Complex Trauma Linked to Cognitive Impairments and Mental Health Disorders

Summary: Young people who experienced complex early life trauma as a result of interpersonal violence or child abuse had more severe mental health problems and cognitive impairments than their peers with no exposure to trauma.

Source: King’s College London

New research from King’s has explored whether different types of trauma confer the same risk of future mental illness, in the first study of its kind.

The study, published in the British Journal of Psychiatry, investigated the theory that traumas occurring at an early age, that involve interpersonal violence and are repeated could represent a particularly detrimental type of trauma named complex trauma.

Participants were from the E-Risk Study, which tracks the development of 2,232 children born in England and Wales in 1994-1995. They were assessed for complex trauma exposure (such as repeated child abuse), exposure to other non-complex traumas (such as car accidents), as well as mental health problems, and cognitive function at age 18.

The researchers found that young people who had been exposed to complex trauma had more severe mental health problems and cognitive impairments, compared not only to trauma-unexposed peers but also to those exposed to non-complex traumas. These difficulties were seen across several mental health disorders and cognitive domains.

The researchers also found that several early childhood vulnerabilities, measured at age 5, predicted later exposure to complex trauma, but not non-complex trauma. These vulnerabilities also largely explained the associations between complex trauma exposure and cognitive impairments.

This shows a head made of bubbles
Findings showed that complex trauma exposure is linked with a wide range of mental health disorders and cognitive impairments. Image is in the public domain

Professor Andrea Danese, Professor of Child and Adolescent Psychiatry at King’s IoPPN said, “Our findings highlight that not all difficulties experienced by people exposed to complex trauma are necessarily caused by the exposure.

“The pre-existing vulnerabilities that increase risk of complex trauma exposure also seem to be responsible for cognitive impairments. Clinicians should therefore avoid making causal assumptions in their formulations and aim to address vulnerabilities in their management plans.”

Nevertheless, the researchers found that early childhood vulnerabilities did not explain mental health problems linked with complex trauma. This finding suggests that features of the trauma (such as severity) or responses to the trauma (such as self-blame) could lead to mental health disorders.

Further research that provides a better understanding of these underlying mechanisms could inform the development of new, more effective interventions for the mental illness experienced by people exposed to complex trauma.

Funding: This study was possible thanks to funding from the Medical Research Council (UK).

King’s IoPPN, in partnership with the South London and Maudsley NHS Foundation Trust and the Maudsley Charity, are in the process of opening a world-leading center for children and young people's mental health. The Pears Maudsley Centre for Children and Young People is expected to open in 2023 and will bring together researchers and clinicians to help find solutions that will transform the landscape for children’s mental health.

About this trauma and mental health research news

Author: Patrick O’Brien
Source: King’s College London
Contact: Patrick O’Brien – King’s College London
Image: The image is in the public domain

Original Research: Open access.
Unravelling the contribution of complex trauma to psychopathology and cognitive deficits: a cohort study” by Stephanie Lewis et al. British Journal of Psychiatry


Unraveling the contribution of complex trauma to psychopathology and cognitive deficits: a cohort study


Complex traumas are traumatic experiences that involve multiple interpersonal threats during childhood or adolescence, such as repeated abuse. These traumas are hypothesized to cause more severe psychopathology and poorer cognitive function than other non-complex traumas. However, empirical testing has been limited to clinical/convenience samples and cross-sectional designs.


To investigate psychopathology and cognitive function in young people exposed to complex, non-complex or no trauma, from a population-representative longitudinal cohort, and to consider the role of pre-existing vulnerabilities.


Participants were from the Environmental Risk Longitudinal Twin Study, a population-representative birth cohort of 2232 British children. At age 18 years (93% participation), we assessed lifetime exposure to complex and non-complex trauma, past-year psychopathology, and current cognitive function. We also prospectively assessed early childhood vulnerabilities: internalizing and externalizing symptoms at 5 years of age, IQ at 5 years of age, family history of mental illness, family socioeconomic status, and sex.


Participants exposed to complex trauma had more severe psychopathology and poorer cognitive function at 18 years of age, compared with both trauma-unexposed participants and those exposed to non-complex trauma. Early childhood vulnerabilities predicted risk of later complex trauma exposure, and largely explained associations of complex trauma with cognitive deficits, but not with psychopathology.


By conflating complex and non-complex traumas, current research and clinical practice underestimate the severity of psychopathology, cognitive deficits, and pre-existing vulnerabilities linked with complex trauma. A better understanding of the mental health needs of people exposed to complex trauma could inform the development of new, more effective interventions.