Impairment of Executive Functions in Boys with Attention Deficit/Hyperactivity Disorder

Abstract

The main aim of the present study is to compare the efficiency of executive control processes in 24 boys with attention deficit/hyperactivity disorder (ADHD) and 58 normal controls of similar age (between 8 and 11 years). Three reaction time (RT) paradigms were utilized: a dual task that requires coordination of two tasks responses, a shift task that makes it necessary to disengage attention from one task and engage into another one, and a stimulus-response spatial compatibility task that requires participants to inhibit a prepotent response. Another purpose of the study is to examine whether Barkley’s (1997) executive dysfunction or Sergeant et al.’s (1999) resource allocation/arousal model best account for the behavioral deficits associated with ADHD. Examination of raw RT data showed significantly poorer performance in ADHD children with respect to age-matched controls on both the higher-level cognitive functions of executive control and on lower-level abilities (e.g., speed of processing) of all tasks of this study. However, using proportional transformations of raw RT data, we could demonstrate that, in addition to differences in processing speed, also executive control processes were significantly impaired in children with ADHD.

Keywords:

• ADD/ADHD
• monitoring processes
• divided attention
• response inhibition
• task switching
• frontal lobe dysfunction

This research was funded by my parents: Cav. Giuseppe Fuggetta and Gatto Lidia, and is dedicated to their memory. The author is grateful for the collaboration of Sandro Conforto and Manolo Venturin, who programmed the software Neuropsychological Investigator, utilized for the presentation of stimuli, recording the responses, and filtering the recorded raw data of tasks employed in this study. I wish to thank Julia Burst and Antonella Santarossa for their help in collecting the data in Germany and Italy, respectively. I thank Carlo Alberto Marzi, Joseph Di Duro, Sergio Morra, and Carlo Umiltà for their suggestions and helping with earlier versions of this manuscript.