Losing a parent or sibling during childhood is linked to the development of a psychotic illness such as schizophrenia or bipolar disorder in later life, new research suggests.

A population cohort study of almost 1 million births in Sweden showed that the children who lost a close family member some time before the age of 13 years were at an increased risk for psychosis. This association was even stronger in the children who experienced the traumatic event before the age of 3 years and for those exposed to a parent or sibling suicide.

Although the overall results were as they expected, lead author Kathryn M. Abel, MRCPsych, PhD, professor of psychological medicine at the Center for Women's Mental Health at the University of Manchester, United Kingdom, told Medscape Medical News that the investigators "were a little surprised" that the effect was so great for the youngest children.

"We think this simply reflects a longer time to accumulate harmful/nonsupportive family effects," she explained.

Dr. Abel added that the study's key messages include that more support should be provided to bereaved families and that death and bereavement should be better managed in these families so that it is a less stressful experience and has less broad consequences on childhood.

"Children losing parents or families with severe bereavement need to be supported, and particular care needs to be taken to minimize other known harms, like bullying," she said.

The study was published online January 21 in BMJ.

Death of Family Members

The investigators examined data from Statistics Sweden and from the Swedish National Board of Health and Welfare for 946,994 children born between 1973 and 1985.

They defined psychosis as nonaffective psychosis, including schizophrenia; or affective psychosis, including bipolar disorder and unipolar depression.

Dr. Kathryn Abel

The researchers also divided bereavement exposures into an "any prenatal" group, which consisted of exposures prior to birth, and an "any postnatal" group, which consisted of exposures between birth and 13 years of age. Priority was given to the earliest exposure if more than 1 occurred during the time of the study.

In addition, the groups were further subdivided by trimester and by 3 age periods (0 - 2.9 years, 3 - 6.9 years, and 7 - 12.9 years). Deaths by parent or sibling were also categorized into 3 groups: suicide, fatal injury/accident, and other.

Results showed that 33.9% of the children included in the study were exposed to the death of a family member before they were 13 years of age; these included 15,189 deaths from accidents and 11,117 deaths from suicide. A total of 280,172 deaths were attributed to other/natural causes, such as cancer or cardiac arrest.

Of all the children who experienced a family death, 0.4% went on to develop a nonaffective psychosis, and 0.17% developed an affective psychosis.

"Any prenatal exposure" was not associated with an increased risk for psychosis. Postnatally, the overall risk for any psychosis increased modestly when the child was exposed to any death of a family member.

Youngest Children at Highest Risk

The highest risk for all psychosis was for those exposed before the age of 3 years to a death in the nuclear family (adjusted odds ratio [AOR], 1.84; 95% confidence interval [CI], 1.41 - 2.41). This risk decreased as the age at exposure increased (3 - 6.9 years: AOR, 1.47; 7 - 12.9 years: AOR, 1.32).

The pattern continued for risk for nonaffective psychosis (AOR, 1.82, 1.46, and 1.22, respectively) and for affective psychosis (AOR, 2.28, 1.75, and 1.68, respectively).

Compared with exposure to deaths from accidents, exposure to a familial suicide was associated with a greater risk for all psychosis, and exposure to a death from natural causes was associated with a lower risk.

Finally, risk for affective psychosis was especially high for all 3 child age groups after experiencing a family member's suicide (birth to 2.9 years: AOR, 3.33; 3 - 6.9 years: AOR, 1.84; 7 - 12.9 years: AOR, 2.68). For nonaffective psychosis, the AORs were 1.73, 1.63, and 1.31, respectively.

"Our research shows childhood exposure to death of a parent or sibling is associated with excess risk of developing a psychotic illness later in life [and] is particularly associated with early childhood exposure," said Dr. Abel in a release.

"Further investigation is now required, and future studies should consider the broader contexts of parental suicide and parental loss in non-Western, ethnically diverse populations," she added.

Screen, Monitor Closely

"This is a very important study adding to the already existing evidence of the long-lasting impact of exposure to bereavement in childhood on future risk for psychopathology," Nadine Melhem, PhD, assistant professor of psychiatry at the University of Pittsburgh School of Medicine in Pennsylvania, told Medscape Medical News.

Dr. Nadine Melhem

Dr. Melhem, who was not involved with this research, has published several previous studies assessing the effects of child bereavement. In 2011, as reported at the time by Medscape Medical News, her investigative team published a study in the Archives of General Psychiatry showing that prolonged grief due to the loss of a parent in both teens and their surviving parents significantly increased the risk for clinical depression and functional impairment in the teens.

"Most childhood bereavement studies report an increased risk for depression and posttraumatic stress disorder in children and later in adulthood," she said.

"The loss of a child and parental separation and death have been associated with increased risk for psychosis. However, [the current report] is the first linkage study to document such an increased risk at a population level," Dr. Melhem added.

Still, she noted that although the investigators adjusted for family history of any psychiatric illness, the "adjustment attenuated" but did not explain the associations with risk.

"It would have been interesting to test the impact of adjusting for family history of psychosis, specifically, on overall risk and to examine the time to onset of psychosis following bereavement, which better accounts for survival times and censoring."

Overall, Dr. Melhem said that the take-home message for clinicians is that they should pay particular attention to children exposed to bereavement of a close relative "and to screen and monitor them closely to detect those at risk early on in time for preventions and interventions."

The study authors and Dr. Melhem have reported no relevant financial relationships.

BMJ. Published online January 21, 2014. Full article