The ongoing Ukraine–Russia war and Israel–Palestinian conflict have plunged millions of people into humanitarian crisis, displacing families and leaving children vulnerable to continued violence and instability.

The psychological harm of witnessing the horrors of war, of loss, fear, and insecurity, is widely acknowledged, but emerging research suggests that the harm runs even deeper.

A ground-breaking study from the University of Surrey reveals how war affects children at a biological level, altering their DNA through a process called DNA methylation.

These changes can have lifelong effects on their mental and physical health, revealing the hidden costs of war on the youngest and most vulnerable victims.

biological effects of war on children

The first-of-its-kind research, published in JAMA Psychiatry, involved saliva samples from 1,507 Syrian refugee children aged 6 to 19 living in informal settlements in Lebanon.

The researchers analyzed DNA methylation (DNAm), an epigenetic process that modifies DNA by adding chemical tags, potentially activating or silencing genes without altering the underlying genetic code.

This means that changes in DNA may increase susceptibility to anxiety, depression, and post-traumatic stress (PTST) by impairing the brain’s ability to process and regulate emotions or by increasing sensitivity to stress.

At the physical level, children may have weakened immune systems, be prone to chronic inflammation, or have slowed physical development, as seen in children exposed to trauma such as war.

To assess war-related trauma, questionnaires were completed by both the children and their caregivers.

In collaboration with University College London, Lebanese research institutions and an international NGO, the team discovered DNM changes in children exposed to war events. These changes were found in genes responsible for important functions such as neurotransmission (nerve cell communication) and intracellular transport (movement of materials within cells).

Interestingly, the study revealed that these DNA changes are specific to war trauma and differ from changes caused by other adversities such as poverty or bullying.

Lead researcher Professor Michael Plous, from the University of Surrey, said: “Our findings show that war impacts children not only mentally but also biologically. We observed slower epigenetic aging in these children, indicating that war “Can also affect their development.”

He added, “This study highlights the widespread and tragic cost of war on the millions of children who are vulnerable to it.”

Key Insights from the BioPath Study

Part of the BIOPATH study, which began in 2017, this research is a milestone in understanding the long-term effects of trauma on refugee children. The study also revealed significant gender differences.

Girls exposed to war events displayed more significant DNA changes than boys, particularly in genes related to stress response and brain development. This suggests that girls may be biologically more sensitive to the long-term effects of trauma.

DNA methylation is a natural process in which methyl groups are added to DNA, acting as switches that control gene activity. While necessary for normal development, DNM can be affected by environmental factors such as stress and trauma.

Chronic experiences such as war can alter DNA patterns, causing lasting biological effects on mental and physical health.

The findings provide a deeper understanding of how extreme stress reshapes the biology of children in war zones.