Adversity as a causal mechanism

Dan Johnson's article on adverse childhood experiences (ACEs) is a welcome précis of the importance of adversity in warping normative developmental trajectories ('What should we do about trauma?', June 2018). The term ACEs is becoming ubiquitous in child psychology, among service leaders and policymakers. At a recent forensic event I attended, speakers talked enthusiastically about ACEs as being primarily causal in serious violence – with no basis for such claims apart from their experience. At the time I mused about how many prosocial researchers and practitioners in the audience likely experienced ACEs.

The serious study of ACEs as a causal mechanism is a scientific endeavour, currently in its infancy. Dan Johnson recognises the problems of association research versus causal mechanisms yet stops short of elucidating the kinds of methodologies which are needed to shine light on potential causal mechanisms. Dan omits the need for genetically informative designs that take account of complex gene x environment interactions within a theoretical framework of differential susceptibility. Genetically informative research designs cut across our preconceived biases, such as simplistic linear associations between ACEs and life outcomes. Also, it is essential to highlight critical mechanisms that might mediate ACEs and life outcomes, such as emotional dysregulation, which in turn are important targets 
in psychological interventions (Poole et al. 2018).

For children with neurodevelopmental disorders (NDDs), genetically informative studies focusing on ACEs as causal or contributing factors, are beginning to illuminate complex causal pathways, raising far more questions. A recent co-twin control study demonstrates paradoxically that, child maltreatment was not associated with an increased load for NDDs. This counterintuitive result perhaps indicated that co-occurrence of child maltreatment with NDDs seems to a large extent to be accounted for by a shared genetic liability, increasing both the risk of being maltreated and having more co-occurring NDDs (Dinkler et al. 2017).

Parenting children with NDDs is stressful especially if the parent also has NDDs impacting on their capacity. The point of studying causal mechanisms is to prevent adversity at a broader policy level and target early interventions that are effective. But most importantly perhaps, scientific causal mechanism research may facilitate the development of novel approaches to interventions. ACEs are critical in psychological formulations and contribute to a range of psychological problems, but the scientific study of causal complexity unfolding before us challenges some of our assumptions.  As Thomas Henry Huxley stated in 1870, at his presidential address of the British Association for the Advancement of Science: 'The great tragedy of science is the slaying of a beautiful hypothesis, by an ugly fact.'

John Marshall
Dumbarton

References
Dinkler, L. , Lundström, S. , Gajwani, R. et al. (2017), Maltreatment‐associated neurodevelopmental disorders: A co-twin control analysis. Journal of Child Psychology and  Psychiatry, 58, 691–701.
Poole, J.C. , Dobson, K.S. & Pusch, D. (2018). Do adverse childhood experiences predict adult interpersonal difficulties? Child Abuse and Neglect, 80, 123–133.