• By Kevin Mount
  • Posted on Wednesday 28th May, 2008

For nature versus nurture the war is over

Since Avshalom Caspi’s groundbreaking 2002 study demonstrated how the MAOA gene and exposure to maltreatment interact and predict anti-social behavior, there has been an explosion of studies of the effect of GxE on children’s psychological and physical health. [See also: How gene research is entering the child protection arena] Enormous effort has gone toward better understanding of the G component of this work, but the E has received much less attention, to the frustration of those keen to translate GxE findings into practice. On Friday, three speakers at the Society for Prevention Research annual meeting in San Francisco will share their thoughts on the GxE revolution, the opportunities and challenges for child development specialists and some of the implications for science, policy and practice in the prevention arena. Stephen Gilman from Harvard will report the results of a systematic review of all GxE work in psychopathology between 2000-2007, which has highlighted the lack of any unifying framework for conceptualizing what is meant by environment. He’ll show how inconsistency across each of the studies undermines the extent to which they can contribute to understanding of the etiology of childhood disorders. In many cases environment is represented by a single measurement using whatever data is available. Work by Kenneth Dodge at Duke University consequently focuses on the need for a sharper environment “lens” – a more sophisticated understanding of environment – to replace what Leslie Leve from Oregon Social Learning Center calls the current “snapshot” approach to environment adopted by genetic researchers. It’s quite a tall order. Leslie Leve will offer some practical wisdom to take this work forward, such as focusing on specific modifiable environmental processes and repeated measurement, but Kenneth Dodge argues that our theoretical understanding of environment must be improved. In other words, we must come to some understanding of how different types of environmental context work together and influence each other. Temporal relationships between factors have also to be mastered – the processes through which environments affect individuals over time. Similarly, the developmental status and age of children have to be reckoned with; genetic and environmental factors may influence children in different ways at different stages of their development. Adding still another layer of complexity, Kenneth Dodge is expected to describe how recent findings in this field are suggesting that GxE might be replaced with GxExD: gene by environment by development. This notion of triple interaction effects elevates the role of age and developmental status from a variable to be noted and controlled in such work to something of much more significance. Leve, Dodge and Gilman all agree that prevention and intervention studies are potentially the most appropriate place for testing hypotheses about interaction effects. Dodge goes as far as to argue that “prevention science could become the leading experimentalist for basic science”. They are also expected to highlight some of the challenges arising from advancing the GxE field. From Dodge will come the argument that policy-makers and practitioners responsible for commissioning, developing and delivering programs must concede that programs will only be effective for certain individuals or sub groups of children. As a result, new screening measures and an element of evidence-based matching of program to person will be required. On the policy side, the balance of costs and benefits will have to be weighed for any program that only affects sub-groups.References Caspi A, McClay J, Moffitt T, Mill J, Martin J, Craig I, Taylor A, Poulton R, “Role of geneotype in the cycle of violence in maltreated children”, Science , 297, 2001, 851-854

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