Cognitive and executive functions in ADHD

Abstract

Introduction. Some studies have reported that attention-deficit/hyperactivity disorder (ADHD) children show alterations in different cognitive functions. Recently, a deficiency in the executive functions (EF) is proposed as the cause underlying all of these symptoms. However discrepancies exist about these findings.

Objective. Assessment of cognitive and executive functions of subjects with both ADHD hyperactive-impulsive type and combined type, in order to reveal their neuropsychological characteristics and analyze if those functions are related to hyperactive-impulsive behavior.

Method. Neuropsychological Battery, Stroop test, Wisconsin Card Sorting test and London Tower test were applied to 51 children between 7 and 12 years old (25 controls and 26 ADHD).

Results. ADHD children showed worst performance in sustained attention, rapid serial naming of figures and colors, comprehension of written instructions, word dictation, number comparison, arithmetical problems, visual working memory, long term memory and the scores of WCST.

Variables related to hyperactivity-impulsivity were: errors and decreased velocity in rapid serial naming of colors and figures, comprehension of written instructions, arithmetical problems and the scores of total errors, perseverating errors and perseverating responses of WCST.

Conclusion. ADHD children show a great variety of cognitive deficiencies and had deficit only in some domains of executive functions. These deficiencies could explain to some extent the hyperactive and impulsive behavior.