ABSTRACT

A core deficit observed in a number of disorders of childhood is difficulty suppressing inappropriate thoughts and behaviors. For example, children with Attention Deficit/Hyperactivity Disorder (ADHD) have problems focusing attention and are often characterized as distractible and impulsive (Barkley, 1994; Casey et al., 1997; Trommer et al., 1991). Other childhood disorders have a similar problem suppressing inappropriate behaviors, but the nature of the deficit appears more specific to a particular behavior. For example, children with Tourette Syndrome have difficulty suppressing often quite complex movements in addition to vocalizations that are sometimes emotionally provocative in content (Leckman et al., 1987). Obsessive Compulsive Disorder (OCD) in children and adults alike is characterized by an inability to stop intrusive thoughts and ritualistic behaviors that appear to be specific in content (Insel, 1988). Stereotypes and repeated self-injurious behaviors are also examples of inhibitory problems observed in a wide range of children including those with autism and mental retardation. Even in Childhood Onset Schizophrenia, the child appears unable to stop attending to irrelevant thoughts and information (Asarnow et al., 1995). Clearly, the prevalence of these inhibitory problems in children with developmental disabilities highlights the need for a clearer understanding of these behaviors and their biological bases.