This study examined the role of ADHD in the association between physical aggression and
two types of executive functions. Boys received a cognitive-neuropsychological test battery
over the ages of 13, 14, and 15 years. Diagnostic Interview Schedule for Children (DISC 2.25)
data were collected from the boys and one parent between ages 14 and 16, and an IQ estimate
was obtained at age 15. Three groups, differing in stability and level of physical aggression
since kindergarten, were formed: Stable Aggressive, Unstable Aggressive, and Non-aggressive. Composite scores of validated executive function tests of working memory
representing subjective ordering and conditional association learning were formed. A
MANCOVA (N=149) using ADHD status, teacher-rated negative emotionality, general
memory abilities, and IQ as covariates was performed on the two composite scores. ADHD
and teacher-rated emotionality did not provide significant adjustment to the dependent
variables. Number of ADHD symptoms was negatively associated only with general
memory and IQ. General memory contributed significantly to adjusting for conditional
association test scores. Group differences indicated lower conditional association scores for
Unstable Aggressive boys relative to the other groups. Both IQ and general memory abilities
interacted with subjective ordering within the groups. Specifically, Stable Aggressive boys
performed poorly on this measure and did not benefit from increases in IQ whereas
Nonaggressive boys performed best and were not disadvantaged by lower general memory
abilities. This suggests a relationship exists between aspects of working memory and a
history of physical aggression regardless of ADHD and IQ.