Attention-deficit hyperactivity disorder reduces automatic attention in young adults

Early Attentional Modulation by Working Memory Training in Young Adult ADHD Patients during a Risky Decision-Making Task

Background: Working memory (WM) deficits and impaired decision making are among the characteristic symptoms of patients affected by attention deficit/hyperactivity disorder (ADHD). The inattention associated with the disorder is likely to be due to functional deficits of the neural networks inhibiting irrelevant sensory input. In the presence of unnecessary information, a good decisional process is impaired and ADHD patients tend to take risky decisions. This study is aimed to test the hypothesis that the level of difficulty of a WM training (WMT) is affecting the top-down modulation of the attentional processes in a probabilistic gambling task. Methods: Event-related potentials (ERP) triggered by the choice of the amount wagered in the gambling task were recorded, before and after WMT with a the dual n-back task, in young ADHD adults and matched controls. For each group of participants, randomly assigned individuals were requested to perform WMT with a fixed baseline level of difficulty. The remaining participants were trained with a performance-dependent adaptive n-level of difficulty. Results: We compared the ERP recordings before and after 20 days of WMT in each subgroup. The analysis was focused on the time windows with at least three recording sites showing differences before and after training, after Bonferroni correction ( p < 0.05 ). In ADHD, the P1 wave component was selectively affected at frontal sites and its shape was recovered close to controls' only after adaptive training. In controls, the strongest contrast was observed at parietal level with a left hemispheric dominance at latencies near 900 ms, more after baseline than after adaptive training. Conclusion: Partial restoration of early selective attentional processes in ADHD patients might occur after WMT with a high cognitive load. Modified frontal sites' activities might constitute a neural marker of this effect in a gambling task. In controls, conversely, an increase in late parietal negativity might rather be a marker of an increase in transfer effects to fluid intelligence.

The Role of the Gut-Brain Axis in Attention-Deficit/Hyperactivity Disorder

Genetic and environmental factors play a role in the cause and development of attention-deficit/hyperactivity disorder (ADHD). Recent studies have suggested an important role of the gut-brain axis (GBA) and intestinal microbiota in modulating the risk of ADHD. Here, the authors provide a brief overview of the clinical and biological picture of ADHD and how the GBA could be involved in its cause. They discuss key biological mechanisms involved in the GBA and how these may increase the risk of developing ADHD. Understanding these mechanisms may help to characterize novel treatment options via identification of disease biomarkers.

Sensory Gating Capacity and Attentional Function in Adults With ADHD: A Preliminary Neurophysiological and Neuropsychological Study

Objective: The inability to filter sensory input correctly may impair higher cognitive function in ADHD. However, this relationship remains largely elusive. The objectives of the present study is to investigate the relationship between sensory input processing and cognitive function in adult patients with ADHD. Method: This study investigated the relationship between deficit in sensory gating capacity (P50 amplitude changes in a double-click conditioning-testing paradigm and perceptual abnormalities related to sensory gating deficit with the Sensory Gating Inventory [SGI]) and attentional and executive function (P300 amplitude in an oddball paradigm and attentional and executive performances with a neuropsychological test) in 24 adult patients with ADHD. Results: The lower the sensory gating capacity of the brain and the higher the distractibility related to sensory gating inability that the patients reported, the lower the P300 amplitude. Conclusion: The capacity of the brain to gate the response to irrelevant incoming sensory input may be a fundamental protective mechanism that prevents the flooding of higher brain structures with irrelevant information in adult patients with ADHD.

Overlaps and distinctions between attention deficit/hyperactivity disorder and autism spectrum disorder in young adulthood: Systematic review and guiding framework for EEG-imaging research

Attention deficit/hyperactivity disorders (ADHD) and autism spectrum disorders (ASD) frequently co-occur. However, we know little about the neural basis of the overlaps and distinctions between these disorders, particularly in young adulthood - a critical time window for brain plasticity across executive and socioemotional domains. Here, we systematically review 75 articles investigating ADHD and ASD in young adult samples (mean ages 16-26) using cognitive tasks, with neural activity concurrently measured via electroencephalography (EEG) - the most accessible neuroimaging technology. The majority of studies focused on event-related potentials (ERPs), with some beginning to capitalise on oscillatory approaches. Overlapping and specific profiles for ASD and ADHD were found mainly for four neurocognitive domains: attention processing, performance monitoring, face processing and sensory processing. No studies in this age group directly compared both disorders or considered dual diagnosis with both disorders. Moving forward, understanding of ADHD, ASD and their overlap in young adulthood would benefit from an increased focus on cross-disorder comparisons, using similar paradigms and in well-powered samples and longitudinal cohorts.

Daytime Sleepiness in Adults With ADHD: A Pilot Trial With a Multiple Sleep Latency Test

OBJECTIVE

To evaluate sleep latency (SL) during the multiple sleep latency test (MSLT) and subjective daytime sleepiness in adult ADHD and controls.

METHOD

Subjective daytime sleepiness was assessed by Epworth Sleepiness Scale (ESS) in 27 unmedicated adults with ADHD and in 182 controls. Thirteen ADHD patients and 26 controls underwent MSLT after one night of polysomnography (PSG).

RESULTS

Mean MSLT-SL was 10.6 ± 4.8 min in ADHD and 12.2 ± 4.2 min in controls (n.s.). Mean ESS score was 9.3 ± 4.9 points in ADHD and 6.9 ± 3.4 points in controls (p < .005). MSLT-SL and ESS scores correlated inversely by trend (r = -.45, p < .1) but not with ADHD symptoms or ADHD subtype.

CONCLUSION

Adults with ADHD do not differ from controls in mean MSLT-SL but experience increased subjective daytime sleepiness. Patients with subjective higher daytime tiredness fell asleep faster during MSLT.

Validation of the French sensory gating inventory: a confirmatory factor analysis

The Sensory Gating Inventory (SGI) is an instrument investigating daily experiences of sensory gating deficit developed for English speaking schizophrenia patients. The purpose of this study is to design and validate a French version of the SGI. A forward-backward translation of the SGI was performed. The psychometric properties of the French SGI version were analyzed. A confirmatory factor analysis (CFA) was carried out to determine whether factor structure of the French version is similar to the original English version. In a sample of 363 healthy subjects (mean age=31.8 years, S.D.=12.2 years) the validation process revealed satisfactory psychometric properties: the internal consistency reliability was confirmed for each dimension; each item achieved the 0.40 standard threshold for item-internal consistency; each item was more highly correlated with its contributive dimension than with the other dimensions; and based on a CFA, we found a 4-factor structure for the French version of the SGI similar to the original instrument. Test-retest reliability was not determined. The French version of the SGI is a psychometrically sound self-report for measuring phenomenological sensory gating experiences.

Event related potentials study of aberrations in voice control mechanisms in adults with attention deficit hyperactivity disorder

OBJECTIVE

The present study was designed to test for neural signs of impulsivity related to voice motor control in young adults with ADHD using EEG recordings in a voice pitch perturbation paradigm.

METHODS

Two age-matched groups of young adults were presented with brief pitch shifts of auditory feedback during vocalization. Compensatory behavioral and corresponding bioelectrical brain responses were elicited by the pitch-shifted voice feedback.

RESULTS

The analysis of bioelectrical responses showed that the ADHD group had shorter peak latency and onset time of motor-related bioelectrical brain responses as compared to the controls.

CONCLUSIONS

These results were interpreted to suggest differences in executive functions between ADHD and control participants.

SIGNIFICANCE

We hypothesize that more rapid motor-related bioelectrical responses found in the present study may be a manifestation of impulsiveness in adults with ADHD at the involuntary level of voice control.