Neurobiology of suicidal behavior. An integration of biological and clinical findings

Genetic liability to suicidal thoughts and behaviors and risk of suicide attempt in US military veterans: moderating effects of cumulative trauma burden

BACKGROUND

Little is known about environmental factors that may influence associations between genetic liability to suicidality and suicidal behavior.

METHODS

This study examined whether a suicidality polygenic risk score (PRS) derived from a large genome-wide association study (N = 122,935) was associated with suicide attempts in a population-based sample of European-American US military veterans (N = 1664; 92.5% male), and whether cumulative lifetime trauma exposure moderated this association.

RESULTS

Eighty-five veterans (weighted 6.3%) reported a history of suicide attempt. After adjusting for sociodemographic and psychiatric characteristics, suicidality PRS was associated with lifetime suicide attempt (odds ratio 2.65; 95% CI 1.37-5.11). A significant suicidality PRS-by-trauma exposure interaction emerged, such that veterans with higher levels of suicidality PRS and greater trauma burden had the highest probability of lifetime suicide attempt (16.6%), whereas the probability of attempts was substantially lower among those with high suicidality PRS and low trauma exposure (1.4%). The PRS-by-trauma interaction effect was enriched for genes implicated in cellular and developmental processes, and nervous system development, with variants annotated to the DAB2 and SPNS2 genes, which are implicated in inflammatory processes. Drug repurposing analyses revealed upregulation of suicide gene-sets in the context of medrysone, a drug targeting chronic inflammation, and clofibrate, a triacylglyceride level lowering agent.

CONCLUSION

Results suggest that genetic liability to suicidality is associated with increased risk of suicide attempt among veterans, particularly in the presence of high levels of cumulative trauma exposure. Additional research is warranted to investigate whether incorporation of genomic information may improve suicide prediction models.

Fight the Fire: Association of Cytokine Genomic Markers and Suicidal Behavior May Pave the Way for Future Therapies

The fight against suicide is highly challenging as it may be one of the most complex and, at the same time, most threatening among all psychiatric phenomena. In spite of its huge impact, and despite advances in neurobiology research, understanding and predicting suicide remains a major challenge for both researchers and clinicians. To be able to identify those patients who are likely to engage in suicidal behaviors and identify suicide risk in a reliable and timely manner, we need more specific, novel biological and genetic markers/indicators to develop better screening and diagnostic methods, and in the next step to utilize these molecules as intervention targets. One such potential novel approach is offered by our increasing understanding of the involvement of neuroinflammation based on multiple observations of increased proinflammatory states underlying various psychiatric disorders, including suicidal behavior. The present paper overviews our existing understanding of the association between suicide and inflammation, including peripheral and central biomarkers, genetic and genomic markers, and our current knowledge of intervention in suicide risk using treatments influencing inflammation; also overviewing the next steps to be taken and obstacles to be overcome before we can utilize cytokines in the treatment of suicidal behavior.

Suicidal behavior among inpatients with severe mental conditions in a public mental health hospital in Uganda

BACKGROUND

Suicidal behaviors are prevalent among inpatients with severe mental conditions and may result in many dying by suicide. Few studies have focused on the burden of suicidal behaviors among these inpatients in low-income settings, despite suicide being consistently higher in lower-income countries such as Uganda. This study, therefore, provides the prevalence and associated factors of suicidal behaviors and suicide attempts among inpatients with severe mental conditions in Uganda.

METHOD

This was a retrospective chart review of all individuals admitted with severe mental conditions to a large psychiatry inpatient unit in Uganda for four years (2018-2021). Two separate logistic regressions were conducted to determine the factors associated with suicidal behaviors or suicidal attempts among the admitted individuals.

RESULTS

The prevalence of suicidal behavior and suicidal attempts among 3104 (mean age = 33, Standard deviation [SD] = 14.0; 56% were males) were 6.12% and 3.45%, respectively. Having a diagnosis of depression increased the likelihood of both suicidal behaviors (adjusted odds ratio [aOR]: 5.36; 95% confidence interval [CI]: 2.14-13.37; p =0.001) and attempts (aOR: 10.73; 95% CI: 3.44-33.50; p < 0.001). However, a diagnosis of substance-related disorder increased the likelihood of having attempted suicide (aOR: 4.14; 95% CI: 1.21-14.15; p = 0.023). The likelihood of having suicidal behavior decreased as one increased in age (aOR: 0.97; 95% CI: 0.94-0.99; p = 0.006) and increased among individuals reporting stress from financial constraints (aOR: 2.26; 95% CI: 1.05-4.86; p = 0.036).

CONCLUSION

Suicidal behaviors are common among inpatients managed for severe mental health conditions in Uganda, especially those with substance use and depressive disorders. In addition, financial stressors are a main predictor in this low-income country. Therefore, regular screening for suicide behaviors is warranted, especially among individuals with depression, and substance use, among those who are young, and among those reporting financial constraints/stress.

How to save a life: From neurobiological underpinnings to psychopharmacotherapies in the prevention of suicide

The impact of suicide on our societies, mental healthcare, and public health is beyond questionable. Every year approximately 700 000 lives are lost due to suicide around the world (WHO, 2021); more people die by suicide than by homicide and war. Although suicide is a key issue and reducing suicide mortality is a global imperative, suicide is a highly complex biopsychosocial phenomenon, and in spite of several suicidal models developed in recent years and a high number of suicide risk factors identified, we still have neither a sufficient understanding of underpinnings of suicide nor adequate management strategies to reduce its prevalence. The present paper first overviews the background of suicidal behavior including its epidemiology, prevalence, age and gender correlations and its association with neuropsychiatric disorders as well as its clinical assessment. Then we give an overview of the etiological background, including its biopsychosocial contexts, genetics and neurobiology. Based on the above, we then provide a critical overview of the currently available intervention options to manage and reduce risk of suicide, including psychotherapeutic modalities, traditional medication classes also providing an up-to-date overview on the antisuicidal effects of lithium, as well as novel molecules such as esketamine and emerging medications and further molecules in development. Finally we give a critical overview on our current knowledge on using neuromodulatory and biological therapies, such as ECT, rTMS, tDCS and other options.

Predicting Suicide in Counties: Creating a Quantitative Measure of Suicide Risk

Rising rates of suicide over the past two decades have increased the need for wide-ranging suicide prevention efforts. One approach is to target high-risk groups, which requires the identification of the characteristics of these population sub-groups. This suicidology study was conducted using large-scale, secondary data to answer the question: using the research on suicide, are there variables studied at the community level that are linked to suicide and are measurable using quantitative, demographic data that are already collected and updated? Data on deaths from suicide in U.S. counties for the years 2000, 2005, 2010 and 2015 were analyzed using multiple regression, longitudinal regression, and cluster analysis. Results indicated that the suicide rate in a county can be predicted by measuring the financial stability of the residents, the quality of mental health in the county, and the economic opportunity in the county. The results are further analyzed using two sociological theories, Social Strain Theory and the Theory of Anomie, and two psychological theories, the Shame Model and the Interpersonal Theory of Suicide.

Development of a Checklist for Predicting Suicidality Based on Risk and Protective Factors: The Gwangju Checklist for Evaluation of Suicidality

OBJECTIVE

The aim of the study was to develop a checklist for mental health clinicians to predict and manage suicidality.

METHODS

A literature review of the risk and protective factors for suicide was conducted to develop a checklist for evaluating suicidality.

RESULTS

The fixed risk factors included sex (male), age (older individuals), history of childhood adversity, and a family history of suicide. Changeable risk factors included marital status (single), economic status (poverty), physical illness, history of psychiatric hospitalization, and history of suicide attempts. Recent discharge from a mental hospital and a recent history of suicide attempts were also included. Manageable risk factors included depression (history and current), alcohol problems (frequent drinking and alcohol abuse), hopelessness, agitation, impulsivity, impaired reality testing, and command hallucinations. Protective factors included responsibility to family, social support, moral objections to suicide, religiosity, motivation to get treatment, ability to cope with stress, and a healthy lifestyle. A final score was assigned based on the sum of the risk and protective factor scores.

CONCLUSION

We believe that the development of this checklist will help mental health clinicians to better assess those at risk for suicidal behavior. Further studies are necessary to validate the checklist.

Neurocognitive functioning predicts suicidal behaviour in young people with affective disorders

BACKGROUND

Neurocognitive impairment is recognised as a risk factor for suicidal behaviour in adults. The current study aims to determine whether neurocognitive deficits also predict ongoing or emergent suicidal behaviour in young people with affective disorders.

METHODS

Participants were aged 12-30 years and presented to early intervention youth mental health clinics between 2008 and 2018. In addition to clinical assessment a standardised neurocognitive assessment was conducted at baseline. Clinical data was extracted from subsequent visits using a standardised proforma.

RESULTS

Of the 635 participants who met inclusion criteria (mean age 19.6 years, 59% female, average follow up 476 days) 104 (16%) reported suicidal behaviour during care. In 5 of the 10 neurocognitive domains tested (cognitive flexibility, processing speed, working memory, verbal memory and visuospatial memory) those with suicidal behaviour during care were superior to clinical controls. Better general neurocognitive function remained a significant predictor (OR=1.94, 95% CI 1.29- 2.94) of suicidal behaviour in care after controlling for other risk factors.

LIMITATIONS

The neurocognitive battery used was designed for use with affective and psychotic disorders and may not have detected some deficits more specific to suicidal behaviour.

CONCLUSION

Contrary to expectations, better neurocognitive functioning predicts suicidal behaviour during care in young people with affective disorders. While other populations with suicidal behaviour, such as adults with affective disorders or young people with psychotic disorders, tend to experience neurocognitive deficits which may limit their capacity to engage in some interventions, this does not appear to be the case for young people with affective disorders.

Dysregulation of Protein Kinase C in Adult Depression and Suicide: Evidence From Postmortem Brain Studies

BACKGROUND

Several lines of evidence suggest the abnormalities of protein kinase C (PKC) signaling system in mood disorders and suicide based primarily on the studies of PKC and its isozymes in the platelets and postmortem brain of depressed and suicidal subjects. In this study, we examined the role of PKC isozymes in depression and suicide.

METHODS

We determined the protein and mRNA expression of various PKC isozymes in the prefrontal cortical region (Brodmann area 9) in 24 normal control subjects, 24 depressed suicide (DS) subjects, and 12 depressed nonsuicide (DNS) subjects. The levels of mRNA in the prefrontal cortex were determined by quantitative real-time reverse transcription PCR, and the protein expression was determined by western blotting.

RESULTS

We observed a significant decrease in mRNA expression of PKCα, PKCβI, PKCδ, and PKCε and decreased protein expression in either the membrane or the cytosol fraction of PKC isozymes PKCα, PKCβI, PKCβII, and PKCδ in DS and DNS subjects compared with normal control subjects.

CONCLUSIONS

The current study provides detailed evidence of specific dysregulation of certain PKC isozymes in the postmortem brain of DS and DNS subjects and further supports earlier evidence for the role of PKC in the platelets and brain of the adult and teenage depressed and suicidal population. This comprehensive study may lead to further knowledge of the involvement of PKC in the pathophysiology of depression and suicide.

Modeling endophenotypes of suicidal behavior in animals

Suicide is a major public health concern. One of the common contributors to the increased risk for suicide is the genetic constitution of individuals, which determines certain endophenotypic traits used as quantifiable measure of neurobiological functions. Therefore, a logical deconstruction of the originating endophenotypes associated with suicidal risk could provide a better understanding of this complex disorder. In this regard, non-human animals can be a useful resource to test endophenotypes of suicidal behavior and the neurobiology underlying these endophenotypes. In this review, we have focused on the neurobiological abnormalities, primarily genetic and epigenetic abnormalities, associated with suicidal behavior and the scope of their modeling in animals. This can substantially advance the current understanding of suicidal behavior manifested with certain trait-based endophenotypes and may provide an opportunity to test novel hypotheses as well as aid in the development of treatment opportunities and risk assessment.

Educational attainment reduces the risk of suicide attempt among individuals with and without psychiatric disorders independent of cognition: a bidirectional and multivariable Mendelian randomization study with more than 815,000 participants

Rates of suicidal behavior are increasing in the United States and identifying causal risk factors continues to be a public health priority. Observational literature has shown that educational attainment (EA) and cognitive performance (CP) influence suicide attempt risk; however, the causal nature of these relationships is unknown. Using summary statistics from genome-wide association studies (GWAS) of EA, CP, and suicide attempt risk with > 815,000 combined white participants of European ancestry, we performed multivariable Mendelian randomization (MR) to disentangle the effects of EA and CP on attempted suicide. In single-variable MR (SVMR), EA and CP appeared to reduce suicide attempt risk (EA odds ratio (OR) per standard deviation (SD) increase in EA (4.2 years), 0.524, 95% CI, 0.412-0.666, P = 1.07 × 10-7; CP OR per SD increase in standardized score, 0.714, 95% CI, 0.577-0.885, P = 0.002). Conversely, bidirectional analyses found no effect of a suicide attempt on EA or CP. Using various multivariable MR (MVMR) models, EA seems to be the predominant risk factor for suicide attempt risk with the independent effect (OR, 0.342, 95% CI, 0.206-0.568, P = 1.61 × 10-4), while CP had no effect (OR, 1.182, 95% CI, 0.842-1.659, P = 0.333). In additional MVMR analyses accounting simultaneously for potential behavioral and psychiatric mediators (tobacco smoking; alcohol consumption; and self-reported nerves, tension, anxiety, or depression), the effect of EA was little changed (OR, 0.541, 95% CI, 0.421-0.696, P = 3.33 × 10-6). Consistency of results across complementary MR methods accommodating different assumptions about genetic pleiotropy strengthened causal inference. Our results show that even after accounting for psychiatric disorders and behavioral mediators, EA, but not CP, may causally influence suicide attempt risk among white individuals of European ancestry, which could have important implications for health policy and programs aimed at reducing the increasing rates of suicide. Future work is necessary to examine the EA-suicide relationship populations of different ethnicities.

Hopelessness, Dissociative Symptoms, and Suicide Risk in Major Depressive Disorder: Clinical and Biological Correlates

Background: Major depressive disorder (MDD) has different clinical presentations and is associated with neurobiological alterations. Hopelessness, anhedonia, and dissociation represent some of the most pervasive psychopathological symptoms that often lead to suicidal thoughts, attempts, and actions. To further research on the concept of depression endophenotypes, this study aimed to assess the possible relationships between hopelessness and other clinical and biological correlates (i.e., striatal dopaminergic dysfunction) in depressed patients. Methods: We recruited 51 subjects with MDD. All subjects underwent ¹²³I-FP-CIT SPECT to assess striatal dopamine transporter (DAT) availability and a psychometric evaluation using the psychometric scale to assess depressive, anxious, dissociative, and hopelessness symptoms aside from suicidal ideation. Result: An inverse correlation between the hopelessness score and dopamine transporter availability in all basal ganglia was bilaterally found. (Right Putamen, r = −0.445, p < 0.01; Left Putamen, r = −0.454, p < 0.01; Right Caudate, r = −0.398, p < 0.01; Left Caudate, r = −0.467, p < 0.01) Moreover, a positive correlation was also found between hopelessness and dissociative symptoms. Conclusions: These results provide important evidence on the neurobiological and clinical correlates of different psychopathological symptoms of depression with potential implications in terms of devising more effective treatment programs.

Evaluation of COMT (rs4680), CNR2 (rs2501432), CNR2 (rs2229579), UCP2 (rs659366), and IL-17 (rs763780) gene variants in synthetic cannabinoid use disorder patients

Synthetic cannabinoids (SC) are psychoactive drugs that generally produce more severe clinical outcomes compared to Δ9-tetrahydrocannabinol. This study aimed to evaluate the relationship between clinical features of synthetic cannabinoid use disorder (SCUD) and COMT (rs4680), CNR2 (rs2501432), CNR2 (rs2229579), UCP2 (rs659366), and IL-17 (rs763780) gene variants in SCUD patients by comparing the genotype distributions of gene variants between patients and healthy controls. Based on the DSM-5 criteria, 94 patients with SCUD, confirmed with a positive urine test, and 95 healthy volunteers were included in the study. Self-mutilation, suicidal behavior, psychotic symptoms, drug-induced psychosis, tobacco use disorder (TUD) or alcohol use disorder (AUD) comorbidity, and family history of TUD or AUD were evaluated in all patients. PCR-RFLP was used to identify gene variants from DNA material. The distributions of CNR2 (rs2229579) and UCP2 (rs659366) variants were significantly different in patients diagnosed with SCUD compared to the control group. SC-related psychotic symptoms were associated with the IL-17 (rs763780) variant in SCUD patients who had an onset of SC usage under 18 years of age. While the COMT Val108Met gene variant was related to self-mutilation, the COMT Val158Met variant was associated with attempted suicide. In addition, in SCUD patients, the UCP2 (rs659366) variant was associated with a family history of AUD or TUD. In summary, CNR2 (rs2229579) and UCP2 (rs659366) variants were associated with SCUD. While SC-related psychotic symptoms were related to the IL-17 (rs763780) variant, the COMT variants were associated with self-mutilation or attempted suicide in SCUD patients.

Unextracted plasma oxytocin levels decrease following in-laboratory social exclusion in young adults with a suicide attempt history

Social exclusion is associated with greater suicide risk and more needs to be known about the biological processes contributing to this association. Oxytocin, a neuropeptide that regulates social interactions, may protect against the negative effects of exclusion by motivating social engagement. Oxytocin levels and desire for social engagement increase when non-psychiatric controls experience acute social exclusion. However, among individuals with borderline personality disorder and chronic depression, oxytocin levels decrease following exclusion. Both of these psychiatric illnesses are associated with high rates of suicidal behavior. No research has examined changes in oxytocin following social exclusion among individuals at risk for suicide. This quasi-experimental study examined differences in oxytocin levels and perceptions of social connectedness following an in-laboratory, acute social exclusion task among (a) individuals with no depression or suicide attempt histories, (b) individuals with current depression symptoms, and (c) individuals with current depression symptoms and suicide attempt histories. Young adults (N = 100) completed self-report measures and provided blood samples before and after an acute social exclusion task (Cyberball). Oxytocin was quantified via enzyme-linked immunosorbent assay. Mixed-design ANCOVAs were used to evaluate changes in unextracted and extracted oxytocin levels, desire for emotional support, thwarted belongingness, and perceived burdensomeness. Among suicide attempters, unextracted oxytocin levels decreased and desire for emotional support did not significantly change following exclusion. Among depressed and healthy controls, desire for emotional support increased and unextracted oxytocin levels did not significantly change. No significant changes in extracted oxytocin levels, thwarted belongingness and perceived burdensomeness emerged. Further research is needed to determine if dysregulated oxytocin-related processes biologically predispose individuals with suicide attempt histories to greater social disconnection and suicide risk.

The Mediating Role of Impulsivity in the Relationship Between Suicidal Behavior and Early Traumatic Experiences in Depressed Subjects

Background: Depressed patients with early traumatic experiences may represent a clinically and biologically distinct subtype, with worse clinical outcomes and greater risk of suicide. Since early traumatic experiences alter development of systems that regulate the stress response, increasing sensitivity to stress and mood disorders later in life, certain personality features may influence coping strategies, putting individuals with depression and a history of early traumatic experiences at greater risk of suicidal behavior. Objective: To determine whether impulsivity mediates the relationship between early traumatic experiences and suicidal behavior in patients with major depressive disorder (MDD). Methods: The total sample consists of 190 patients [mean age (SD) = 53.71 (10.37); females: 66.3%], with current MDD (DSM-5 criteria). The Childhood Trauma Questionnaire-Short Form (CTQ-SF), the List of Threatening Experiences (LTE), and the Barratt Impulsiveness Scale-11 (BIS-11) were used to assess childhood and adulthood adverse life events and impulsivity, respectively. We developed mediation models by bootstrap sampling methods. Results: Eighty-one (42.6%) patients had a history of previous suicide attempts (SA). CTQ-SF-Total and BIS-11-Total scores were significantly higher in MDD patients with previous SA. Correlation analyses revealed significant correlations between the CTQ-SF-Total and BIS-11-Total, CTQ-SF-Total and HDRS-Total, and BIS-11-Total and HDRS-Total scores. Regression models found that CTQ-SF-Total, BIS-11-Total, and HDRS-Total scores were associated with SA. Mediation analyses further revealed the association between CTQ-SF-Total and SA was mediated by the indirect effect of the BIS-11-Total score (b = 0.007, 95% CI = 0.001, 0.015), after statistically controlling for sex, the HDRS-Total, and the LTE-Total. Discussion: Data suggest that impulsivity could mediate the influence of childhood trauma on suicidal behavior. This will help understand the role of risk factors in suicidal behavior and aid in the development of prevention interventions focused on modifiable mediators when risk factors are non-modifiable.

Suicidal ideation is common in autosomal dominant Alzheimer's disease at-risk persons

OBJECTIVES

To study the frequency of suicidal ideation and its association with clinical and neurobiological correlates among cognitively intact autosomal dominant Alzheimer's disease (ADAD) at-risk individuals.

METHODS/DESIGN

In a cross-sectional study of 183 ADAD at-risk individuals (91 mutation carriers and 92 noncarriers), we compared the frequency of suicidal ideation among carriers and noncarriers. Linear mixed-effects models with family-level random effects evaluated the relationships between geriatric depression scale (GDS), neuropsychiatric inventory-questionnaire (NPI-Q), and suicidal ideation scores among all ADAD at-risk individuals. An interaction term was added to the regression models to evaluate the interactions of suicidal ideation and mutation status on neuropsychiatric symptoms.

RESULTS

Twenty-six (14.20%) ADAD at-risk individuals (13 [14.28%] carriers and 13 [14.13%] noncarriers) had suicidal ideation. The frequency of suicidal ideation did not differ between carriers and noncarriers. Suicidal ideation was associated with higher GDS among all ADAD at-risk individuals. When stratified into mutation carrier status, noncarriers with suicidal ideation had higher GDS than carriers. There was no statistically significant association between suicidal ideation and NPI-Q among ADAD at-risk individuals. Awareness of mutation status, neuropsychological performances, and cerebrospinal fluid AD biomarkers were not associated with suicidal ideation among carriers and noncarriers.

CONCLUSIONS

Suicidal ideation is common among cognitively intact ADAD at-risk individuals. While ADAD at-risk individuals with suicidal ideation have greater depressive symptoms, noncarriers with suicidal ideation have higher GDS scores than carriers. Interestingly, awareness of the mutation status was not associated with suicidal ideation in our study. Early identification of suicidal thoughts can facilitate timely interventions to prevent suicidal behaviours. Keywords autosomal dominant Alzheimer's diseasedominantly inherited Alzheimer's networkneuropsychiatric symptomssuicidal ideation.

Stress Response in Suicide Attempters with Borderline Personality Disorder: The Role of Behavioral Problems in Childhood

Objective: Suicidal individuals are a heterogeneous population and may differ in systematic ways in their responsiveness to stress. The primary aim of the present study was to identify whether a different pattern of physiological stress response exists among adult suicide attempters with a history of behavioral problems during childhood and adolescence, which earlier studies have related to both decreased activity of the HPA axis and to suicidal behaviors. Method: Seventy-eight participants with Borderline Personality Disorder were assessed using the SCID-II, and completed self-report measures assessing their history of suicide attempts, history of aggressive behaviors, depressive symptoms, history of lifetime abuse and demographics. Participants' cortisol reactivity was assessed using the Trier Social Stress Test. Results: Analyses indicated that suicide attempters with a history of behavioral problems in youth (n = 30) had a significantly lower response to stress than both suicide attempters without such a history (n = 26) and non-attempters (n = 22), when controlling for lifetime history of abuse. The groups did not differ in basal cortisol. Conclusions: These findings suggest a unique subtype of suicide attempter among those with Borderline Personality Disorder, characterized by a blunted physiological stress response.

Impulsivity in the self-harm and suicidal behavior of young people: A systematic review and meta-analysis

BACKGROUND

Impulsivity is considered a possible phenotype underlying the expression of self-harm and suicidal behaviors. Yet impulsivity is a not a unitary construct and there is evidence that different facets of impulsivity follow different neurodevelopmental trajectories and that some facets may be more strongly associated with such behaviors than others. Moreover, it is unclear whether impulsivity is a useful predictor of self-harm or suicidal behavior in young people, a population already considered to display heightened impulsive behavior.

METHODS

A systematic review and meta-analysis of studies published in Medline, PubMed, PsychInfo or Embase between 1970 and 2017 that used a neurocognitive measure to assess the independent variable of impulsivity and the dependent variable of self-harm and/or suicidal behavior among young people (mean age < 30 years old).

RESULTS

6183 titles were identified, 141 full texts were reviewed, and 18 studies were included, with 902 young people with a self-harm or suicidal behavior and 1591 controls without a history of these behaviors. Deficits in inhibitory control (13 studies, SMD 0.21, p-value = 0.002, 95% confidence interval (CI) (0.08-0.34), prediction interval (PI) = 0.06-0.35) and impulsive decision-making (14 studies, SMD 0.17, p-value = 0.008, 95% CI (0.045-0.3), PI = 0.03-0.31) were associated with self-harm or suicidal behavior. There were no significant differences between measures of different facets of impulsivity (ie. delay discounting, risky decision-making, cognitive or response inhibition) and self-harm or suicidal behavior.

CONCLUSION

Multiple facets of impulsivity are associated with suicidal behavior in young people. Future suicide research should be designed to capture impulsive states and investigate the impact on different subtypes of impulsivity.

Alterations in anterior cingulate cortex myoinositol and aggression in veterans with suicidal behavior: A proton magnetic resonance spectroscopy study

Studies investigating the neurochemical changes that correspond with suicidal behavior (SB) have not yielded conclusive results. Suicide correlates such as aggression have been used to explore risk factors for SB. Yet the neurobiological basis for the association between aggression and SB is unclear. Aggression and SB are both prevalent in veterans relative to civilian populations. The current study evaluated the relationship between brain chemistry in the anterior (ACC) and the posterior cingulate cortex (POC), as well as the relationship between aggression and SB in a veteran population using proton magnetic resonance spectroscopy (¹H-MRS). Single-voxel MRS data at 3 Tesla (T) were acquired from the ACC and POC voxels using a 2-dimensional J-resolved point spectroscopy sequence and quantified using the ProFit algorithm. Participants also completed a structured diagnostic interview and a clinical battery. Our results showed that the myoinositol (mI)/H2O ratio in the ACC and POC was significantly higher in veterans who reported SB when compared to veterans who did not. The two groups did not differ significantly with regard to other metabolites. Second, verbal aggression and SB measures positively correlated with mI/H2O in the ACC. Finally, verbal aggression mediated the relationship between mI/H2O in the ACC and SB.

Understanding the Neuroepigenetic Constituents of Suicide Brain

Stressful life incidents often cause a predisposition for developing mental disorders such as major depressive disorder (MDD). Impaired neurocognitive and neuro-vegetative functions of the central nervous system are the hallmarks of this mental illness. Blunted responses from emotionally salient regions of the brain including cortex, hippocampus, and amygdala have been associated with MDD-related behavioral changes. Moreover, improper signal processing and neuronal atrophy were held responsible for the overall dysfunctionality of these vulnerable regions in the MDD brain. The prevalence of genetic susceptibility along with adverse environmental stimuli often makes the situation worse for MDD patients, leading to an increased risk of suicidal behavior and eventually death by suicide. Despite considerable efforts to understand the complex neurobiology associated with MDD and suicidal behavior, their pathological determinants remain mostly elusive. Recent research, however, has shown that epigenetic perturbations have a formidable impact on the etiopathogenesis of MDD. Understanding the neuroepigenetic nature of this mental disorder may provide opportunities to devise more effective treatment strategies. Moreover, this can potentially lead to identifying predictive biomarkers associated with suicide risk. The present chapter critically reviews studies pertaining to epigenetic signatures of MDD and suicide brain.

Understanding epigenetic architecture of suicide neurobiology: A critical perspective

Current understanding of environmental cross-talk with genetic makeup is found to be mediated through an epigenetic interface which is associated with prominent reversible and heritable changes at gene expression level. Recent emergence of epigenetic modulation in shaping the genetic information has become a key regulatory factor in answering the underlying complexities associated with several mental disorders. A comprehensive understanding of the pertinent changes in the epigenetic makeup of suicide phenotype exhibits a characteristic signature with the possibility of using it as a biomarker to help predict the risk factors associated with suicide. Within the scope of this current review, the most sought after epigenetic changes of DNA methylation and histone modification are thoroughly scrutinized to understand their close functional association with the broad spectrum of suicide phenotype.

Clinical Correlates of Planned and Unplanned Suicide Attempts

Suicide attempters differ in the degree of planning for their suicide attempts. The purpose of this study was to identify differences between individuals who make planned (≥3 hours of planning) and unplanned (<3 hours of planning) suicide attempts. Depressed suicide attempters (n = 110) were compared based on degree of planning of their most recent suicide attempt on demographic and clinical variables. Participants who made planned suicide attempts were more likely to have family history of completed suicide, more severe and frequent suicidal ideation, greater trait impulsivity, and greater suicidal intent and more severe medical consequences for both their most recent and most serious suicide attempts. These results suggest clear clinical differences based on the degree of suicide attempt planning. Severe suicidal ideation, high suicide intent, family history of suicide completion, and high levels of motor impulsivity contribute to a phenotype that is at greater risk of planned, highly lethal suicide attempts.

Classic psychedelic use is associated with reduced psychological distress and suicidality in the United States adult population

Mental health problems are endemic across the globe, and suicide, a strong corollary of poor mental health, is a leading cause of death. Classic psychedelic use may occasion lasting improvements in mental health, but the effects of classic psychedelic use on suicidality are unknown. We evaluated the relationships of classic psychedelic use with psychological distress and suicidality among over 190,000 USA adult respondents pooled from the last five available years of the National Survey on Drug Use and Health (2008-2012) while controlling for a range of covariates. Lifetime classic psychedelic use was associated with a significantly reduced odds of past month psychological distress (weighted odds ratio (OR)=0.81 (0.72-0.91)), past year suicidal thinking (weighted OR=0.86 (0.78-0.94)), past year suicidal planning (weighted OR=0.71 (0.54-0.94)), and past year suicide attempt (weighted OR=0.64 (0.46-0.89)), whereas lifetime illicit use of other drugs was largely associated with an increased likelihood of these outcomes. These findings indicate that classic psychedelics may hold promise in the prevention of suicide, supporting the view that classic psychedelics' most highly restricted legal status should be reconsidered to facilitate scientific study, and suggesting that more extensive clinical research with classic psychedelics is warranted.

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

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

The relation between child maltreatment and adolescent suicidal behavior: a systematic review and critical examination of the literature

A large body of research suggests that child maltreatment (CM) is associated with adolescent suicidal ideation and attempts. These studies, however, have not been critically examined and summarized in a manner that allows us to draw firm conclusions and make recommendations for future research and clinical work in this area. In this review, we evaluated all of the research literature to date examining the relationship between CM and adolescent suicidal ideation and attempts. Results generally suggest that childhood sexual abuse, physical abuse, emotional abuse, and neglect are associated with adolescent suicidal ideation and attempts across community, clinical, and high-risk samples, using cross-sectional and longitudinal research designs. In most studies, these associations remain significant when controlling for covariates such as youth demographics, mental health, family, and peer-related variables. When different forms of CM are examined in the same multivariate analysis, most research suggests that each form of CM maintains an independent association with adolescent suicidal ideation and suicide attempts. However, a subset of studies yielded evidence to suggest that sexual abuse and emotional abuse may be relatively more important in explaining suicidal behavior than physical abuse or neglect. Research also suggests an additive effect-each form of CM contributes unique variance to adolescent suicide attempts. We discuss the current limitations of this literature and offer recommendations for future research. We conclude with an overview of the clinical implications of this research, including careful, detailed screening of CM history, past suicidal behavior, and current suicidal ideation, as well as the need for integrated treatment approaches that effectively address both CM and adolescent suicidal ideation and suicide attempts.

Triglycerides as a biological marker of repeated re-hospitalization resulting from deliberate self-harm in acute psychiatry patients: a prospective observational study

BACKGROUND

Biological factors have been associated with deliberate self-harm (DSH) but have not been integrated with clinical factors in routine risk assessments.This study aimed to examine the incremental validity of lipid levels and platelet serotonin when combined with psychosocial factors in risk assessments for repeated admissions due to DSH.

METHODS

In this prospective observational study of 196 acutely admitted patients, results of blood tests performed upon admission and the MINI Suicidal Scale and psychosocial DSH risk factor assessments performed at discharge were compared with the incidence of DSH recorded during the first 3 and 12 months after discharge.

RESULTS

High triglyceride levels were found to be a significant marker for patients admitted 3 or more times due to DSH (repeated DSH, DSH-R) when tested against other significant risk factors. When all (9) significant univariate factors associated with 12-month post-discharge DSH-R were analyzed in a multivariate logistic regression, the MINI Suicidal Scale (p = 0.043), a lack of insight (p = 0.040), and triglyceride level (p = 0.020) remained significant. The estimated 12-month area under the curve of the receiver operator characteristic (ROC-AUC) for DSH-R was 0.74 for triglycerides, 0.81 for the MINI, 0.89 for the MINI + psychosocial factors, and 0.91 for the MINI + psychosocial factors + triglycerides. The applied multifaceted approach also significantly discriminated between 12-month post-discharge DSH-R patients and other DSH patients, and a lack of insight (p = 0.047) and triglycerides (p = 0.046) remained significant for DSH-R patients in a multivariate analysis in which other DSH patients served as the reference group (rather than non-DSH patients).

CONCLUSION

The triglyceride values provided incremental validity to the MINI Suicidal Scale and psychosocial risk factors in the assessment of the risk of repeated DSH. Therefore, a bio-psychosocial approach appears promising, but further research is necessary to refine and validate this method.

Migraine and psychiatric disorders co-morbidity explained by sinus hypoxic nitric oxide theory - a new hypothesis on the Sino rhinogenic theory

Migraine is an extremely common incapacitating neurovascular disorder and has co morbidity with many psychiatric illnesses which are caused by neurotransmitter imbalance, neurodegenerative changes and genetic predisposition. The sinus hypoxic nitric oxide theory presents, diffused paranasal sinus nitric oxide in the nasal mucosa has been hypothesized as the primary molecule that initiates migraine. Existence of such pathophysiology in human beings is termed as sinus hypoxic nitric oxide phenomena. According to this new hypothesis the sinorhinogenic trigeminal nerve impulse distribution of the central nervous system, is suggested to cause central neurotransmitter track dysfunction and cortical spreading depression with neurodegeneration that may relate to co morbidity. Moreover, avoidance of the excess sinorhinogenic central neuronal influence to the brain in early child hood and early intervention in the case of genetic susceptible history with psychiatric illnesses would help to prevent the progression or aggravation of psychiatric illnesses according to this hypothesis. This article explains a new pathophysiological initiation between central effects of sinorhinogenic nitric oxide phenomena and psychiatric disorders. It also provides an etiologically important neuro vascular impulse generating pathway to cause or aggravate psychiatric disorders. Therefore patients who are clinically suspected of having migraine headache and psychiatric disorders should receive a comprehensive sinorhinological examination and evaluation based on the sinus hypoxic nitric oxide phenomena.

Genetic variability at IMPA2, INPP1 and GSK3β increases the risk of suicidal behavior in bipolar patients

Bipolar patients (BP) are at high risk of suicide. Causal factors underlying suicidal behavior are still unclear. However, it has been shown that lithium has antisuicidal properties. Genes involved in its putative mechanism of action such as the phosphoinositol and the Wnt/β-catenine pathways could be considered candidates for suicidal behavior (SB). Our aim was to investigate the association of the IMPA1 and 2, INPP1, GSK3α and β genes with suicidal behavior in BP. 199 BP were recruited. Polymorphisms at the IMPA1 (rs915, rs1058401 and rs2268432) and IMPA2 (rs66938, rs1020294, rs1250171 and rs630110), INPP1 (rs3791809, rs4853694 and 909270), GSK3α (rs3745233) and GSK3β (rs334558, rs1732170 and rs11921360) genes were genotyped. All patients were grouped and compared according to the presence or not of history of SB (defined as the presence of at least one previous suicidal attempt). Single SNP analyses showed that suicide attempters had higher frequencies of AA genotype of the rs669838-IMPA2 and GG genotype of the rs4853694-INPP1gene compared to non-attempters. Results also revealed that T-allele carriers of the rs1732170-GSK3β gene and A-allele carriers of the rs11921360-GSK3β gene had a higher risk for attempting suicide. Haplotype analysis showed that attempters had lower frequencies of A:A haplotype (rs4853694:rs909270) at the INPP1 gene. Higher frequencies of the C:A haplotype and lower frequencies of the A:C haplotype at the GSK-3β gene (rs1732170:rs11921360) were also found to be associated to SB in BP. Therefore, our results suggest that genetic variability at IMPA2, INPP1 and GSK3β genes is associated with the emergence of SB in BP.

Clinical and neurocognitive markers of suicidality in young adults

BACKGROUND

Suicide represents a leading cause of death in young people, yet relatively little is known regarding the neurobiological sequelae of preceding suicidal thoughts and behaviours. Although some studies have reported cognitive deficits associated with suicidality, very few studies have been undertaken in young people, especially from non-clinical contexts.

AIMS

To quantify cognitive deficits associated with suicidality using a representative sample of young people, recruited from the general community using media advertisements.

METHOD

304 adults (18-29 years) undertook the Mini-International Neuropsychiatric Inventory (MINI) suicidality module, along with Cambridge Gamble and Stop-Signal tasks. Suicidality was defined as non-zero MINI scores (broad definition) and a past history of suicide attempt(s) (narrow definition). Clinical features and cognitive performance were compared between those with and those without suicidality, using analysis of variance/chi-square; findings were further explored using linear regression.

RESULTS

Suicidality was relatively common (broad definition: 14.8%; narrow definition: 5.3%) in young people and was associated with impaired decision-making on the Cambridge Gamble task (p < 0.05, Bonferroni corrected at the analysis level of each suicidality definition). Linear regression demonstrated that decision-making performance was associated with a significant incremental benefit with respect to predicting suicidality, over and above the utility of demographic and clinical variables considered (p < 0.05 uncorrected).

CONCLUSIONS

Impaired decision-making exists in young people with suicidality, and may thereby predispose towards a range of suicidal thoughts and behaviours. Further work is needed to clarify the chain of progression from such thoughts/behaviours, which are relatively common, through to actual suicide, which is not.

NEUROBIOLOGICAL ASPECTS OF SUICIDE AND SUICIDE ATTEMPTS IN BIPOLAR DISORDER

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

Suicide bereavement and complicated grief

Losing a loved to suicide is one is one of life's most painful experiences. The feelings of loss, sadness, and loneliness experienced after any death of a loved one are often magnified in suicide survivors by feelings of quilt, confusion, rejection, shame, anger, and the effects of stigma and trauma. Furthermore, survivors of suicide loss are at higher risk of developing major depression, post-traumatic stress disorder, and suicidal behaviors, as well as a prolonged form of grief called complicated grief. Added to the burden is the substantial stigma, which can keep survivors away from much needed support and healing resources. Thus, survivors may require unique supportive measures and targeted treatment to cope with their loss. After a brief description of the epidemiology and circumstances of suicide, we review the current state of research on suicide bereavement, complicated grief in suicide survivors, and grief treatment for survivors of suicide.

Suicide bereavement and complicated grief

Losing a loved to suicide is one is one of life's most painful experiences. The feelings of loss, sadness, and loneliness experienced after any death of a loved one are often magnified in suicide survivors by feelings of quilt, confusion, rejection, shame, anger, and the effects of stigma and trauma. Furthermore, survivors of suicide loss are at higher risk of developing major depression, post-traumatic stress disorder, and suicidal behaviors, as well as a prolonged form of grief called complicated grief. Added to the burden is the substantial stigma, which can keep survivors away from much needed support and healing resources. Thus, survivors may require unique supportive measures and targeted treatment to cope with their loss. After a brief description of the epidemiology and circumstances of suicide, we review the current state of research on suicide bereavement, complicated grief in suicide survivors, and grief treatment for survivors of suicide.

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

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

CYP2D6 and the severity of suicide attempts

Aim: Among people who die by suicide, an increased frequency of CYP2D6 active gene multiplication has been described. Therefore, the present study analyzed the relationship between the severity of the suicidal intent and CYP2D6 number of active genes among survivors. Materials & methods: A group of 342 individuals were evaluated with Beck Suicide Intent Scale within 24 h of the failed attempt. ‘Severe’ suicide attempters were classified as those scoring above percentile 75 in the objective circumstances section of the Suicide Intent Scale Scale. A group of 377 healthy controls were also genotyped. Results: A higher number of ‘severe’ suicide attempters carrying ≥2 active CYP2D6 genes as compared with the rest of the patients population (p < 0.01) or the healthy control group (p < 0.01) was found. Conclusion: Considering that ‘severe’ suicide attempters are more likely eventually to die by suicide, CYP2D6 genetic polymorphism might be of use as a biomarker of death by suicide, which is in agreement with previous findings.

Original submitted: 17 July 2011; Revision submitted: 21 September 2011

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

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

Association study of EP1 gene polymorphisms with suicide completers in the Japanese population

BACKGROUND

Both environmental and genetic factors have been reported to be involved in suicidal behaviors. Considerable evidence indicates that impulsive aggression is one of the important risk factors that contribute to suicide. A recent study has shown that prostaglandin E2 type 1 receptor (EP1) signaling regulates impulsive-aggressive behaviors in mice under both social and environmental stresses. To test the possible involvement of the EP1 gene in suicide, we carried out an association study of EP1 gene polymorphisms with suicide completers in the Japanese population.

METHODS

We studied 5 SNPs including one SNP in exon 2 (rs3745459) and four SNPs in the potential promoter region of the EP1 gene (rs3810255, rs3810254, rs3810253 and rs10416814) in 374 healthy control and 287 completed suicide victims using standard Taqman probe genotyping assays.

RESULTS

No significant differences of the genotypic distribution, allelic frequency or haplotype distribution between controls and suicide completers were found. Gender based analysis revealed that genotypic, allelic and haplotypic distributions of rs3810255, rs3810254, rs3810253 and rs10416814 SNPs were significantly different between the female control and female suicide groups, although the differences did not withstand correction for multiple comparisons.

CONCLUSION

We could not find an association of EP1 gene with suicide in the Japanese population. Because several SNPs in the promoter region of the EP1 gene were nominally significantly associated with suicide in the female, further studies with a larger sample size and different population are needed to confirm this result.

Familial factors and suicide: an adoption study in a Swedish National Cohort

BACKGROUND

Parental characteristics influence the risk of offspring suicide. In this study we wanted to separate the hereditary from the environmental influence of such factors by comparing their effects in the adopted versus non-adopted.

METHOD

A register study was conducted in a national cohort of 2,471,496 individuals born between 1946 and 1968, including 27,600 national adoptees, followed-up for suicide during 1987-2001. Cox regression was used to calculate hazard ratios (HR) for suicide of socio-economic indicators of the childhood household and biological parents' suicide, alcohol abuse and psychiatric morbidity separately in the adopted and non-adopted. Differences in effects were tested in interaction analyses.

RESULTS

Suicide and indicators of severe psychiatric disorder in the biological parents had similar effects on offspring suicide in the non-adopted and adopted (HR 1.5-2.3). Biological parents' alcohol abuse was a risk factor for suicide in the non-adopted group only (HR 1.8 v. 0.8, interaction effect: p=0.03). The effects of childhood household socio-economic factors on suicide were similar in adopted and non-adopted individuals, with growing up in a single parent household [HR 1.5 (95% confidence interval 1.4-1.5)] as the most important socio-economic risk factor for the non-adopted.

CONCLUSIONS

The main familial effects of parental suicide and psychiatric morbidity on offspring suicide are not mediated by the post-natal environment or imitation, in contrast to effects of parental alcohol abuse that are primarily mediated by the post-natal environment. Social drift over generations because of psychiatric disorders does not seem likely to explain the association of socio-economic living conditions in childhood to suicide.

Demonstration of disturbed activity of the lateral amygdaloid nucleus projection neurons in depressed patients by the AgNOR staining method

BACKGROUND

The aim to find a morphological biomarker of disturbed activity of the lateral amygdaloid nucleus in depression was approached by a karyometric analysis of projection neurons.

METHODS

The study was performed on paraffin-embedded brains from 19 depressed patients from both the major depressive disorder (MDD) and the bipolar disorder (BD) diagnostic groups, including 10 suicides, and 24 matched controls. The karyometric parameters of the lateral amygdaloid nucleus (La) projection neurons bilaterally were evaluated by the argyrophilic nucleolar organiser region (AgNOR) silver staining method.

RESULTS

An increased AgNOR number was found in the right La in suicides compared to controls. The intra-group comparisons between the hemispheres suggest a disturbed amygdaloid lateralisation in depressed patients. The effects were independent from psychotropic medication. There was a strong positive correlation between the nuclear area in La projection neurons and prefrontal limbic areas pyramidal neurons in the right hemisphere specific for suicide and MDD.

LIMITATIONS

A major limitation of this study is the relatively small number of cases. A further limitation is given by the lack of data on drug exposure across the entire lifespan.

CONCLUSION

The results suggest that depressed patients from both the MDD and BD diagnostic groups exhibit an increased activity of the La output neurons specific for suicidal patients. The distinctness of the diagnostic groups of mood disorders was accentuated in the correlation analysis. This putative hyperactivity was specific for the right hemisphere and psychotropic medication most likely did not counteract it.

Season of birth is significantly associated with the risk of completed suicide

BACKGROUND

Previous studies have provided somewhat inconsistent results about the effects of season of birth on the risk of suicidal behavior. Therefore, we decided to investigate this question in a large sample of suicide completers.

METHODS

We determined the season of birth-associated risk of completed suicide between the years 1970 and 2008 among all individuals who were born in the area of today's Hungary between 1930 and 1939, 1941 and 1942, and 1944 and 1969.

RESULTS

The final sample of participants included around six and a half million people. About 80,000 completed suicides occurred among participants during the period investigated (the number of suicide completers in our study greatly exceeds the number of suicide completers in any previous studies). A significantly (p < .05) elevated risk of completed suicide was found among those individuals who were born in the high-risk period (spring and summer). Quantitatively, the biggest increase (7.6% [95% confidence interval: 5.4-9.9]) in suicide risk was detected among those who were born in July compared with the average risk of suicide in the population investigated. The associations between season of birth and the risk of completed suicide were stronger among male subjects than among female subjects and among those who committed suicide using violent methods than among those who chose nonviolent methods.

CONCLUSIONS

Our results from a large sample of suicide completers from Hungary--a country with one of the highest suicide rates in the world over the last century--strongly support the concept that the season of birth is significantly associated with the risk of completed suicide.

Secondary prevention of suicide

Leo Sher and colleagues discuss recent research on interventions to prevent secondary suicide and discuss the additional research that is needed.

The interpersonal-psychological theory of suicidal behavior: current status and future directions

The interpersonal-psychological theory of suicidal behavior (Joiner, 2005) holds that an individual will die by suicide if he or she has both the desire for suicide and capability to act on that desire. According to the theory, suicidal desire results from the convergence of two interpersonal states: perceived burdensomeness and thwarted belongingness. However, desire alone is not sufficient to result in death by suicide--a third component must be present: the acquired capability for suicide, which develops from repeated exposure and habituation to painful and provocative events. The purpose of this article is to discuss four viable and timely directions for future research, given the current status of the theory.

Pathways to high-lethality suicide attempts in individuals with borderline personality disorder

The purpose of this study was to develop and test a model of high-lethality suicide attempts (HLSA) in individuals with Borderline Personality Disorder (BPD). An increased number of prior suicide attempts, substance use immediately prior to the attempt, and objective planning were proposed to lead directly to a HLSA, while aggression and impulsivity were hypothesized to lead indirectly to a HLSA through their associations with prior attempts. Path analysis revealed a revised model in which impulsivity was found to be significantly associated with both the lethality of the most recent attempt and the number of prior attempts. These results are discussed in terms of trait and crescendo models of suicidal behavior and their implications for suicide risk assessment among individuals with BPD.

Demonstration of disturbed activity of external globus pallidus projecting neurons in depressed patients by the AgNOR staining method

BACKGROUND

The external globus pallidus (EGP) is thought to play the most important integrating and conveying role in the striatopallidal system involved in the transfer from motivation to action. The aim to find a morphological biomarker of disturbed EGP activity in depression was approached by the karyometric analysis of large projecting neurons.

METHODS

The study was performed on paraffin-embedded brains from 19 depressed patients from both the major depressive disorder (MDD) and the bipolar disorder (BD) diagnostic groups encompassing 10 suicides and from 24 controls. The karyometric parameters of EGP neurons bilaterally were evaluated by argyrophilic nucleolar organiser (AgNOR) silver staining method.

RESULTS

A significantly decreased AgNOR area was found in the left EGP neurons in depressed patients compared to controls. The distinctness of the diagnostic groups and suicidal vs non-suicidal patients was not shown in the statistical comparisons. The AgNOR parameter which was decreased correlated positively with the mean dose of benzodiazepines in non-suicidal patients.

LIMITATIONS

A major limitation of this study is the relatively small number of cases. A further limitation is given by the lack of data on drug exposure across the whole lifespan of patients.

CONCLUSION

The results suggest disturbed, most likely decreased, activity of the left EGP projecting neurons in depressed patients, a disturbed activity that should hypothetically be counteracted by the applied pharmacotherapy in non-suicidal patients.

Characterization of QKI gene expression, genetics, and epigenetics in suicide victims with major depressive disorder

BACKGROUND

A number of studies have suggested deficits in myelination and glial gene expression in different psychiatric disorders. We examined the brain expression and genetic/epigenetic regulation of QKI, an oligodendrocyte-specific RNA binding protein important for cell development and myelination.

METHODS

The microarray-based expression of QKI was evaluated in cortical and subcortical brain regions from suicide victims with a diagnosis of major depression (n = 16) and control subjects (n = 13). These findings were also assessed with a real-time (quantitative polymerase chain reaction [qPCR]) approach, with QKI protein levels evaluated through immunoblotting. Identification of a QKI promoter sequence was then used to examine genetic and epigenetic variation at the QKI locus.

RESULTS

The messenger RNA (mRNA) levels of multiple transcripts of QKI were evaluated on Affymetrix microarrays, revealing significant reductions in 11 cortical regions and the hippocampus and amygdala of suicide victims compared with control subjects. Microarray findings were confirmed by qPCR, and reduced expression of QKI protein was identified in orbitofrontal cortex. Analysis of promoter variation and methylation state in a subset of individuals did not identify differences at the genetic or epigenetic level between depressed suicide victims and control subjects.

CONCLUSIONS

The observation of consistent reductions in multiple isoforms of QKI mRNA in depressed suicide victims supports the growing body of evidence for a role of myelination-related deficits in the etiology of psychiatric disorders. A specific role of QKI in this process is implied by its reduced expression and known interactions with genes involved in oligodendrocyte determination; however, QKI gene variation responsible for these changes remains to be identified.