| Prospective studies have shown that clinically referred pre-schoolers who present severe hyperactivity, irritability, and impulsiveness are at high risk to be diagnosed with an externalizing disorder at age 6 or 9 year (Campbell, 1995). There is a paucity of knowledge about the possibility to predict externalizing disorders at an even earlier age, i.e. infancy. The aim of the study is to explore early predictors of externalizing disorders. This research focuses on measures of temperament, behavioral inhibition and attachment at the age of 21 and 42 months as predictors of externalizing disorders. First, we hypothesize that both passive and active behavioral inhibition systems in two high-risk groups are underdeveloped compared to normals at 21 months of age. Second, we expect that early inhibition determines the quality of focussed and sustained attention in two high-risk groups compared to normals at 21 months of age. Finally, we hypothesize that a disorganised attachment classification at 21 and 42 months enhances the risk for developing externalizing problems at an older age. Passive behavioral inhibition will be assessed in view of the work of Kagan and his colleagues (1998). A strong passive behavioral inhibition has been reported to protect from developing delinquent behavior at adult age (Kerr et al., 1997). Tasks of the Laboratory Temperament Assessment Battery (Goldsmith & Rothbart, 1999) will be used to assess passive inhibitory behavior. Active behavioral inhibition reflects effortful impulse control. In research with both human infants and young monkeys, it has been argued that the development of the prefrontal cortex underlies the ability to exercise inhibitory control (Diamond & Gilbert, 1989). Kochanska and co-workers have shown that inhibitory control can be measured reliably and consistently at toddler and pre-school age, using a comprehensive battery of tasks developed by Kochanska et al. (1996,1997). On the basis of the work of Van IJzendoorn et al. (1999) the pattern of attachment is examined as it is found to be one of the risk factors for later externalizing problems. The child and parent will be observed in a standardised Strange Situation Procedure as described by Ainsworth (Ainsworth and Witting, 1969; Ainsworth et al., 1978). |
