Summary: Association Between Response Inhibition and Working
Memory in Adult ADHD: A Link to Right Frontal
Luke Clark, Andrew D. Blackwell, Adam R. Aron, Danielle C. Turner, Jonathan Dowson,
Trevor W. Robbins, and Barbara J. Sahakian
Background: We sought to assess the relationship between response inhibition and working memory in adult patients with attention-
deficit/hyperactivity disorder (ADHD) and neurosurgical patients with frontal lobe damage.
Methods: The stop-signal reaction time (SSRT) test and a spatial working memory (SWM) task were administered to 20 adult patients with
ADHD and a group of matched controls. The same tasks were administered to 21 patients with lesions to right frontal cortex and 19 patients
with left frontal lesions.
Results: The SSRT test, but not choice reaction time, was significantly associated with search errors on the SWM task in both the adult ADHD
and right frontal patients. In the right frontal patients, impaired performance on both variables was correlated with the volume of damage
to the inferior frontal gyrus.
Conclusions: Response inhibition and working memory impairments in ADHD may stem from a common pathologic process rather than
being distinct deficits. Such pathology could relate to right frontal-cortex abnormalities in ADHD, consistent with prior reports, as well as
with the demonstration here of a significant association between SSRT and SWM in right frontal patients.
Key Words: Executive function, hyperactivity, impulsivity, prefron-
he symptoms of childhood attention-deficit/hyperactivity