In children and adolescents who have experienced child abuse, the body appears to remain in a state of alert for too long, and this situation can affect several bodily systems, such as the neuroendocrine, immune and metabolic systems. When this alert response is prolonged, it leads to cumulative wear and tear on all the biological systems that normally respond to stress, a phenomenon known as allostatic load. Furthermore, victims who have experienced a greater accumulation of different types of maltreatment also show a higher prevalence of psychiatric disorders.

But is it possible to identify children who are biologically more vulnerable to child maltreatment and to the development of mental health disorders?

Now, a study published in the Journal of Affective Disorders presents a methodology that could help identify profiles of greater biological and clinical vulnerability in children and adolescents who have been exposed to maltreatment. The study identifies a set of biomarkers that could indicate greater wear and tear on the biological systems that facilitate adaptation to the stress caused by the trauma of maltreatment.

The study is led by Lourdes Fañanás, a professor at the Faculty of Biology and a researcher at the Institute of Biomedicine (IBUB) at the University of Barcelona, and a member of the CIBER Area for Mental Health (CIBERSAM).

Other leading experts in the study include Laia Marques-Feixa and Nerea San Martín (UB, IBUB and CIBERSAM) and Soledad Romero (Hospital Clínic, IDIBAPS and CIBERSAM).

Child maltreatment: a situation of chronic stress

Child maltreatment is a form of chronic stress that is particularly significant in terms of mental health because it occurs at stages when the brain is still developing and maturing.

“These experiences usually occur within the child’s familiar environment and attachment context, which can place them in a particularly ambivalent position: they need protection, care and a bond with the very same figures who may be causing them emotional, physical or relational harm,” explain Laia Marques-Feixa and Lourdes Fañanás, from the UB’s Department of Evolutionary Biology, Ecology and Environmental Sciences.

The study analysed the maltreatment among 187 children and adolescents aged between 7 and 17 — whether they had a psychiatric diagnosis or not — including emotional neglect, physical neglect, emotional abuse, physical abuse and sexual abuse. “All these experiences were analysed cumulatively by creating an index, as it has been shown that, in practice, many do not occur in isolation in a child’s life story, but rather in combination,” says Marques-Feixa, the article’s lead author.

Peripheral biomarkers, the brain and vulnerability to abuse

The study focused on identifying whether there were any biological markers that might reflect a greater biological vulnerability to the effects of maltreatment. To this end, a comprehensive index was designed to reflect this allostatic load through 10 biomarkers from different systems of the body, including the neuroendocrine, immune, metabolic and anthropometric systems.

Children who had been abused had a higher number of biomarkers above the risk threshold described in the general population. Furthermore, a particularly informative combination of three biomarkers was identified: high diurnal cortisol levels, elevated serum C-reactive protein (CRP) and a higher waist-to-height ratio (referred to as AL3 in the study).

“This combination could help identify profiles of greater biological and clinical vulnerability in children and adolescents who have been exposed to abuse,” the authors explain.

Furthermore, according to Fañanás, recent studies by Professor Ed Bullmore’s team at the University of Cambridge suggest that part of the link between early maltreatment and the brain changes detected by neuroimaging in exposed subjects could be explained by biological intermediary pathways, for example, low-grade systemic inflammation —measured by C-reactive protein — or by metabolic and physical factors, such as body mass index or abdominal adiposity.

In this regard, findings on allostatic load provide a further piece of the puzzle in understanding how early-life stress can become biologically embedded in an individual and be linked to changes in the brain and mental health problems in both childhood and adulthood.

In this regard, findings on allostatic load provide more information to understand how early-life stress can become biologically embedded in an individual and be linked to changes in the brain and mental health issues in both childhood and adulthood.

Protecting children from child maltreatment

Finally, the paper reinforces the idea that child maltreatment should be understood as a cross-cutting vulnerability factor, as it is not associated with specific psychiatric diagnoses but, in these early stages of life, manifests itself in the form of psychological distress and, above all, in the form of difficulties with emotional, behavioural and relational regulation.

Although no differences in outcomes are apparent between boys and girls, the authors highlight the need for studies on the impact of child abuse on mental health from a gender perspective, particularly during puberty, a period characterized by hormonal, neuroendocrine and physical changes.

Ensuring the child’s safety and putting a stop to the abuse or neglect is the first step in combating child abuse. Early detection, family and social support, and specialist psychological treatment for trauma are other measures that should also be considered.