Neuropsychological assessment of response inhibition in adults with ADHD.

Several theoretical models suggest that the core deficit of ADHD is a deficiency in response inhibition. While neuropsychological deficits in response inhibition are well documented in ADHD children, research on these deficits in adult ADHD populations is minimal. Twenty-five adult ADHD patients, 15 anxiety-disordered adult patients, and 30 normal adults completed three neuropsychological tests of response inhibition: the Continuous Performance Test, Posner Visual Orienting Test, and the Stop Signal Task. ADHD adults demonstrated response inhibition performance deficits when compared to both normal adults and anxiety disordered adults only on the Continuous Performance Test. A similar pattern of differences was not observed on the other two neuropsychological tests. Differing results between tasks may be due to differences in test reliability, task parameters, or the targeted area of brain functioning assessed by each test.