Christopher W N Saville1,2, Bernd Feige3, Christian Kluckert1, Stephan Bender4, Monica Biscaldi1, Andrea Berger5, Christian Fleischhaker1, Klaus Henighausen1, Christoph Klein1,2. 1. Department of Child and Adolescent Psychiatry, Psychotherapy, and Psychosomatics, University of Freiburg, Freiburg, Germany. 2. School of Psychology, Bangor University, Bangor, UK. 3. Department of Psychiatry and Psychotherapy, University of Freiburg, Freiburg, Germany. 4. Department of Child and Adolescent Psychiatry, University of Frankfurt, Frankfurt, Germany. 5. Department of Psychology, Ben Gurion University of the Negev, Negev, Israel.
Abstract
BACKGROUND: Increased intra-subject variability (ISV) in reaction times (RTs) is a promising endophenotype for attention-deficit hyperactivity disorder (ADHD) and among the most robust hallmarks of the disorder. ISV has been assumed to represent an attentional deficit, either reflecting lapses in attention or increased neural noise. Here, we use an innovative single-trial event-related potential approach to assess whether the increased ISV associated with ADHD is indeed attributable to attention, or whether it is related to response-related processing. METHODS: We measured electroencephalographic responses to working memory oddball tasks in patients with ADHD (N = 20, aged 11.3 ± 1.1) and healthy controls (N = 25, aged 11.7 ± 1.1), and analysed these data with a recently developed method of single-trial event-related potential analysis. Estimates of component latency variability were computed for the stimulus-locked and response-locked forms of the P3b and the lateralised readiness potential (LRP). RESULTS: ADHD patients showed significantly increased ISV in behavioural ISV. This increased ISV was paralleled by an increase in variability in response-locked event-related potential latencies, while variability in stimulus-locked latencies was equivalent between groups. This result held across the P3b and LRP. Latency of all components predicted RTs on a single-trial basis, confirming that all were relevant for speed of processing. CONCLUSIONS: These data suggest that the increased ISV found in ADHD could be associated with response-end, rather than stimulus-end processes, in contrast to prevailing conceptions about the endophenotype. This mental chronometric approach may also be useful for exploring whether the existing lack of specificity of ISV to particular psychiatric conditions can be improved upon.
BACKGROUND: Increased intra-subject variability (ISV) in reaction times (RTs) is a promising endophenotype for attention-deficit hyperactivity disorder (ADHD) and among the most robust hallmarks of the disorder. ISV has been assumed to represent an attentional deficit, either reflecting lapses in attention or increased neural noise. Here, we use an innovative single-trial event-related potential approach to assess whether the increased ISV associated with ADHD is indeed attributable to attention, or whether it is related to response-related processing. METHODS: We measured electroencephalographic responses to working memory oddball tasks in patients with ADHD (N = 20, aged 11.3 ± 1.1) and healthy controls (N = 25, aged 11.7 ± 1.1), and analysed these data with a recently developed method of single-trial event-related potential analysis. Estimates of component latency variability were computed for the stimulus-locked and response-locked forms of the P3b and the lateralised readiness potential (LRP). RESULTS:ADHDpatients showed significantly increased ISV in behavioural ISV. This increased ISV was paralleled by an increase in variability in response-locked event-related potential latencies, while variability in stimulus-locked latencies was equivalent between groups. This result held across the P3b and LRP. Latency of all components predicted RTs on a single-trial basis, confirming that all were relevant for speed of processing. CONCLUSIONS: These data suggest that the increased ISV found in ADHD could be associated with response-end, rather than stimulus-end processes, in contrast to prevailing conceptions about the endophenotype. This mental chronometric approach may also be useful for exploring whether the existing lack of specificity of ISV to particular psychiatric conditions can be improved upon.
Authors: Christopher W N Saville; H M de Morree; Neil M Dundon; S M Marcora; C Klein Journal: Psychopharmacology (Berl) Date: 2017-12-23 Impact factor: 4.530
Authors: Annet Bluschke; Witold X Chmielewski; Moritz Mückschel; Veit Roessner; Christian Beste Journal: Front Hum Neurosci Date: 2017-06-28 Impact factor: 3.169