a1 Department of Psychiatry and Psychotherapy, RWTH Aachen, University Hospital
a2 Department of Child and Adolescence Psychiatry and Psychotherapy, RWTH Aachen, University Hospital
a3 Department of Psychiatry and Psychotherapy, Munich University (LMU)
a4 Department of Psychiatry and Psychotherapy, Rostock University, Germany
Background Although attention-deficit/hyperactivity disorder (ADHD) is thought to be an inhibitory disorder, the question remains of how specific the inhibitory deficit is in adults and whether it distinguishes ADHD from borderline personality disorder (BPD), with which it shares several clinical features, particularly impulsiveness.
Method The study assessed various motor and cognitive inhibitory functions (inhibition of prepotent, ongoing and interfering responses) in addition to working memory in adult ADHD patients with and without BPD, compared to subjects with BPD alone and controls. In addition, questionnaire data on various aspects of impulsiveness and anger regulation were assessed in all groups.
Results ADHD patients performed worse than BPD individuals and controls in two inhibitory tasks: the stop signal task and the conflict module of the Attentional Network Task (ANT). In addition, they exhibited longer reaction times (RTs) and higher intra-individual variance in nearly all attentional tasks. The co-morbid group exhibited poor performance on the stop signal task but not on the conflict task. The BPD group barely differed from controls in neuropsychological performance but overlapped with ADHD in some behavioural problems, although they were less severe on the whole.
Conclusions Impaired inhibition is a core feature in adults with ADHD. In addition, slow RTs and high intra-individual variance in performance may reflect deficits in the regulation of activation and effort in ADHD patients. ADHD and BPD share some symptoms of behavioural dysregulation without common cognitive deficits, at least in the attentional realm.
(Online publication May 17 2007)
c1 Address for correspondence: Professor Dr Sabine C. Herpertz, Director of the Department of Psychiatry and Psychotherapy, Rostock University, Gehlsheimer Str. 20, D-18147 Rostock, Germany. (Email: firstname.lastname@example.org)
† These authors contributed equally to this work.