Summary: War exposure in Syrian refugee children triggered unique DNA methylation changes, marking genes involved in brain development and stress responses. These epigenetic changes suggest potential long-term effects on health and development, distinct from other traumas like poverty.
Researchers also found that girls exhibit stronger biological responses than boys, highlighting differences in vulnerability. The study highlights the profound biological and mental cost of war on young lives. These findings pave the way for deeper insights into trauma’s biological footprint and its implications for health.
Key Facts:
- DNA methylation changes linked to war exposure were observed in critical genes for brain function and stress regulation.
- Girls showed more significant DNA changes than boys, suggesting higher vulnerability.
- The study found evidence of slower epigenetic aging in children exposed to war, potentially affecting development.
Source: University of Surrey
Children living in war-torn countries not only suffer from poor mental health outcomes, but war may cause adverse biological changes at the DNA level, which could have lifelong health impacts, according to a ground-breaking study from the University of Surrey.
In the first study of its kind, the research team collected saliva samples from 1,507 Syrian refugee children, aged 6 to 19, living in informal settlements in Lebanon.
They analysed DNA methylation (DNAm), an epigenetic process where chemical tags are added to DNA at various sites in the genome (the complete set of genes). These DNAm changes can turn genes on or off without changing the DNA code.
Questionnaires, completed by both the children and their caregivers, were used to measure exposure to the war-related events experienced by the child.
Surrey – in collaboration with University College London, Institute for Development, Research, Advocacy and Applied Care, Lebanon, St Georges University Lebanon, and a leading international NGO – found that children who had been exposed to war events showed DNA m changes at several sites and regions in the genome.
Some of these changes were linked to genes involved in critical functions like neurotransmission (how nerve cells communicate) and intracellular transport (how materials move within cells).
These specific changes are not known to be present in other forms of trauma, like poverty or bullying, suggesting that war may trigger unique biological responses in the body.
This research is funded by the National Institutes of Health (NIH).
Professor Michael Pluess, lead author of the study from the School of Psychology at the University of Surrey, said:
“While it’s common knowledge that war has an adverse impact on the mental health of children, our study has found evidence of the biological mechanisms underlying this effect. We also found that war is linked to slower epigenetic ageing – which could mean that war could be impacting the development of children.
“All told, our study paints a clearer picture of the tragic cost of war, beyond the mental stress, for the many millions of children caught in the middle of it.”
This paper is part of the BIOPATH study, a cohort study which began in 2017. BIOPATH is the first large-scale study of its kind among refugee children, setting the stage for a deeper understanding of how trauma impacts mental health development.
Additionally, the researchers also looked into how the biological effects of war differ between boys and girls. They found that girls who experienced war events showed more significant DNA m changes than boys, particularly in genes linked to stress response and brain development.
While both boys and girls were affected, girls showed a stronger biological response to war exposure, suggesting that they may be more vulnerable to the long-term effects of trauma at a molecular level.
DNA m is a natural process where small chemical groups, called methyl groups, are added to certain parts of our DNA. These groups act like switches, turning genes on or off or adjusting how strongly they are expressed. Importantly, this doesn’t change the actual DNA sequence itself.
DNA m plays a key role in normal development and can be influenced by things like diet, stress, and exposure to trauma. When someone experiences extreme events, such as war, it can lead to changes in DNA m, which might affect their long-term physical and mental health. Scientists study these changes to understand how stressful experiences can leave lasting biological marks on the body.
About this genetics, trauma, and neurodevelopment research news
Author: Dalitso Njolinjo
Source: University of Surrey
Contact: Dalitso Njolinjo – University of Surrey
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Associations between war exposure and DNA methylation in Syrian refugee children and adolescents” by Michael Pluess et al. JAMA Psychiatry
Abstract
Associations between war exposure and DNA methylation in Syrian refugee children and adolescents
Importance
Exposure to war is associated with poor mental health outcomes. Adverse and traumatic experiences can lead to long-lasting DNA methylation changes, potentially mediating the link between adversity and mental health.
To date, limited studies have investigated the impact of war on DNA methylation in children or adolescents, hampering our understanding of the biological impact of war exposure.
Objective
To identify salivary DNA methylation differences associated with war exposure in refugee children and adolescents.
Design, Setting, and Participants
This cohort study included Syrian refugee children and adolescents, and their primary caregiver were recruited from tented settlements in Lebanon. Data collection was carried out in 2 waves, 1 year apart, from October 2017 to January 2018 and October 2018 to January 2019. Children and their caregiver were interviewed, and children provided saliva samples for DNA extraction. Data analysis was conducted in 2022, 2023, and 2024.
Exposure
War exposure assessed by interviewing children and their caregiver using the War Events Questionnaire.
Main Outcomes and Measures
Salivary DNA methylation levels were assayed with the Infinium MethylationEPIC BeadChip (Illumina). Epigenetic aging acceleration was estimated using a set of preexisting epigenetic aging clocks. A literature search was conducted to identify previously reported DNA methylation correlates of childhood trauma.
Results
The study population included 1507 children and adolescents (mean [SD] age, 11.3 [2.4] years; age range, 6-19 years; 793 female [52.6%]). A total of 1449 children provided saliva samples for DNA extraction in year 1, and 872 children provided samples in year 2.
Children who reported war events had a number of differentially methylated sites and regions. Enrichment analyses indicated an enrichment of gene sets associated with transmembrane transport, neurotransmission, and intracellular movement in genes that exhibited differential methylation.
Sex-stratified analyses found a number of sex-specific DNA methylation differences associated with war exposure. Only 2 of 258 (0.8%) previously reported trauma-associated DNA methylation sites were associated with war exposure (B = −0.004; 95% CI, −0.005 to −0.003; Bonferroni P = .04 and B = −0.005; 95% CI, −0.006 to −0.004; Bonferroni P = .03).
Any war exposure or bombardment was nominally associated with decreased epigenetic age using the Horvath multitissue clock (B = −0.39; 95% CI, −0.63 to −0.14; P = .007 and B = −0.42; 95% CI, −0.73 to −0.11; P = .002).
Conclusions and Relevance
In this cohort of Syrian refugee children and adolescents, war exposure was associated with a small number of distinct differences in salivary DNA methylation.
