Suicidal behaviors in surviving monozygotic and dizygotic co-twins: is the nature of the co-twin's cause of death a factor?

Mortality among twin individuals exposed to loss of a co-twin

BACKGROUND

Although the death of a child, sibling or spouse has been associated with elevated risk of mortality, less is known about the survival of twin siblings exposed to a co-twin loss.

METHODS

In a Swedish population-based sibling-matched cohort, we compared the mortality of 5548 twin individuals who lost their co-twin between 1932 and 2011 with that of 27 740 age-matched and sex-matched twin individuals without such a loss and 6772 full siblings of these exposed twin individuals. Cox regression models were used to estimate the hazard ratios (HRs) of all-cause and cause-specific mortality.

RESULTS

We found increased risk of all-cause mortality among twin individuals exposed to a co-twin loss compared with matched unexposed twin individuals (HR = 1.30, 95% CI: 1.18-1.43) and their full siblings (HR = 1.10, 95% CI: 0.96-1.27) after adjusting for multiple covariates. The all-cause mortality risk was greater for loss of a co-twin due to unnatural deaths (HR = 1.54, 95% CI: 1.17-2.03) than natural deaths (HR = 1.26, 95% CI: 1.14-1.40). For cause-specific mortality, co-twin loss was associated with a higher risk of unnatural deaths both among twin individuals who lost their co-twin due to unnatural deaths (HR = 1.98, 95% CI: 1.27-3.10) and those whose loss was due to natural deaths (HR = 1.48, 95% CI: 1.07-2.06). The risk elevations were generally stronger for loss of a monozygotic co-twin than loss of a dizygotic co-twin.

CONCLUSION

Loss of a co-twin, especially a monozygotic co-twin, was associated with increased mortality, particularly of unnatural causes, among the surviving twin individuals. The excess mortality is likely attributable to both shared disease susceptibility within the twin pair and the adverse health sequelae of bereavement.

Genome-wide association study meta-analysis of suicide death and suicidal behavior

Suicide is a worldwide health crisis. We aimed to identify genetic risk variants associated with suicide death and suicidal behavior. Meta-analysis for suicide death was performed using 3765 cases from Utah and matching 6572 controls of European ancestry. Meta-analysis for suicidal behavior using data across five cohorts (n = 8315 cases and 256,478 psychiatric or populational controls of European ancestry) was also performed. One locus in neuroligin 1 (NLGN1) passing the genome-wide significance threshold for suicide death was identified (top SNP rs73182688, with p = 5.48 × 10-8 before and p = 4.55 × 10-8 after mtCOJO analysis conditioning on MDD to remove genetic effects on suicide mediated by MDD). Conditioning on suicidal attempts did not significantly change the association strength (p = 6.02 × 10-8), suggesting suicide death specificity. NLGN1 encodes a member of a family of neuronal cell surface proteins. Members of this family act as splice site-specific ligands for beta-neurexins and may be involved in synaptogenesis. The NRXN-NLGN pathway was previously implicated in suicide, autism, and schizophrenia. We additionally identified ROBO2 and ZNF28 associations with suicidal behavior in the meta-analysis across five cohorts in gene-based association analysis using MAGMA. Lastly, we replicated two loci including variants near SOX5 and LOC101928519 associated with suicidal attempts identified in the ISGC and MVP meta-analysis using the independent FinnGen samples. Suicide death and suicidal behavior showed positive genetic correlations with depression, schizophrenia, pain, and suicidal attempt, and negative genetic correlation with educational attainment. These correlations remained significant after conditioning on depression, suggesting pleiotropic effects among these traits. Bidirectional generalized summary-data-based Mendelian randomization analysis suggests that genetic risk for the suicidal attempt and suicide death are both bi-directionally causal for MDD.

Risk of psychiatric disorders among the surviving twins after a co-twin loss

Losing a co-twin by death is a severely stressful event yet with unknown impact on the surviving twin's risk of psychiatric disorders. We identified all Swedish-born twins who lost a co-twin by death between 1973 and 2013 (n = 4,528), their 4939 non-twin full siblings, together with 22,640 age- and sex-matched non-bereaved twins. Compared to the non-bereaved twins, exposed twins were at increased risk of receiving a first diagnosis of psychiatric disorders (hazard ratio = 1.65, 95% confidence interval1.48-1.83), particularly during the first month after loss. Similarly, compared to non-twin full siblings, the relative risks were significantly increased after loss of monozygotic co-twin (2.45-fold), and loss of a dizygotic co-twin (1.29-fold), with higher HR observed with greater age gaps between twins and non-twin siblings. As dizygotic twins share equal genetic relatedness to the deceased twin as their full siblings, this pattern suggests that beyond the contribution of genetic factors, shared early life experiences and attachment contribute to the risk of psychiatric disorders among surviving twins after co-twin loss.

Suicidal attempts, insomnia, and major depressive disorder among family members of suicide victims in South Korea

BACKGROUND

Suicide survivors are defined as victims who experienced suicide of siblings or parents, spouses, or lineal relatives within the fourth degree who had lived with them. We compared the effects of major depressive disorder (MDD), symptoms of posttraumatic stress disorder (PTSD), and impulsivity on lifetime suicide attempts among suicide survivors.

METHODS

Participants included 272 suicide survivors. We compared them to 5,200 members from the general population who were matched by age, sex, and years of education. We evaluated participants using the Patient Health Questionnaire-9 (PHQ-9), the EuroQuality of Life (EuroQol) scale, the Impact of Events Scale-Revised (IES-R), the Barratt Impulsiveness Scale-11 (BIS-11), and the Composite International Diagnostic Interview (K-CIDI).

RESULTS

Among the 272 suicide survivors, MDD was nine times higher (47.1% vs. 5.3%), and suicidal attempts were six times higher (20.5% vs. 3.3%) than reported among the general population. The suicide survivors showed more severe depression, greater impulsivity, and poorer quality of life than did the general population. In multivariate logistic regression analyses performed to evaluate each IES-R item, "trouble staying asleep" was the only PTSD symptom item that was significantly associated with suicide attempts among suicide survivors. Suicide survivors who had both MDD with insomnia and high impulsivity were at four times higher risk for suicide attempts than the general population with no MDD (AOR = 4.04, 95% CI: 1.25-13.09).

CONCLUSIONS

Surviving suicide by family members is an important risk factor for suicide attempts. In particular, MDD with insomnia and impulsivity are associated with suicide attempts among suicide survivors.

Stigma, grief and depressive symptoms in help-seeking people bereaved through suicide

BACKGROUND

The painful experience of mourning after suicide can be further complicated by the stigma surrounding suicide survival. We investigated how grief and depression influence the perception of stigma towards survivors in a sample of help-seeking persons bereaved through suicide.

METHODS

Cross-sectional design. Information on sociodemographic variables and responses to the Stigma of Suicide Survivor Scale, Beck Depression Inventory (BDI) and Inventory of Complicated Grief (ICG) was collected from 240 people bereaved through suicide who consecutively accessed an online support initiative.

RESULTS

Despite the strong correlation between ICG and BDI scores, the intensity of depressive but not of grief symptoms was related to perceived stigma towards survivors. Time since loss was also positively related to levels of perceived stigma against survivors. The links between depression and perceived stigma persisted after taking into account relationship with the deceased and other sociodemographic factors.

LIMITATIONS

The main study limitations are the cross-sectional design, reliance on self-report measures, and the self-selection of the sample of people bereaved through suicide, seeking help through a website. Social support was not measured and the sample included a large proportion of women.

CONCLUSIONS

Specific interventions designed for persons bereaved by suicide should consider that psychological distress and mourning are qualitatively different reactions to a suicide loss. The relationship among perceived stigma, depressive suffering and time elapsed since the suicide loss suggests the usefulness of closely investigating the experience of stigma in all people bereaved through suicide with depressive symptoms, even long after the event.

Effects of suicide bereavement on mental health and suicide risk

Between 48 million and 500 million people are thought to experience suicide bereavement every year. Over the past decade, increased policy attention has been directed towards suicide bereavement, but with little evidence to describe the effect of exposure or to provide appropriate responses. We used a systematic approach to carry out a narrative review of studies of the effect of suicide bereavement on mortality, mental health, and social functioning, and compared them with effects from other bereavements. We found 57 studies that satisfied strict inclusion criteria. Results from these studies suggested that exposure to suicide of a close contact is associated with several negative health and social outcomes, depending on an individual's relationship to the deceased. These effects included an increased risk of suicide in partners bereaved by suicide, increased risk of required admission to psychiatric care for parents bereaved by the suicide of an offspring, increased risk of suicide in mothers bereaved by an adult child's suicide, and increased risk of depression in offspring bereaved by the suicide of a parent. Some evidence was shown for increased rejection and shame in people bereaved by suicide across a range of kinship groups when data were compared with reports of relatives bereaved by other violent deaths. Policy recommendations for support services after suicide bereavement heavily rely on the voluntary sector with little input from psychiatric services to address described risks. Policymakers should consider how to strengthen health and social care resources for people who have been bereaved by suicide to prevent avoidable mortality and distress.

Suicidal Behavior and Neurological Illnesses

OBJECTIVE

Suicidal ideation and behavior have been associated with a variety of neurological illnesses. Studies are ongoing in combat veterans and other groups to examine possible mechanisms and pathways that account for such associations.

METHOD

This article provides a review of the literature on suicide ideation and suicidal behavior in patients with neurological illnesses including publications on veteran's health and military medicine. Studies of suicide attempts and deaths in people with neurological illnesses are also reviewed.

RESULTS

The studies summarized in this review indicate that there are important linkages between suicidal ideation and behavior and neurological conditions, including epilepsy, multiple sclerosis, and amyotrophic lateral sclerosis.

CONCLUSION

Additional studies are needed to further clarify why suicide ideation and suicidal behavior are associated with neurological diseases, in order to improve quality of life, alleviate patient distress, and prevent nonfatal and fatal suicide attempts in veteran and non-veteran populations.

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.

Solvent Exposure and Parkinson's Disease: Co-Twin Control Study/ Twin Research Reports / Human Interest Stories

Naturally occurring co-twin control designs can assess associations between environmental hazards and disease risk because the genotypes of monozygous twins are the same. The first population-based study to explore links between solvent exposure and Parkinson's disease used 49 discordant monozygous twin pairs, as well as a comparison group of 50 discordant dizygous twin pairs. The methods, findings and implications from this important study are reviewed. Reviews of twin research concerning gender identity disorder, prenatal development and the VATER syndrome follow. A sampling of engaging and informative twin-related news items is also presented.

Genetic and environmental contributions to self-reported thoughts of self-harm and suicide

Thoughts of self-harm and suicidal behavior are thought to be influenced by both genetics and environment. Molecular genetic studies are beginning to address the question of which genes may be involved and whether different genes may be expressed in men and women. We examined thoughts of self-harm and suicidal behavior in a large general population twin sample including male and female same- and opposite-sex twins. In this study, data on self-reported thoughts of self-harm and suicide were obtained from self-report questionnaires (Beck Depression Inventory and Youth or Adult Self Report forms) in 6,265 twin pairs (11,008 individuals) aged 11-90 (62% female) from the Netherlands Twin Registry. Liability threshold models were compared including sex and age (linear and quadratic) effects. Models were compared using measures of parsimony to calculate the simplest model to the data. A model with additive genetic and unique environmental contributions fitted the data for both males and females. There were no qualitative sex differences, but the relative contributions differed between men and women. Heritability was higher in women (0.74, 95% CI 0.65-0.81) than men (0.45, 95% CI 0.28-0.61). The remaining variance was accounted for by environmental influence unique to an individual. These results suggest contributions from additive genetic factors to self-reported thoughts of self-harm and suicide and support the continued study of both molecular genetic and individual-specific environmental risk factors.

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSIONS

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