Inhibitory control allows individuals to suppress unwanted actions and to resist irrelevant stimuli. It is thought to be a core deficit in Attention-deficit/hyperactivity disorder (ADHD). The present study aims at evaluating this deficit in adults with ADHD. Executive and inhibitory capacities, as well as the neural mechanisms underlying inhibitory control, will be assessed in adults with ADHD and two control groups of participants.
ADHD is a psychiatric disorder characterized by symptoms of inattention, hyperactivity, and impulsivity (DSM-V, 2013). An impairment of inhibitory control has been suggested as the primary deficit in children with ADHD, which is thought to cause secondary impairments in executive functioning. A few studies investigated executive capacities in adults with ADHD. Specifically, an impairment in action inhibition has been reported in ADHD participants. Moreover, inhibition of action is often associated with distinctive electroencephalographic (EEG) correlates. The present study aim at combining both novel inhibitory control measurement techniques and EEG analysis in temporal and frequency domains to assess the sensitivity and the specificity of an inhibitory deficit in adults with ADHD. This is part of an improvement in the procedures for diagnosing ADHD syndrome and its functional evaluation. The study will analyze the EEG activity associated with two stop-signal tasks requiring inhibitory capacities. A set of other cognitive skills will also be evaluated during a neuropsychological assessment. The results of ADHD patients will be compared with those of a control group (healthy volunteers) to assess the sensitivity of an inhibition deficit to the disorder. These same results will also be compared with those of a second control group (patients with a negative diagnosis of ADHD) to assess the specificity of the inhibitory deficit. This experimental strategy results in the involvement of three groups of participants (ADHD patients and two control groups) in three visits (neuropsychological assessment and two EEG sessions).
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
45
An EEG experimentation session on the stop-signal task of inhibiting a prepared discrete graphic action.
An EEG experimentation session on the stop-signal task of inhibiting an ongoing rhythmic action
Toulouse Purpan University Hospital
Toulouse, France
EEG correlates of inhibition
The main objective of this study is to evaluate, by electrophysiological measures, the presence of a deficit of action inhibition in adults with ADHD. To this end, the EEG correlates of inhibition will be compared between participants in the three groups. Thus, the ERP (N2 / P3) and ERSP (Theta, Delta) variations observed in terms of amplitude and latency in the stop-signal task tests will be computed in each of the three groups.
Time frame: 2 weeks
Inhibition performance from a rhythmic-action task
The inhibition performance from a rhythmic-action task, expressed as stop-signal reaction time (SSRT, in ms). This latency is measured by identifying a statistical deviation evoked by the STOP signal in the participants' movement on a graphic tablet (following the procedure described in Hervault et al., 2019).
Time frame: 2 weeks
Inhibition performance from a discrete-action task
The inhibition performance from a discrete-action task, expressed as an SSRT (in ms). According to the horse-race model of inhibition, this latency is estimated based on the response time and the response probability obtained by the participants when responding to the GO and STOP stimuli used in the task (following recent guidelines from Verbruggen et al., 2019).
Time frame: 2 weeks
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