A new study demonstrates the influence of genetic factors and resilience — the resources and capacities for overcoming adversity — on changes in levels of psychosocial stress and mental health for Syrian refugee youth who experienced war and forced displacement.

“Individual children vary in how quickly they recover from highly stressful and traumatic experiences, and the extent to which they respond to brief humanitarian programs intended to alleviate profound stress in war-affected populations. This may be because individuals are differentially sensitive and responsive to their environments,” said Catherine Panter-Brick, professor of anthropology at Yale and the study’s principal investigator. “We tested whether the interplay between genetic and psychosocial factors matters for stress and mental health recovery.”

The study, published July 17 in PLOS ONE, provides scientific evidence that genetics and environmental factors play important roles in the mental health of refugee youth, specifically on their perceived levels of stress.

The researchers examined the effect of monoamine oxidase A (MAOA) — a gene that serves as a key regulator of brain function — on changes in the levels of psychosocial stress among Syrian adolescent boys over time. MAOA occurs in low-activity and high-activity variations. The low-activity variant is often associated with violent and antisocial behaviors, particularly in males, and has been labeled “the warrior gene” as a result.

The study found that males with low-activity variants of MAOA had sharper reductions in perceived stress over time than males with high-activity MAOA variants. The study also found that perceived stress was reduced in males with high levels of resilience — a protective factor composed of individual, interpersonal, and cultural resources that the adolescents rely on to foster strength in difficult times. Males with high resilience and low-activity MAOA showed the sharpest reduction in levels of psychosocial stress over time.

Past studies have identified associations between MAOA variants and a wide range of aggressive and antisocial behavior in males, including physical aggression, criminal violence, and reduced social cooperation. Virtually no studies have investigated the influence of MAOA and protective factors on psychosocial and mental health outcomes, said Connie Mulligan, professor of anthropology and genetics at the University of Florida and the paper’s lead author.

“We’re seeing the effects of nature and nurture in the way these kids perceive and respond to stress,” Mulligan said. “It’s unusual to have a project like ours where we test the effects of genetics and the environment in the same study.”

The research team studied a cohort of 399 Syrian refugee youth, male and female, between the ages of 12 and 18. The participants were living in four cities in northern Jordan — Irbid, Jarash, Mafraq, and Zarqa — that have been heavily affected by the Syrian crisis. The youth were engaged in an eight-week stress attunement program implemented by the humanitarian organization Mercy Corps.

At three different points over the course of a year, the research team collected DNA samples via cheek swabs, as well as other markers of physiological and psychosocial stress. The researchers worked in partnership with local communities to ensure careful and ethical data collection. They measured trauma exposure, resilience, and mental health outcomes, including a range of biological and genetic markers to better identify the factors that might explain youth “getting better” over time. 

“Our findings are a step towards reaching an in-depth understanding of how war-affected youth respond to the trauma of war and the ongoing stressors of forced displacement,” Panter-Brick said. “They are also important to understanding the effectiveness of community-level interventions for war-affected youth.”

Since hostilities began in 2011, the Syrian crisis has forced nearly 5.7 million people to flee the country while another 6.5 million Syrians are internally displaced, creating the world’s largest refugee crisis since World War II, according to the Office of the United Nations High Commissioner for Refugees.

The research benefits the local population in Jordan by putting Syrian refugees on the map of scientific inquiry, which is important to sharing their story with a broader audience, Panter-Brick said. It also forges long-term partnerships between research institutions in the United States and colleagues at universities in Jordan, she said, noting that one of the Syrian women who helped conduct the field research visited Yale and the University of Florida to see lab facilities and lead a class. 

“Our research team worked for 18 months in Jordan and included several young women who had graduated from Jordanian universities with degrees in biotechnology and genetics,” she said. “The study motivated these young women to work as research scientists and pursue graduate education.” 

Panter-Brick’s research team, working with the same cohort of Syrian youth, has developed and tested a tool for measuring resilience in Syrian refugee youth; evaluated the effectiveness of a humanitarian intervention meant to improve the mental health of youth affected by the Syrian crisis; and showed that a humanitarian program reduced levels of cortisol, a hormone associated with stress, in Syrian refugee youth.

The PLOS ONE study’s other co-authors are Christopher J. Clukay, a doctoral candidate at the University of Florida’s Genetics Institute; Rana Dajani, professor of biology and biotechnology at the Hashemite University in Jordan; Kristin Hadfield, assistant professor, School of Biological and Chemical Sciences, at Queen Mary University of London; and Jacklyn Quinlan, postdoctoral research fellow at the University of Florida’s Genetics Institute during the period of the study.

The field research was funded by Elrha’s Research for Health in Humanitarian Crises (R2HC) Programme. The University of Florida College of Liberal Arts and Sciences and and the National Science Foundation supported the lab research.