An assessment of the validity of laboratory animal behavioural research as translatable models of early childhood adversity

In mammals, early-life experiences, from post-partum to adolescence, shape the response to chronic stress and its related disorders, later, during their adult lives. Laboratory animals (predominantly rodents) are used in preclinical research models of early life adversity, to determine the pathogenesis of stress-related psychiatric disorders, such as depression, Post-Traumatic Stress Disorder (PTSD) and anxiety disorders. By tracking the behaviour of rodents and obtaining neurochemical data, the impact of early-life traumatic events can provide insights into stressinduced risk of psychiatric disorders in humans. The value of using rodents in models of childhood adversity is dependent on an integrative approach of finding common endophenotypes between the species. This review finds that there are deficiencies in dealing with conceptual issues, including genetic influences and inter-individual differences in vulnerability or resilience to negative consequences of stress. The need for standardisation and quality control, incorporating better experimental design and an understanding of the strengths and limitations of the models used, is prominent in current literature. This review outlines the frameworks and hypotheses that form the basis for the use of rodent models of early childhood adversity. The outcome of this review is that there is justification for the use of laboratory animal models to investigate individual symptoms, or markers, of early childhood adversity and associated psychiatric disorders. The frequently used rodent paradigms of early years adversity, provide a significant wealth of information of the impact of early-life stress on the functioning and architecture of the relevant brain regions and associated behavioural and physiological changes in mammals. Future research should focus on developing high quality rodent models of early childhood stress with the benefit of input from specialists designing human clinical research. This, combined with reproducible, carefully designed experiments, incorporating translatable rodent models, will help achieve increased validity of preclinical research of early childhood adversity.