Unravelling 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. Complex traumas are hypothesized to lead to more severe psychopathology and poorer cognitive function than other non-complex traumas. However, empirical testing of this hypothesis 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 (E-Risk) Longitudinal Twin Study, a population-representative birth-cohort of 2,232 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 age 5, IQ at age 5, family history of mental illness, family socioeconomic status, and sex.

Participants exposed to complex trauma had more severe psychopathology and poorer cognitive function at age 18 compared to 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 under-estimate 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 effective interventions.