• By Dartington SRU
  • Posted on Monday 20th April, 2009

Is gene expression forging the missing link?

The way children are cared for from the moment they are born may affect how their genes are expressed and consequently how likely they are to grow up to be violent. Longitudinal research from Canada shows that chronically violent young men demonstrate underdeveloped gene expression in the hormonal system that would help them to deal with stress. Presenting at last month’s Parents Matter conference in London, Professor Richard Tremblay from the University of Montreal guided his audience through striking findings from the Montreal Longitudinal Experimental Study (MLES). [See Take the long view and parents still matter]The data showed that young adults who display chronic aggression demonstrate only partial expression of the genes vital to the development of the hypothalamic-pituitary-adrenal axis (HPA axis). This is the hormonal system responsible for, among other things, how individuals react to stressful situations.DNA is the blueprint for human development. But not everything found in the code is put into action. For genes to be expressed, DNA must be translated into proteins that will change something in our bodies. Researchers now broadly agree that gene expression is influenced to a large extent by environmental factors.The Montreal study has been following the progress of over 1,000 boys since 1984. From poor and deprived neighborhoods, they were selected for the study as being at high risk of becoming young offenders. Tremblay’s analysis separated them into four groups: those who exhibited no physical aggression and who were prone to use “normal,” high and chronic levels. Individuals on a trajectory of chronic aggression showed poorer gene expression for the HPA axis; the normal group showed typical gene expression in this area. The study also collected a large amount of contextual data about the children. Tremblay and his team then looked for the most important risk factors for chronic aggression. Two were prominent: having a teenage mother or a mother with little or no education.One interpretation of these risk factors is that there is a connection between poor parenting, low gene expression and chronic aggression.Tremblay explained how the analysis applied to the Montreal Longitudinal Experimental Study was based on a study of rats by university colleagues. In investigating the importance of parenting on rat development and in particular the significance of grooming, the researchers discovered that the rats who were licked most, lived longest.Licking and grooming had a chemical impact on the expression of their genes – a factor key to the proper development of the HPA axis. Tremblay also discussed the potential implications of his human findings in policy making when he spoke at the London conference. If the quality of care children received affected the development of their hormonal systems, early intervention was essential. Investments in attempts to modify the behavior of aggressive adolescent boys were bound to be largely wasted. Future efforts should focus on the well-being of the teenage mothers of the aggressive young men of tomorrow, he argued. [For more about the political implications of Richard Tremblay’s argument for early intervention, see, Walking the line between intervention and intrusion.]

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