A new study published in the Lancet looked at associations between childhood trauma and childhood psychiatric disorders in Brazil.
“This study looks at the impact of childhood trauma exposure on the mental health of adolescents at ages 15 and 18 in a Brazilian birth cohort,” study author Megan Bailey told us. Bailey is an ESRC-Funded PhD Researcher in the Department of Psychology at the University of Bath. “Most studies investigating the association between childhood trauma and mental health problems have been conducted in high-income countries and/or have relied on adults retrospectively recalling their childhood trauma exposures during adulthood. Comparatively little research has been conducted with youth living in low- and middle-income countries, despite higher rates of trauma exposure in these countries compared to high-income countries.”
The researchers expected that the prevalence of childhood trauma exposure would be higher in this middle-income sample compared to equivalent samples in high-income countries. Consistent with the findings from studies conducted in high-income countries, they expected childhood trauma exposure to significantly increase the odds of mental health problems among Brazilian adolescents, and that these effects would be evidenced across diagnostic classes, including anxiety, mood, attention-hyperactivity, and conduct-oppositional disorders.
“Children and adolescents living in low- and middle-income countries are disproportionately underrepresented in research, and much of the research investigating the impact of childhood trauma on mental health has been conducted with adults living in high-income countries,” Bailey told us. “The overall aim of this study, and of my PhD as a whole, has been to investigate the impact of childhood trauma on those that are most likely to experience traumatic events and the subsequent impact this might have on their mental health. This is particularly important in low- and middle-income countries where access to mental health support can be limited.”
The research team used data from the 2004 Pelotas Birth Cohort in Brazil. This cohort is an ongoing, longitudinal, population-based birth cohort that recruited 99.2% of all children born in the city of Pelotas in 2004 and has since followed these children up to the age of 18. Both trauma exposure and mental health problems have been repeatedly assessed throughout childhood and adolescence.
The researchers were therefore able to look at the concurrent associations between lifetime trauma exposure and mental health problems at ages 15 and 18 years, as well as the longitudinal associations between trauma exposure up to age 11 and mental health problems at ages 15 and 18, and trauma exposure up to age 15 and mental health problems at age 18.
“We found that among the 4229 adolescents included in our analyses, 81.2% reported trauma exposure before age 18, with 25.3% reporting that they had been exposed to three or more traumas, and 38.6% met criteria for at least one mental health problem at age 18,” Bailey told us. “Concurrently, we observed that childhood trauma exposure up to age 15 increased the odds of any disorder, anxiety disorders, and conduct-oppositional disorders at age 15.”
Additionally, concurrently at age 18, childhood trauma exposure increased the odds of any psychiatric disorder, as well as anxiety, mood, attention-hyperactivity, and conduct-oppositional disorders, such that each additional trauma exposure increased the odds of meeting criteria for a mental health problem.
Longitudinally, trauma exposure up to age 11 increased the odds of psychiatric disorders at age 15, and trauma exposure up to age 15 increased the odds of psychiatric disorders at age 18, but no effect was observed for trauma exposure up to age 11 and psychiatric disorders at age 18.
Overall, the research team observed particularly strong associations for the effect of childhood trauma exposure on conduct and oppositional disorders and anxiety disorders. They also calculated population attributable fractions to estimate the proportion of adolescent mental health problems explained by trauma exposure, and found that trauma exposure up to age 18 years accounted for at least 30.6% of psychiatric disorders at age 18.
“Surprisingly, we found that trauma exposure up to age 11 was not associated with mental health problems at age 18, despite an abundance of evidence from adult samples in high-income countries indicating that childhood trauma exposure is associated with increased odds of psychiatric disorders much later in life,” Bailey told us. “This could indicate that the effects of childhood trauma on mental health problems reduce over time, though it is also worth noting that trauma exposure up to age 11 were based solely on parent reports, while age 18 disorders were captured using adolescent self-reports.”
Moving forward, Bailey believes more research is still needed to examine the impact of childhood trauma on children and adolescents in other low- and middle-income countries.
“Our study indicates that the prevalence of childhood trauma exposure among youth in low- and middle-income countries is high, and that childhood trauma can have a substantial impact on youth mental health,” Bailey told us. “It highlights a critical need for improved access to and uptake of interventions for mental health problems, and increased efforts at preventing trauma exposure.”