‘Natural Experiments’ as a Means of Testing Causal Inferences

Risk factors for disruptive behaviours: protocol for a systematic review and meta-analysis of quasi-experimental evidence

INTRODUCTION

Disruptive behaviour disorders, including oppositional defiant disorder and conduct disorder, are a common set of diagnoses in childhood and adolescence, with global estimates of 5.7%, 3.6% and 2.1% for any disruptive disorder, oppositional defiant disorder and conduct disorder, respectively. There are high economic and social costs associated with disruptive behaviours and the prevalence of these disorders has increased in recent years. As such, disruptive behaviours represent an escalating major public health concern and it is important to understand what factors may influence the risk of these behaviours. Such research would inform interventions that aim to prevent the development of disruptive behaviours. The current review will identify the most stringent evidence of putative risk factors for disruptive behaviour from quasi-experimental studies, which enable stronger causal inference.

METHODS AND ANALYSIS

The review will be carried out according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. An electronic search of references published between 1 January 1980 and 1 March 2020 will be conducted using Medline, Embase, PsycINFO and Web of Science. Initial abstract and title screening, full-text screening and data extraction will be completed independently by two reviewers using Evidence for Policy and Practice Information (EPPI)-Reviewer 4 software. Quasi-experimental studies in the English language examining the association between any putative risk factor and a clearly defined measure of disruptive behaviour (eg, a validated questionnaire measure) will be included. We will conduct meta-analyses if we can pool a minimum of three similar studies with the same or similar exposures and outcomes.

ETHICS AND DISSEMINATION

The proposed review does not require ethical approval. The results will help to identify risk factors for which there is strong evidence of causal effects on disruptive behaviours and also highlight potential risk factors that require further research. The findings will be disseminated via publication in a peer-reviewed scientific journal and through presentations at international meetings and conferences.

PROSPERO REGISTRATION NUMBER

CRD42020169313.

Translation gone awry: differences between commonsense and science

A general assumption is that science is just organised commonsense. It is noted that translation involves a two-way pathway between basic laboratory science and patient care, and that some scientific findings have implications for prevention rather than treatment. A succinct critique follows on the key features that differentiate science and commonsense. The main part of the paper discusses six rather different examples of translation that went awry because people treated science and commonsense as equivalent. Examples based on empirical evidence of translation going awry include (i) the claim that only early intervention can bring lasting benefits; (ii) the claim that the main policy goal for children should be the elimination of all stresses; (iii) the claim that exposure in utero to maternal smoking causes ADHD and conduct disturbance; (iv) the claim that tax benefits should be used to encourage couples to marry; (v) the effects of profound institutional deprivation are similar to those of any adversity; and (vi) environmental effects are largely independent of genetic influences. Much of science is 'unnatural' in the sense that technical tools (such as imaging or DNA) are employed, or because animal models are used, or because unusual comparisons are made. Science cannot be based solely on an inductive process; rather, there must be some form of experiment and the testing of two or more alternative explanations. Translation needs to be based on top quality science and an appreciation that even the best science needs to take account of multiple strategies and multiple evaluations.

Developmental psychopathology: A paradigm shift or just a relabeling?

Developmental psychopathology is described as a conceptual approach that involves a set of research methods that capitalize on developmental and psychopathological variations to ask questions about mechanisms and processes. Achievements are described in relation to attachment and attachment disorders, autism, schizophrenia, childhood antecedents of adult psychopathology, testing for environmental mediation of risk effects, gene–environment interplay, intellectual and language functioning, effects of mentally ill parents on the children, stress and vulnerability to depression, ethnicity and schizophrenia, and drug response. Continuities and discontinuities over the course of development are discussed in relation to attention-deficit/hyperactivity disorder, antisocial behavior, eating disorders, substance abuse and dependency, pharmacological and behavioral addictions, and a range of other disorders. Research challenges are considered in relation to spectrum concepts, the adolescent development of a female preponderance for depression, the mechanisms involved in age differences in response to drugs and to lateralized brain injury, the processing of experiences, the biological embedding of experiences, individual differences in response to environmental hazards, nature–nurture integration, and brain plasticity.

Longitudinal studies using a "natural experiment" design: the case of adoptees from Romanian institutions

OBJECTIVE

To summarize the advantages and limitations of general population, high-risk and "natural experiment" longitudinal studies for studying psychological change. The English and Romanian Adoptees study is used as an example of a "natural experiment," and detailed findings are provided.

METHOD

What is new is a focus on the young people who spent the whole of their life in institutional care up to the time of adoption and who did not show subnutrition. The results were compared with a composite comparison group who had not experienced institutional care or who were adopted before the age of 6 months. The outcomes were assessed in terms of previously established deprivation-specific patterns (DSPs).

RESULTS

"Pure" psychosocial deprivation was associated with a substantial increase in the rate of DSPs. It was not associated with significantly impaired head growth if institutional care lasted less than 6 months, whereas thereafter there was a 2.5 standard deviation reduction. Subnutrition differed in being accompanied by impaired head and body growth even with institutional care lasting less than 6 months. In the pure psychosocial deprivation group, 45.5% showed a DSP at 15 years compared with 1.3% in the comparison group.

CONCLUSION

"Pure" psychosocial deprivation (in the absence of subnutrition) had a profound effect on psychological functioning in the form of DSPs. Subnutrition had a surprisingly small effect on DSPs.