Cognitive studies in children with mild mental retardation with externalizing behavioural disorders

This study had an exploratory character. The aim was to gain more insight into the complex behaviour of children with mild mental retardation and externalizing behavioural disorders. This study is one of the first to focus on such a complex target-group. The goals were: making recommendations for future research, discovering tendencies central to behaviour and improving the treatment that such children receive. The children in this study are institutionalized and have a long history of care prior to their admission. Outpatient care proved to be inadequate because of their severe complex behavioural problems, which are difficult to treat. These children have been diagnosed as mildly mentally retarded (MMR) with Attention Deficit/Hyperactivity Disorder (ADHD) and Conduct Disorder (CD). As well as the official diagnoses, the children have many comorbid problems. They are limited in their cognitive skills, have attentional deficits and memory problems, are impaired in their social functioning, are aggressive and impulsive, come from stressful family backgrounds and are often abused. There are few studies concerning dual-diagnosis children. The number of MMR children with comorbid problems is increasing and there is a lack of scientific knowledge about this (target-) group. This study will focus on attentional abilities and impulsiveness, which are related to the disorders mentioned above. The many comorbid problems made it difficult to create an ideal design, because it was impossible to deal with all the variables present in the target group. The children in this target group will play a central role in this study and, depending on the research question, will be compared to control groups. Therefore it has been decided to take a broad approach and carry out seven experiments. About half of the children in the target group were receiving medication during the experiments. This was a low dosage of pipamperon, usually not the first choice of drug used to treat ADHD and CD; it is an anti-psychotic drug. In the Netherlands and Belgium it is also prescribed for mentally retarded patients with integration disabilities. It is unusual to combine medicated and non-medicated subjects in the same group. However, a number of statistical analyses revealed that medication had no effect on the experimental tasks, and in addition the nonmedicated group did not perform any differently from the medicated group when compared to the normal control group.