Sudden death of father or sibling in early childhood increases risk for psychotic disorder☆
Introduction
Recent evidence has shown that childhood trauma is a risk factor for the development of schizophrenia (Read et al., 2005, Morgan and Fisher, 2007, Heins et al., 2011) and psychotic symptoms (Kelleher et al., 2008, Harley et al., 2010). Previous work has shown that individuals with schizophrenia and bipolar disorder have a 4-fold increased rate of parental loss, through death or separation, compared with healthy controls and that this increased risk for psychotic disorder is particularly marked in those who lost a parent before 9-years-of-age (Agid et al., 1999). Data from the Helsinki Birth cohort shows that individuals who were separated from their parents during early childhood, for an average of 1.7 years, had a higher rate of any mental health disorder in adulthood (Pesonen and Räikkönen, 2012).
There is some evidence that an individual's long-term outcome after a significant bereavement is moderated by the mode of death involved. Sudden and violent death of a family member has been found to increase the risk of an individual having an adverse mental health outcome compared with those bereaved as a result of a chronic illness (Miyabayashi and Yasuda, 2007). In particular, the loss of a child or spouse was shown to lead to more intensive and persistent grief than other types of loss and to have a negative impact on mental health outcomes (Prigerson et al., 1997, Li et al., 2005). Young adults who experience loss were found to have higher rates of grief symptoms and mortality than older adults who experience loss (Neria and Litz, 2010). It has also been found that children of parents who died by suicide, accident or sudden natural death had higher rates of new-onset depression and post-traumatic stress disorder at both 9-month and 21-month follow-ups compared to non-bereaved controls (Brent et al., 2009). Similarly, a study based on Danish-register data showed that maternal suicide in childhood was associated with the development of bipolar disorder in adulthood (Tsuchiya et al., 2005) and that the earlier the child was exposed to loss, the higher the risk of later developing bipolar disorder. There was a 7.7-fold increase in risk for those exposed during the first 7 years of life and a 3-fold increase in risk for those exposed between ages 10 and 17. These findings were similar for those who experienced the suicide of a sibling during childhood. The majority of these studies did not look specifically at type of sudden death as a moderator of the impact on the mental health of those exposed to the consequences. Miyabayashi and Yasuda (2007) found that suicide had a larger adverse impact on the mental health of first degree relatives compared to sudden death from other causes; however, shared genetic effects between suicide and mental illness may have mediated this association and were not controlled for in this study. Brent et al. (2009) found that the rate of depression was higher among those whose parents died as a result of suicide than as a result of sudden natural death but not compared to those whose parents died as a result of sudden accident-related death. However, this study did not control for psychiatric history in the parents although psychiatric history in the offspring prior to the death was controlled for. Tsuchiya et al. (2005) controlled for psychiatric history in the parents in their analysis showing an association between parental suicide and bipolar disorder in the offspring, indicating an independent association.
To the best of our knowledge this is the first study to examine mode of death among parents and risk of schizophrenia and bipolar disorder in the bereaved offspring in adulthood. We examined the risk of developing schizophrenia and bipolar disorder among individuals who were exposed to the sudden death of their father or sibling before 5-years-of-age compared to those who were exposed to death of a father or sibling as a result of an illness. Sudden death included accidents, intentional self-harm and assault. We hypothesized that the sudden loss of a father or sibling would significantly increase the risk of psychotic disorders among those exposed.
Section snippets
Method
All live-born individuals in Finland are assigned a unique personal identification number at birth. This personal identification number is used in all registers which ensures accurate linkage of information between registers. For this study, three national registers were linked: the Finnish Hospital Discharge Register (FHDR), the Cause of Death Register and the Finnish Population Register. The FDHR covers all public and private hospitals in Finland and the discharge diagnoses for each admission
Results
From the national registers we identified 11,855 individuals whose father or sibling died before they were 5-years-old and for whom the cause of death was available. 6136 individuals had a father or sibling who died suddenly. Of these, 2201 were deaths by suicide. 5719 individuals had a father or sibling who died as a result of an illness. In total, 129 individuals had a diagnosis of schizophrenia and 165 individuals had a diagnosis of bipolar disorder.
The sudden death of a father or sibling
Discussion
Our findings are in keeping with evidence showing an association between traumatic experiences during childhood and risk of psychotic illness (Heins et al., 2011). Our exposure category of ‘sudden death’ included a number of different types of death including suicides and accidents, all of which involve an injury of some kind. Previous work has shown that deaths that have a sudden and a violent element to them are similar in their impact on grief reactions and mental health outcomes (Dyregrov
Role of funding source
None of our sources of funding had any input to or influence over the design of the study, the interpretation of results or the presentation of results in this manuscript.
Contributors
M Clarke was involved in the design of the study, the analysis of the results and the writing of the manuscript.
A Tanskanen was involved in the design of the study, the analysis of the results and the writing of the manuscript.
M Huttunen was involved in the design of the study, the analysis of the results and the writing of the manuscript.
M Cannon was involved in the design of the study, the analysis of the results and the writing of the manuscript.
Conflict of interest
We report no conflict of interest.
Acknowledgements
This work was supported by the Health Research Board (Ireland), the Stanley Medical Research Institute, and a Grable Independent Investigator Award from NARSAD to M Cannon.
M Clarke had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
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Cited by (0)
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This work was presented at the 3rd Biennial Schizophrenia International Research Conference in Florence on 16th April, 2012.