Researchers investigate how trauma can be transmitted between generations
February 19, 2020
By Maria Fernanda Ziegler | Agência FAPESP – Extremely painful experiences in early childhood, such as negligence, physical or sexual abuse and mental torture, are known to have the potential to impair mental health in adult life. Research has shown that the negative effects of traumatic childhood experiences can be transmitted to descendants, even those who have never had similar experiences. This is called intergenerational trauma and was first noted in descendants of Holocaust concentration camp survivors.
The mechanisms involved in this transmission will now be investigated in a research project with 580 pregnant women living in situations of vulnerability in Guarulhos, a major city in metropolitan São Paulo, Brazil.
The study is being funded by FAPESP and the US National Institutes of Health (NIH) and conducted by researchers at Columbia University in New York and the Federal University of São Paulo’s Medical School (EPM-UNIFESP) in Brazil.
“Although some studies have demonstrated the influence of adverse events that occurred in the expectant mother’s infancy on the mental development of her children, the mechanisms involved are poorly understood. Our study is the first to analyze placental alterations and the neurodevelopment of the baby using genetics, neonatal MRI scans and cognitive assessments,” said Andrea Parolin Jackowski, a professor at EPM-UNIFESP and principal investigator for the project in Brazil.
Transmission via the placenta
According to Jackowski, the predominant hypotheses link intergenerational trauma to high levels of inflammatory markers or the stress hormone cortisol during pregnancy, resulting in epigenetic alterations (biochemical changes in the cells that control gene activation or silencing), which are transmitted to offspring.
Pro-inflammatory substances and cortisol produced during pregnancy by women traumatized in childhood somehow switch on or off genes associated with mental health problems such as depression or attention deficit disorder, among others.
“This is transmitted to the fetus via the placenta, the channel for communication between mother and fetus. These placental epigenetic alterations affect fetal brain development,” Jackowski said.
In addition to understanding the mechanisms of intergenerational trauma, the project also aims to explore possible ways to prevent mental health problems in the children of traumatized women.
“We’d like to find out which behaviors are altered by these mechanisms and think about methods of prevention that might be employed during pregnancy,” Jackowski said.
The study will evaluate 580 pregnant women who attend units of SUS, Brazil’s national health system, in Guarulhos. They will be divided into two groups, one half with and the other half without adverse childhood experiences.
In addition to genomic and epigenomic analysis of placental and blood samples in search of inflammation markers, as well as hair samples from mothers and babies to measure cortisol levels, the researchers will monitor the infants’ neurodevelopment and cognitive control for 24 months after birth.
The links between maternal trauma and infant brain development will be investigated by neonatal MRI scanning and behavioral analysis of cognitive control at 12 and 24 months.
“Mothers with a history of adverse childhood experiences are known to run a higher risk of having children with neonatal alterations in brain circuits that are responsible for cognitive control,” Jackowski said. “At 24 months, it’s possible to detect these developmental alterations. At age 5 or 6, these children exhibit an augmented risk of developing impulsive behavior.”
None of the child development studies in progress at Columbia University and elsewhere prioritize investigating in depth the pathways linking adverse childhood experiences, inflammation, and placenta and brain development, Jackowski noted.
“Unfortunately, we’re able to do this kind of study in Brazil because of the existence of groups who are vulnerable to various kinds of violence, and fortunately, the existence of the SUS enables us to collect detailed high-quality information in a low-income population in the right context for future interventions aiming to break this cycle of violence and its impacts as early as possible,” she said.
The project follows a pilot study conducted with 40 pregnant women and their babies attending three public healthcare centers and a maternity hospital in São Paulo. “In the future, we plan to extend the study of 580 pregnant women and track the development of their children until they reach school age,” Jackowski said.
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