[Executive system: a conceptual review and its study in children with attention deficit hyperactivity disorder].

OBJECTIVES: To review the different concepts and definitions of the executive system (ES) and its relationship with attention and working memory. To apply these concepts to the theories about executive dysfunction in children with attention deficit hyperactivity disorder (ADHD). DEVELOPMENT: A functional and terminological definition about ES is made considering previous theories and mainly based on the theory of the control of the action. The concepts of working memory and attention are defined and their relationship with the ES is analysed. The evidence of executive dysfunction in children with ADHD is described and recent hypothesis on the nature of the neuropsychological key deficit of the disorder are discussed. CONCLUSIONS: There is a lack of an universally accepted theory about the executive system function, although there is an agreement between different authors in considering that it involves the cognitive processes needed for complex, novel and aimed actions. Attention is a function that is different from the ES, but it is required for the ES functioning. Working memory is one of the most important components of the ES, but it does not account for the whole concept of ES. Although the characteristic pattern of ES dysfunction in children with ADHD is still unknown, there are some recent evidences showing that they have specific difficulties in behavioral inhibition.