Event-Related Potentials during a Gambling Task in Young Adults with Attention-Deficit/Hyperactivity Disorder

Abstract

Attention-deficit hyperactivity disorder (ADHD) is characterized by deficits in executive functions and decision making during childhood and adolescence. Contradictory results exist whether altered event-related potentials (ERPs) in adults are associated with the tendency of ADHD patients toward risky behavior. Clinically diagnosed ADHD patients (n = 18) and healthy controls (n = 18), aged between 18 and 29 (median 22 Yo), were screened with the Conners' Adult ADHD Rating Scales and assessed by the Mini-International Neuropsychiatric Interview, adult ADHD Self-Report Scale, and by the 60-item HEXACO Personality Inventory. The characteristic personality traits of ADHD patients were the high level of impulsiveness associated with lower values of agreeableness. All participants performed a probability gambling task (PGT) with two frequencies of the feedback information of the outcome. For each trial, ERPs were triggered by the self-paced trial onset and by the gamble selection. After trial onset, N2-P3a ERP component associated with the attentional load peaked earlier in the ADHD group than in controls. An N500 component related to the feedback frequency condition after trial onset and an N400-like component after gamble selection suggest a large affective stake of the decision making and an emphasized post-decisional evaluation of the choice made by the ADHD participants. By combining ERPs, related to the emotions associated with the feedback frequency condition, and behavioral analyses during completion of PGT, this study provides new findings on the neural dynamics that differentiate controls and young ADHD adults. In the patients' group, we raise the hypothesis that the activity of frontocentral and centroparietal neural circuits drive the decision-making processes dictated by an impaired cognitive workload followed by the build-up of large emotional feelings generated by the conflict toward the outcome of the gambling choice. Our results can be used for new investigations aimed at studying the fine spatiotemporal distribution of cortical activity, and the neural circuits that underly the generation of that activity, associated with the behavioral deficits characteristic of ADHD.

Keywords: ADHD; N2-P3; N400-like; decision-making; evoked potentials; personality.

Figure 1

Experimental design of the probabilistic gambling task. Each trial began by pressing the spacebar (trigger event S), which was immediately followed by a message on the computer-controlled monitor with the request to choose a selected amount of points to gamble in a game. The response time (RT) was determined by the lag until the selection of the investment to gamble (trigger event I). After an additional fixed interval of 4 s (I+4s), the participant was informed about the outcome of the gamble (HF Loss or HF Win) in the HF condition or simply informed about the determination of the gamble in the LF condition.

Figure 2

Scatter plot of the total gain TotG, cumulated during both feedback frequency conditions, as a function of CAARS, the normalized ADHD Index T-score. The robust regression equations for controls and ADHD are equal to y = 4, 800−24.7x [F_{(1, 16)} = 6.43, p = 0.02, R² = 0.294] and y = 1541+33.2x [F_{(1, 16)} = 6.74, p = 0.02, R² = 0.307]). All points were included for the robust regression. Each point represents the data from one participant. Dashed lines represents 95% confidence interval.

Figure 3

Event-Related Potentials (ERPs) during the probabilistic gambling task. Grand average at Fz, FCz, Cz, CPz, Pz, and POz sites for all participants (N = 32) and at all conditions (HF, LF) pooled together. (A) ERPs triggered by the event S, corresponding to the trial onset. (B) ERPs triggered by the event I, corresponding to the gambling choice. C1, visual evoked potential component; CNV, Contingent Negative Variation; M, premotor response; N2-P3a, the complex of components associated with expectation-attention-orienting processing; P3b, positive peak associated with the cognitive workload.

Figure 4

Effect of feedback condition on the grand-averaged ERPs. (A) ERPs averaged for all participants (N = 32) at electrodes sites POz, Pz, CPz, Cz, FCz, and Fz across conditions HF (red lines) and LF (blue lines) after the trial onset (S). (B) ERPs after the gambling choice (I). Dotted lines correspond to the difference waves, computed by subtracting LF curves from HF curves.

Figure 5

Feedback related differential activities triggered by the trial onset (S). (A) The curves were computed by subtracting ERPs associated with LF from ERPs associated with HF for controls (green lines, N = 18) and ADHD participants (blue lines, N = 14). The confidence interval (mean curve ± SEM) is shown by the shaded areas. (B) The relative density plot shows the spatial distribution of the estimated amplitude of the differential curves integrated along three intervals emphasized by the gray stripes, centered at latencies 80 ms (C1, dark gray), 260 ms (N2-P3, red), and 490 ms (N500, orange). The shaded areas correspond to non-parametric estimation of the 95% confidence intervals. Circles show those values not significantly different from zero. See Table S3 for more details.

Figure 6

Feedback related differential activities triggered by the gambling choice (I). (A) The curves were computed in the same way as Figure 5A. (B) The relative density plot shows the spatial distribution of the estimated amplitude of the differential curves integrated along four intervals emphasized by the gray stripes, centered at latencies 450 ms (yellow) and 140 ms (brown) before the gambling choice and 490 ms (N400-like, turquoise) and 850 ms (LPP, teal blue) after the gambling choice. Circles show those values not significantly different from zero. The shaded areas correspond to non-parametric estimation of the 95% confidence intervals. See Table S3 for more details.