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

Investigating the relationship between DNA methylation, genetic variation, and suicide attempt in bipolar disorder

Individuals with bipolar disorder are at increased risk for suicide, and this can be influenced by a range of biological, clinical, and environmental risk factors. Biological components associated with suicide include DNA modifications that lead to changes in gene expression. Common genetic variation and DNA methylation changes are some of the most frequent types of DNA findings associated with an increased risk for suicidal behavior. Importantly, the interplay between genetic predisposition and DNA methylation patterns is becoming more prevalent in genetic studies. We hypothesized that DNA methylation patterns in specific loci already genetically associated with suicide would be altered in individuals with bipolar disorder and a history of suicide attempt. To test this hypothesis, we searched the literature to identify common genetic variants (N=34) previously associated with suicidal thoughts and behaviors in individuals with bipolar disorder. We then created a customized sequencing panel that covered our chosen genomic loci. We profiled DNA methylation patterns from blood samples collected from bipolar disorder participants with suicidal behavior (N=55) and without suicidal behavior (N=51). We identified seven differentially methylated CpG sites and five differentially methylated regions between the two groups. Additionally, we found that DNA methylation changes in MIF and CACNA1C were associated with lethality or number of suicide attempts. Finally, we identified three meQTLs in SIRT1 , IMPA2 , and INPP1 . This study illustrates that DNA methylation is altered in individuals with bipolar disorder and a history of suicide attempts in regions known to harbor suicide-related variants.

NR3C1 and NR3C2 Genes Increase the Risk of Suicide Attempt in Psychiatric Disorder Patients with History of Childhood Trauma

Background

Hypothalamic-pituitary-adrenal axis gene variants and childhood trauma (CT) are considered risk factors for suicide attempt (SA). The aim of the present study was analyzed gene x environment (GxE) interaction of NR3C1, NR3C2, and CT, and NR3C1 and NR3C2 gene expression in the development of SA with CT.

Participants and Methods

A total of 516 psychiatric Mexican patients from Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz. Among them, 274 had SA at least once and 242 had not SA. Genetic variants of NR3C1 and NR3C2 were genotyped in all the patients, of which were obtained the CT information from medical records. Additionally, the gene expression of NR3C1 and NR3C2 was also analyzed for a subsample of 96 patients, obtaining the TC information from Childhood Trauma Questionnaire (CTQ).

Results

The analysis showed a GxE interaction of NR3C1, NR3C2, and CT (OR=2.8, 95% CI [1.9-3.9], p<0.0001). Interactions were also observed with neglect (OR=2.1, 95% CI [1.4-3.1], p<0.0001), emotional abuse (OR=2.1, 95% CI [1.5-3], p<0.0001), and sexual abuse (OR=2.4, 95% CI [1.4-2.9], p<0.0001) in the prediction of SA. The analysis of gene expression identified an overexpression of NR3C1 in SA patients with high scores for physical and sexual abuse (p<0.0001; p<0.0006, respectively) and emotional neglect (p=0.014). An underexpression was observed of NR3C2, associated with high scores of trauma subtypes (p<0.0001) except physical neglect. Additionally, we observed an overexpression of NR3C1 gene in patients with SA carriers of A allele of rs6191 (p=0.0015). Also, overexpression of NR3C1 gene in carriers of G allele of rs6198 and underexpression of NR3C2 gene in carriers of G allele of rs5522 (p<0.0001).

Conclusion

Our findings suggest that genetic variants of NR3C1 and NR3C2 differentially affect expression levels, increasing the susceptibility to SA in psychiatric patients with a history of CT.

Gene-environment interaction between HPA-axis genes and trauma exposure in the suicide behavior: A systematic review

Suicide behavior (SB) emerge from complex interactions among traumatic events and multiple genetic factors. We conducted the first systematic review to assess the evidence of a link among trauma exposure, HPA-axis genes, and SB. A systematic search of PubMed, EBSCO, Science Direct, PsychInfo, and Scopus databases on gene-environment interaction, and susceptibility to SB was carried out until February 2022. Our study was prospectively registered in PROSPERO (CRD42022316141). A total of 13 epidemiological studies (11,756 subjects) were included: eight studies focused on traumatic experiences in the childhood and five studies on lifetime trauma exposure. All studies reported a positive association between the trauma exposure with SB. Gene-environment interaction was reported for CRHR1 (n = 6), CRHR2 (n = 2), FKBP5 (n = 2), and CRHBP (n = 1), however, for CRH, NR3C1, MC2R, and POMC genes no found gene-environment effects on SB. Trauma exposure could be one mechanism that links HPA-axis genes activity with the development of SB.

Association and Genetic Expression between Genes Involved in HPA Axis and Suicide Behavior: A Systematic Review

BACKGROUND

Suicide behavior (SB) has been highly associated with the response to stress and the hypothalamic-pituitary-adrenal (HPA) axis. The aim of this study was to summarize the results obtained in genetic studies that analyzed the HPA axis-stress pathway and SB through a systematic review.

METHODS

We performed an online search in PubMed, EBSCO, Web of Science, Scopus, and PsycoInfo databases up to May 2021. We followed the PRISMA guidelines for systematic reviews. We included case-control and expression studies that provided data on mRNA expression and single-nucleotide polymorphisms of genes associated with SB.

RESULTS

A total of 21,926 individuals participated across 41 studies (not repeats); 34 studies provided data on single-nucleotide polymorphisms in 21,284 participants and 11 studies reported data on mRNA expression in 1034 participants. Ten genes were identified: FKBP5, CRH, CRHBP, CRHR1, CRHR2, NR3C1, NR3C2, SKA2, MC2R, and POMC.

CONCLUSIONS

Our findings suggest that key stress pathway genes are significantly associated with SB and show potential as biomarkers for SB.

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

PURPOSE OF REVIEW

We identify the recent evidence for gene-by-environment interaction studies in relation to psychiatric disorders. We focus on the key genotypic data as well as environmental exposures and how they interact to predict psychiatric disorders and psychiatric symptomatology. We direct our focus on the psychiatric outcomes that were focused on by the Psychiatric Genetics Consortium.

RECENT FINDINGS

Many of the studies focus on candidate gene approaches, with most of the studies drawing upon previous literature to decide the genes of interest. Other studies used a genome-wide approach. While some studies demonstrated positive replication of previous findings, replication is still an issue within gene-by-environment interaction studies. Gene-by-environment interaction research in psychiatry globally suggests some susceptibility to environmental exposures based on genotype; however, greater clarity is needed around the idea that genetic risk may not be disorder specific.

Association of childhood trauma and genetic variability of CRH-BP and FKBP5 genes with suicidal behavior in bipolar patients

BACKGROUND

Around 8% of bipolar disorder (BD) patients die by suicide every year, accounting for the highest rate among the psychiatric population. Suicidal behavior (SB) is mediated by an intertwining system of extrinsic and intrinsic factors. Childhood trauma (CT) and gene variants of the stress-management hypothalamic-pituitary-adrenal (HPA) axis have been reported as risk factors for SB. The aim of this study was to elucidate the association of CT and HPA axis genetic variants with SB.

METHODS

135 BD patients were recruited for clinical assessment of CT and SB by means of the Childhood Trauma Questionnaire (CTQ) and the Columbia Suicide Severity Rating Scale (C-SSRS), respectively. A total of 28 single nucleotide polymorphisms (SNPs) from 8 HPA axis genes (POMC, NR3C2, CRH-BP, NR3C1, FKBP5, CRHR2, CRHR1, and MC2R) were genotyped.

RESULTS

The analyses showed an association of total CTQ score (p = 0.003), emotional abuse (p = 0.001), sexual abuse (p = 0.005) and emotional neglect (p = 0.005) with SB. CRH-BP rs7728378-C carriers (p = 0.004; OR = 3.05), FKBP5 rs3777747-AA (p = 0.039; OR = 0.34) and FKBP5 rs2766533-GG genotypes (p = 0.001; OR = 2.93) were associated with SB although only rs2766533 survived multiple test correction. No gene-environment interaction was found.

LIMITATIONS

The relatively small sample size limits the statistical power to detect smaller environmental and genetic effects. Cross-sectional data collection in psychometric assessments can yield biased data.

CONCLUSIONS

The present study characterizes novel SB risk factors and replicates previous findings in BD patients. CT and variability in CRH-BP and FKBP5 genes should be further studied for a better understanding of SB and ultimately help in suicide prevention.

Effect of CRHR1 and CRHR2 gene polymorphisms and childhood trauma in suicide attempt

Family, twin, and adoption studies have suggested that genetic factors might be involved in suicidal behavior. Corticotropin-releasing receptor type 1 (CRHR1) and 2 (CRHR2) genes play a key role in the activation and modulation of the hypothalamic-pituitary-adrenal (HPA) axis, which is considered a major stress regulator. Childhood trauma is an environmental risk factor associated with suicide attempt (SA) and it has been related to HPA axis dysregulation. This study aimed at analyzing the relationship of CRHR1 and CRHR2 genes with childhood trauma concerning the development of SA. In this study, we included 366 affective disorder patients. Among them, 183 patients had SA at least once and 183 had not SA. Information regarding SA and childhood trauma was obtained from medical records. Multifactor Dimensionality Reduction program was used to detect gene-environment interactions between CRHR1 (rs110402, rs242924, and rs16940665) and CRHR2 (rs2190242, rs2284217, and rs2014663) with childhood trauma in SA. The analysis showed an interaction of CRHR1 and CRHR2 with childhood trauma, thus conferring increased risk of having presented at least one SA (OR 7.44; 95% CI 4.58-12.07; p < 0.0001). In addition, we observed the following in the trauma subtypes analysis: physical negligence (OR 4.72; 95% CI 3.01-7.40; p < 0.0001), emotional abuse (OR 5.76; 95% CI 3.67-9.05; p < 0.0001), and sexual abuse (OR 5.70; 95% CI 3.62-8.97; p < 0.0001). Our results suggested that genetic variants of CRHR1 and CRHR2 genes in addition to physical negligence, and emotional and sexual abuse, contribute to increase risk of presented at least one SA.

Genes involved in stress response influence lithium efficacy in bipolar patients

OBJECTIVES

In mood disorders, chronic stimulation with stress results in aberrant regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Lithium was shown to influence HPA axis function. The underlying genetic background as well as environmental context may influence the stress response, and therefore lithium efficacy. The aim of the present study was to analyze if genetic variants located in genes involved in HPA axis regulation affect the response to long-term lithium treatment in bipolar patients.

METHODS

We included 93 patients with bipolar disorder (32 males and 61 females), aged 31-80 years. The patients had been treated with lithium carbonate for at least 5 years. The magnitude of the lithium response was assessed using the Alda scale. Genotyping was performed for 28 polymorphisms in the genes encoding the following proteins involved in HPA axis regulation: corticotropin-releasing hormone receptor 1 (CRHR1), arginine vasopressin receptor 1B (AVPR1b), FK506 binding protein (FKBP) 5, FKBP4, BCL2-associated athanogene 1 (BAG1), stress induced phosphoprotein 1 (STIP1), glucocorticoid-induced transcript 1 (GLCC1), dual specificity phosphatase 1 (DUSP1) serine and arginine rich splicing factor (SRSF) 3, SRSF9, SRSF5, and acid phosphatase 1 (ACP1). Linkage disequilibrium and haplotype analysis were then performed, followed by statistical analysis (Statistica v.12; Stasoft, Krakow, Poland).

RESULTS

We found a correlation between stressful life events at first episode and worse response to lithium (P=.019). In single marker analysis, we observed a significant association between three FKBP5 polymorphisms (rs1360780, rs7748266 and rs9296158), one ACP1 variant (rs300774) and one glucocorticoid-induced transcript 1 gene (GLCC1) variant (rs37972) and the degree of lithium response. Five out of seven FKBP5 polymorphisms showed strong linkage with one haplotype demonstrating an association with lithium efficacy (P=.008). No relationship was found between the other analyzed polymorphisms and lithium response.

CONCLUSION

The response to lithium may depend on the variants of genes regulating the HPA axis and stressful life events in bipolar patients.

Interactions Between Variation in Candidate Genes and Environmental Factors in the Etiology of Schizophrenia and Bipolar Disorder: a Systematic Review

Schizophrenia and bipolar disorder (BD) are complex and multidimensional disorders with high heritability rates. The contribution of genetic factors to the etiology of these disorders is increasingly being recognized as the action of multiple risk variants with small effect sizes, which might explain only a minor part of susceptibility. On the other site, numerous environmental factors have been found to play an important role in their causality. Therefore, in recent years, several studies focused on gene × environment interactions that are believed to bridge the gap between genetic underpinnings and environmental insults. In this article, we performed a systematic review of studies investigating gene × environment interactions in BD and schizophrenia spectrum phenotypes. In the majority of studies from this field, interacting effects of variation in genes encoding catechol-O-methyltransferase (COMT), brain-derived neurotrophic factor (BDNF), and FK506-binding protein 5 (FKBP5) have been explored. Almost consistently, these studies revealed that polymorphisms in COMT, BDNF, and FKBP5 genes might interact with early life stress and cannabis abuse or dependence, influencing various outcomes of schizophrenia spectrum disorders and BD. Other interactions still require further replication in larger clinical and non-clinical samples. In addition, future studies should address the direction of causality and potential mechanisms of the relationship between gene × environment interactions and various categories of outcomes in schizophrenia and BD.

Modeling suicide in bipolar disorders

INTRODUCTION

Suicide is a multicausal human behavior, with devastating and immensely distressing consequences. Its prevalence is estimated to be 20-30 times greater in patients with bipolar disorders than in the general population. The burden of suicide and its high prevalence in bipolar disorders make it imperative that our current understanding be improved to facilitate prediction of suicide and its prevention. In this review, we provide a new perspective on the process of suicide in bipolar disorder, in the form of a novel integrated model that is derived from extant knowledge and recent evidence.

METHODS

A literature search of articles on suicide in bipolar disorder was conducted in recognized databases such as Scopus, PubMed, and PsycINFO using the keywords "suicide", "suicide in bipolar disorders", "suicide process", "suicide risk", "neurobiology of suicide" and "suicide models". Bibliographies of identified articles were further scrutinized for papers and book chapters of relevance.

RESULTS

Risk factors for suicide in bipolar disorders are well described, and provide a basis for a framework of epigenetic mechanisms, moderated by neurobiological substrates, neurocognitive functioning, and social inferences within the environment. Relevant models and theories include the diathesis-stress model, the bipolar model of suicide and the ideation-to-action models, the interpersonal theory of suicide, the integrated motivational-volitional model, and the three-step theory. Together, these models provide a basis for the generation of an integrated model that illuminates the suicidal process, from ideation to action.

CONCLUSION

Suicide is complex, and it is evident that a multidimensional and integrated approach is required to reduce its prevalence. The proposed model exposes and provides access to components of the suicide process that are potentially measurable and may serve as novel and specific therapeutic targets for interventions in the context of bipolar disorder. Thus, this model is useful not only for research purposes, but also for future real-world clinical practice.

Influence of CRHR1 Polymorphisms and Childhood Abuse on Suicide Attempts in Affective Disorders: A GxE Approach

Background: Previous studies have shown that the hypothalamus-pituitary-adrenal-axis (HPA-axis) is closely involved in the development of affective disorders. Given that early life events are also linked to dysregulation of the same system, there might be an association between childhood adversities and suicidal behavior in affective disorders, moderated by HPA-axis genes. We aimed to investigate a potential association between childhood trauma and previous suicide attempts in affective disorder patients, moderated by variants of the corticotropin-releasing hormone receptor 1 (CRHR1) gene. Methods: The current pilot study is part of an ongoing study on suicidal behavior in affective disorders (VieSAD). Two hundred fifty eight Caucasian affective disorder patients were assessed at the Department of Psychiatry and Psychotherapy of the Medical University Vienna and the Karl Landsteiner University for Health and Science. An assemblage of psychiatric interviews was performed (e.g., SCAN, HAMD, SBQ-R, CTQ) and DNA samples of peripheral blood cells were genotyped with TaqMan® SNP Genotyping Assays (rs7209436, rs4792887, rs110402, rs242924, and rs242939). Results: Neither genetic, nor haplotypic associations between CRHR1 polymorphisms and previous suicide attempts could be established for the present sample. Using a binary logistic regression model, significant gene-environment-interactions were found for the single nucleotide polymorphisms (SNPs) rs7209436 and rs110402, reflecting the impact of childhood trauma and CRHR1 polymorphisms on previous suicide attempts. Limitations: A larger sample size will be required to ultimately elucidate the link between childhood trauma and the HPA axis in suicidal behavior. Conclusion: This pilot study presents promising gene-environment-interaction findings in affective disorder patients with a history of suicide attempts.

Don't stress about CRF: assessing the translational failures of CRF1antagonists

BACKGROUND

Dr. Athina Markou sought treatments for a common neural substrate shared by depression and drug dependence. Antagonists of corticotropin-releasing factor (CRF) receptors, a target of interest to her, have not reached the clinic despite strong preclinical rationale and sustained translational efforts.

METHODS

We explore potential causes for the failure of CRF1 antagonists and review recent findings concerning CRF-CRF1 systems in psychopathology.

RESULTS

Potential causes for negative outcomes include (1) poor safety and efficacy of initial drug candidates due to bad pharmacokinetic and physicochemical properties, (2) specificity problems with preclinical screens, (3) the acute nature of screens vs. late-presenting patients, (4) positive preclinical results limited to certain models and conditions with dynamic CRF-CRF1 activation not homologous to tested patients, (5) repeated CRF1 activation-induced plasticity that reduces the importance of ongoing CRF1 agonist stimulation, and (6) therapeutic silencing which may need to address CRF2 receptor or CRF-binding protein molecules, constitutive CRF1 activity, or molecules that influence agonist-independent activity or to target structural regions other than the allosteric site bound by all drug candidates. We describe potential markers of activation towards individualized treatment, human genetic, and functional data that still implicate CRF1 systems in emotional disturbance, sex differences, and suggestive clinical findings for CRF1 antagonists in food craving and CRF-driven HPA-axis overactivation.

CONCLUSION

The therapeutic scope of selective CRF1 antagonists now appears narrower than had been hoped. Yet, much remains to be learned about CRF's role in the neurobiology of dysphoria and addiction and the potential for novel anti-CRF therapies therein.

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.

Bipolarity and suicidal ideation in children and adolescents: a systematic review with meta-analysis

BACKGROUND

Affective disorders in children and adolescents have received growing attention in the world scenario of mental health. Additionally, there has been an increasing prevalence of suicidal ideation in this population.

OBJECTIVE

A systematic review with meta-analysis was conducted to demonstrate the main risk factors regarding the development of suicidal ideation in the bipolar disorder.

METHODS

This is a systematic review with meta-analysis using the PRISMA protocol (http://www.prisma-statement.org/). This study included secondary data. Original data in mental health were collected by mapping the evidence found in the following electronic databases: MEDLINE/PubMed, LILACS, SciELO, and ScienceDirect in the period from 2005 to 2015.

RESULTS

We found 1418 registrations in such databases, and 46 of them were selected to comprise this review. The result introduces a joint risk between the studies of 2.94 CI [2.29-3.78]. A significant correlation was verified between the risk factors and the suicidal ideation. The result was r (Pearson) = 0.7103 and p value <0.001.

CONCLUSION

Children and adolescents living with bipolar disorder are more vulnerable to suicidal ideation. These results reinforce the need of a more effective public policy directed toward this population.

Bipolar Disorder and Early Emotional Trauma: A Critical Literature Review on Indicators of Prevalence Rates and Clinical Outcomes

LEARNING OBJECTIVES

After participating in this activity, learners should be better able to:• Evaluate the prevalence of early emotional trauma in patients with bipolar disorder (BD)• Assess the impact of these traumas on patients and on their development of BD OBJECTIVES: We performed a systematic literature review to (1) evaluate the prevalence of early emotional trauma (EET) in patients with bipolar disorder (BD) and the impact of these traumas on the development of the disorder, and (2) integrate the findings of our review with those previously reported by Fisher and Hosang, Daruy-Filho and colleagues, and Maniglio.

METHODS

The literature search was performed on PubMed, SciELO, and PsycINFO databases using the keywords bipolar disorder, early trauma, physical abuse, emotional abuse, sexual abuse, maltreatment, adversity, and neglect.

RESULTS

Twenty-eight articles were selected and analyzed. Taken together, the articles described a high prevalence of EET in BD, consisting mainly of emotional neglect/abuse (approximately 40%), particularly when compared to healthy subjects. The review also identified substantial evidence regarding an association between the presence of EET, early disease onset, rapid cycling, comorbidity with anxiety/stress disorders, and cannabis use.

CONCLUSION

The integration of the current findings with the identified studies reveals that (1) the methodological limitations noted by Daruy-Filho and colleagues have been largely resolved in more recent studies and (2) the presence of EET in patients with BD is associated with worse clinical outcomes, particularly early disease onset, presence of clinical or psychiatric comorbidities, suicide, and presence of psychotic episodes/symptoms. The review shows that patients with BD experience more traumatic situations than controls and that emotional trauma is the most frequent type of trauma in this group.

Targeted Sequencing of FKBP5 in Suicide Attempters with Bipolar Disorder

FKBP5 is a critical component of the Hypothalamic-Pituitary-Adrenal (HPA) axis, a system which regulates our response to stress. It forms part of a complex of chaperones, which inhibits binding of cortisol and glucocorticoid receptor translocation to the nucleus. Variations in both the HPA axis and FKBP5 have been associated with suicidal behavior. We developed a systematic, targeted sequencing approach to investigate coding and regulatory regions in or near FKBP5 in 476 bipolar disorder suicide attempters and 473 bipolar disorder non-attempters. Following stringent quality control checks, we performed single-variant, gene-level and haplotype tests on the resulting 481 variants. Secondary analyses investigated whether sex-specific variations in FKBP5 increased the risk of attempted suicide. One variant, rs141713011, showed an excess of minor alleles in suicide attempters that was statistically significant following correction for multiple testing (Odds Ratio = 6.65, P-value = 7.5 x 10⁻⁴, Permuted P-value = 0.038). However, this result could not be replicated in an independent cohort (Odds Ratio = 0.90, P-value = 0.78). Three female-specific and four male-specific variants of nominal significance were also identified (P-value < 0.05). The gene-level and haplotype association tests did not produce any significant results. This comprehensive study of common and rare variants in FKBP5 focused on both regulatory and coding regions in relation to attempted suicide. One rare variant remained significant following correction for multiple testing but could not be replicated. Further investigation is required in larger sample sets to fully elucidate the association of this variant with suicidal behavior.

Association between FKBP5 and CRHR1 genes with suicidal behavior: A systematic review

Suicide is one of the leading causes of death around the world with approximately one million suicides per year. An increasing number of neurobiological studies implicate HPA system dysfunction in suicide behavior, stimulating genetic research to focus on genes related to this system. This systematic review was focused on searching a correlation between FKBP5 and CRHR1 genes with suicidal behavior. Therefore, an electronic search strategy, using PubMed, EBSCO and Cochrane Library databases, was conducted from the inception of the studies into the databases to July 2016. The inclusion criteria were: use of at least one analysis investigating the relation between either the genetic variants in FKBP5 and/or CRHR1 genes with suicidal behavior. 2) use of a case-control design; 3) investigation about suicidal behavior in the form of suicide completion or history of at least one suicide attempt, as defined by each individual study; 4) inclusion of samples comprising control subjects; and 6) inclusion of reports written only in English language. The PRISMA guidelines were followed and the search strategy ensured that all possible studies were identified to compile the review. Using the keyword combinations, the search strategy provided 3334 articles, of which only 15 case-control studies were included in this systematic review. The included studies comprised 2526 subjects with suicidal behavior. A quantitative synthesis of results from the included studies was not undertaken due to marked methodological heterogeneity. This review showed a significant genetic association in most studies in FKBP5 and CRHR1 genes with a high rate of attempted suicide, pointing out that the expression of these genes and its polymorphisms could be a key predictor of suicide risk. In conclusion, this systematic review supports an association between suicidal behavior and genetic variants in FKBP5 and CRHR1 genes.

Neutrophil-to-lymphocyte ratio predicting suicide risk in euthymic patients with bipolar disorder: Moderatory effect of family history

BACKGROUND

Neutrophil-to-lymphocyte ratio (NLR) has been independently related to bipolar disorder (BD) and factors associated with suicidal risk. The aim of our study was to explore the relationship between NLR and suicide risk in euthymic BD patients. We also sought to propose a model of interaction between NLR and stress-diathesis factors, leading to suicidal risk in BD.

METHODS

The study group consisted of 83 patients diagnosed with BD (36 suicide attempters; 47 suicide non-attempters), compared to the healthy control group (n=73) and matched according to age, gender, and body mass index (BMI). NLR was measured according to the complete blood count. Mood symptoms have been assessed by Young Mania Rating Scale and Montgomery-Asberg Depression Rating Scale. Early trauma and acute stress were evaluated by Early Trauma Inventory Self Report-Short Form and List of Threatening Experiences Questionnaire, respectively. Suicide risk has been assessed by Suicide Behaviors Questionnaire-Revised (SBQ-R).

RESULTS

Significant correlation was found between NLR and SBQ-R score. The main effects of suicide attempts on NLR, after covarying for confounders, were observed, indicating increased NLR in BD suicide attempters compared to healthy controls. We found significant moderatory effects of family history on NLR relationship to suicidal risk, with NLR being significant positive predictor of suicidal risk only in the patients with positive family history of suicide attempts.

CONCLUSIONS

The results suggest an enhancing effect of positive family history of suicide attempts on predictive effect of NLR on suicide risk. Our data support the idea that immune markers can predict suicide attempt risk in BD, but only in the subpopulation of BD patients with family history of suicide attempts. This could lead to prevention in suicide behavior in the patient population at particular risk of suicide.