Meta-analysis supports association between serotonin transporter (5-HTT) and suicidal behavior

Candidate gene-environment interactions in substance abuse: A systematic review

BACKGROUND

The abuse of psychogenic drugs can lead to multiple health-related problems. Genetic and environmental vulnerabilities are factors in the emergence of substance use disorders. Empirical evidence regarding the gene-environment interaction in substance use is mixed. Summaries of the latest findings from a candidate gene approach will be useful for revealing the significance of particular gene contributions. Thus, we aim to identify different gene-environment interactions in patterns of substance use and investigate whether any effects trend notably across different genders and races.

METHODS

We reviewed published studies, until March 1, 2022, on substance use for candidate gene-environment interaction. Basic demographics of the included studies, target genes, environmental factors, main findings, patterns of gene-environment interaction, and other relevant information were collected and summarized.

RESULTS

Among a total of 44 studies, 38 demonstrated at least one significant interaction effect. About 61.5% of studies on the 5-HTTLPR gene, 100% on the MAOA gene, 42.9% on the DRD2 gene, 50% on the DRD4 gene, 50% on the DAT gene, 80% on the CRHR1 gene, 100% on the OPRM1 gene, 100% on the GABRA1 gene, and 50% on the CHRNA gene had a significant gene-environment interaction effect. The diathesis-stress model represents a dominant interaction pattern (89.5%) in the studies with a significant interaction effect; the remaining significant effect on substance use is found in the differential susceptibility model. The social push and swing model were not reported in the included studies.

CONCLUSION

The gene-environment interaction research on substance use behavior is methodologically multidimensional, which causes difficulty in conducting pooled analysis, or stated differently-making it hard to identify single sources of significant influence over maladaptive patterns of drug taking. In decreasing the heterogeneity and facilitating future pooled analysis, researchers must (1) replicate the existing studies with consistent study designs and measures, (2) conduct power calculations to report gene-environment correlations, (3) control for covariates, and (4) generate theory-based hypotheses with factorial based experiments when designing future studies.

Genetic predictors of cultural values variation between societies

Associations between the STin2 and 5-HTTLPR polymorphisms within the serotonin transporter gene, SLC6A4, and culture across societies were examined. Based on an analysis of 75 primary studies (28,726 individuals), STin2 allelic frequencies were found to vary widely across countries, ranging from 26% in Germany to 85% in Singapore. Across 53 countries, and after controlling for all major environmental influences of culture, STin2 and 5-HTTLPR were found to explain 23.6% unique variance in monumentalism but none in individualism. Our findings evidence a significant role of genetics in predicting cross-societal cultural values variation, and potentially speak to the need for and importance of incorporating both nature and nurture in theories of cultural values variation across societies.

Association of HTTLPR, BDNF, and FTO Genetic Variants with Completed Suicide in Slovakia

Since suicide and suicidal behavior are considered highly heritable phenotypes, the identification of genetic markers that can predict suicide risk is a clinically important topic. Several genes studied for possible associations between genetic polymorphisms and suicidal behaviors had mostly inconsistent and contradictory findings. The aim of this case-control study was to evaluate the associations between completed suicide and polymorphisms in genes BDNF (rs6265, rs962369), SLC6A4 (5-HTTLPR), and FTO (rs9939609) in relation to sex and BMI. We genotyped 119 completed suicide victims and 137 control subjects that were age, sex, and ethnicity matched. A significant association with completed suicide was found for BDNF rs962369. This variant could play a role in completed suicide, as individuals with the CC genotype were more often found among suicides than in control subjects. After sex stratification, the association remained significant only in males. A nominally significant association between the gene variant and BMI was observed for BDNF rs962369 under the overdominant model. Heterozygotes with the TC genotype showed a lower average BMI than homozygotes with TT or CC genotypes. FTO polymorphism (rs9939609) did not affect BMI in the group of Slovak suicide completers, but our findings follow an inverse association between BMI and completed suicide.

Genetic analysis of suicide: a sample study in Tuscany (Central Italy)

Many studies have examined the genetic contribution to suicide. However, data on suicide in the Italian population are scarce. We therefore aimed to address this gap by investigating a cohort of 111 Italians for whom a verdict of suicide had been declared in court in Florence, Italy between 2007 and 2017. This cohort included 86 men and 25 women. DNA samples were obtained from tissues or blood, and 22 genes from multiple neurobiological pathways previously shown to be associated with the pathogenesis of suicide were analysed. Next-generation sequencing was used to compare these gene sequences with those from a large, normal population. In this study, we identified 19 gene variants that were present at significantly lower frequencies in our Italian cohort than in the general population. In addition, four missense mutations were identified in four different genes: Monoamine Oxidase A (MAOA), 5-Hydroxytryptamine Receptor 2 A (HTR2A), Sodium Voltage-Gated Channel Alpha Subunit 8 (SCN8A), and Nitric Oxide Synthase 3 (NOS3). Our study identified several potential genetic links with suicide in a cohort of Italians and supports a relationship between specific genetic variants and suicidal behaviour in this population.

Selective serotonin reuptake inhibitor (SSRI) antidepressants reduce COVID-19 infection: prospects for use

Purpose

The absence of specific treatments for COVID-19 leads to an intense global effort in the search for new therapeutic interventions and better clinical outcomes for patients. This review aimed to present a selection of accepted studies that reported the activity of antidepressant drugs belonging to the selective serotonin receptor inhibitor (SSRI) class for treating the novel coronavirus.

Methods

A search was performed in PubMed and SciELO databases using the following search strategies: [(coronavirus) OR (COVID) OR (SARS-CoV-2) AND (antidepressant) OR (serotonin) OR (selective serotonin receptor inhibitors)]. In the end, eleven articles were included. We also covered information obtained from ClinicalTrials.gov in our research.

Results

Although several clinical trials are ongoing, only a few drugs have been officially approved to treat the infection. Remdesivir, an antiviral drug, despite favorable preliminary results, has restricted the use due to the risk of toxicity and methodological flaws. Antidepressant drugs were able to reduce the risk of intubation or death related to COVID-19, decrease the need for intensive medical care, and severely inhibit viral titers by up to 99%. Among the SSRIs studied so far, fluoxetine and fluvoxamine have shown to be the most promising against SARS-CoV-2.

Conclusion

If successful, these drugs can substantially reduce hospitalization and mortality rates, as well as allow for fully outpatient treatment for mild-to-moderate infections. Thus, repositioning SSRIs can provide benefits when faced with a rapidly evolving pandemic such as COVID-19.

Genome-wide association study of suicidal behaviour severity in mood disorders

OBJECTIVE

Suicide is a major public health problem and it has a prominent genetic component. We performed a genome-wide association study (GWAS) of suicidal behaviour severity.

METHODS

Suicide behaviour severity was assessed within the Schedules for Clinical Assessment in Neuropsychiatry in our mood disorder sample (n = 3506) for the GWAS. We also performed polygenic risk score analyses to explore genetic sharing between suicidal behaviour severity and a number of phenotypes, including bipolar disorder, major depressive disorder, alcoholism, post-traumatic stress disorder, impulsivity, insomnia, educational attainment, loneliness, maltreatment, and amygdala volume.

RESULTS

We did not detect genome-wide significant findings at the single-marker or gene level. We report a number of suggestive single-marker and gene-based findings. Our polygenic risk score analyses did not yield significant findings with these phenotypes.

CONCLUSIONS

Larger sample sizes are required to detect moderate effects.

Machine learning as the new approach in understanding biomarkers of suicidal behavior

In psychiatry, compared to other medical fields, the identification of biological markers that would complement current clinical interview, and enable more objective and faster clinical diagnosis, implement accurate monitoring of treatment response and remission, is grave. Current technological development enables analyses of various biological marks in high throughput scale at reasonable costs, and therefore 'omic' studies are entering the psychiatry research. However, big data demands a whole new plethora of skills in data processing, before clinically useful information can be extracted. So far the classical approach to data analysis did not really contribute to identification of biomarkers in psychiatry, but the extensive amounts of data might get to a higher level, if artificial intelligence in the shape of machine learning algorithms would be applied. Not many studies on machine learning in psychiatry have been published, but we can already see from that handful of studies that the potential to build a screening portfolio of biomarkers for different psychopathologies, including suicide, exists.

Nature and nurture? A review of the literature on childhood maltreatment and genetic factors in the pathogenesis of borderline personality disorder

BACKGROUND

Borderline Personality Disorder (BPD) is a psychiatric disorder associated with significant morbidity and mortality. However, the neurobiological alterations underlying the condition remain poorly understood. As a result, existing treatments remain inadequate. One of the main risk factors for the development of BPD is a history of childhood maltreatment. However, it is considered neither causative nor specific to the condition. Current theory is therefore increasingly moving toward a 'Gene x Environment' (GxE) model of the condition. The purpose of the current work was to conduct a systematic literature review, which comprehensively identifies all published molecular level GxE studies that have explored the role of specific genetic loci, in influencing the risk of BPD following exposure to childhood abuse or neglect.

METHODS

Four electronic databases were used to systematically search for molecular level GxE studies of any design, which focused on the development of BPD following exposure to childhood abuse or neglect, without language or date restrictions. Articles were screened independently by two reviewers and results were synthesized narratively.

RESULTS

A total of 473 articles were screened of which sixteen were selected for inclusion in our review. Implicated genes were categorised according to their influence on; Neurotransmitter Systems, Neurodevelopment and Neuroendocrine Systems.

CONCLUSIONS

The identified studies have produced several relevant and statistically significant results. Of particular note, is the repeated finding that genes involved in HPA axis regulation, may be altered by exposure to childhood maltreatment, influencing subsequent susceptibility to BPD. This is both biologically plausible and of potential clinical significance.

Cerebrospinal fluid levels of monoamines among suicide attempters: A systematic review and random-effects meta-analysis

BACKGROUND

It remains unclear whether the dopaminergic and noradrenergic systems may be implied in suicide attempt risk. In addition, although the serotonergic system has been extensively studied, no formal meta-analysis has been performed to examine its association with suicide attempt.

METHODS

Using PRISMA methodology, we performed a systematic literature review and random-effects meta-analyses of the differences in cerebrospinal fluid (CSF) levels of 5-HIAA, HVA and MHPG between suicide attempters and individuals who never attempted suicide.

RESULTS

We identified 30 studies including 937 suicide attempters and 1128 non-attempters; 29 of them measured CSF levels of 5-HIAA, 22 measured CSF levels of HVA and 14 measured CSF levels of MHPG. CSF levels of 5-HIAA and HVA were significantly lower in suicide attempters than in non-attempters [SMD = -0.43 (95% CI: -0.71 to -0.15; p < 0.01) and SMD = -0.45 (95% CI: -0.72 to -0.19; p < 0.01), respectively]. We did not find a significant association between CSF MHPG levels and suicide attempt.

LIMITATIONS

Our analyses relied on a limited number of studies of good quality and most studies included small sample sizes.

CONCLUSION

Both serotonin and dopamine systems may play a role in suicide attempt risk. Our findings suggest that a silo approach to biomarkers should be phased out in favor of the study of multiple systems in parallel and in the same populations to progress in the identification of the biological components independently associated with suicide risk, with the goal of identifying new treatment targets and improving suicide risk prediction.

The role of the 5-HTTLPR polymorphism in acquired capability for suicide

OBJECTIVE

According to the Interpersonal Psychological Theory of Suicide, capability for suicide comprises two dimensions: fearlessness about death and elevated pain tolerance. The short (S) allelic variant of the serotonin transporter gene-linked polymorphic region (5-HTTLPR) has repeatedly been associated with more violent and lethal suicide methods and lethality of suicide attempts. The current study aimed to investigate whether 5-HTTLPR allelic variants are associated with fearlessness about death and pain tolerance/persistence and whether it moderates the relationship between childhood maltreatment and acquired capability for suicide.

METHOD

A cohort of 208 inpatients hospitalized due to a recent suicide attempt or severe suicidal ideation was genotyped for the 5-HTTLPR and assessed for childhood maltreatment. Subjective pain tolerance and fearlessness about death as well as objective pain persistence was assessed using a pressure algometer.

RESULTS

Fearlessness about death, pain tolerance, and pain persistence did not differ between 5-HTTLPR genotypes. However, there was a significant correlation between self-reported childhood maltreatment and fearlessness about death that emerged exclusively in homozygous S-allele carriers.

CONCLUSION

Results suggest that there are no "high-risk"-alleles that generally increase capability for suicide. However, in terms of future suicide-related behaviors exposure to childhood maltreatment events could exert a particularly negative influence on homozygous S-allele carriers by increasing their fearlessness about death.

The impact of twenty-first century personalized medicine versus twenty-first century medicine's impact on personalization

BACKGROUND

Over the past decade, the exponential growth of the literature devoted to personalized medicine has been paralleled by an ever louder chorus of epistemic and ethical criticisms. Their differences notwithstanding, both advocates and critics share an outdated philosophical understanding of the concept of personhood and hence tend to assume too simplistic an understanding of personalization in health care.

METHODS

In this article, we question this philosophical understanding of personhood and personalization, as these concepts shape the field of personalized medicine. We establish a dialogue with phenomenology and hermeneutics (especially with E. Husserl, M. Merleau-Ponty and P. Ricoeur) in order to achieve a more sophisticated understanding of the meaning of these concepts We particularly focus on the relationship between personal subjectivity and objective data.

RESULTS

We first explore the gap between the ideal of personalized healthcare and the reality of today's personalized medicine. We show that the nearly exclusive focus of personalized medicine on the objective part of personhood leads to a flawed ethical debate that needs to be reframed. Second, we seek to contribute to this reframing by drawing on the phenomenological-hermeneutical movement in philosophy. Third, we show that these admittedly theoretical analyses open up new conceptual possibilities to tackle the very practical ethical challenges that personalized medicine faces.

CONCLUSION

Finally, we propose a reversal: if personalization is a continuous process by which the person reappropriates all manner of objective data, giving them meaning and thereby shaping his or her own way of being human, then personalized medicine, rather than being personalized itself, can facilitate personalization of those it serves through the data it provides.

Brazilian Psychiatric Association guidelines for the management of suicidal behavior. Part 1. Risk factors, protective factors, and assessment

Suicide is a global public health problem that causes the loss of more than 800,000 lives each year, principally among young people. In Brazil, the average mortality rate attributable to suicide is approximately 5.23 per 100,000 population. Although many guidelines have been published for the management of suicidal behavior, to date, there are no recent guidelines based on the principles of evidence-based medicine that apply to the reality of suicide in Brazil. The objective of this work is to provide key guidelines for managing patients with suicidal behavior in Brazil. This project involved 11 Brazilian psychiatry professionals selected by the Psychiatric Emergencies Committee (Comissão de Emergências Psiquiátricas) of the Brazilian Psychiatric Association for their experience and knowledge in psychiatry and psychiatric emergencies. For the development of these guidelines, 79 articles were reviewed (from 5,362 initially collected and 755 abstracts). In this review, we present definitions, risk and protective factors, assessments, and an introduction to the Safety Plan.

Systematic review registry number: CRD42020206517

Can selective serotonin reuptake inhibitors have a neuroprotective effect during COVID-19?

The absence of a specific treatment for SARS-CoV-2 infection led to an intense global effort in order to find new therapeutic interventions and improve patient outcomes. One important feature of COVID-19 pathophysiology is the activation of immune cells, with consequent massive production and release of inflammatory mediators that may cause impairment of several organ functions, including the brain. In addition to its classical role as a neurotransmitter, serotonin (5-hydroxytryptamine, 5-HT) has immunomodulatory properties, downregulating the inflammatory response by central and peripheral mechanisms. In this review, we describe the roles of 5-HT in the regulation of systemic inflammation and the potential benefits of the use of specific serotonin reuptake inhibitors as a coadjutant therapy to attenuate neurological complications of COVID-19.

The serotonin transporter gene polymorphism (5-HTTLPR) and affective symptoms among women diagnosed with borderline personality disorder

Gene variants of the serotonin transporter have been associated with vulnerability to affective disorders. In particular, the presence of one or two copies of the short (s) allele of the 5-HTTLPR polymorphism has been associated with reduced serotonin transporter expression and function, and vulnerability to affective disorders. To test for an association between variants of the serotonin transporter gene polymorphism (5-HTTLPR) and relevant clinical features of borderline personality disorder (BPD), a psychiatric disorder with symptoms characteristic for serotonin dysfunction, 77 women with BPD were genotyped in the 5-HTTLPR polymorphism. They rated their subjective experience of borderline-specific, depressive, anxious and obsessive-compulsive symptoms, and were interviewed about lifetime incidence of suicide attempts and self-harming acts. Carriers of two s alleles of the 5-HTTLPR reported more symptoms of borderline, depression, anxiety and obsessive-compulsive behaviours, but not of suicidal and self-injury behaviour, compared to carriers of a long (l) allele. This indicates that the 5-HTTLPR ss homozygous genotype might influence serotonin function affecting susceptibility to both borderline-specific, depressive, anxious and obsessive-compulsive symptoms in BPD, and leading to a more severe symptomatology related to these clinical features. Further, this suggests that 5-HTT gene variants may not be as influential on suicidal and self-injury behaviour in BPD.

Modification of the risk of post-traumatic stress disorder (PTSD) by the 5-HTTLPR polymorphisms after Lorca's earthquakes (Murcia, Spain)

Information of the modulation effect of the serotonin transporter gene-linked polymorphic region (5-HTTLPR) on post-traumatic stress disorder (PTSD) after earthquakes is scarce and contradictory. A cross-sectional face-to-face interview survey of a representative sample of the adults was carried out after the Lorca (Spain) earthquakes (May 11, 2011). Socio-demographic variables, DSM-IV diagnostic assessment and earthquake-related stressors were obtained from the Composite International Diagnostic Interview (CIDI). The triallelic and biallelic classification of the 5-HTTLPR polymorphism were genotyped from buccal swabs. Multivariate logistic regression models were used to predict PTSD, including interaction terms to explore gene-environment (G x E) interactions. The vast majority (83%, n = 341) of the Lorca survey respondents (n = 412, 71% response rate) were genotyped. Both classifications of the 5-HTTLPR genotype were in Hardy-Weinberg equilibrium. Prior lifetime PTSD was the only variable that remained a significant predictor after adjustments. There were no significant main effects of earthquake related stressors or 5-HTTLPR. However, G x E interactions of 5-HTTLPR with high emotional impact and prior lifetime anxiety disorders were statistically significant. These results provide new evidence of the modulation effect of the 5-HTTLPR polymorphisms on PTSD risk. This information might characterize people at higher risk of developing PTSD after an earthquake exposure.

Childhood adversities and 5-HTTLPR polymorphism as risk factors of substance use disorders: retrospective case-control study in Murcia (Spain)

OBJECTIVE

To explore the separate and joint associations of childhood adversities and 5-HTTLPR polymorphism as risk factors for substance use disorders among adults. : Design : Retrospective case-control study.

SETTING

Cases from the substance unit and controls from a representative sample of the adult general population in the metropolitan area of Murcia (Spain).

PARTICIPANTS

Cases were defined as outpatients 18 years old or older currently in the treatment for alcohol, opioids or cocaine use disorders in the clinical unit. Controls were randomly selected among individuals without substance use disorders who participated in the Psychiatric Enquiry to General Population in Southeast Spain-Murcia (PEGASUS-Murcia) project, a cross-sectional study of a representative sample of the adult general population. In all, 142 cases and 531 controls were interviewed and a subsample of 114 cases (80.3%) and 329 controls (62%) provided a biological sample.

EXPOSURE

A history of 12 childhood adversities, lifetime mental disorders and sociodemographic variables was assessed with the Composite International Diagnostic Interview (CIDI)version 3.0). Buccal swabs were obtained to genotype the 5-HTTLPR polymorphism with the biallelic and the triallelic classification.

MAIN OUTCOME AND MEASURE

Multivariable logistic regression models were performed to estimate adjusted ORs and 95% CI.

RESULTS

Childhood adversities were associated with an elevated risk of substance use disorders (OR=5.77, 95% CI 3.46 to 9.61). Homozygotes for the short allele of the 5-HTTLPR polymorphism also showed the elevated risk of substance use disorders for the biallelic and triallelic classification: (1.97 (1.10 to 3.55) and 2.01 (1.11 to 3.64), respectively). No evidence for gene × environment interactions was found.

CONCLUSIONS

Childhood adversities and the 5-HTTLPR polymorphism are involved in the aetiology of substance use disorders though findings exploring the existence of a gene-environment interaction were inconclusive.

An examination of genes, stress and suicidal behavior in two First Nations communities: The role of the brain-derived neurotropic factor gene

Suicide claims over 800,000 lives each year worldwide. Suicide rates in indigenous populations in Canada are about double that of the national average, making it a serious public health issue. Numerous factors are involved in suicide risk, including genetic factors, as well as various psychosocial stressors, such as historical experience with the Indian Residential School system for Indigenous populations, as well as protective variables such as social support. Here, we report the first genetic study of suicidal behaviors that includes multiple measures of stress and social supports. We investigated the role of the functional Val66Met marker (rs6265) in the Brain-Derived Neurotropic Factor (BDNF) gene in suicidal ideation and suicide attempt in a First Nations community sample (N = 278). We did not find a significant association between the BDNF rs6265 marker and suicidal behaviors. We found childhood adversities, recent life stress, chronic stress, perceived stress, difficulties, and hazardous alcohol use to be associated with both suicidal ideation and suicide attempt. Thus, while additional studies with larger samples are required to elucidate the genetic component of suicide, addressing environmental stressors may be important for suicide prevention.

Predicting Suicide Ideation in the Military: The Independent Role of Aggression

The purpose of this study was to examine the longitudinal relationship between aggression and suicide ideation when controlling for other externalizing (i.e., alcohol misuse and risk-taking) and internalizing (i.e., depression and sleep problems) risk factors in an active duty, military sample. Preexisting data from a longitudinal study were analyzed to assess the wellness of service members across the deployment cycle. Participants were 944 active duty service members (95% male, 48% between 18 and 24 years old) who completed surveys upon initial return from deployment and approximately 3 months later. After controlling for other externalizing (alcohol misuse, risk-taking) and internalizing (depression, sleep problems) risk factors, service members reporting aggression were significantly more likely to report suicide ideation than those reporting no aggression (OR = 3.19; OR 95% CI: 1.16-8.80). The independent nature of the relationship between anger and suicidality suggests aggression may be an important indicator of suicidality for service members. Understanding the role of aggression in suicidality may improve the ability to identify at-risk service members and to develop effective interventions to reduce suicide risk.

Prolonged Risk of Suicide Reattempts in Patients with Alcohol Use Disorder and Acute Alcohol Use: A Register-Based Follow-Up Study (2010-2015)

OBJECTIVE

This study aimed to clarify the role of acute alcohol use and alcohol use disorder in individuals exhibiting suicidal behaviors, including repetition of suicide attempt.

METHODS

Data pertaining to 691 suicide attempters who had visited an emergency center and had been followed-up from 2010 to 2015 were gathered. Participants were categorized into following three groups according to alcohol use pattern at the time of the suicide attempt: 1) suicide attempters with neither alcohol use disorder nor acute alcohol consumption (NAU), 2) suicide attempters who had used alcohol during the suicide attempt but did not have alcohol use disorder (AAU), and 3) suicide attempters with alcohol use disorder (AUD). Group comparisons and multivariate Cox proportional models for suicidal behavior were used for statistical analysis.

RESULTS

AUD have been shown to have lower lethality of suicide attempt but higher risk of suicide reattempts in the future. Furthermore, positive relationships between suicide reattempts and AUD persisted throughout the longer period than other groups.

CONCLUSION

Suicide attempters with AUD should be considered a high-risk group for suicide reattempts in future, and this group should be followed-up for a longer period with specialized care program.

The influence of the serotonin transporter gene 5-HTTLPR polymorphism on suicidal behaviors: a meta-analysis

Suicidal Behavior (SB) is the second leading cause of death among youths worldwide and the tenth among all age groups. Inherited genetic differences have a role in suicidality with heritability ranging from 30 to 55%. The SLC6A4 5-HTTLPR gene variant has been largely investigated for association with SB, with controversial results. In this work, we sought to determine whether the results of previous meta-analyses were confirmed or modified subsequent to the inclusion of more recent literature data. An electronic literature search was performed to identify relevant studies published until July 2018. Data were analysed through RevMan v5.3. Subgroup and sensitivity meta-analyses were performed considering different SB sub-phenotypes, ethnicity, gender and psychiatric diagnostic categories. Our literature search yielded 1186 articles; among these, we identified 45 pertinent case-control studies (15,341 subjects). No association was found between low-expressing alleles or genotypes (S + L_G alleles or S' carrier genotypes) and SB in the primary analyses. However, low-expressing alleles (S + L_G) were associated with an increased risk of Violent Suicide Attempt (OR = 1.44, C.I. 1.17-1.78, p = .0007). An effect of the same alleles on SB was found in a subpopulation of substance abusers, but this result was not confirmed after the exclusion of healthy subjects from the control group. The other sensitivity meta-analyses did not show any significant effect. Our findings contribute to clarify the conflicting previous evidence by suggesting an association between the 5-HTTLPR and Violent SB. Nonetheless, many other modulators, including environmental factors and epigenetic mechanisms may act to further increase the level of complexity.

Association Between 5-HTTLPR Polymorphism and the Risk of Autism: A Meta-Analysis Based on Case-Control Studies

Background: Recently, many case-control studies have reported the association between 5-HTTLPR polymorphism and autism risk. However, the results are inconclusive and conflicting. To investigate the genetic association of 5-HTTLPR polymorphism and autism risk, we conducted a comprehensive meta-analysis based on previous case-control studies. Methods: Literature search was performed through PubMed, Embase, Web of Knowledge and CNKI databases until June 27, 2018. The strength of the association was assessed by relative risk (RR) and its corresponding 95% confidence interval (CI). Fixed or random effect model was selected based on the results of heterogeneity test. Further, subgroup analyses were conducted to explore the association of 5-HTTLPR polymorphism and autism risk in different population. Results: Eleven studies with 930 cases and 1234 controls were identified. Although there was a significant association between 5-HTTLPR polymorphism and autism risk under the dominant model after removing the studies causing heterogeneity, the significance did not exist after Bonferroni's correction. Subgroup analyses also showed similar results after Bonferroni's correction. In addition, there was no obvious publication bias in our meta-analysis. Conclusions: Our present meta-analysis does not support a direct effect of 5-HTTLPR polymorphism on autism risk according to present results. Further analyses of the effect of genetic networks and more well designed studies with larger sample size are required.

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.

Ambient air pollution and completed suicide in 26 South Korean cities: Effect modification by demographic and socioeconomic factors

Air pollution has been recently associated with suicide mortality. However, limited studies have examined possible effect modification of the association by various demographic and socioeconomic factors, despite their crucial roles on suicide risk. In 73,445 completed suicide cases from 26 South Korean cities from 2002 to 2013, we studied the association of suicide risk with exposure to particles <10 μm (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), and carbon monoxide (CO), using a city-specific conditional logistic regression analysis with a case-crossover design. Random effects meta-analysis was used to pool the results. We considered a delayed effect of air pollution by constructing lags of up to 7 days. We explored effect modification by demographic and socioeconomic factors (sex, age, education level, job, and marital status) as well as place of death, method of suicide, and season, through stratified subgroup analyses. Among five pollutants, NO₂ showed the strongest association at immediate lags (percent change in odds ratio; PM₁₀: 1.2% [95% CI, 0.2%, 2.3%]; NO₂: 4.3% [95% CI, 1.9%, 6.7%]; SO₂: 2.2% [95% CI, 0.7%, 3.8%]; O₃: 1.5% [95% CI, -0.3%, 3.2%]; and CO: 2.4% [95% CI, 0.9%, 3.8%] per interquartile range increase at lag0). In subgroup analyses by socioeconomic factors, stronger associations were observed in the male sex, the elderly, those with lower education status, white-collar workers, and the married; the largest association was an 11.0% increase (95% CI, 4.1%, 18.4%) by NO₂ among white-collar workers. We add evidence of effect modification of the association between air pollution exposure and suicide risk by various demographic and socioeconomic factors. These findings can serve as the basis for suicide prevention strategies by providing information regarding susceptible subgroups.

Differential Allelic Expression of HTR1B in Suicide Victims: Genetic and Epigenetic Effect of the Cis-Acting Variants

OBJECTIVES

In the present study, we tested the allelic imbalance of the C861G single nucleotide polymorphism (SNP) of HTR1B in the frontal cortex of suicide victims.

METHODS

The study was conducted using 3 sets of samples. First, C861G allele-specific mRNA levels in the frontal cortex were compared between suicide (n = 13) and nonsuicide controls (n = 13) from the Stanley Medical Research postmortem brain collection. Second, we tested common variants in the HTR1B promoter for linkage disequilibrium (LD) with the C861G variant in an unrelated sample of suicide attempters (SA; n = 38) and non-SA (NSA; n = 42). Finally, we performed a family-based association study of the C861G and promoter variants in 162 nuclear families using suicidal behavior severity scores as phenotype.

RESULTS

We observed no alterations in the C/G expression ratio in suicide victims compared to nonsuicide controls (p = 0.370). When comparing the LD between the C861G and cis-acting SNPs, we did not find any differences in SA and NSA. There was no association between preferential transmission of cis-acting SNPs and suicidal behavior severity scores in both maternal and paternal meiosis.

CONCLUSIONS

We found several promoter variants in LD that may potentially influence the allelic imbalance in the C861G variant. However, no evidence of allelic imbalance nor parent-of-origin effects of the C861G variant was observed in suicidal behavior. Further research is required to assess this marker in larger cohorts.

Meta-analysis of the interaction between serotonin transporter promoter variant, stress, and posttraumatic stress disorder

Exposure to stress predicts the occurrence of posttraumatic stress disorder (PTSD) in individuals harboring the serotonin transporter promoter variant 5-HTTLPR. We carried out a meta-analysis of studies investigating the interaction between 5-HTTLPR, stress, and PTSD to clarify the interrelatedness of these factors. We reviewed all relevant studies published in English before May 2016. The Lipták-Stouffer z-score method for meta-analysis was applied to combined data. The z score was separately calculated for the stressful life events, childhood adversity, bi- and triallelic loci, and cross-sectional and longitudinal studies subgroups. A total of 14 studies with 15,883 subjects met our inclusion criteria. We found strong evidence that the presence of 5-HTTLPR influenced the relationship between stress and PTSD (P = 0.00003), with the strongest effects observed in the cross-sectional and longitudinal groups (P = 0.01 and 2.0 × 10-6, respectively). Stressful life events and childhood adversity separately interacted with 5-HTTLPR in PTSD (P = 2.0 × 10-8 and 0.003, respectively). When the studies were stratified by locus classification, the evidence was stronger for the triallelic (P = 4.0 × 10-8) than for the biallelic (P = 0.054) locus subgroup. There was strong evidence that 5-HTTLPR influences the relationship between stress and PTSD.

Serotonergic 5HTTLPR/rs25531 s-allele homozygosity associates with violent suicides in male citalopram users

Depressive disorders are involved as a background factor in over 50% of suicide cases. The most widely used antidepressants today are serotonin selective reuptake inhibitors (SSRIs). However, not all users benefit from SSRI medication. Although the overall number of suicides in Finland have decreased notably during the last decade, the annual rate is still relatively high, particularly in male population. In this study, we tested the hypothesis that the genetic variants associated with decreased citalopram efficiency, 5HTTLPR/rs25531, and increased impulsive behavior, MAOA-uVNTR and HTR2B Q20*, are more frequent among citalopram users committing suicide than among the citalopram users in general. Also the effect of alcohol was evaluated. The study population comprised 349 suicide victims (184 males and 165 females). Based on the suicide method used, cases were divided into two groups; violent (88 males and 49 females) and non-violent (96 males and 116 females). The control group (284; 159 males and 125 females) consisted of citalopram users who died of causes other than suicide. We found that male citalopram users with low functioning s/s genotype of 5HTTLPR/rs25531 were in increased risk to commit violent suicide (OR 2.50, 95%CI 1.15-5.42, p = 0.020). Surprisingly, high blood alcohol concentration was observed to be a risk factor only in non-violent suicides (both males and females), but not in violent ones. No association between suicides and MAOA-uVNTR and HTR2B Q20*, which have been previously connected to violent and impulsive behavior, was detected.

Association of 5-HTTLPR Polymorphism with the Nursing Diagnoses and the Achievement of Nursing Outcomes in Patients with Major Depression

The aim of this study is to investigate whether a 44-base-pair insertion/deletion polymorphism in the upstream regulatory region of the serotonin transporter gene (5-HTTLPR) is associated with the nursing diagnoses and the achievement of the desired nursing outcomes in inpatients with major depression. Thirty five patients were evaluated. The nursing diagnoses of risk for suicide and imbalanced nutrition are reported less often in homozygotes of the high-expressing gene (L_A). Carriers of the low-expressing genes (L_G or S) have a worse response to interventions which aim to increase low self-esteem, indicating that they may need more intensive care in order to achieve the desired outcome. Genetics in psychiatric nursing could help refine personalized care, however further studies with large sample sizes and multiple gene evaluations are needed.

[Suicide risk in somatoform disorders]

BACKGROUND

The somatoform disorders include a group of complex disorders consist of somatic symptoms for which there are no identifiable organic cause or pathogenetic mechanisms. Given the importance of these disorders and the need to clarify the diagnosis of somatoform disorder affecting the suicide risk, we took into consideration the scientific literature to investigate the correlation between the two conditions.

METHODS

We performed a bibliographic search through Medline, Embase, PsycINFO, Scopus, SciELO, ORCID, Google Scholar, DOAJ using the following terms: somatoform, somatization disorder, pain disorder AND psychological factor, suicide, parasuicide, suicidality.

RESULTS

In all studies reported in our review, the suicidal behavior risk is high. But in the majority, the data are relatively unreliable because it takes into account the category nosographic "Neurotic, stress-related and somatoform disorders", too wide to be able to identify the clinical characteristics of patients at risk of only somatoform disorder.

CONCLUSIONS

Several studies conclude that psychiatric comorbidity increases the suicide risk: patients with two or more psychiatric disorders are more likely to commit a suicide attempt; in particular if there is a axis I diagnosis, the risk reduplicate. The somatization disorder seems to have a significant psychiatric comorbidity in particular with anxious and affective disorders spectrum.

Suicidality and Activation of the Kynurenine Pathway of Tryptophan Metabolism

A recent report by the World Health Organization declared suicide to be a major global problem. With more than 800,000 lives lost each year, suicide is calculated to be the 14th leading cause of death around the world. While the biological mechanisms causing suicidal ideation and behavior are not fully understood, increased levels of inflammation, arising from various sources, have been detected in the central nervous system and the peripheral blood of suicidal patients and suicide completers. Inflammation induces the kynurenine pathway of tryptophan metabolism, which generates a range of metabolites with potent effects on neurotransmitter systems as well as on inflammation. Recent evidence indicates that a dysregulation of the enzymes in the kynurenine pathway may be present in suicidal patients, with a resulting imbalance of metabolites that modulate glutamate neurotransmission and neuroinflammation. As the body of research in these areas grows, targeting the kynurenine pathway enzymes and metabolites may provide novel therapeutic opportunities for detection, treatment, and ultimately prevention of suicidal behavior.

Understanding Suicide Risk within the Research Domain Criteria (RDoC) Framework: Insights, Challenges, and Future Research Considerations

Suicide is a leading cause of death worldwide. Prior research has focused primarily on sociodemographic and psychiatric risk factors with little improvement in the prediction or prevention of suicidal behavior over time. The Research Domain Criteria (RDoC) may be an especially useful framework for advancing research in this area. This paper provides a brief and broad overview of research on suicidal behavior relating to each of the RDoC domains-highlighting the RDoC construct(s) where research has focused, construct(s) where research is lacking, and suggestions for future research directions. We also discuss major challenges for suicide research within the RDoC framework, including the intersection of RDoC domains, interaction of domains with the environment, incorporation of developmental stage, integration of distal and proximal processes, and inclusion of suicide-specific constructs. We conclude by underscoring important considerations for future research aimed at using the RDoC framework to study suicidal behavior and other forms of psychopathology.

Predictors for self-directed aggression in Italian prisoners include externalizing behaviors, childhood trauma and the serotonin transporter gene polymorphism 5-HTTLPR

Suicidal behavior and self-mutilation can be regarded as the expression of self-directed aggression and both are common in prison populations. We investigated the influence of externalizing behaviors, depressive symptoms, childhood trauma, 5-HTTLPR variants on self-directed aggression (N = 145) in a group of 702 male Italian prisoners. Participants were comprehensively evaluated, including for psychiatric disorders, impulsive traits, lifetime aggressive behavior [Brown-Goodwin Lifetime History of Aggression (BGHA)], hostility, violent behavior during incarceration, depressive symptomatology [Hamilton Depression Rating Scale (HDRS)], childhood trauma [Childhood Trauma Questionnaire (CTQ)]. Logistic regression analysis showed false discovery rate corrected independent main effects of externalizing behaviors: BGHA (P = 0.001), violent behavior in jail (P = 0.007), extraversion (P = 0.015); HDRS (P = 0.0004), Axis I disorders (P = 0.015), CTQ (P = 0.004) and 5-HTTLPR genotype (P = 0.02). Carriers of 5-HTTLPR high (LA LA ), intermediate (LA LG , SLA ) activity variants were more likely to have exhibited self-directed aggression relative to the low activity (LG LG , SLG , SS) variant: high/low: odds ratio (OR) = 2.3, 95% confidence interval (CI) 1.27-4.68, P = 0.007; intermediate/low: OR = 1.96, 95% CI 1.09-3.68, P = 0.025. The CTQ main effect was driven by physical abuse. There was no interactive effect of 5-HTTLPR and CTQ. Secondary logistic regression analyses in (1) all suicide attempters (N = 88) and (2) all self-mutilators (N = 104), compared with controls showed that in both groups, childhood trauma (P = 0.008-0.01), depression (P = 0.0004-0.001) were strong predictors. BGHA, violent behavior in jail predicted self-mutilation (P = 0.002) but not suicide attempts (P = 0.1). This study was able to distinguish differing influences on self-directed aggression between groups of closely related predictor variables within the externalizing behavioral domain. 5-HTTLPR had an independent, variant dosage effect.

Genetic Polymorphism in the Promoter Region of Serotonin Transporter: Implications for Ethanol Abuse in Children and Adolescents

OBJECTIVES

To provide a review of published literature regarding genetic polymorphism of serotonin transporter gene, named as 5-HTTLPR, and its potential role as a susceptibility marker for ethanol abuse in childhood and adolescence.

METHODS

A literature review of several databases was conducted with the following keywords: 5-HTTLPR, children or adolescents or teenagers, susceptibility, alcohol or ethanol, abuse or misuse.

RESULTS

Alcohol interacts with serotonergic synaptic transmission in several ways, and the reduced availability of serotonin transporters might foster brain dysfunction, driving to alcohol abuse. The initial use of ethanol in children and adolescents is determined primarily by environmental influences, whereas the establishment of drinking patterns is strongly controlled by genetic factors. Functional polymorphic variants in the promoter region of the 5-HTTLPR gene have age-dependent effects in alcohol abuse. This polymorphism, mapped to the 5' region of the SLC6A4, is a variable number of tandem repeats (VNTR) and involves a direct repeat of 20-23 base pairs GC-rich sequences, comprising a short (S) allele, consisting of 14 repeats, and a long (L) allele, with 16 repeats. Additional variants have been described, although their influences on childhood and adolescence ethanol use are not clear.

CONCLUSION

The influence of the 5-HTTLPR allelic variants in children and adolescent misuse of alcohol might be considered for clinical management, preventing long-term behavior problem. Identifying genetic markers associated to the potential alcohol misuse or abuse could be useful in guiding management and formulating effective coping strategies.

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.

Evaluation of psychiatric and genetic risk factors among primary relatives of suicide completers in Delhi NCR region, India

Suicide as a public health problem is studied worldwide and association of psychiatric and genetic risk factors for suicidal behavior are the point of discussion in studies across different ethnic groups. The present study is aimed at evaluating psychiatric and genetic traits among primary relatives of suicide completer families in an urban Indian population. Bi-variate analysis shows significant increase in major depression (PHQ and Hamilton), stress, panic disorder, somatoform disorder and suicide attemptamong primary compared to other relatives. Sib pair correlations also reveal significant results for major depression (Hamilton), stress, suicide attempt, intensity of suicide ideation and other anxiety syndrome. 5-HTTLPR, 5-HTT (Stin2) and COMT risk alleles are higher among primary relatives, though statistically insignificant. Backward conditional logistic regression analysis show only independent variable, Depression (Hamilton) made a unique statistically significant contribution to the model in primary relatives.

Suicidal ideation modulates the reduction in serotonin transporter availability in male military conscripts with major depression: A 4-[18F]-ADAM PET study

OBJECTIVES

Suicide is an important issue in the military service, since it can influence military morale and create dangerous situations for other personnel. The serotonin transporter (SERT) has been suggested to be involved in the pathophysiology of depression and suicidal behaviours. The aims of this study were to examine whether the brain SERT availability differs between military conscripts with depression and control subjects, and whether suicidal ideation is correlated with SERT availability.

METHODS

We used N,N-dimethyl-2-(2-amino-4-[(18)F]-fluorophenylthio)benzylamine (4-[(18)F]-ADAM) as a radioligand for positron emission tomography (PET) imaging. All participants completed the Hamilton Depression Rating Scale and Beck Scale for Suicide Ideation (BSS) prior to PET imaging.

RESULTS

The effect of major depression and BSS scores had an interaction on SERT availability. After adjusting for the BSS score, subjects with depression had lower SERT availability than control subjects (F1,17 = 23.85, P < 0.001). A positive correlation between SERT availability and BSS scores was observed in the depression group (F1,8 = 30.67, P = 0.001). The status of depression and intensity of suicidal ideation exert opposite effects on SERT availability.

CONCLUSIONS

The extent of suicidal ideation may moderate the reduction effect in SERT binding observed in major depression in male military conscripts.

Genetic association of single nucleotide polymorphisms in dystrobrevin binding protein 1 gene with schizophrenia in a Malaysian population

Dystrobrevin binding protein 1 (DTNBP1) gene is pivotal in regulating the glutamatergic system. Genetic variants of the DTNBP1 affect cognition and thus may be particularly relevant to schizophrenia. We therefore evaluated the association of six single nucleotide polymorphisms (SNPs) with schizophrenia in a Malaysian population (171 cases; 171 controls). Associations between these six SNPs and schizophrenia were tested in two stages. Association signals with p < 0.05 and minor allele frequency > 0.05 in stage 1 were followed by genotyping the SNPs in a replication phase (stage 2). Genotyping was performed with sequenced specific primer (PCR-SSP) and restriction fragment length polymorphism (PCR-RFLP). In our sample, we found significant associations between rs2619522 (allele p = 0.002, OR = 1.902, 95%CI = 1.266 – 2.859; genotype p = 0.002) and rs2619528 (allele p = 0.008, OR = 1.606, 95%CI = 1.130 – 2.281; genotype p = 6.18 × 10⁻⁵) and schizophrenia. Given that these two SNPs may be associated with the pathophysiology of schizophrenia, further studies on the other DTNBP1 variants are warranted.

Possible Association between Serotonin Transporter Gene Polymorphism and Suicide Behavior in Major Depressive Disorder

OBJECTIVE

The serotonin transporter (5-HTT) genes are major candidate genes for modulating the suicidal behavior. We investigated the association between serotonin transporter polymorphisms and suicidal behavior in patients with major depressive disorder (MDD).

METHODS

Serotonin transporter intron 2 VNTR polymorphism (5-HTTVNTR) and serotonin transporter linked polymorphic region polymorphism (5-HTTLPR) were analyzed in 132 depressed patients with suicidal attempt as well as in 122 normal controls. Hamilton's 17-item Depression Rating Scale (HDRS), the Risk-Rescue rating system (RRR) and the Lethality Suicide Attempt Rating Scale updated (LSARS-II) were assessed for the depressed patients.

RESULTS

Although not statistically significant, a trend was found such that the 10/10 and 10/12 alleles of 5-HTTVNTR were more common in suicidal subjects than in control subjects. Comparing allele frequency, those with a 10 allele or 10 allele carriers were higher in suicidal subjects than in control subjects. No difference was noted in 5-HTTLPR genotypes and haplotype distribution between the suicidal subjects and control subjects. The RRR scores in subjects with the 10/10 5-HTTVNTR genotype or 10 5-HTTVNTR allele were significantly lower than those in subjects with other genotypes.

CONCLUSION

These results show the possibility that 10 allele of 5-HTTVNTR is related to suicidal behavior in the suicidal subjects with MDD and suggest that 12 allele of 5-HTTVNTR might be related to more lethality in the suicidal subjects with MDD.

The impact of 5-HTTLPR on acute serotonin transporter blockade by escitalopram on emotion processing: preliminary findings from a randomised, crossover fMRI study

OBJECTIVE

Benefit from antidepressant treatment such as selective serotonin reuptake inhibitors (SSRIs) may depend on individual differences in acute effects on neural emotion processing. The short ('S') allele of the serotonin transporter (5-HTT)-linked polymorphic region (5-HTTLPR) is associated with both negative emotion processing biases and poorer treatment outcomes. Therefore, the aim of the present study was to explore the effects of 5-HTTLPR on the impact of the SSRI escitalopram during processing of positive and negative emotional images, as well as neutral stimuli.

METHODS

The study employed a double-blind, randomised, placebo-controlled crossover design on 36 healthy Caucasian female participants who underwent functional magnetic resonance imaging (fMRI) scanning following placebo or escitalopram treatment, separated by a 7-day washout period.

RESULTS

Changes in the left amygdala signal with escitalopram treatment during processing of emotional stimuli were linearly related to the 5-HTTLPR 'S' allele load such that the signal to positive stimuli decreased and the signal to negative stimuli increased with an increasing number of low-expressing 'S' alleles. While 5-HTTLPR subgroups were small in size, individual subject changes with treatment and task condition increase confidence in the findings.

CONCLUSIONS

While preliminary, our findings comprise the first pharmacogenetic study demonstrating an effect of the 5-HTTLPR 'S' allele load on escitalopram-induced changes in amygdala activity during emotional processing, consistent with a 5-HTT expression dosage model. The present findings have implications for the impact of this polymorphism on antidepressant efficacy in patients with mood and anxiety disorders.

Association of BDNF promoter methylation and genotype with suicidal ideation in elderly Koreans

OBJECTIVES

Brain-derived neurotrophic factor (BDNF) has been considered a risk factor for suicidal behavior in adult populations. BDNF secretion is influenced by epigenetic (DNA promoter methylation) and genetic (val66met polymorphism) profiles. We investigated the independent and interactive effects of BDNF methylation status and val66met polymorphisms on late-life suicidal ideation.

METHODS

In total, 732 Korean community residents aged 65+ years were evaluated; of 639 without suicidal ideation, 579 (90.6%) were followed up 2 years later. The prevalence and incidence of suicidal ideation were ascertained using the Geriatric Mental State Schedule. Sociodemographic and clinical covariates included age, sex, education, depressive symptoms, cognitive function, and disability. The independent effects of BDNF methylation status on the prevalence and incidence of suicidal ideation were investigated using multivariate logistic regression models. The two-way interactions of BDNF methylation status and val66met polymorphism on suicidal ideation were assessed using the same models.

RESULTS

Higher BDNF methylation status was significantly associated with both prevalence and incidence of suicidal ideation, independent of potential covariates. No significant methylation-genotype interaction was found.

CONCLUSIONS

The BDNF hypothesis and the epigenetic origin of the suicidal behavior were supported, even in old age. BDNF promoter methylation status may be useful as a biological marker for suicidality in late life.

Genetic association of impulsivity in young adults: a multivariate study

Impulsivity is a heritable, multifaceted construct with clinically relevant links to multiple psychopathologies. We assessed impulsivity in young adult (N~2100) participants in a longitudinal study, using self-report questionnaires and computer-based behavioral tasks. Analysis was restricted to the subset (N=426) who underwent genotyping. Multivariate association between impulsivity measures and single-nucleotide polymorphism data was implemented using parallel independent component analysis (Para-ICA). Pathways associated with multiple genes in components that correlated significantly with impulsivity phenotypes were then identified using a pathway enrichment analysis. Para-ICA revealed two significantly correlated genotype-phenotype component pairs. One impulsivity component included the reward responsiveness subscale and behavioral inhibition scale of the Behavioral-Inhibition System/Behavioral-Activation System scale, and the second impulsivity component included the non-planning subscale of the Barratt Impulsiveness Scale and the Experiential Discounting Task. Pathway analysis identified processes related to neurogenesis, nervous system signal generation/amplification, neurotransmission and immune response. We identified various genes and gene regulatory pathways associated with empirically derived impulsivity components. Our study suggests that gene networks implicated previously in brain development, neurotransmission and immune response are related to impulsive tendencies and behaviors.

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.

Ethnicity moderates the association between 5-HTTLPR and national suicide rates

The association between ethnicity, national suicide rates, and the functional serotonin transporter gene polymorphism (5-HTTLPR), under consideration of the role of economic indicators, national alcohol intake, and national happiness scores was analyzed with an ecologic analysis. Data on allelic frequencies of the short (s) allele from 38 countries from over 100,000 healthy screened or general population individuals were analyzed with multiple regression models. Allele frequency varied widely both within and across ethnicities and an ethnicity-based interaction between national suicide rates and 5-HTTLPR allele frequency was revealed with the s allele acting as protective factor in Caucasian and as a risk factor in non-Caucasian populations. This interaction effect underlines the importance of ethnicity as a moderating factor in the genetics of suicide.

Genetic association studies between SNPs and suicidal behavior: a meta-analytical field synopsis

The large number of published meta-analyses on the associations between single-nucleotide polymorphisms (SNPs) and suicidal behavior mirrors the enormous research interest in this topic. Although meta-analytic evidence is abundant and certain patterns are apparent, those have not been integrated into a general framework as of yet. In a systematic review, genetic association studies between SNPs and suicidal behavior were identified. Previously published meta-analyses for eight SNPs were updated and the results of the different meta-analyses were compared. Meta-analyses for 15 SNPs, which had not been subjected to meta-analysis before, were conducted. The present meta-analytical field synopsis showed five major similarities between new and published analyses: 1) Summary effect sizes were small and rarely statistically significant, 2) heterogeneity between studies was often substantial, 3) there were no time trends, 4) effects were easily swayed and were largely dependent on individual studies, and 5) publication bias does not play a role in this field of research. Meta-analytic data show once more that major contributions of single genes are unlikely. However, association studies and corresponding meta-analyses have been an important and necessary stepping stone in the development of modern and more complex approaches in the genetics of suicidal behavior.

Serotonergic genes and suicide: a systematic review

Suicide is one of the leading causes of death in the world. Its aetiology is complex and diverse, however, epidemiological studies show that suicidal behavior is partly heritable. Neurobiological evidence implicates serotonergic dysfunction in suicidality, stimulating genetic research to focus on genes related to the serotonergic system. In this paper, we review evidence from studies examining the association between various serotonergic genes (Tryptophan Hydroxylase genes: TPH1; TPH2, Serotonin Transporter gene: 5-HTTLPR in SLC6A4, Serotonin Receptor genes: HTR1A, HTR2A, HTR1B, HTR2C and Monoamine Oxidase A gene: MAOA) and suicidal behavior. The data show associations between variation on the TPH1 gene and 5-HTTLPR gene and violent suicidal behavior in Caucasian populations, with the least inconsistencies. Results are mixed for the TPH2 gene and serotonin receptor genes, but for some genes, studies that include haplotypic analyses or that examine a larger coding region of the genes tend to provide more reliable results. Findings on endophenotypes of suicidality, such as aggression and impulsivity traits, show positive associations for the TPH1, HTR2A, and MAOA genes, but need further replication, since negative associations are also occasionally reported. Since genes can only partially explain suicidal risk, several studies during the past decade have tried to incorporate environmental factors in the susceptibility model. Studies to date show that variation on the 5-HTTLPR, MAOA and HTR2A gene can interact with stressful life events to increase risk for suicidal behavior. Limitations of case-control studies are discussed and future considerations are put forward with regard to endophenotypic measurements and gene-environment interactions.

Decreased brainstem and putamen SERT binding potential in depressed suicide attempters using [11C]-zient PET imaging

BACKGROUND

Deficits in serotonergic neurotransmission have been implicated in the pathogenesis of depression and suicidality. The present study utilized a novel positron-emission tomography (PET) ligand to quantitate and compare brain regional serotonin transporter (SERT) binding potential in depressed patients with a past history of suicide attempts to that of healthy comparison subjects.

METHOD

We used [(11) C]-ZIENT PET to label SERT in the serotonergic cell body rich brainstem, and forebrain projection fields. Quantitative PET emission data from 21 adults (10 healthy controls and 11 drug-free patients with major depression) was used for group comparison. SERT binding potential (BPND ) in eight MRI-based brain regions of interest (ROI) were compared in high-resolution PET images.

RESULTS

SERT binding potential was significantly decreased in the midbrain/pons (P = .029) and putamen (P = .04) of depressed patients with a past suicide attempt relative to comparison subjects. Forebrain SERT binding was also reduced in the patient sample, though these region effects did not survive a multiple comparison correction.

CONCLUSION

These results suggest that decreased availability of the brainstem and basal ganglia SERT represents a biomarker of depression and thus confirm and extend the role of dysregulation of brain serotonergic neurotransmission in the pathophysiology of depression and suicide.

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.

Multi-cultural association of the serotonin transporter gene (SLC6A4) with substance use disorder

A number of studies have reported associations between the serotonin transporter gene (SLC6A4) and alcohol, heroin, cocaine, or methamphetamine abuse. Other studies have yielded contrary results. There are a number of reasons for non-replication, including inadequate statistical power, population stratification, and poor phenotype definition. This study was to test the association using a meta-analytic approach across a variety of racial and ethnic populations. Using the genotype data of 55 studies (7999 cases, 8264 controls, and 676 families or parent-offspring trios) published in the past 15 years, we have conducted comprehensive meta-analyses to examine the associations of the 5-HTTLPR and STin2 polymorphisms with substance use disorder. The meta-analyses support the associations of 5-HTTLPR with alcohol, heroin, cocaine, and methamphetamine dependence and abuse (eg, the smallest P-values were 0.0058 with odds ratio (OR)=0.54 (0.35, 0.84); 0.0024 with OR=0.77 (0.66, 0.91); 0.018 with OR=1.38 (1.06, 1.81); and 0.028 with OR=0.46 (0.23, 0.92) for alcohol, heroin, cocaine, and methamphetamine dependence/abuse, respectively). When all the phenotypes are combined, the P-value was 0.0006 with OR=0.86 (0.78, 0.94) in the combined European, Asian, and Mexican populations and P-value was 0.0028 with OR=1.41 (1.13, 1.78) in the African populations. Evidence of significant associations was also identified in other subgroup analyses regarding differently combined substance and populations. The effect sizes of 5-HTTLPR were comparable among the European, Asian, and Mexican populations, however, the risk allele was more frequent in Asians than in Europeans and Mexicans. The opposite directions of risk allele in African population might be driven by the opposite directions of risk allele in cocaine dependence. This meta-analysis supports that the association of the SLC6A4 gene with substance use disorder varies depending on substances with different risk allele frequencies in the multi-cultural populations. Further studies using larger sample size are warranted.