Suicide Contagion Research Articles

Spatial clusters of suicide in Australia

BackgroundUnderstanding the spatial distribution of suicide can inform the planning, implementation and evaluation of suicide prevention activity. This study explored spatial clusters of suicide in Australia, and investigated likely socio-demographic determinants of these clusters.MethodsNational suicide and population data at a statistical local area (SLA) level were obtained from the Australian Bureau of Statistics for the period of 1999 to 2003. Standardised mortality ratios (SMR) were calculated at the SLA level, and Geographic Information System (GIS) techniques were applied to investigate the geographical distribution of suicides and detect clusters of high risk in Australia.ResultsMale suicide incidence was relatively high in the northeast of Australia, and parts of the east coast, central and southeast inland, compared with the national average. Among the total male population and males aged 15 to 34, Mornington Shire had the whole or a part of primary high risk cluster for suicide, followed by the Bathurst-Melville area, one of the secondary clusters in the north coastal area of the Northern Territory. Other secondary clusters changed with the selection of cluster radius and age group. For males aged 35 to 54 years, only one cluster in the east of the country was identified. There was only one significant female suicide cluster near Melbourne while other SLAs had very few female suicide cases and were not identified as clusters. Male suicide clusters had a higher proportion of Indigenous population and lower median socio-economic index for area (SEIFA) than the national average, but their shapes changed with selection of maximum cluster radii setting.ConclusionThis study found high suicide risk clusters at the SLA level in Australia, which appeared to be associated with lower median socio-economic status and higher proportion of Indigenous population. Future suicide prevention programs should focus on these high risk areas.

Suicide Clusters in Young People

Suicide clusters have commonly been documented in adolescents and young people. The current review conducts a literature search in order to identify and evaluate postvention strategies that have been employed in response to suicide clusters in young people. Online databases, gray literature, and Google were searched for relevant articles relating to postvention interventions following a suicide cluster in young people. Few studies have formally documented response strategies to a suicide cluster in young people, and at present only one has been longitudinally evaluated. However, a number of strategies show promise, including: developing a community response plan; educational/psychological debriefings; providing both individual and group counseling to affected peers; screening high risk individuals; responsible media reporting of suicide clusters; and promotion of health recovery within the community to prevent further suicides. There is a gap in formal evidence-based guidelines detailing appropriate postvention response strategies to suicide clusters in young people. The low-frequency nature of suicide clusters means that long-term systematic evaluation of response strategies is problematic. However, some broader suicide prevention strategies could help to inform future suicide cluster postvention responses.

An Adolescent Suicide Cluster and the Possible Role of Electronic Communication Technology

Since the development of Centers for Disease Control's (CDC) guidelines for the management of suicide clusters, the use of electronic communication technologies has increased dramatically. To describe an adolescent suicide cluster that drew our attention to the possible role of online social networking and SMS text messaging as sources of contagion after a suicide and obstacles to recognition of a potential cluster. A public health approach involving a multidisciplinary community response was used to investigate a group of suicides of New Zealand adolescents thought to be a cluster. Difficulties in identifying and managing contagion posed by use of electronic communications were assessed. The probability of observing a time-space cluster such as this by chance alone was p = .009. The cases did not belong to a single school, rather several were linked by social networking sites, including sites created in memory of earlier suicide cases, as well as mobile telephones. These facilitated the rapid spread of information and rumor about the deaths throughout the community. They made the recognition and management of a possible cluster more difficult. Relevant community agencies should proactively develop a strategy to enable the identification and management of suicide contagion. Guidelines to assist communities in managing clusters should be updated to reflect the widespread use of communication technologies in modern society.

Media Guidelines in the Internet Age

In recent years, there has been growing concern over the reporting by the media of those who die by suicide. Recommendations have been proposed by various groups, such as the Centers for Disease Control (1994), the World Health Organization and the International Association for Suicide Prevention (IASP) (WHO & IASP, 2008). In addition, scholarly research has studied the impact of the media on suicidal behavior. Recent research confirmed that media attention can trigger copycat suicides. For example, Kunrath, Baumert, and Ladwig (2011) documented media reports of railway suicides in Germany affecting the subsequent number of railway suicides. Similarly, in Taiwan, Chen et al. (2012) documented an increase in suicides using charcoal burning after the suicide of a popular young female singer using this method. Bale (2001), writing on behalf of Befrienders International, stressed the importance of collaboration with the media in order to advance suicide prevention. Bale discussed the work of Keith Hawton from the Center for Suicide Research at Oxford University (UK), who was commissioned by Befrienders International to review research examining the links between suicide and media coverage. Hawton’s review resulted in several conclusions: First, reports and portrayals of suicide in the media can increase suicidal behavior, especially when those reports are emphasized (for example, put on the front page of a newspaper) and repeated; and when they describe the methods in detail (with the young and old at particular risk in this case). Second, changes made to the reporting of methods can help to prevent subsequent suicides. Third, positive benefits are found in giving information regarding crisis hotlines and encouraging their use alongside the article about a particular suicidal individual. Finally, the media often underreport the role of mental illness in suicidal behavior. Hawton’s review also suggested a series of practical considerations for dealing with the media. The first is to be realistic when working with the media: Suicides remain newsworthy, especially the suicides of celebrities, so these deaths are going to be covered by reporters regardless. Second, a media strategy should be developed for preparing and rehearsing official spokespersons in order to make the messages to reporters clear and simple. Finally, it may be useful to accept the help of prominent individuals to pass on appropriate messages. By collaborating with others, the attention of the media may be steered to topics that they can include in their articles. Pirkis and Blood (2001a, 2001b) published a series of articles in Crisis on suicide and the media. They reviewed studies on the reporting of suicide in the media in newspapers, television, and nonfiction books, and concluded that there was indeed an association between suicidal behavior and the media reporting of suicide. They urged that suicide reporting be done in a responsible manner. Pirkis and Blood also reviewed studies on fictional depictions of suicidal behavior. While the relationship between suicidal behavior and fictional portrayals of suicide (on television, in plays, and in songs) was much less clear than nonfictional reporting, the authors concluded that caution should still be taken by producers of plays and dramas that will be shown on television and in films. Pirkis and Blood noted that the influence of the Internet on suicidal behavior needs investigation as neither of their reviews examined the effects of the Internet. Gould, Jamieson, and Romer (2003) discussed the role of the media among the young and concluded that the evidence suggests they are at increased risk of contagion from media reports. They also concluded that educating producers and journalists about the risk of irresponsible reporting and about the proper ways to report suicide could prevent subsequent suicides. They further recommended that journalists and producers be educated in the best ways to present suicide that are conducive to prevention. On the other hand, Goldney (2001), while acknowledging that there is an association between media portrayals of suicide and subsequent suicidal behavior, pointed out that this association is relatively weak. Goldney recommended focusing on the positive effect that media can have on suicide prevention.

Darstellung von Suizidalität in deutschsprachigen Jugendmedien in Oesterreich und ihr Einfluss auf die Suizidprävalenz

We analyzed the quality of suicide reporting in youth magazines and assessed potential copycat effects following media reports on suicide. We obtained suicide-related articles from five Austrian and German youth magazines published between 1996 and 2008. Reported sex, suicide (attempt) methods, suicide motives, the portrayal of suicide in a positive or negative light, accusations of blame and consistency with media recommendations for the reporting of suicide were analysed using qualitative content analysis. The suicide frequency among adolescents in Austria was compared 2 weeks before and after the publication of reports on suicide and suicide attempts. 59 articles were identified, most of which had been published in the magazine Bravo. There was an overrepresentation of suicide among girls and an underrepresentation of attempted suicide. The frequency of specific suicide and suicide attempt methods was consistent with epidemiological distributions of suicide methods. Fall from height was most frequently described for girls and hanging for boys. Regarding motives for suicide, factors like psychiatric diseases were underrepresented. Girls who died by suicide were often positively described in articles, but boys were more often negatively described. Parents were frequently blamed as being guilty of their child's suicidal behaviour, in particular when reporting on suicide attempts. Photos, suicide notes and details concerning method were frequently described. There was no indication of a Werther effect following reporting. The identified discrepancies between epidemiologic data regarding suicidal behaviour in adolescents and media reporting in youth media constitutes an important basis for suicide prevention in the community.

Workplace Dignity in a Total Institution: Examining the Experiences of Foxconn’s Migrant Workforce

In 2010, a cluster of suicides at the electronics manufacturing giant Foxconn Technology Group sparked worldwide outcry about working conditions at its factories in China. Within a few short months, 14 young migrant workers jumped to their deaths from buildings on the Foxconn campus, an all-encompassing compound where they had worked, eaten, and slept. Even though the language of workplace dignity was invoked in official responses from Foxconn and its business partner Apple, neither of these parties directly examined workers’ dignity in their ensuing audits. Based on our analysis of media accounts of life at Foxconn, we argue that its total institution structure imposed unique indignities on its workers that both raised questions of their self-respect and self-worth, as well as gave rise to multiple episodes of disrespectful communication. We interpret our findings in light of the larger cultural context and meanings of work in China to understand more fully the experience of dignity of Foxconn’s migrant workforce.

Social Aspects of Suicidal Behavior and Prevention in Early Life: A Review

Purpose: The present review summarizes the updated literature on the social aspects of suicidal behavior and prevention in adolescents. Recent findings: The predictive role of psychiatric disorders and past history are well recognized in adolescent suicide, but the role of social and cultural factors is less clear. Studies have focused on the importance of ethnicity, gender, family characteristics, and socioeconomic status. More recently, attention has been addressed to broader social risk factors, such as bullying in adolescents, suicide contagion, sexual orientation, and the popular media. Further empirical evidence is needed to advance our understanding of suicidal youth, develop better assessment tools, and formulate effective prevention and treatment programs. Summary: Suicidal behavior remains an important clinical problem and major cause of death in youth. Social factors may be at least as important as genetics. Advancing our understanding of underlying cultural and sociological issues in youth suicide will help clinicians achieve more efficient prediction, prevention and treatment.

Does place of residence affect risk of suicide? a spatial epidemiologic investigation in Kentucky from 1999 to 2008

BackgroundApproximately 32,000 people take their own lives every year in the United States. In Kentucky, suicide mortality rates have been steadily increasing since 1999. Few studies in the United States have assessed spatial clustering of suicides. The purpose of this study was to identify high-risk clusters of suicide at the county level in Kentucky and assess the characteristics of those suicide cases within the clusters.MethodsA spatial epidemiological study was undertaken using suicide data for the period January 1, 1999 to December 31, 2008, obtained from the Kentucky Office of Vital Statistics. Descriptive analyses using Pearson's chi-square test and t-test were performed to determine whether differences existed in age, marital status, year, season, and suicide method between males and females, and between cases inside and outside high-risk spatial clusters. Annual age-adjusted cumulative incidence rates were also calculated. Suicide incidence rates were spatially smoothed using the Spatial Empirical Bayesian technique. Kulldorff's spatial scan statistic was applied on all suicide cases at the county level to identify counties with the highest risks of suicide. Temporal cluster analysis was also performed.ResultsThere were a total of 5,551 suicide cases in Kentucky from 1999 to 2008, of which 5,237 (94%) were included in our analyses. The majority of suicide cases were males (82%). The average age of suicide victims was 45.4 years. Two statistically significant (p < 0.05) high-risk spatial clusters, involving 15 counties, were detected. The county level cumulative incidence rate in the most likely high-risk cluster ranged from 12.4 to 21.6 suicides per 100,000 persons. The counties inside both high-risk clusters had relative risks ranging from 1.24 to 1.38.ConclusionsStatistically significant high-risk spatial clusters of suicide were detected at the county level. This study may be useful for guiding future research and intervention efforts. Future studies will need to focus on these high-risk clusters to investigate reasons for these occurrences.

Suicide Clusters: Introducing a Novel Type of Categorization

A suicide cluster within a given community may be defined as a group of suicides or suicide attempts, or both, that happen closer together in time and space than would generally be expected. However, since the perception of clustering may itself be a risk factor for suicide, suicide clusters differ almost from all other event clusters. The aim of this article, therefore, is to discuss the unique pattern of suicide cluster and introduce a novel type of categorization taking into account varieties of studies, which investigate suicide clusters within diverse settings. This article concludes with challenging areas in suicide cluster studies and emphasizing that each community must deal rapidly and appropriately with any perceived suicide clusters.

Media roles in suicide prevention: a systematic review.

The aim of the current systematic review was to monitor and provide an overview of the research performed about the roles of media in suicide prevention in order to find out possible effects media reporting on suicidal behaviours might have on actual suicidality (completed suicides, attempted suicides, suicidal ideation). The systematic review was performed following the principles of the PRISMA statement and includes 56 articles. Most of the studies support the idea that media reporting and suicidality are associated. However, there is a risk of reporting bias. More research is available about how irresponsible media reports can provoke suicidal behaviours (the ‘Werther effect’) and less about protective effect media can have (the ‘Papageno effect’). Strong modelling effect of media coverage on suicide is based on age and gender. Media reports are not representative of official suicide data and tend to exaggerate sensational suicides, for example dramatic and highly lethal suicide methods, which are rare in real life. Future studies have to encounter the challenges the global medium Internet will offer in terms of research methods, as it is difficult to define the circulation of news in the Internet either spatially or in time. However, online media can provide valuable innovative qualitative research material.

Effects of media reports and the subsequent voluntary withdrawal from sale of suicide-related products on the suicide rate in Japan

Media reports of suicides have an impact on suicide rates. However, countermeasures to this media effect have not been evaluated. We examined the association between media reports of suicides accomplished with the use of hydrogen sulfide, the voluntary stoppage of sales of suicide-related products, and suicide rates for people in their 20s, 30s, and 40s in Japan. The Box-Jenkins transfer function model was applied to monthly time series data from February 2003 to December 2009 (83 months). In the male suicide time series, media reports of suicide were not related to suicide counts (ω((R)) = 8.988, P = 0.694). Similarly, stopping the sale of bath salts was not related to the number of suicides (ω((S)) = -7.344, P = 0.694). However, in the female suicide time series, media reports of suicide were related to the number of suicides (ω((R)) = 17.225, P = 0.049). Similarly, stopping the sale of bath salts was related to the number of suicides (ω((S)) = -18.545, P = 0.040). The results suggest that stopping the sale of bath salts might be effective in reducing the number of copycat suicides among the women in their 20s, 30s, and 40s. In practice, stopping the sale of suicide-related products might be a potentially effective countermeasure to prevent copycat suicides triggered by media coverage of suicides.

Suicide-nearness assessed with PORT, the Percept-genetic Object-Relation Test: A replication and a reliability study

To determine the reliability and validity of a previously identified "suicide cluster" in the Percept-genetic Object-Relation Test (PORT), which test documents subliminal perception of object-relation pictures, 20 suicide attempters and 70 controls were investigated. The correspondence between scores assigned by two judges was 95%-100%. The suicide-cluster signs in PORT, notably "lack of attachment relationships" and "Motor activity," were significant. Differences between the results of this and the previous study are discussed as is the role of psychiatric disorder in suicide.

Belief in a Werther Effect: Third‐Person Effects in the Perceptions of Suicide Risk for Others and the Moderating Role of Depression

Werther Effect research has almost solely focused on the behavioral level of media effects. Clinically relevant predispositions like depression as well as the moderating role of media effects on a perceptional level have been omitted so far. To bridge this gap, we reanalyzed the data of an experiment conducted by Rustad, Small, Jobes, Safer, and Peterson: volunteer students' ratings for their self-risk of depression and suicide as well as their perceptions of others' suicide risk were investigated. While a Werther Effect could not be observed, there is a general overestimation of media influences on others--presumed Werther Effects--that are moderated by the personal degree of depression.

The foxconn suicides and their media prominence: is the werther effect applicable in china?

BackgroundMedia reporting of suicide and its relationship with actual suicide has rarely been investigated in Mainland China. The "Foxconn suicides" is a description referring to a string of suicides/attempts during 2010, all of which were related to a giant electrical manufacturing company, Foxconn. This study aimed to examine the clustering and copycat effects of the Foxconn suicides, and to investigate temporal patterns in how they were reported by the media in Mainland China, Hong Kong (HK), and Taiwan (TW).MethodsRelevant articles were collected from representative newspapers published in three big cities in Mainland China (Beijing (BJ), Shenzhen (SZ), and Guangzhou (GZ)), HK, and TW, together with searching intensity data on the topic conducted using the Baidu search engine in Mainland China. The temporal clustering effects of the Foxconn suicides and their media prominence were assessed using the Kolmogorov-Smirnov test. The media reports of the Foxconn suicides' temporal patterns were explored using a nonparametric curve estimation method (that is, the local linear method). The potential mutual interactions between the Foxconn suicides and their media prominence were also examined, using logistic and Poisson regression methods.ResultsThe results support a temporal clustering effect for the Foxconn suicides. The BJ-based newspapers' reporting and the occurrence of a Foxconn suicide/attempt are each found to be associated with an elevated chance of a further Foxconn suicide 3 days later. The occurrence of a Foxconn suicide also immediately influenced the intensity of both Baidu searching and newspaper reporting. Regional diversity in suicide reporting tempo-patterns within Mainland China, and similarities between HK and TW, are also demonstrated.ConclusionsThe Foxconn suicides were temporally clustered. Their occurrences were influenced by the reporting of BJ-based newspapers, and contagion within the company itself. Further suicide research and prevention work in China should consider its special media environment.

Suicide Announcement on Facebook

The media and the Internet may be having an influence on suicidal behavior. Online social networks such as Facebook represent a new facet of global information transfer. The impact of these online social networks on suicidal behavior has not yet been evaluated. To discuss potential effects of suicide notes on Facebook on suicide prevention and copycat suicides, and to create awareness among health care professionals. We present a case involving a suicide note on Facebook and discuss potential consequences of this phenomenon based on literature found searching PubMed and Google. There are numerous reports of suicide notes on Facebook in the popular press, but none in the professional literature. Online social network users attempted to prevent planned suicides in several reported cases. To date there is no documented evidence of a copycat suicide, directly emulating a suicide announced on Facebook. Suicide notes on online social networks may allow for suicide prevention via the immediate intervention of other network users. But it is not yet clear to what extent suicide notes on online social networks actually induce copycat suicides. These effects deserve future evaluation and research.

The Role of the Media in Shaping the UK Debate on ‘Assisted Dying’

This paper reviews the legislative background, the major stakeholders and the alignment of the various media in the UK debate on ‘assisted dying’. It explains the way the four main arenas of debate—parliament, the institutions, the courts and the media—have engaged with the issues and then outlines how the pro-legalisation lobby has courted media publicity through high-profile personal stories, court cases, parliamentary bills and amendments, celebrity endorsement and the Falconer commission. In particular it argues that the BBC has breached its own editorial guidelines on both impartiality and suicidal portrayal and is at risk of promoting further suicides by fuelling suicide contagion. It concludes that the police and the courts must uphold the will of parliament and that the media must act responsibly in covering the debate, giving equal weight and exposure to the arguments of both sides and following international guidelines on the coverage of individual cases.

Internet Searches for a Specific Suicide Method Follow Its High-Profile Media Coverage

Back to table of contents Previous article Next article Communications and UpdatesFull AccessInternet Searches for a Specific Suicide Method Follow Its High-Profile Media CoverageShu-Sen Chang, M.D., Ph.D., Andrew Page, Ph.D., and David Gunnell, Ph.D.Shu-Sen ChangSearch for more papers by this author, M.D., Ph.D., Andrew PageSearch for more papers by this author, Ph.D., and David GunnellSearch for more papers by this author, Ph.D.Published Online:1 Aug 2011https://doi.org/10.1176/appi.ajp.2011.11020284AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail To the Editor: Widespread media coverage of specific methods of suicide may lead to copycat deaths and could initiate changes in the popularity of particular methods. At-risk individuals may use the Internet to research particular methods of suicide (1, 2), and a person's choice of method can influence case fatality (3). However, there is little research into the impact of news reports of suicide on subsequent Internet search activity.We investigated the effect of media coverage of suicides by hydrogen sulfide gassing on trends in Internet searches in two countries. In Japan, news reports of three deaths using this method in late February 2008 were followed by more than 200 hydrogen sulfide suicides during the subsequent 4 months (4). This epidemic was thought to be fueled by information on the Internet about making the gas. In the United Kingdom, extensive media coverage on September 20, 2010, of a suicide pact using this method was followed by a second hydrogen sulfide suicide pact within 10 days and another in February 2011.We investigated search volume patterns from Google searches (http://www.google.com/insights/search) using the terms “suicide” and “hydrogen sulfide” (or “hydrogen sulphide”), filtering for Japan from January 2004 to January 2011 (Figure 1A) and for the United Kingdom from August 2009 to January 2011 (Figure 1B). The searches were performed in Japanese and English. Google provides a relative figure based on search activity for the study period but does not provide absolute numbers of searches. The month or week in the selected period with the highest number of searches is assigned the value 100, and other months/weeks are scaled accordingly.FIGURE 1. Trends in Internet Searches Using the Terms “Suicide” and “Hydrogen Sulfide” (or “Hydrogen Sulphide”) on Google in Japan, January 2004–January 2011, and in the United Kingdom, August 2009–January 2011aa The month or week with the highest number of searches is assigned the value 100, and other months/weeks are scaled accordingly.In Japan, online searches for “hydrogen sulfide” increased 50 times in April 2008 after the initial media reports in February 2008, surpassing the search volume for “suicide” (Figure 1A). In the United Kingdom, the number of online searches for “hydrogen sulfide” did not increase as much as they did in Japan, but the searches nevertheless rose by more than nine times in the week of the suicide pact reports compared with the previous 4 weeks (Figure 1B). The search volume for “hydrogen sulfide” in this period was only 7.1% of that for “suicide,” which also increased by 57% in the week of the suicide pact reports compared with the previous 4 weeks.These data suggest a striking impact of media coverage of an unusual method of suicide on Internet searches relating to that method. It is too early to determine whether differences in the relative changes in Internet searching between Japan and the United Kingdom, and likely cultural differences in attitudes toward suicidal behavior, will be reflected in the numbers of copycat suicides in the two countries, as U.K. suicide data for this period will not be available for 2 years. However, only two subsequent suicide pacts using hydrogen sulfide have been reported by the media in the United Kingdom, suggesting a smaller effect. The Internet may provide a real-time barometer of the impact of media reporting.Bristol, United KingdomBrisbane, AustraliaBristol, United KingdomThe authors report no financial relationships with commercial interests.This letter was accepted for publication in May 2011.

SP3-73 Increase of railway suicides in Germany after the railway suicide death of Robert Enke, a famous German football player

IntroductionRobert Enke, an internationally respected German football goal keeper committed railway suicide on the 10 November 2009. Concerns were raised about the potential of this event to spark copycat suicides...

The effects of celebrity suicide on copycat suicide attempt: a multi-center observational study

The effect of celebrity suicides on copycat suicide attempts is not well known. Our objective was to determine the association between celebrity suicide and copycat suicide attempts. We conducted a retrospective multicenter observational time series analysis. Celebrity suicides were selected by an operational definition via three nationwide television news internet sites from January 2005 to December 2008. The reference week was defined as the week preceding date of suicide notification to the public. Then two pre-event weeks and four post-event weeks were analyzed for suicide attempts. We derived a prediction model for suicide attempt visits for each ED for these seven observational weeks using a General Additive Model with data from the National Emergency Department Information System (NEDIS) database. We calculated the mean excess visit (EV=observed visit-expected visit) and mean excess visit ratio (EVR=EV/expected visit). We tested the mean EV and EVR between reference weeks versus the observational weeks using independent t test and repeated measures ANOVA. Five celebrity suicides occurred during the study period. Total number of ED visits was 5,453,441 in the 85 EDs over the 4-year period, and suicide attempt or self-injury occurred in 27,605. The mean excess visit for each observational interval per ED was less than 0.1 during pre-event periods but increased to 0.695 in the second post-event week. EVs were significantly higher in the first to the third post-event weeks (p=0.02, p<0.01, p=0.03, respectively) compared to reference week. The mean EVRs were significantly higher (=0.215) in the second post-week intervals compared with the reference week (p=0.03). Mean EVs and mean EVRs showed significant increase in the post event period compared with the observational period (p=0.001 in EV, p=0.021 in EVR). From a prediction model using a 4-year nationwide ED database, ED visits for suicide attempts or self injury increased following the announcements of celebrity suicides.

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

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.