Response Inhibition, Memory, and Attention in Boys with Attention-Deficit/Hyperactivity Disorder

Newly developed measures of response inhibition, verbal and non-verbal memory, and attention were applied to a sample of boys diagnosed with ADHD (n = 50; 14 predominantly inattentive type and 36 combined type) with no diagnosed comorbid conditions, who had received no stimulant medication for a minimum period of 20 hours prior to test administration. Performance was assessed relative to 50 individually age-matched control boys. Results revealed significant multivariate group differences on all three tests, supported by univariate effects on measures of verbal memory and attentional switching. In all cases, ADHD boys performed more poorly than the control boys. However, contrary to expectations, boys with ADHD made significantly fewer impulsive responses (false positives) on the specific measure of response, despite recording significantly more misses than the controls. Furthermore, no significant differences were observed according to ADHD subtype. The present research therefore demonstrates and more fully characterises the nature of the observed memory and attentional impairments in boys with ADHD and would appear to have clear implications for education and the further development of theory.