Ahmed was 8 years old when the war in Syria began. He and his family fled to Lebanon, where they live in a crowded informal settlement. During the war, Ahmed witnessed the destruction of his home, the death of neighbors, and the constant fear of bombings. These traumatic events deeply affected Ahmed’s mental health, leading to anxiety, nightmares, and difficulty concentrating in school.
However, when a team of researchers studied DNA methylation (DNAm) in war-affected children, like Ahmed, it found that trauma related to conflict not only produced a mental scar in these impressionable minds but also unique biological responses in the body.
This could have lasting health implications, the first study of its kind warned. The research team from Surrey University among others collected saliva samples from 1,507 Syrian refugee children, aged 6 to 19, living in informal settlements in Lebanon. They analysed 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 DNAm 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), as per the study published in JAMA Psychiatry.
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.
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.”
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.
DNAm 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.
These changes are often not seen in other forms of trauma, like bullying or poverty. The methylation of certain genes—those involved in stress response, neurotransmission, and brain development—can have lasting effects on mental health, cognitive abilities, and overall well-being.
