Aggressive behaviour in preschool children. Neuropsychological correlates, costs of service use, and preventive efforts.

At ages two and three the vast majority of children shows a high level of aggression. During the preschool period the level of aggression generally declines. However, some children continue to show a high level of aggression and are at risk for the development of Disruptive Behavior Disorders (DBD), potentially resulting in substance abuse, delinquency and high costs at later ages. Aggressive behavior in preschool children has been associated with several individual and environmental factors, e.g., neuropsychological functioning and parenting practices. Neuropsychological functioning The neuropsychological performance on tasks measuring working memory, inhibition, set shifting, and verbal fluency of 82 preschool children with aggressive behavior was assessed and compared to the performance of 99 control children. Factor analysis revealed that only inhibition could be identified as a distinct factor. Children with aggressive behavior showed deficits in inhibition, with girls outperforming boys. This association between inhibition deficits and aggression was maintained when attention problems were controlled. This indicates that inhibition deficits are robust correlates of aggressive behavior in the preschool period. Costs of service use and impact on family functioning The costs of service use and the burden on the family of 4-year-old children with aggressive behavior were investigated. A sample of 317 preschool children was divided into groups with low, moderate, borderline and clinical levels of aggression. Families of children with a borderline or clinical level of aggression were found to be more impaired in daily functioning than families of children with lower levels of aggression. Children with clinical levels of aggression were also more costly than children with low levels of aggression, due to higher costs of service use. Performance of a nonrandomized study design The performance of a case control design was compared to a randomized study design by simulating hypothetical intervention and control groups, based on data from our study into a preventive parent program. The results of this study indicate that matching in a case control design is a viable alternative for studies in which randomization is not feasible. Preventive efforts: The Incredible Years parent program Preventive parenting programs have been designed to improve parent-child interactions, and to avert the risk for DBD. The IY parent program emerged as effective from treatment studies, but evidence on the preventive effectiveness remained inconclusive. We evaluated the preventive effectiveness of the IY parent program in a population-based sample of 4-year-old children at risk for DBD. Data were collected on 72 intervention- and 72 matched control children at pre-, post-, and 1-year-follow up assessment. Results revealed significant sustained improvements in both observed and parent-rated parenting. Observed child behavior also showed sustained intervention-effects. However, parents did not report improvements in child behavior. At follow up the presence of DBD diagnoses did not differ between the groups. Children with a low IQ or poor inhibitory control, and parents with a high level of stress benefited most from the intervention. In sum, our study demonstrates the promising character of the IY parent program as a preventive intervention for preschool children at risk for DBD