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

Abstract

BackgroundResearch 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.MethodWe 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.ResultsPatterns 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.ConclusionsFamilial 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.

Killing the Mother of One’s Child

“…In line with our findings, the risk of being convicted for a violent crime is also elevated for offspring bereaved of a parent by any cause and regardless of age at loss. 17 Previous research has demonstrated a high level of heritability in suicidal behavior, 32 and, therefore, we adjusted the analyses on suicide for earlier self-harm among parents and children. Likewise, mental disorders have a hereditary component of various degrees for different disorders.…”

Population-Based, Multigenerational Family Clustering Study of Obsessive-compulsive Disorder

“…This approach has been previously validated and successfully applied to study other mental disorders and problematic behaviors, such as schizophrenia, 19 bipolar disorder, 19 violent offending, 20 and suicide. 21 As a complementary measure of familial risk, tetrachoric correlations were calculated from the matched data. From this, we estimated additive genetic effects comparing full siblings and maternal half siblings (assuming that they have similar shared environments but 50.0% vs 25.0% genetic similarity on average).…”

“…This model did not fit the data significantly better than the full ACE model, thus providing no evidence of qualitative sex differences in the liability for obsessive-compulsive symptoms (P = . 21). Next, we tested for quantitative sex differences by constraining the parameters A, C, and E to be equal across sexes (model 5).…”

Family history of suicide and exposure to interpersonal violence in childhood predict suicide in male suicide attempters

“…Several family and twin studies support the notion of higher rates of both completed suicide and suicide attempts in relatives of suicide completers . The familial transmission is not solely dependent on the existence of a psychiatric disorder Tidemalm et al, 2011). Biological, social and psychological factors are all contributing to suicidality within an individual (Caspi et al, 2003;Fu et al, 2002).…”