Summary: A new NIH study reveals mental health problems associated with childhood adversity, such as being evacuated from a war zone, can be passed down from generation to generation.
Mental illness associated with early childhood adversity may be passed from generation to generation, according to a study of adults whose parents evacuated Finland as children during World War II. The study was conducted by researchers at the National Institutes of Health, Uppsala University in Sweden, and Helsinki University in Finland. It appears in JAMA Psychiatry.
The research team found that daughters of female evacuees had the same high risk for mental health disorders as their mothers, even though they did not experience the same adversity. The study could not determine why the higher risk for mental illness persisted across generations. Possible explanations include changes in the evacuees’ parenting behavior stemming from their childhood experience or epigenetic changes — chemical alterations in gene expression, without any changes to underlying DNA.
“Many studies have shown that traumatic exposures during pregnancy can have negative effects on offspring,” said study author Stephen Gilman, Sc.D., of the Division of Intramural Population Health Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development. “Here, we found evidence that a mother’s childhood traumatic exposure — in this case separation from family members during war — may have long-lasting health consequences for her daughters.”
From 1941 to 1945, roughly 49,000 Finish children were evacuated from their homes to protect them from bombings, malnutrition and other hazards during the country’s wars with the Soviet Union. The children, many of them only preschoolers, were placed with foster families in Sweden. In addition to separation from their families, the children faced the stresses of adapting to their foster families, and in many cases, learning a new language. Upon their return, many children experienced the additional stress of readjusting to Finnish society.
During the same time, thousands of Finnish families chose not to evacuate all their children and often kept some at home, but little information exists on the rationale for their decisions. The researchers compared the risk of being hospitalized for a psychiatric (mental health) disorder among offspring of the evacuees to the risks of psychiatric hospitalization among the offspring of the siblings who remained with their parents. Studying the two groups—cousins to each other—allowed the researchers to compensate for family-based factors that can contribute to mental health problems and to focus instead on the evacuees’ wartime experience.
In a previous study, the researchers found that women evacuated as children were more than twice as likely to be hospitalized for a psychiatric disorder than their female siblings who remained at home. For the current study, the researchers linked records from this generation — more than 46,000 siblings born between 1933 and 1944 — to those of their offspring, more than 93,000 individuals born after 1950. Of these, nearly 3,000 were offspring of parents who had been evacuated to Sweden as children, and more than 90,000 were offspring of parents who remained in Finland during the war.
The researchers found that female evacuees and their daughters were at the greatest risk for being hospitalized for mood disorders, such as depression and bipolar disorder. In fact, the evacuees’ daughters had more than four times the risk of hospitalization for a mood disorder, compared to the daughters of mothers who stayed home — regardless of whether their mothers were hospitalized for a mood disorder.
The researchers did not find any increase in psychiatric hospitalizations for the sons or daughters of males who had been evacuated as children.
The study could not determine why the daughters of female evacuees had a higher risk of mental illness. One possibility is that the stresses of the evacuees’ experience affected their psychological development in ways that influenced their parenting style. Another possibility is that the evacuee experience resulted in epigenetic changes. For example, the researchers cited an earlier finding that Holocaust survivors have higher levels of compounds known as methyl groups bound to the gene FKBP5 and have passed this change on to their children. This higher level of methyl groups appears to alter the production of cortisol, a hormone that regulates the stress response.
“The Finnish evacuation was intended to protect children from the many harms associated with the country’s wars with the Soviet Union,” said study co-author Torsten Santavirta, Ph.D., of Uppsala University. “Our observation of long-term psychiatric risk that reached into the next generation is concerning and underscores the need to weigh benefits as well as potential risks when designing policies for child protection.”
The authors concluded that future studies are needed to understand how the experience of war affects the mental health of parents and their offspring and to develop interventions to help families affected by armed conflict.
Source: Meredith Daly – NIH
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Original Research: Full open access research for “Association of the World War II Finnish Evacuation of Children with Psychiatric Hospitalization in the Next Generation” by Santavirta, T, Santavirta, N, and Gilman, SE in JAMA Psychiatry. Published online November 29 2017 doi:10.1001/jamapsychiatry.2017.3511
Association of the World War II Finnish Evacuation of Children with Psychiatric Hospitalization in the Next Generation
Importance Although there is evidence that adverse childhood experiences are associated with worse mental health in adulthood, scarce evidence is available regarding an emerging concern that the next generation might also be affected.
Objective To compare the risk of psychiatric hospitalization in cousins whose parents were vs were not exposed to the Finnish evacuation policy that involved a mean 2-year stay with a Swedish foster family.
Design, Setting, and Participants This multigenerational, population-based cohort study of Finnish individuals and their siblings born between January 1, 1933, and December 31, 1944, analyzed the association of evacuee status as a child during World War II in the first generation with the risk of psychiatric hospitalization among offspring in the second generation. Evacuee status during World War II was determined using the Finnish National Archive’s registry of participants in the Finnish evacuation. Data on evacuee status were linked to the psychiatric diagnoses in the Finnish Hospital Discharge Register from January 1, 1971, through December 31, 2012, for offspring (n = 93 391) born between January 1, 1950, and December 31, 2010. Sex-specific Cox proportional hazards regression models were used to estimate hazard ratios for risk of psychiatric hospitalization during the follow-up period. Because offspring of evacuees and their nonevacuated siblings are cousins, the Cox proportional hazards regression models included fixed effects to adjust for confounding factors in families. Data analysis was performed from June 15, 2016, to August 26, 2017.
Exposures Parental participation in the evacuation during World War II (coded 1 for parents who were evacuated and placed in foster care and 0 for those not evacuated).
Main Outcomes and Measures Offspring’s initial admission to the hospital for a psychiatric disorder, obtained from the Finnish Hospital Discharge Register from January 1, 1971, through December 31, 2012.
Results Of the 93 391 study persons, 45 955 (49.2%) were women and 47 436 (50.8) were men; mean (SD) age in 2012 among survivors was 45.4 (6.58) years. Female offspring of mothers evacuated to Sweden during childhood had an elevated risk of psychiatric hospitalization (hazard ratio for any type of psychiatric disorder: 2.04 [95% CI, 1.04-4.01]; hazard ratio for mood disorder: 4.68 [95% CI, 1.92-11.42]). There was no excess risk of being hospitalized for a psychiatric disorder among women whose fathers were exposed to the Finnish evacuation policy during World War II or among men whose mothers or fathers were exposed.
Conclusions and Relevance In a prior follow-up study of the Finnish evacuees, girls evacuated to Swedish foster families during World War II were more likely to be hospitalized for a psychiatric disorder—in particular, a mood disorder—in adulthood than their nonevacuated sisters. The present study found that the offspring of these individuals were also at risk for mental health problems that required hospitalization and suggests that early-life adversities, including war-related exposures, may be associated with mental health disorders that persist across generations.
“Association of the World War II Finnish Evacuation of Children with Psychiatric Hospitalization in the Next Generation” by Santavirta, T, Santavirta, N, and Gilman, SE in JAMA Psychiatry. Published online November 29 2017 doi:10.1001/jamapsychiatry.2017.3511