Neural Correlates of Working Memory Deficits in Different Adult Outcomes of ADHD: An Event-Related Potential Study

Parental Report of Remission in ADHD: Results From a Community-Based, Nationally Representative Sample

OBJECTIVE

Various studies have examined rates of remission in ADHD with mixed results.

METHOD

Survival curve analyses were performed on a community-based sample.

RESULTS

The results of the current study appear to support the contemporary literature that rates of remission in ADHD are lower than have been found in many earlier studies. The current study also reports a mean age of remission in ADHD of around 14 years old, which has not been previously reported via survival curve analyses. Additionally, the results of the current study found several variables to be significantly associated with remission in ADHD which included: the presence of comorbid disorder; lower symptoms of ADHD; sex of the child (being female); and the receipt of behavioral treatment.

CONCLUSION

Implications and limitations are discussed as related to these findings.

Microstate dynamics and spectral components as markers of persistent and remittent attention-deficit/hyperactivity disorder

OBJECTIVE

We leveraged microstate characteristics and power features to examine temporal and spectral deviations underlying persistent and remittent attention-deficit/hyperactivity disorder (ADHD).

METHODS

50 young adults with childhood ADHD (28 persisters, 22 remitters) and 28 demographically similar healthy controls (HC) were compared on microstates features and frequency principal components (f-PCs) of eye-closed resting state. Support vector machine model with sequential forward selection (SVM-SFS) was utilized to discriminate three groups.

RESULTS

Four microstates and four comparable f-PCs were identified. Compared to HC, ADHD persisters showed prolonged duration in microstate C, elevated power of the delta component (D), and compromised amplitude of the two alpha components (A1 and A2). Remitters showed increased duration and coverage of microstate C, together with decreased activity of D, relatively intact amplitude of A1, and amplitude reduction in A2. The SVM-SFS algorithm achieved an accuracy of 93.59% in classifying persisters, remitters and controls. The most discriminative features selected were those exhibiting group differences.

CONCLUSIONS

We found widespread anomalies in ADHD persisters in brain dynamics and intrinsic EEG components. Meanwhile, the neural features in remitters exhibited multiple patterns.

SIGNIFICANCE

This study underlines the use of microstate dynamics and spectral components as potential markers of persistent and remittent ADHD.

Neural basis of the attention bias during addiction stroop task in methamphetamine-dependent patients with and without a history of psychosis: an ERP study

Background

Attentional bias plays an important role in sustaining various types of drug addiction. No prior studies examined methamphetamine (MA)-associated psychosis (MAP) relationships between ERP time course and performance on an addiction Stroop task in MA abusers. The aim of the present study was to determine whether MA abusers with (MAP+) or without (MAP-) psychosis exhibit alterations of the ERP during the addiction Stroop task.

Methods

Thirty-one healthy controls (CTRL), 14 MAP-, and 24 MAP+ participants were recruited and completed the addiction Stroop task during EEG recording using 32 electrodes. Group variations were compared on measures of behavioral task performance and event-related potentials (ERP) of performance monitoring (N200, P300, N450). The Barratt impulsiveness scores were analyzed to investigate correlations with ERP changes.

Results

MA-related word stimulus elicited a more negative N200 amplitude over left-anterior electrodes in MAP- abusers; furthermore, a positive association between the N200 amplitude and Barratt attentional scores and non-planning scores was observed, while no such differences were found in MAP+ abusers. There were no significant differences in reaction time (RT) and error rate between each group.

Conclusion

This is the first study to examine psychosis relationships between ERP time course and performance on an addiction Stroop task in MA abusers with or without psychosis. These findings support the association between attentional bias measured by the MA addiction Stroop task and N200 component as well as indicate the possibility of using this cognitive task in combination with ERP technology to detect psychosis factors among abstinent MA abusers.

Theta power and functional connectivity as neurophysiological markers of executive functions in individuals with cognitive complaints in daily life

Impairments in executive functions (EFs) are common across psychological disorders. Research into the neural oscillations underlying EFs has the potential to help understand these impairments and contribute to the development of interventions. The aim of this study is to assess theta power and functional theta connectivity in the sensor space of the regions of the superordinate network for the core EFs: conflict monitoring, response inhibition, set-shifting, and working memory updating. We recruited adults with self-reported everyday EFs complaints and formed two groups: one with attention deficit hyperactivity disorder (ADHD) (n=27) and another without any diagnosis (n=22), and compared them to controls (n=21) on the Stroop, Stop-signal, Switching, and N-back task using EEG. Power and functional connectivity analyses were conducted for four regions of interest: frontal-midline, frontolateral left and right, and parietal region. For all four EFs, the groups showed a dynamical increase in theta power over time in the four regions of interest, as well as in functional theta connectivity between these regions. Group differences were found especially for conflict monitoring, with differences in theta power in the frontal-midline and frontolateral right region. These neural markers are also associated with behavioural performance and complaints in daily life. For set-shifting, group differences were less pronounced and for response inhibition and working memory updating no group differences were observed.

Convergence mechanism of mindfulness intervention in treating attention deficit hyperactivity disorder: Clues from current evidence

This paper reviews the underlying evidence for various aspects of the convergence mechanism of mindfulness intervention in attention deficit hyperactivity disorder (ADHD). There may be compatibility among various ADHD remission models and the therapeutic mechanism of mindfulness intervention in ADHD may be mainly via the convergence mechanism. However, neuroimaging-based analysis of the mechanisms of mindfulness intervention in treating ADHD is lacking. Differences in the efficacy of various subtypes of mindfulness intervention, and corresponding specific imaging changes need further investigation. Future research may focus on the neuroimaging features of specific mindfulness intervention subtypes.

Compensatory mechanism of attention-deficit/hyperactivity disorder recovery in resting state alpha rhythms

Alpha rhythms in the human electroencephalogram (EEG), oscillating at 8-13 Hz, are located in parieto-occipital cortex and are strongest when awake people close their eyes. It has been suggested that alpha rhythms were related to attention-related functions and mental disorders (e.g., Attention-deficit/hyperactivity disorder (ADHD)). However, many studies have shown inconsistent results on the difference in alpha oscillation between ADHD and control groups. Hence it is essential to verify this difference. In this study, a dataset of EEG recording (128 channel EGI) from 87 healthy controls (HC) and 162 ADHD (141 persisters and 21 remitters) adults in a resting state with their eyes closed was used to address this question and a three-gauss model (summation of baseline and alpha components) was conducted to fit the data. To our surprise, the power of alpha components was not a significant difference among the three groups. Instead, the baseline power of remission and HC group in the alpha band is significantly stronger than that of persister groups. Our results suggest that ADHD recovery may have compensatory mechanisms and many abnormalities in EEG may be due to the influence of behavior rather than the difference in brain signals.

Trust violations affect the emotional working memory updating: An event-related brain potential study

Previous studies found that trust violations impaired the ability of working memory (WM) updating, however, these studies did not consider the emotional context in the WM updating. Individuals who experience trust violations have the characteristics of negative bias and enhanced negative emotion. Thus it is necessary to explore how emotional contexts moderate the relationship between trust violations and WM updating. In this study, the trust game was used to manipulate trust violations. Fifty-three participants performed the emotional two-back task while event-related potentials were recorded. Results showed that compared to the control group, the violation group had smaller P2 and P3 amplitudes both in emotional and nonemotional contexts and larger N2 amplitudes in the emotional contexts. There were no significant differences between the two groups on the behavioral data. These results suggest that trust violations result in the inefficient allocation of attention in the early attention (P2) and updating maintenance stages (P3) regardless of the emotional type of the material. Trust violations also improve the abilities of response inhibition, conflict monitoring, or sequential match (N2) when processing emotional material, which may play a compensatory role to maintain a level of behavioral performance comparable to the control group. Together, trust violations affect the sub-processes underlying emotional WM updating differently, and these influences are not valence specific.

Changes in temporal properties for epidemics of notifiable infectious diseases in China during the COVID-19 epidemic: population-based surveillance study

BACKGROUND

The COVID-19 was first reported in 2019, and the Chinese government immediately carried out stringent and effective control measures in response to the epidemics.

OBJECTIVE

These non-pharmaceutical interventions may have impacted incidences of other infectious diseases as well. Potential explanations underlying this reduction, however, are not clear. Hence, in this study, we aimed to study the influence of the COVID-19 prevention policies on other infectious diseases (mainly class B infectious diseases) in China.

METHODS

The time-series datasets between 2017 and 2021 for 23 notifiable infectious diseases were extracted from public datasets from the National Health Commission of China. Several indices (peak and trough amplitude, infection selectivity, preferred time to outbreak, oscillatory strength) of each infectious disease were calculated before and after the COVID-19 outbreak.

RESULTS

We found that the prevention and control policies for COVID-19 had a strong significant reduction effect on outbreaks of other infectious diseases. A clear event-related trough (ERT) was observed after the outbreak of COVID-19 under the strict control policies, and its decreasing amplitude is related to the infection selectivity and preferred outbreak time of the disease before the COVID-19. We also calculated the oscillatory strength before and after the COVID-19 outbreak and found that it is significantly stronger before the COVID-19 outbreak, and does not correlate with the trough amplitude.

CONCLUSIONS

Our results directly demonstrate that prevention policies for the COVID-19 have immediate additional benefits for controlling most class B infectious diseases, and several factors (infection selectivity, preferred outbreak time) may have contributed to the reduction of outbreaks. This study may guide the implementation of non-pharmaceutical interventions to control a wider range of infectious diseases.

CLINICALTRIAL

Altered Processing of Social Emotions in Individuals With Autistic Traits

Social impairment is a defining phenotypic feature of autism. The present study investigated whether individuals with autistic traits exhibit altered perceptions of social emotions. Two groups of participants (High-AQ and Low-AQ) were recruited based on their scores on the autism-spectrum quotient (AQ). Their behavioral responses and event-related potentials (ERPs) elicited by social and non-social stimuli with positive, negative, and neutral emotional valence were compared in two experiments. In Experiment 1, participants were instructed to view social-emotional and non-social emotional pictures. In Experiment 2, participants were instructed to listen to social-emotional and non-social emotional audio recordings. More negative emotional reactions and smaller amplitudes of late ERP components (the late positive potential in Experiment 1 and the late negative component in Experiment 2) were found in the High-AQ group than in the Low-AQ group in response to the social-negative stimuli. In addition, amplitudes of these late ERP components in both experiments elicited in response to social-negative stimuli were correlated with the AQ scores of the High-AQ group. These results suggest that individuals with autistic traits have altered emotional processing of social-negative emotions.

A comparative experimental study of visual brain event-related potentials to a working memory task: virtual reality head-mounted display versus a desktop computer screen

Virtual reality head mounted display (VR HMD) systems are increasingly utilised in combination with electroencephalography (EEG) in the experimental study of cognitive tasks. The aim of our investigation was to determine the similarities/differences between VR HMD and the computer screen (CS) in response to an n-back working memory task by comparing visual electrophysiological event-related potential (ERP) waveforms (N1/P1/P3 components). The same protocol was undertaken for VR HMD and CS with participants wearing the same EEG headcap. ERP waveforms obtained with the VR HMD environment followed a similar time course to those acquired in CS. The P3 mean and peak amplitudes obtained in VR HMD were not significantly different to those obtained in CS. In contrast, the N1 component was significantly higher in mean and peak amplitudes for the VR HMD environment compared to CS at the frontal electrodes. Significantly higher P1 mean and peak amplitudes were found at the occipital region compared to the temporal for VR HMD. Our results show that successful acquisition of ERP components to a working memory task is achievable by combining VR HMD with EEG. In addition, the higher amplitude N1/P1 components seen in VR HMD indicates the potential utility of this VR modality in the investigation of early ERPs. In conclusion, the combination of VR HMD with EEG/ERP would be a useful approach to advance the study of cognitive function in experimental brain research.

Recognition memory for pictures in children with ADHD: an event-related potential study

OBJECTIVE

Children with ADHD are reported to accompany by various degrees of recognition memory cognitive deficits. We aimed to investigate age-related changes of the amplitude in event-related potential recordings on recognition memory in Chinese children with ADHD and to provide theoretical basis of neuro-electrophysiology for the cognition development of children.

METHOD

ERP and behavioral data of 6- to -10-year-old children with ADHD (n = 94) and typically developing controls (TD, n = 96) were collected while the children performed a classical visual study-test paradigm task.

RESULTS

Children with ADHD have defects in pictures recognition and showed a significantly smaller P2 component than that of TD children. The development of P2 and P3 component were different between the two groups. Moreover, the TD children showed the frontal old/new effect (N2) taken as a correlate of familiarity at 6 years old, and a parietal old/new effect (P3) taken as a correlate of recollection at 9 years old, while children with ADHD showed a parietal old/new effect (P3) only at 6 years old.

CONCLUSION

Our study provided the novel evidence that recognition memory follow different developmental trajectories at the age of 6-10 between TD and ADHD.

AOAR: an automatic ocular artifact removal approach for multi-channel electroencephalogram data based on non-negative matrix factorization and empirical mode decomposition

OBJECTIVE

Electroencephalogram (EEG) signals suffer inevitable interference from artifacts during the acquisition process. These artifacts make the analysis and interpretation of EEG data difficult. A major source of artifacts in EEGs is ocular activity. Therefore, it is important to remove ocular artifacts before further processing the EEG data.

APPROACH

In this study, an automatic ocular artifact removal (AOAR) method for EEG signals is proposed based on non-negative matrix factorization (NMF) and empirical mode decomposition (EMD). First, the amplitude of EEG data was normalized in order to ensure its non-negativity. Then, the normalized EEG data were decomposed into a set of components using NMF. The components containing ocular artifacts were extracted automatically through the fractal dimension. Subsequently, the temporal activities of these components were adaptively decomposed into some intrinsic mode functions (IMFs) by EMD. The IMFs corresponding to ocular artifacts were removed. Finally, the de-noised EEG data were reconstructed.

MAIN RESULTS

The proposed method was tested against seven other methods. In order to assess the effectiveness and reliability of the AOAR method in processing EEG data, experiments on ocular artifact removal were performed using simulated EEG data. Experimental results indicated that the proposed method was superior to the other methods in terms of root mean square error, signal-to-noise ratio (SNR) and correlation coefficient, especially in cases with a lower SNR. To further evaluate the potential applications of the proposed method in real life, the proposed method and others were applied to preprocess real EEG data recorded from children with and without attention-deficit/hyperactivity disorder (ADHD). After artifact rejection, the event-related potential feature was extracted for classification. The AOAR method was best at distinguishing the children with ADHD from the others.

SIGNIFICANCE

These results indicate that the proposed AOAR method has excellent prospects for removing ocular artifacts from EEG data.