuanced understanding of specific clinical problems, through consideration of how general biobehavioral liabilities interface with distinct problem-promoting processes.

ABCA1 Polymorphism, a Genetic Risk Factor of Harm Avoidance

Abstract. Even though cholesterol homeostasis and self-harm behaviors have shown to be associated, gene polymorphisms of the cholesterol system have not been studied yet in the context of self-harm related personality traits. Here we present an association study between six ABCA1 polymorphisms and temperament scales measured by Cloninger’s Temperament and Character Inventory on 253 young adults. An association between ABCA1 rs4149264 and harm avoidance has been observed. This association remained significant after Bonferroni correction. Haplotype analysis confirmed an independent association between rs4149264 and harm avoidance. ABCA1, a cholesterol homeostasis gene, is a candidate gene for harm related personality traits.

Assessment of Whole-Exome Sequence Data in Attempted Suicide within a Bipolar Disorder Cohort

Suicidal behavior is a complex and devastating phenotype with a heritable component that has not been fully explained by existing common genetic variant analyses. This study represents the first large-scale DNA sequencing project designed to assess the role of rare functional genetic variation in suicidal behavior risk. To accomplish this, whole-exome sequencing data for ∼19,000 genes were generated for 387 bipolar disorder subjects with a history of suicide attempt and 631 bipolar disorder subjects with no prior suicide attempts. Rare functional variants were assessed in all exome genes as well as pathways hypothesized to contribute to suicidal behavior risk. No result survived conservative Bonferroni correction, though many suggestive findings have arisen that merit additional attention. In addition, nominal support for past associations in genes, such as BDNF, and pathways, such as the hypothalamic-pituitary-adrenal axis, was also observed. Finally, a novel pathway was identified that is driven by aldehyde dehydrogenase genes. Ultimately, this investigation explores variation left largely untouched by existing efforts in suicidal behavior, providing a wealth of novel information to add to future investigations, such as meta-analyses.

Inflammatory markers and suicidal attempts in depressed patients: A review

Major depressive disorder is a chronic and invalidating psychiatric illness and is associated with a greater risk of suicidal behaviors. In recent decades many data have supported a biological link between depressive states and inflammation. Pro-inflammatory cytokines have been found to rise, first of all TNF-α and IL-6. Suicidal behaviors have been consistently associated with increased levels of IL-6 and decreased levels of IL-2. The aim of this review is to investigate the relationship between inflammatory markers in depressed patients with or without suicidal attempts compared to healthy controls.

A targeted sequencing study of glutamatergic candidate genes in suicide attempters with bipolar disorder

Suicidal behavior has been shown to have a heritable component that is partly driven by psychiatric disorders [Brent and Mann, 2005]. However, there is also an independent factor contributing to the heritability of suicidal behavior. We previously conducted a genome-wide association study (GWAS) of bipolar suicide attempters and bipolar non-attempters to assess this independent factor [Willour et al., 2012]. This GWAS implicated glutamatergic neurotransmission in attempted suicide. In the current study, we have conducted a targeted next-generation sequencing study of the glutamatergic N-methyl-D-aspartate (NMDA) receptor, neurexin, and neuroligin gene families in 476 bipolar suicide attempters and 473 bipolar non-attempters. The goal of this study was to gather sequence information from coding and regulatory regions of these glutamatergic genes to identify variants associated with attempted suicide. We identified 186 coding variants and 4,298 regulatory variants predicted to be functional in these genes. No individual variants were overrepresented in cases or controls to a degree that was statistically significant after correction for multiple testing. Additionally, none of the gene-level results were statistically significant following correction. While this study provides no direct support for a role of the examined glutamatergic candidate genes, further sequencing in expanded gene sets and datasets will be required to ultimately determine whether genetic variation in glutamatergic signaling influences suicidal behavior. © 2016 Wiley Periodicals, Inc.

Pronounced prefronto-temporal cortical thinning in schizophrenia: Neuroanatomical correlate of suicidal behavior?

Schizophrenia is characterized by increased mortality for which suicidality is the decisive factor. An analysis of cortical thickness and folding to further elucidate neuroanatomical correlates of suicidality in schizophrenia has not yet been performed. We searched for relevant brain regions with such differences between patients with suicide-attempts, patients without any suicidal thoughts and healthy controls. 37 schizophrenia patients (14 suicide-attempters and 23 non-suicidal) and 50 age- and gender-matched healthy controls were included. Suicidality was documented through clinical interview and chart review. All participants underwent T1-weighted MRI scans. Whole brain node-by-node cortical thickness and folding were estimated (FreeSurfer Software) and compared. Additionally a three group comparison for prefrontal regions-of-interest was performed in SPSS using a multifactorial GLM. Compared with the healthy controls patients showed a typical pattern of cortical thinning in prefronto-temporal regions and altered cortical folding in the right medial temporal cortex. Patients with suicidal behavior compared with non-suicidal patients demonstrated pronounced (p<0.05) cortical thinning in the right DLPFC and the superior temporal cortex. Comparing cortical thickness in suicidal patients with non-suicidal patients significant (p<0.05) cortical thinning was additionally found in the right superior and middle temporal, temporopolar and insular cortex. Our findings extend the evidence for neuroanatomical underpinnings of suicidal behaviour in schizophrenia. We identified cortical thinning in a network strongly involved in regulation of impulsivity, emotions and planning of behaviour in suicide attempters, which might lead to neuronal dysregulation in this network and consequently to a higher risk of suicidal behavior.

Migraine and the Risk of Suicide

Rarely and tragically, migraineurs commit suicide or overdose on medications we prescribe.

Genetic Association Studies of Suicidal Behavior: A Review of the Past 10 Years, Progress, Limitations, and Future Directions

Suicidal behaviors (SBs), which range from suicidal ideation to suicide attempts and completed suicide, represent a fatal dimension of mental ill-health. The involvement of genetic risk factors in SB is supported by family, twin, and adoption studies. The aim of this paper is to review recent genetic association studies in SBs including (i) case-control studies, (ii) family-based association studies, and (iii) genome-wide association studies (GWAS). Various studies on genetic associations have tended to suggest that a number of genes [e.g., tryptophan hydroxylase, serotonin receptors and transporters, or brain-derived neurotrophic factors (BDNFs)] are linked to SBs, but these findings are not consistently supported by the results obtained. Although the candidate-gene approach is useful, it is hampered by the present state of knowledge concerning the pathophysiology of diseases. Interpretations of GWAS results are mostly hindered by a lack of annotation describing the functions of most variation throughout the genome. Association studies have addressed a wide range of single-nucleotide polymorphisms in numerous genes. We have included 104 such studies, of which 10 are family-based association studies and 11 are GWAS. Numerous meta-analyses of case-control studies have shown significant associations of SB with variants in the serotonin transporter gene (5-HTT or SLC6A4) and the tryptophan hydroxylase 1 gene (TPH1), but others report contradictory results. The gene encoding BDNF and its receptor (NTRK2) are also promising candidates. Only two of the GWAS showed any significant associations. Several pathways are mentioned in an attempt to understand the lack of reproducibility and the disappointing results. Consequently, we review and discuss here the following aspects: (i) sample characteristics and confounding factors; (ii) statistical limits; (iii) gene-gene interactions; (iv) gene, environment, and by time interactions; and (v) technological and theoretical limits.

Investigating the role of early childhood abuse and HPA axis genes in suicide attempters with bipolar disorder

OBJECTIVE

Genes and the environment both play a major role in the risk for attempted suicide, and environments harboring stressors, such as early childhood abuse, have been linked to suicidal behavior. Such environments also disrupt the hypothalamic-pituitary-adrenal (HPA) axis pathway, which has been hypothesized to play a role in suicidal behavior. We investigated whether the risk for attempted suicide was attributable in part to the interaction between childhood physical and/or sexual abuse and genetic variation in 19 genes (±5 kb) integral to the HPA axis pathway.

MATERIALS AND METHODS

Using the Genetic Association Information Network Bipolar Disorder and Translational Genomics Research Institute cohorts, we implemented PLINK's logistic regression-based 'interaction' approach to search for evidence of an interaction between 235 genotyped HPA axis single-nucleotide polymorphisms and early childhood abuse. Our study included 631 bipolar disorder suicide attempters and 657 bipolar disorder nonattempters with information on abuse.

RESULTS

After correction for multiple testing, no significant interaction between the 235 HPA axis single-nucleotide polymorphisms and early childhood abuse was found. In our study, the strongest interaction was found with rs2664008 in the corticotropin-releasing hormone receptor 1 (CRHR1) gene, with a nominal interaction P-value of 1.22×10 and an interaction odds ratio of 0.47.

CONCLUSION

Our findings suggest that further work and larger sample sizes are required to elucidate the link between early childhood abuse and the HPA axis in suicidal behavior.

Separate and interactive contributions of weak inhibitory control and threat sensitivity to prediction of suicide risk

Biobehavioral dispositions can serve as valuable referents for biologically oriented research on core processes with relevance to many psychiatric conditions. The present study examined two such dispositional variables-weak response inhibition (or disinhibition; INH-) and threat sensitivity (or fearfulness; THT+)-as predictors of the serious transdiagnostic problem of suicide risk in two samples: male and female outpatients from a U.S. clinic (N=1078), and a population-based male military cohort from Finland (N=3855). INH- and THT+ were operationalized through scores on scale measures of disinhibition and fear/fearlessness, known to be related to DSM-defined clinical conditions and brain biomarkers. Suicide risk was assessed by clinician ratings (clinic sample) and questionnaires (both samples). Across samples and alternative suicide indices, INH- and THT+ each contributed uniquely to prediction of suicide risk-beyond internalizing and externalizing problems in the case of the clinic sample where diagnostic data were available. Further, in both samples, INH- and THT+ interactively predicted suicide risk, with individuals scoring concurrently high on both dispositions exhibiting markedly augmented risk. Findings demonstrate that dispositional constructs of INH- and THT+ are predictive of suicide risk, and hold potential as referents for biological research on suicidal behavior.

An overview of the neurobiology of suicidal behaviors as one meta-system

Suicidal behaviors (SB) may be regarded as the outmost consequence of mental illnesses, or as a distinct entity per se. Regardless, the consequences of SB are very large to both society and affected individuals. The path leading to SB is clearly a complex one involving interactions between the subject's biology and environmental influences throughout life. With the aim to generate a representative and diversified overview of the different neurobiological components hypothesized or shown implicated across the entire SB field up to date by any approach, we selected and compiled a list of 212 gene symbols from the literature. An increasing number of novel gene (products) have been introduced as candidates, with half being implicated in SB in only the last 4 years. These candidates represent different neuro systems and functions and might therefore be regarded as competing or redundant explanations. We then adopted a unifying approach by treating them all as parts of the same meta-system, using bioinformatic tools. We present a network of all components connected by physical protein-protein interactions (the SB interactome). We proceeded by exploring the differences between the highly connected core (~30% of the candidate genes) and its peripheral parts, observing more functional homogeneity at the core, with multiple signal transduction pathways and actin-interacting proteins connecting a subset of receptors in nerve cell compartments as well as development/morphology phenotypes and the stress-sensitive synaptic plasticity processes of long term potentiation/depression. We suggest that SB neurobiology might also be viewed as one meta-system and perhaps be explained as intrinsic unbalances acting within the core or as imbalances arising between core and specific peripheral components.

Epigenetic studies of suicidal behavior

Recent studies have shown an association between gene alterations by epigenetic mechanisms and suicidal behavior. These epigenetic mechanisms are mitotically, and in some cases meiotically, heritable changes in the genome through non-DNA sequence coding processes that alter gene expression as a result of variable changes in environmental stimuli. Genome-wide association studies have been inconsistent in elucidating the association between genes and suicidal behavior, thereby making the heritability of suicidal behavior is unclear. However, recent epigenetic studies have provided evidence that epigenetic mechanisms could deliver the missing link between the heritability of suicidal behavior and the interaction between environment and the genome. The present review provides an in-depth discussion of epigenetic mechanisms that may regulate gene expression in suicidal behavior. The findings of current epigenetic studies on suicidal behavior will also be discussed considering future epigenome-wide association studies on elucidating the contributions of environment and genome on suicidal behavior.

Suicidal behavior and haplotypes of the dopamine receptor gene (DRD2) and ANKK1 gene polymorphisms in patients with alcohol dependence--preliminary report

Suicide is a significant public health issue and a major cause of death throughout the world. According to WHO it accounts for almost 2% of deaths worldwide. The etiology of suicidal behavior is complex but the results of many studies suggest that genetic determinants are of significant importance. In our study,--we have analyzed selected SNPs polymorphisms in the DRD2 and ANKK1 genes in patients with alcohol dependence syndrome (169 Caucasian subjects) including a subgroup of individuals (n = 61) who have experienced at least one suicide attempt. The aim of the study was to verify if various haplotypes of selected genes, comprising Taq1A, Taq1B, and Taq1D single nucleotide polymorphisms (SNP), play any role in the development of alcohol dependence and suicidal behavior. The control group comprised 157 unrelated individuals matched for ethnicity, gender,- and age and included no individuals with mental disorders. All subjects were recruited in the North West region of Poland. The study showed that alcohol dependent subjects with a history of at least one suicidal attempt were characterized by a significantly higher frequency of the T-G-A2 haplotype when compared to individuals in whom alcohol dependence was not associated with suicidal behavior (p = 0.006). It appears that studies based on identifying correlation between SNPs is the future for research on genetic risk factors that contribute to the development of alcohol addiction and other associated disorders. To sum up, there is a necessity to perform further research to explain dependencies between the dopaminergic system, alcohol use disorders and suicidal behavior.

The molecular bases of the suicidal brain

Suicide ranks among the leading causes of death around the world and takes a heavy emotional and public health toll on most societies. Both distal and proximal factors contribute to suicidal behaviour. Distal factors - such as familial and genetic predisposition, as well as early-life adversity - increase the lifetime risk of suicide. They alter responses to stress and other processes through epigenetic modification of genes and associated changes in gene expression, and through the regulation of emotional and behavioural traits. Proximal factors are associated with the precipitation of a suicidal event and include alterations in key neurotransmitter systems, inflammatory changes and glial dysfunction in the brain. This Review explores the key molecular changes that are associated with suicidality and discusses some promising avenues for future research.

Interactions between a serotonin transporter gene, life events and social support on suicidal ideation in Korean elders

INTRODUCTION

The functional polymorphism in the serotonin transporter gene linked promoter region (5-HTTLPR) may modify associations between environmental stressors and suicidality in adolescents and working-age adults. We investigated whether the 5-HTTLPR s/l polymorphism interacts with stressful life events (SLEs) and social support deficits (SSDs) on late-life suicidal ideation.

METHODS

732 Korean community residents aged 65+ were evaluated and, of 639 without suicidal ideation, 579 (90.6%) were followed two years later. Prevalence and incidence of suicidal ideation was ascertained. Information on SLEs and SSDs were gathered, and covariates included socio-demographic characteristics, depressive symptoms, cognitive function, and disability.

RESULTS

Significant interactions were observed between 5-HTTLPR genotype, SLEs and SSDs on both prevalence and incidence of suicidal ideation after adjustment for covariates. The associations of SLEs and SSDs with suicidal ideation were strengthened in combination with higher numbers of s alleles, and were only significant predictors in those with s/s genotype. A significant three-way interaction between 5-HTTLPR genotype, SLEs and SSDs was also found.

LIMITATIONS

The generalizability of suicidal ideation as a marker of suicidality should be considered.

CONCLUSIONS

Gene-environment interactions on suicidal behavior are therefore identifiable even in old age.

Investigating the role of BDNF and CCK system genes in suicidality in a familial bipolar cohort

BACKGROUND

Suicidal behaviour is a phenotype widely associated with psychiatric disorders such as major depressive disorder and bipolar disorder. However, recent evidence indicates that part of the heritability of suicidal behaviour is independent of the heritability of individual psychiatric disorders. This allows investigation into genetic risk factors for suicidal behaviour within a disorder using a candidate gene association approach.

METHODS

We used family-based association testing in a cohort of 130 multiplex bipolar pedigrees, comprising 795 individuals, to look for associations between suicidal behaviour and 32 single nucleotide polymorphisms (SNPs) from across the genes brain-derived neurotrophic factor (BDNF), cholecystokinin (CCK) and the cholecystokinin beta-receptor (CCKBR).

RESULTS

We found associations (p≤0.05) between suicide attempt and 12 SNPs of CCKBR and five SNPs of BDNF. After correction for multiple testing, seven SNPs of CCKBR remained significantly associated. No association was found between CCK and suicidal behaviour.

LIMITATIONS

The study relied on retrospective self-reporting by individuals to determine phenotype, and the sample size was relatively small.

CONCLUSIONS

The results of the study support the hypothesis that some CCKBR polymorphisms may contribute to an underlying predisposition towards suicidal behaviour in bipolar disorder.

Are structural brain abnormalities associated with suicidal behavior in patients with psychotic disorders?

Suicide represents a major health problem world-wide. Nevertheless, the understanding of the neurobiological underpinnings of suicidal behavior remains far from complete. We compared suicide attempters to non-attempters, and high vs. low lethality attempters, to identify brain regions associated with suicidal behavior in patients with psychotic disorders. 489 individuals with schizophrenia, schizoaffective disorder, or psychotic bipolar disorder I and 262 healthy controls enrolled in the B-SNIP study were studied. Groups were compared by attempt history and the highest medical lethality of previous suicide attempts. 97 patients had a history of a high lethality attempt, 51 of a low lethality attempt and 341 had no attempt history. Gray matter volumes were obtained from 3T structural MRI scans using FreeSurfer. ANCOVAs were used to examine differences between groups, followed by Hochberg multiple comparison correction. Compared to non-attempters, attempters had significantly less gray matter volume in bilateral inferior temporal and superior temporal cortices, left superior parietal, thalamus and supramarginal regions, right insula, superior frontal and rostral middle frontal regions. Among attempters, a history of high lethality attempts was associated with significantly smaller volumes in the left lingual gyrus and right cuneus. Compared to non-attempters, low lethality attempters had significant decreases in the left supramarginal gyrus, thalamus and the right insula. Structural brain abnormalities may distinguish suicide attempters from non-attempters and high from low lethality attempters among individuals with psychotic disorders. Regions in which differences were observed are part of neural circuitries that mediate inhibition, impulsivity and emotion, visceral, visual and auditory perception.

Childhood emotional environment and self-injurious behaviors: the moderating role of the BDNF Val66Met polymorphism

BACKGROUND

Previous theory has suggested that invalidating environments in the form of emotional maltreatment should be a specific risk factor for the development of self-injurious behaviors (Linehan, 1993, Cognitive-Behavioral Treatment of Borderline Personality Disorder, New York, Guilford Press). However, results from previous studies have been mixed, possibly indicating that this effect may not be the same for all individuals. In fact, some individuals may be more susceptible to environmental influences (i.e., phenotypic plasticity), and this susceptibility may be in part a function of genes that are involved in neuroplasticity (e.g., the brain-derived neurotrophic factor [BDNF] Val66Met polymorphism).

METHOD

We explored the interaction between retrospective reports of childhood emotional environment and the BDNF Val66Met polymorphism in relation to a history of two main types of self-injurious behaviors, suicide attempt and nonsuicidal self-injury (NSSI), in a sample of individuals with a history of involvement in the criminal justice system.

RESULTS

For individuals with two Val alleles, there was a significant direct relationship between emotional maltreatment and self-injurious behaviors. However, the relationship was not significant for Met carriers.

LIMITATIONS

The data are cross-sectional, which means causal inferences cannot be drawn.

CONCLUSIONS

The results indicate the possibility of a common etiological pathway for NSSI and suicide attempts.

Family-based study of AVPR1B association and interaction with stressful life events on depression and anxiety in suicide attempts

The cortisol response to psychosocial stress may become dysregulated in stress-related disorders. It is potentiated by pituitary secretion of adrenocorticotropic hormone (ACTH), which is, in part, regulated by arginine vasopressin receptor-1B (AVPR1B). AVPR1B variants were previously reported to associate with mood and anxiety disorders. This study aims, for the first time, to investigate association of AVPR1B genetic variants with mood and anxiety outcomes in suicidal behavior.Using a family-based study design of 660 complete nuclear family trios with offspring who have made a suicide attempt (SA), we tested the direct association and linkage of AVPR1B single nucleotide polymorphisms (SNPs) with SA, as well as with depression and anxiety in SA. Main findings were the association and linkage of AVPR1B exon 1 SNP rs33990840 and a major 6-SNP haplotype representative of all common AVPR1B-SNPs, on the outcome of high Beck Depression Inventory scores in SA. By contrast, genetic associations with lifetime diagnoses of depression and anxiety in SA or gene-environment interactions between AVPR1B variants and stressful life events (SLEs) were not significant. An exploratory screen of interactions between AVPR1B and CRHR1 (corticotropin-releasing hormone receptor-1), the principal pituitary regulator of ACTH secretion, showed no support for gene-gene interactions on the studied outcomes. The results suggest that AVPR1B genetic variation, eg, non-synonymous SNP rs33990840 mediating putative consequences on ligand binding, has a role in SA etiology characterized by elevated depression symptoms, without involving AVPR1B-moderation of SLEs.

Brain-derived neurotrophic factor Val66Met polymorphism and alcohol-related phenotypes

Alcoholism is a chronic psychiatric disorder affecting neural pathways that regulate motivation, stress, reward and arousal. Brain-derived neurotrophic factor (BDNF) regulates mood, response to stress and interacts with neurotransmitters and stress systems involved in reward pathways and addiction. Aim of the study was to evaluate the association between a single nucleotide polymorphism (BDNF Val66Met or rs6265) and alcohol related phenotypes in Caucasian patients. In ethnically homogenous Caucasian subjects of the Croatian origin, the BDNF Val66Met genotype distribution was determined in 549 male and 126 female patients with alcohol dependence and in 655 male and 259 female healthy non-alcoholic control subjects. Based on the structured clinical interview, additional detailed clinical interview, the Brown-Goodwin Scale, the Hamilton Rating Scale for Depression and the Clinical Global Impression scores, alcoholic patients were subdivided into those with or without comorbid depression, aggression, delirium tremens, withdrawal syndrome, early/late onset of alcohol abuse, prior suicidal attempt during lifetime, current suicidal behavior, and severity of alcohol dependence. The results showed no significant association between BDNF Val66Met variants and alcohol dependence and/or any of the alcohol related phenotypes in either Caucasian women, or men, with alcohol dependence. There are few limitations of the study. The overall study sample size was large (N=1589) but not well-powered to detect differences in BDNF Val66Met genotype distribution between studied groups. Healthy control women were older than female alcoholic patients. Only one BDNF polymorphism (rs6265) was studied. In conclusion, these data do not support the view that BDNF Val66Met polymorphism correlates with the specific alcohol related phenotypes in ethnically homogenous medication-free Caucasian subjects with alcohol dependence.

NEUROBIOLOGICAL ASPECTS OF SUICIDE AND SUICIDE ATTEMPTS IN BIPOLAR DISORDER

Suicide and bipolar disorder (BD) are challenging, complex, and intertwined areas of study in contemporary psychiatry. Indeed, BD is associated with the highest lifetime risk for suicide attempt and completion of all the psychiatric conditions. Given that several clinical risk factors for both suicide and BD have been well noted in the literature, exploring the neurobiological aspects of suicide in BD may provide insights into both preventive measures and future novel treatments. This review synthesizes findings regarding the neurobiological aspects of suicide and, when applicable, their link to BD. Neurochemical findings, genes/epigenetics, and potential molecular targets for current or future treatments are discussed. The role of endophenotypes and related proximal and distal risk factors underlying suicidal behavior are also explored. Lastly, we discuss the manner in which preclinical work on aggression and impulsivity may provide additional insights for the future development of novel treatments.

The role of the serotonergic system in suicidal behavior

Serotonin is a widely investigated neurotransmitter in several psychopathologies, including suicidal behavior (SB); however, its role extends to several physiological functions involving the nervous system, as well as the gastrointestinal and cardiovascular systems. This review summarizes recent research into ten serotonergic genes related to SB. These genes - TPH1, TPH2, SLC6A4, SLC18A2, HTR1A, HTR1B, HTR2A, DDC, MAOA, and MAOB - encode proteins that are vital to serotonergic function: tryptophan hydroxylase; the serotonin transporter 5-HTT; the vesicular transporter VMAT2; the HTR1A, HTR1B, and HTR2A receptors; the L-amino acid decarboxylase; and the monoamine oxidases. This review employed a systematic search strategy and a narrative research methodology to disseminate the current literature investigating the link between SB and serotonin.

No association between the HTR1A gene and suicidal behavior: a meta-analysis

OBJECTIVE

Dysfunction of serotonin 1A receptors (HTR1A) may play a role in the genesis of suicidal behavior. We studied the association between a functional polymorphism in the HTR1A gene and suicidal behavior.

METHOD

We performed a meta-analysis of published genetic association studies by searching through Medline, PubMed, and Web of Science databases to analyze a possible correlation between the rs6295 polymorphism and suicidal behavior in different populations.

RESULTS

Four studies comprising a total of nine hundred and fifty seven patients with suicidal behavior and nine hundred and fifty seven controls were the eligible. The G allele of the rs6295 polymorphism may not be associated with suicidal behavior (Random-effects model: OR = 1.08; 95% CI: 0.80-1.45; p(Z) = 0.80) in presence of heterogeneity (Q = 17.84, df = 4, p = 0.0013). In a second analysis that presented no heterogeneity, a negative association was also observed (OR = 0.94; 95%CI: 0.79-1.13; p(Z) = 0.99).

CONCLUSION

To our knowledge, the present study is the first meta-analysis searching for a correlation between rs6295 of HTR1A and suicidal behavior. Our results showed no association between HTR1A and suicidal behavior. However, more studies assessing different populations, as well as larger samples, are needed.

Childhood trajectories of anxiousness and disruptiveness explain the association between early-life adversity and attempted suicide

BACKGROUND

Suicidal behavior is frequently associated with a history of childhood abuse yet it remains unclear precisely how early life adversity may increase suicide risk later in life. As such, our aim was to examine whether lifetime trajectories of disruptiveness and anxiousness trait dysregulation explain the association between childhood adversity and suicidal behavior; and moreover, to test the potential modifying effects of mental disorders on these associations.

METHOD

A sample of 1776 individuals from a prospective school-based cohort followed longitudinally for over 22 years was investigated. We tested the influence of disruptiveness and anxiousness trajectories from age 6 to 12 years on the association between childhood adversity (i.e. sexual and physical abuse) and history of suicide attempts (SA) using logistic regression models. Both adolescent externalizing and internalizing Axis I disorders and gender were tested as potential modifiers of these associations.

RESULTS

Four distinct longitudinal trajectories were identified for both disruptiveness and anxiousness. The high disruptiveness trajectory accounted for the association between childhood adversity and SA, but only for females. The high anxiousness trajectory also explained the association between adversity and SA; however, in this case it was not sex but mental disorders that influenced the potency of the mediating effect. More specifically, anxiousness fully explained the effect of adversity on SA in the presence of externalizing disorders, whereas in the absence of these disorders, this effect was significantly attenuated.

CONCLUSIONS

This study provides evidence that both disruptiveness and anxiousness play an important role in explaining the relationship between childhood adversity and SA.

The association of attempted suicide with genetic variants in the SLC6A4 and TPH genes depends on the definition of suicidal behavior: a systematic review and meta-analysis

The global prevalence of suicide has increased substantially over the last four decades. Suicidal behavior manifests owing to a combination of biological, behavioral and social factors; however, the etiology of suicidality remains elusive. Even though twin studies have reported a significant heritability of 30-50%, meta-analyses have not highlighted a common genetic variant associated with the spectrum of suicidal behavior. Here, we performed a systematic review of the literature (n = 112) to assess the association between serotonergic and non-serotonergic genetic polymorphisms and suicidal behavior. Using an inverse variance random-effects model, we developed pooled odds ratios for the 10 most commonly studied genetic variants related to suicidal behavior, each with at least five independent studies that met our stringent inclusion criteria. Our pooled results indicate no significant correlation between genetic polymorphisms and overall suicidal behavior. However, subgroups of suicide attempts demonstrated actual significance with the serotonin transporter (SLC6A4) 5HTTLPR (OR = 1.13 (95% confidence interval = 1.05-1.21), P = 0.001) and reached nominal significance with the tryptophan hydroxylase rs1800532 (1.22 (1.05-1.41), P = 0.007) variant. Subgroups of suicidal behavior (completions and attempts) displayed reduced heterogeneity compared with the overall suicidal behavior spectrum. Our findings suggest that the 5HTTLPR and rs1800532 polymorphisms are significantly associated with suicide attempts, but not associated with completed suicides. The high degree of heterogeneity in past studies may be attributed to the lack of a phenotypic distinction between suicidal attempts and completions. Consequently, we have identified an important source of phenotypic heterogeneity that provides a rationale for the current lack of a common genetic variant associated with suicidal behavior.

Differential glucocorticoid receptor exon 1(B), 1(C), and 1(H) expression and methylation in suicide completers with a history of childhood abuse

BACKGROUND

Childhood abuse alters hypothalamic-pituitary-adrenal (HPA) function and increases the risk of suicide. Hippocampal glucocorticoid receptor (GR) activation regulates HPA activity, and human GR expression (hGR) is reduced in the hippocampus of suicide completers with a history of childhood abuse compared with controls. The abuse-related decrease in hGR expression associates with increased DNA methylation of the promoter of the hGR(1F) variant in the hippocampus.

METHODS

In this study, we investigated the expression and methylation levels of other hGR splice variants in the hippocampus and anterior cingulate gyrus in suicide completers with and without a history of childhood abuse and in controls. Expression levels were quantified using quantitative reverse-transcriptase polymerase chain reaction and promoter methylation was assessed by pyrosequencing.

RESULTS

In the hippocampus, the expression of total hGR and variants 1(B), 1(C), and 1(H) was decreased in suicide completers with histories of abuse compared with suicides with no histories of abuse and with control subjects. In the anterior cingulate gyrus, however, no group differences in hGR total or variant expression were found. Site-specific methylation in hGR1(B) and 1(C) promoter sequences were negatively correlated with total hGR messenger RNA, as well as with hGR1(B) and 1(C) expression. Luciferase assay showed that methylation in hGR promoter decreases transcriptional activity. In contrast, total and site-specific methylation in the hGR1(H) promoter was positively correlated with total hGR messenger RNA and hGR1(H) expression.

CONCLUSION

These findings suggest that early-life events alter the expression of several hGR variants in the hippocampus of suicide completers through effects on promoter DNA methylation.

An examination of environmental and genetic contributions to the determinants of suicidal behavior among male twins

The purpose of the present study was to examine the relative association of genetic and environmental factors with individual differences in each of the proximal, jointly necessary, and sufficient causes for suicidal behavior, according to the Interpersonal-Psychological Theory of Suicide (IPTS; Joiner, 2005). We examined data on derived scales measuring acquired capability, belongingness, and burdensomeness (the determinants of suicidal behavior, according to theory) from 348 adolescent male twins. Univariate biometrical models were used to estimate the magnitude of additive genetic (A), non-additive genetic (D), shared environmental (C), and non-shared environmental (E) effects associated with the variance in acquired capability, belongingness, and burdensomeness. The best fitting model for the acquired capability allowed for additive genetic and environmental effects, whereas the best fitting model for burdensomeness and belongingness allowed for shared and non-shared environmental effects. The present research extends prior work by specifying the environmental and genetic contributions to the components of the IPTS, and our findings suggest that belongingness and burdensomeness may be more appropriate targets for clinical intervention than acquired capability as these factors may be more malleable or amenable to change.

A genome-wide association study of attempted suicide

The heritable component to attempted and completed suicide is partly related to psychiatric disorders and also partly independent of them. Although attempted suicide linkage regions have been identified on 2p11-12 and 6q25-26, there are likely many more such loci, the discovery of which will require a much higher resolution approach, such as the genome-wide association study (GWAS). With this in mind, we conducted an attempted suicide GWAS that compared the single-nucleotide polymorphism (SNP) genotypes of 1201 bipolar (BP) subjects with a history of suicide attempts to the genotypes of 1497 BP subjects without a history of suicide attempts. In all, 2507 SNPs with evidence for association at P<0.001 were identified. These associated SNPs were subsequently tested for association in a large and independent BP sample set. None of these SNPs were significantly associated in the replication sample after correcting for multiple testing, but the combined analysis of the two sample sets produced an association signal on 2p25 (rs300774) at the threshold of genome-wide significance (P=5.07 × 10(-8)). The associated SNPs on 2p25 fall in a large linkage disequilibrium block containing the ACP1 (acid phosphatase 1) gene, a gene whose expression is significantly elevated in BP subjects who have completed suicide. Furthermore, the ACP1 protein is a tyrosine phosphatase that influences Wnt signaling, a pathway regulated by lithium, making ACP1 a functional candidate for involvement in the phenotype. Larger GWAS sample sets will be required to confirm the signal on 2p25 and to identify additional genetic risk factors increasing susceptibility for attempted suicide.

Association study of serotonin pathway genes in attempted suicide

Epidemiological studies, such as family, twin, and adoption studies, demonstrate the presence of a heritable component to both attempted and completed suicide. Some of this heritability is accounted for by the presence of comorbid psychiatric disorders, but the evidence also indicates that a portion of this heritability is specific to suicidality. The serotonergic system has been studied extensively in this phenotype, but findings have been inconsistent, possibly due to the presence of multiple susceptibility variants and/or gene-gene interactions. In this study, we genotyped 174 tag and coding single nucleotide polymorphisms (SNPs) from 17 genes within the serotonin pathway on 516 subjects with a major mood disorder and a history of a suicide attempt (cases) and 515 healthy controls, with the goal of capturing the common genetic variation across each of these candidate genes. We tested the 174 markers in single-SNP, haplotype, gene-based, and epistasis analyses. While these association analyses identified multiple marginally significant SNPs, haplotypes, genes, and interactions, none of them survived correction for multiple testing. Additional studies, including assessment in larger sample sets and deep resequencing to identify rare causal variants, may be required to fully understand the role that the serotonin pathway plays in suicidal behavior.

Variation in OPRM1 and risk of suicidal behavior in drug-dependent individuals

Completed suicide and nonfatal suicide-related outcomes (SROs), such as suicidal ideation and attempts, are heritable. A recent genetic association study in a sample of suicide victims reported a protective effect of the G allele of Asn40Asp (rs1799971) on risk for completed suicide. We examined the association of three OPRM1 single nucleotide polymorphisms (SNPs) (rs1799971, rs609148, and rs648893) with SRO in 426 European Americans, using GEE logistic regression analysis to examine the association of a lifetime history of SRO. There was no allelic association with the SRO phenotypes. A larger sample may be needed to identify risk variants that convey SRO risk. OPRM1 may not be important in the risk of SRO. 

Familial clustering of suicide risk: a total population study of 11.4 million individuals

BACKGROUND

Research suggests that suicidal behaviour is aggregated in families. However, due to methodological limitations, including small sample sizes, the strength and pattern of this aggregation remains uncertain.

METHOD

We examined the familial clustering of completed suicide in a Swedish total population sample. We linked the Cause of Death and Multi-Generation Registers and compared suicide rates among relatives of all 83 951 suicide decedents from 1952-2003 with those among relatives of population controls.

RESULTS

Patterns of familial aggregation of suicide among relatives to suicide decedents suggested genetic influences on suicide risk; the risk among full siblings (odds ratio 3.1, 95% confidence interval 2.8-3.5, 50% genetic similarity) was higher than that for maternal half-siblings (1.7, 1.1-2.7, 25% genetic similarity), despite similar environmental exposure. Further, monozygotic twins (100% genetic similarity) had a higher risk than dizygotic twins (50% genetic similarity) and cousins (12.5% genetic similarity) had higher suicide risk than controls. Shared (familial) environmental influences were also indicated; siblings to suicide decedents had a higher risk than offspring (both 50% genetically identical but siblings having a more shared environment, 3.1, 2.8-3.5 v. 2.0, 1.9-2.2), and maternal half-siblings had a higher risk than paternal half-siblings (both 50% genetically identical but the former with a more shared environment). Although comparisons of twins and half-siblings had overlapping confidence intervals, they were supported by sensitivity analyses, also including suicide attempts.

CONCLUSIONS

Familial clustering of suicide is primarily influenced by genetic and also shared environmental factors. The family history of suicide should be considered when assessing suicide risk in clinical settings or designing and administering preventive interventions.

No association between COMT val158met polymorphism and suicidal behavior: meta-analysis and new data

BACKGROUND

The polymorphism COMTval158met has been associated with suicidal behavior in case-control and meta-analysis studies, but results and conclusions remain controversial. The objective of this study was to examine the association between COMT val158met with suicidal behavior in a case-control study and to assess the combined evidence -this case-control study and available data from other related studies- we carried out a meta-analysis.

METHODS

We conducted a case-control study with 105 patients with suicide attempts and 236 controls. Subsequently, we performed a meta-analysis of published genetic association studies by searching through Medline, PubMed and Web of Science databases.

RESULTS

No significant differences were found in the distribution of alleles (χ2 = 0.33, 1 df, p = 0.56) or genotypes (χ2 = 2.36, 2 df, p = 0.26). The meta-analysis comprising 12 association studies (including the present one) showed that the risk COMTmet allele of COMTval158/met is not associated with suicidal behavior (OR: 1.09, 95% CI: 0.97-1.23), even in the absence of heterogeneity (OR: 1.09, 95% CI: 0.97-1.23).

CONCLUSION

Our results showed no association between COMTval158/met and suicidal behavior. However, more studies are necessary to determine conclusively an association between COMT and suicidal behavior.

Relationship between a history of a suicide attempt and treatment outcomes in patients with depression

This study aimed to investigate the sociodemographic and clinical correlates of a history of a suicide attempt in people with depression and their relationship with treatment outcomes and subsequent suicidal ideation and deliberate self-harm. Patients with depressive disorders according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, were recruited from 18 hospitals across South Korea. Data on sociodemographic and clinical characteristics were obtained, and scales assessing depression, anxiety, and general functioning were administered during the first 12 weeks of antidepressant treatment. Baseline characteristics, responses to treatment, and suicidal ideation/deliberate self-harm during the follow-up period were compared according to a reported history or not of a suicide attempt. In a total of 723 participants, 143 (19.8%) with a history of a suicide attempt had an earlier age of onset, longer duration of illness, and a greater number of depressive episodes. Levels of depression and anxiety were significantly higher at baseline in this group who also experienced significantly lower remission and response rates, as well as longer time to remission. The case group was more likely to experience new suicidal ideation and carry out a deliberate self-harm act during the 12-week treatment period. In conclusion, a history of a suicide attempt in a Korean population with depression was characterized by more severe psychopathology, poorer treatment outcomes, and higher subsequent suicidal ideation and self-harm. Therefore, more intensive and longer-term treatment with particular ongoing clinical attention to risk is indicated in patients with these distinct, chronic, and severe forms of depression and ongoing high suicide risk.

Analysis of kinase gene expression in the frontal cortex of suicide victims: implications of fear and stress

Suicide is a serious public health issue that results from an interaction between multiple risk factors including individual vulnerabilities to complex feelings of hopelessness, fear, and stress. Although kinase genes have been implicated in fear and stress, including the consolidation and extinction of fearful memories, expression profiles of those genes in the brain of suicide victims are less clear. Using gene expression microarray data from the Online Stanley Genomics Database and a quantitative PCR, we investigated the expression profiles of multiple kinase genes including the calcium calmodulin-dependent kinase (CAMK), the cyclin-dependent kinase, the mitogen-activated protein kinase (MAPK), and the protein kinase C (PKC) in the prefrontal cortex (PFC) of mood disorder patients died with suicide (N = 45) and without suicide (N = 38). We also investigated the expression pattern of the same genes in the PFC of developing humans ranging in age from birth to 49 year (N = 46). The expression levels of CAMK2B, CDK5, MAPK9, and PRKCI were increased in the PFC of suicide victims as compared to non-suicide controls (false discovery rate, FDR-adjusted p < 0.05, fold change >1.1). Those genes also showed changes in expression pattern during the postnatal development (FDR-adjusted p < 0.05). These results suggest that multiple kinase genes undergo age-dependent changes in normal brains as well as pathological changes in suicide brains. These findings may provide an important link to protein kinases known to be important for the development of fear memory, stress associated neural plasticity, and up-regulation in the PFC of suicide victims. More research is needed to better understand the functional role of these kinase genes that may be associated with the pathophysiology of suicide.