Diminished error-related negativity and error positivity in children and adults with externalizing problems and disorders: a meta-analysis on error processing.

BACKGROUND: Deficits in error processing are reflected in an inability of people with externalizing problems to adjust their problem behaviour. The present study contains 2 meta-analyses, testing whether error processing - indexed by the event-related potentials error-related negativity (ERN) and error positivity (Pe) - is reduced in children and adults with externalizing problems and disorders compared to healthy controls. METHODS: We conducted a systematic search in PubMed (1980 to December 2018), PsycInfo (1980 to December 2018) and Scopus (1970 to December 2018), identifying 328 studies. We included studies that measured error processing using the Eriksen flanker task, the go/no-go task or the stop-signal task in healthy controls and in adults or children with clearly described externalizing behavioural problems (e.g., aggression) or a clinical diagnosis on the externalizing spectrum (e.g., addiction). RESULTS: Random-effect models (ERN: 23 studies, 1739 participants; Pe: 27 studies, 1456 participants) revealed a reduced ERN amplitude (Hedges' g = 0.44, 95% confidence interval [CI] 0.29 to 0.58) and a reduced Pe amplitude (Hedges' g = -0.27, 95% CI -0.44 to -0.09) during error processing in people with externalizing problems or disorders compared to healthy controls. Type of diagnosis, age and the presence of performance feedback or comorbidity did not moderate the results. The employed cognitive task was a moderator for Pe but not for ERN. The go/no-go task generated a greater amplitude difference in Pe than the Eriksen flanker task. Small-sample assessment revealed evidence of publication bias for both event-related potentials. However, a p curve analysis for ERN showed that evidential value was present; for Pe, the p curve analysis was inconclusive. LIMITATIONS: The moderators did not explain the potential heterogeneity in most of the analysis, suggesting that other disorder- and patient-related factors affect error processing. CONCLUSION: Our findings indicate the presence of compromised error processing in externalizing psychopathology, suggesting diminished activation of the prefrontal cortex during performance monitoring.

Modulation of control: Can HD-tDCS targeting the dACC reduce impulsivity?

BACKGROUND: The dorsal anterior cingulate cortex (dACC) and its neurocircuits are central in impulsivity, and maladaptive dACC activity has been implicated in psychological disorders characterized by high trait impulsivity. High-Definition transcranial Direct Current Stimulation (HD-tDCS) is a non-invasive neuromodulation tool that, with certain electrode configurations, can be optimized for targeting deeper subcorticalbrainstructures, such as the dACC. OBJECTIVES: Using behavioural and electrophysiological measures we investigated whether HD-tDCS targeting the dACC could modulate two key components of impulsivity, inhibitory control and error processing. METHODS: Twenty-three healthy adults with high trait impulsivity participated in two experimental sessions. Participants received active or sham HD-tDCS in counterbalanced order with a wash-out period of at least 3 days, as part of a single-blind, cross-over design. EEG was recorded during the Go-NoGo task before, directly after, and 30 min after HD-tDCS. RESULTS: HD-tDCS targeting the dACC did not affect inhibitory control performance on the Go-NoGo task, but there was evidence for a delayed change in underlying neurophysiological components of motor inhibition (NoGo P3) and error processing (error related negativity; ERN) after one session of HD-tDCS. CONCLUSION: HD-tDCS has potential to modulate underlying neurophysiological components of impulsivity. Future studies should further explore to what degree the dACC was affected and whether multi-session HD-tDCS has the capacity to also induce behavioural changes, particularly in clinical samples characterized by high trait impulsivity.

Multi-session electrical neuromodulation effects on craving, relapse and cognitive functions in cocaine use disorder: A randomized, sham-controlled tDCS study.

BACKGROUND: The use of transcranial Direct Current Stimulation (tDCS) has previously shown promising results for reducing craving in cocaine use disorder. In this study we further explored the potential of tDCS as add-on intervention in the treatment of cocaine use disorder. METHODS: In a randomized, placebo-controlled, between subject study, we applied tDCS bilaterally with the anodal electrode targeting the right dorsolateral prefrontal cortex (DLPFC; https://clinicaltrials.gov/ct2/show/NCT03025321). Patients with cocaine use disorder were allocated to ten sessions of either active tDCS (n = 29) or sham (n = 30) on five consecutive days. Inhibitory control and risky decision-making were measured via a Go-NoGo task and a two-choice gambling task, respectively, each at baseline, one day after all tDCS sessions and after three months. Relapse at follow-up and craving were also assessed. RESULTS: There was no significant effect of active tDCS on the number of cocaine use days and craving. Relapse was frequent among patients who had received either active or sham tDCS (48.0 % and 69.2 %, respectively), despite an overall decrease in craving during the first two weeks of treatment. No effects were found on cognitive functions. An exploratory analysis for crack cocaine use only revealed that relapse rates were significantly reduced after active tDCS (n = 17) as compared to sham (n = 19). CONCLUSIONS: No beneficial effects of tDCS on number of cocaine use days, craving and cognitive functions were found in the present study, but somewhat promising results were obtained regarding relapse rates among crack-cocaine users specifically. Further research is required to determine the efficacy of tDCS as a complementary treatment in cocaine use disorder.

Long-term tDCS effects on neurophysiological measures of cognitive control in tobacco smokers.

INTRODUCTION: In this study we assessed the effects of transcranial Direct Current Stimulation (tDCS) on inhibitory control and error processing as measures of cognitive control to better understand tDCS modulation of smoking behaviour. METHODS: Smokers were allocated to six sessions of either active tDCS (n = 34) or sham tDCS (n = 35) (https://clinicaltrials.gov/ct2/show/NCT03027687). Immediately before, one day after, and three months after all tDCS sessions, participants performed the Go-NoGo task while we measured behavioural and neurophysiological responses. RESULTS: One day after the intervention no significant effect was found of active tDCS on behavioural and neurophysiological measures of cognitive control in tobacco smokers. However, a significant improvement in reaction times, and a decrease in No-Go P3 amplitudes for smoking cues was found three months after active tDCS. CONCLUSION: Given the direction of the effect, we speculate that tDCS has a long-term modulatory learning effect on selective attention and motor inhibition.

No effect of repetitive tDCS on daily smoking behaviour in light smokers: A placebo controlled EMA study.

INTRODUCTION: The effectiveness of repetitive transcranial Direct Current Stimulation (tDCS) on reducing smoking behaviour has been studied with mixed results. Smoking behaviour is influenced by affect and context, therefore we choose to use mobile ecological momentary assessments (EMA) to measure changes in smoking behaviour after tDCS. METHODS: In a randomized, placebo-controlled, between subject study, we applied tDCS bilaterally with the anodal electrode targeting the right DLPFC (https://clinicaltrials.gov/ct2/show/NCT03027687). Smokers were allocated to six sessions of either active tDCS (n = 35) or sham tDCS (n = 36) and received two sessions on three different days in one week. They were asked to keep track of their daily cigarette consumption, craving and affect in an application on their mobile phones for three months starting one week before the first tDCS session. RESULTS: Number of smoked cigarettes a day progressively decreased up to one week after the last tDCS session in both conditions. Active treatment had no additional effect on cigarette consumption, craving and affect. CONCLUSIONS: In this exploratory study, repetitive bilateral tDCS over the DLPFC had no effect on daily smoking behaviour. Future research needs to investigate how motivation to quit smoking and the number of tDCS sessions affect the efficacy of repetitive tDCS.

Compliance with ecological momentary assessment protocols in substance users: a meta-analysis.

BACKGROUND AND AIMS: While there are considerable benefits to Ecological Momentary Assessment (EMA), poor compliance with assessment protocols has been identified as a limitation, particularly in substance users. Our aim was to identify the pooled compliance rate of EMA studies in substance users and examine variables that may influence compliance with EMA protocols, such as the length and frequency of assessments. DESIGN: A meta-analysis and meta-regression of all possible studies (randomized controlled trials and longitudinal) which incorporated EMA protocols, examining substance use. SETTING: Studies took place from 1998 to 2017, in numerous countries world-wide. PARTICIPANTS: One hundred and twenty-six studies were identified, contributing a total of 19 431 participants (52.32% male, mean age = 28.86). MEASUREMENTS: Compliance data, the proportion of responses to the study protocol, were extracted from each study alongside prompt frequency, total length of assessment period, substance use population and device used to administer EMA prompts. FINDINGS: The pooled compliance rate across all studies was 75.06% [95% confidence interval (CI) = 72.37%, 77.65%]. There was no evidence that compliance rates were significantly associated with prompt frequency [Q(3) = 7.35, P = 0.061], length of assessment period [Q(2) = 2.40, P = 0.301], substance type [Q(3) = 6.30, P = 0.098] or device administration [Q(4) = 4.28, P = 0.369]. However, dependent samples (69.80%) had lower compliance rates than non-dependent samples [76.02%; Q(1) = 4.13, P = 0.042]. CONCLUSIONS: The pooled compliance rate for Ecological Momentary Assessment studies in substance-using populations from 1998 to 2017 was lower than the recommended rate of 80%, and was not associated with frequency or duration of assessments.