Study reveals strong link between childhood trauma and adolescent psychiatric disorders

A new study by a team of researchers from the UK and Brazil has revealed a strong connection between childhood trauma and the development of psychiatric disorders in adolescents living in low-and middle-income countries.

The research findings are based on the 2004 Pelotas Birth Cohort, Brazil, which has tracked more than 4,000 children born in Pelotas, a city in the southern state of Rio Grande do Sul, from birth to age 18. Published in The Lancet Global Health, the study looked at how trauma exposure from childhood affects risk for mental health disorders during adolescence.

The results showed that by age 18, 81% of the adolescents had been exposed to some form of trauma, such as witnessing a violent crime, abuse or neglect. The more different types of trauma experienced, the greater the chances of adolescents developing mental health problems, particularly anxiety, mood, and conduct disorders. By the age of 18, one third of all mental disorders were potentially explained by trauma exposure.

This study builds upon the researchers’ earlier findings in the same cohort, which showed that one in three children living in Pelotas were exposed to trauma by age 11, and that trauma was linked to the emergence of common childhood mental health problems.

Lead researcher Megan Bailey from the Department of Psychology at the University of Bath said:

“Our findings show that childhood trauma has a lasting impact on mental health, particularly in low- and middle-income countries where trauma is very common. In combination with previous studies that have also shown these effects in both young people and adults in high-income countries, it is clear that childhood trauma exposure is a key risk factor for developing mental health problems across the board. Our finding that trauma accounts for at least 31% of all mental health problems by age 18 further underscores this relationship. Early interventions are critical to reduce exposure to trauma and help those most at risk of developing mental health disorders.”

In Pelotas, a city-led intervention programme, the Pelotas Pact for Peace, was launched in 2017 to reduce urban crime and violence through health, education, and criminal justice system projects. Early evaluations of this intervention showed lower rates of violent crimes after the intervention was implemented, though more research is needed to establish whether it also reduces the prevalence of mental health problems in young people.

Co-author Dr. Graeme Fairchild from the Department of Psychology at the University of Bath said:

“This study demonstrates that childhood trauma has long-term consequences on mental health – and risk for mental health problems was seen across the board, with trauma-exposed youth at increased risk for depression, anxiety, ADHD, and severe antisocial behaviour. The study highlights the urgent need for prevention strategies to reduce exposure to trauma in low- and middle-income countries and provide more effective support for traumatised children and teenagers.”

Co-author Professor Sarah Halligan from the Department of Psychology at the University of Bath said:

“Childhood trauma is a robust predictor of poor adolescent mental health, and our work demonstrates that youth in low- and middle-income countries like Brazil may be particularly at risk. As well as efforts to prevent trauma exposure, we need to take steps, such as those being undertaken as part of the Pelotas Pact for Peace programme, to limit its mental health consequences among youth. If left unaddressed, childhood trauma may have persistent negative consequences across the lifespan.”

Co-author, Professor Alicia Matijasevich from the University of São Paulo, Brazil, said:

“Research on the impact of childhood trauma and maltreatment is critically important due to its profound implications for mental health and emotional development. These studies not only enhance our understanding of trauma’s far-reaching effects but also provide essential evidence to guide preventive strategies and interventions that can mitigate the long-term consequences of such adverse experiences.”

This new analysis was funded by a studentship awarded to Megan Bailey by the University of Bath and the South-West Doctoral Training Partnership (Economic and Social Research Council) and by projects funded by the Brazilian National Research Council (CNPq; 409224/2021-9) and the Research Support Foundation of the State of São Paulo (FAPESP)/ Economic and Social Research Council/UK Research and Innovation (UKRI; 2023/12905-0).