Alterations in resting-state gamma-activity is adults with autism spectrum disorder: A High-Density EEG study.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a wide range of symptoms that include deficits in social cognition and difficulties with social interactions. Neural oscillations in the EEG gamma band have been proposed as an important candidate neurobiological marker of higher order cognitive processes and social interactions. We investigated resting-state gamma-activity of patients with ASD (n=23) in order to delineate alterations as compared to typically developing (TD) subjects (n=24). EEG absolute power was examined in the gamma (30-100Hz) frequency band. We found significantly reduced spectral power across the entire gamma range in the ASD group. The decrease was most pronounced over the inferior-frontal and temporo-parietal junction areas. We also found a significant decrease in gamma-activity over the dorsolateral prefrontal cortex, especially in the left side. Since these brain areas have been associated with social functioning, the reduced gamma-activity in ASD may represent a cortical dysfunction that could underlie a diminished capacity to interpret socially important information, thereby interfering with social functioning. The alterations we found may lend support for an improved diagnosis. Furthermore, they can lead to focused therapies, by targeting the dysfunctional brain activity to improve social cognitive and interaction abilities that are compromised in ASD.

Altered interpersonal distance regulation in autism spectrum disorder.

Interpersonal distance regulation is an essential element of social communication. Its impairment in autism spectrum disorder (ASD) is widely acknowledged among practitioners, but only a handful of studies reported empirical research in real-life settings, focusing mainly on children. Interpersonal distance in adults with ASD and related autonomic functions received less attention. Here, we measured interpersonal distance along with heart rate variability (HRV) in adults with ASD, and tested the modulatory effects of eye-contact and attribution. Twenty-two adults diagnosed with ASD and 21 matched neurotypical controls participated in our study from October 2019 to February 2020. Our experimental design combined the modified version of the stop distance paradigm with HRV measurement controlling for eye contact between the experimenter and the participant to measure interpersonal distance. Still, we did not detect significant modulatory effect of eye contact and attribution. Our results showed a greater preferred distance in ASD. Moreover, we found lower baseline HRV and reduced HRV reactivity in ASD; however, these autonomic measurements could not predict preferred interpersonal distance. Our study highlights the importance of interpersonal space regulation in ASD: it might be considered that people with ASD need individually variable, presumably greater interpersonal distance. In addition, regardless of the distance they may have reduced autonomic regulatory capacity in social situations. Our results could help shape future experiments with sophisticated designs to grasp the complexity and underlying factors of distance regulation in typical and atypical populations.

Intact fluency in autism? A comprehensive approach of verbal fluency task including word imageability and concreteness.

Verbal fluency is a cognitive function reflecting executive functions and the ability to retrieve the appropriate information from memory quickly. Previous studies reported conflicting results-impaired and intact verbal fluency-in autism spectrum disorder (ASD). Most studies concentrate on overall word productivity, errors, perseverations, clustering, or switching. We used a comprehensive approach to evaluate the reported discrepancy in the literature and introduced a new angle using the concept of word abstraction and imageability. Moreover, we analyzed the performance in two-time intervals (0-30 s and 31-60 s) to assess the temporal dynamics of verbal fluency and a possible activation or initiation deficit in autism. Sixteen adults with ASD and 16 neurotypical control participants, matched by gender, age, and education level, participated in our study. Contrary to our expectations, we did not find a significant difference between groups in word productivity, the number of errors, clustering, or temporal dynamics, neither in semantic nor in phonemic fluency tasks. Surprisingly, the two study groups' performance did not differ in terms of imageability or concreteness characteristics either. Our results raise the possibility that verbal fluency performance is intact in autism. We also suggest using a comprehensive approach when measuring fluency in autism. LAY SUMMARY: People with autism tend to think and communicate differently. In our study, we tested whether people with autism come up with more concrete or imageable words and whether their performance is better compared with neurotypicals in the beginning or in the later phase of a task measuring how many words they can produce in a minute. We did not detect any difference between the two groups; however, we recommend studying verbal fluency in autism from more and different angles in the future.

Attention deficit hyperactivity disorder: Last in, first out - delayed brain maturation with an accelerated decline?

While early neurodevelopmental processes during the emergence of ADHD in childhood received considerable attention, the neurobiological mechanisms that underlie the changes in ADHD in adulthood remain largely unaddressed. We wanted to delineate neurodevelopmental changes in adult ADHD using an electrophysiological measure, the fronto-central NoGo P3 event-related potential (ERP), which is an important neurophysiological index of brain functioning in ADHD, and biomarker for response inhibition and aging. ERPs were obtained from 45 ADHD and 41 healthy subjects using a 128-channel BioSemi recording-system, applying emotionally-valenced and neutral stimuli in a response inhibition task. Our results indicated that ADHD subjects manifested delayed developmental P3-trajectory in young-adulthood as compared to controls; they also showed P3 reduction across all emotional valences, and the reduction was most pronounced at younger ages. The differences in P3 diminished by mid-adulthood, and started to increase again at more advanced ages. Thus, similar to structural-MRI indices, developmental brain differences in the fronto-central NoGo P3 in ADHD largely normalize in young-adulthood. However, a reduction of P3 occurs again starting from mid-adulthood. As the fronto-central NoGo P3 reflects the functioning of the frontal areas (which show delayed maturation in ADHD), our findings are consistent with the ''last in, first out'' hypothesis, which refers to a mirroring pattern of brain development and aging, and posits that brain regions that develop relatively late degenerate relatively early with age. Thus, ADHD may not only be associated with delayed neurodevelopment, but also with a premature age-related deterioration, at least in some measures of electrophysiological functioning.

Functional impairment in adults positively screened for attention-deficit hyperactivity disorder: the role of symptom presentation and executive functioning.

BACKGROUND: While the number of symptoms of attention-deficit hyperactivity disorder (ADHD) decreases with age, a high proportion of adults with ADHD symptoms suffer from persistent functional impairment (Fi) linked to these symptoms. Our objective was to investigate the specific roles of two potentially important predictors of this Fi: the clinical symptom presentation and the deficit in executive functions (EFs). METHODS: A total of 158 subjects from a community sample positively screened for ADHD were classified into two groups: those with and without Fi. Following a detailed diagnostic process, participants were administered a self-rating scale for ADHD symptoms as well as a neuropsychological test battery containing tests of EF and attention relevant as potential cognitive endophenotypes for ADHD. RESULTS: The overall number as well as the number of inattentive, hyperactive and impulsive symptoms, confirmed both by examiner and self-report, were significantly higher among Fi subjects. The highest odds ratio for Fi was associated with impulsive symptoms. Additionally, self-reported complaints of problems with self-concept were significantly higher among Fi subjects. No significant relationship between Fi and neuropsychological measures of EF and attention was detected. CONCLUSIONS: This study revealed that the number of symptoms, in particular that of impulsivity, had a significant impact on Fi in adults with symptoms of ADHD. Furthermore, our results underline the importance of assessing complaints and behaviors related to self-concept, which are not included in DSM-IV diagnostic criteria of ADHD but nonetheless may be associated with functional outcome of the disorder.