| Not everyone is equally susceptible to environmental influences such as negative life events or rearing effects. Temperamental and genetic factors that are often considered risk factors may however actually be susceptibility factors reflecting heightening susceptibility to the effects of the environment in general, with adverse contexts fostering negative outcomes, and supportive contexts promoting positive outcomes. Based on the evidence generated so far, I have chosen temperamental reactivity and dopamine-related DRD4 and COMTmet158val polymorphisms as candidate susceptibility factors, for children as well as for parents. In the proposed study I test whether these susceptibility factors operate independently, which of them shows the largest effects, and/or whether they operate in interaction. Two projects address differential susceptibility in parents and children: a correlational project and an experimental intervention project. The Correlational Project tests differential susceptibility in the negative direction, that is, the influence of daily hassles on parental responsiveness (for parents), and of unresponsive parenting on externalising behaviour (for children). The Intervention Project tests whether susceptible individuals are more affected by positive environmental support, that is in the case of parents by video-feedback intervention aimed at enhancing parental responsiveness and sensitive discipline, and in the case of children by increased parental responsiveness and positive discipline strategies that result in decreased behaviour problems. For the first time the theory of differential susceptibility is experimentally tested in a complete randomized control trial, with intervention and control groups stratified according to genetic and temperamental susceptibility factors. What works for whom, and why? That is an unresolved and crucial issue in parent training and therapeutic intervention more generally. More insight into differential susceptibility and differential effectiveness of parenting interventions has important implications for family (and childcare) policy. A better fit between target group and intervention will result in a more effective use of resources for parent training. |
