Inhibitory control of proactive interference in adults with ADHD

Adult ADHD: it is old and new at the same time - what is it?

Even though the number of studies aiming to improve comprehension of ADHD pathology has increased in recent years, there still is an urgent need for more effective studies, particularly in understanding adult ADHD, both at preclinical and clinical levels, due to the increasing evidence that adult ADHD is highly distinct and a different entity from childhood ADHD. This review paper outlines the symptoms, diagnostics, and neurobiological mechanisms of ADHD, with emphasis on how adult ADHD could be different from childhood-onset. Data show a difference in the environmental, genetic, epigenetic, and brain structural changes, when combined, could greatly impact the behavioral presentations and the severity of ADHD in adults. Furthermore, a crucial aspect in the quest to fully understand this disorder could be through longitudinal analysis. In this way, we will determine if and how the pathology and pharmacology of ADHD change with age. This goal could revolutionize our understanding of the disorder and address the weaknesses in the current clinical classification systems, improving the characterization and validity of ADHD diagnosis, specifically those in adults.

Non-spatial inhibition of return attenuates audiovisual integration owing to modality disparities

Although previous studies have investigated the relationship between inhibition of return (IOR) and multisensory integration, the influence of non-spatial has not been explored. The present study aimed to investigate the influence of non-spatial IOR on audiovisual integration by using a "prime-neutral cue-target" paradigm. In Experiment 1, which manipulated prime validity and target modality, the targets were positioned centrally, revealing significant non-spatial IOR effects in the visual, auditory, and audiovisual modalities. Analysis of relative multisensory response enhancement (rMRE) indicated substantial audiovisual integration enhancement in both valid and invalid target conditions. Furthermore, the enhancement was weaker for valid targets than for invalid targets. In Experiment 2, the targets were positioned above and below to rule out repetition blindness (RB); this experiment successfully replicated the results observed in Experiment 1. Notably, Experiments 1 and 2 consistently found that the correlation between modality differences and rMRE for valid targets indicated that differences in signal strength between visual and auditory modalities contributed to a reduction in audiovisual integration. However, the absence of correlation with the invalid target suggests that attention, as a key factor, may play a significant role in this process. The present study highlights how non-spatial IOR reduces audiovisual integration and sheds light on the complex interaction between attention and multisensory integration.

Social-Emotional Inhibition of Return in Children with Autism Spectrum Disorder Versus Typical Development

In typical development there is a bias to orient visual attention to social information. Children with ASD do not reliably demonstrate this bias, and the role of attention orienting has not been well studied. We examined attention orienting via the inhibition of return (IOR) mechanism in a spatial cueing task using social-emotional cues; we studied 8- to 17-year-old children with ASD (n = 41) and typically developing controls (TDC) (n = 25). The ASD group exhibited a significantly stronger IOR effect than the TDC group, and the IOR effect correlated positively with social impairments but was unrelated to co-occurring ADHD or anxiety symptoms. The results provide evidence of an early altered attention mechanism that is associated with to core social deficits in ASD.

Real-time MEG neurofeedback training of posterior alpha activity modulates subsequent visual detection performance

It has been demonstrated that alpha activity is lateralized when attention is directed to the left or right visual hemifield. We investigated whether real-time neurofeedback training of the alpha lateralization enhances participants' ability to modulate posterior alpha lateralization and causes subsequent short-term changes in visual detection performance. The experiment consisted of three phases: (i) pre-training assessment, (ii) neurofeedback phase and (iii) post-training assessment. In the pre- and post-training phases we measured the threshold to covertly detect a cued faint Gabor stimulus presented in the left or right hemifield. During magnetoencephalography (MEG) neurofeedback, two face stimuli superimposed with noise were presented bilaterally. Participants were cued to attend to one of the hemifields. The transparency of the superimposed noise and thus the visibility of the stimuli were varied according to the momentary degree of hemispheric alpha lateralization. In a double-blind procedure half of the participants were provided with sham feedback. We found that hemispheric alpha lateralization increased with the neurofeedback training; this was mainly driven by an ipsilateral alpha increase. Surprisingly, comparing pre- to post-training, detection performance decreased for a Gabor stimulus presented in the hemifield that was un-attended during neurofeedback. This effect was not observed in the sham group. Thus, neurofeedback training alters alpha lateralization, which in turn decreases performances in the untrained hemifield. Our findings suggest that alpha oscillations play a causal role for the allocation of attention. Furthermore, our neurofeedback protocol serves to reduce the detection of unattended visual information and could therefore be of potential use for training to reduce distractibility in attention deficit patients, but also highlights that neurofeedback paradigms can have negative impact on behavioral performance and should be applied with caution.

Diminished testing benefits in young adults with attention-deficit hyperactivity disorder

Memory retrieval has been shown to enhance the long-term retention of tested material; however, recent research suggests that limiting attention during retrieval can decrease the benefits of testing memory. The present study examined whether testing benefits are reduced in young adults with attention-deficit hyperactivity disorder (ADHD). College students with and without ADHD read three short prose passages, each followed by a free recall test, a restudy period or a distractor task. Two days later participants recalled the passages. Although participants without ADHD did not show a significant benefit of testing over restudying, testing did produce recall benefits relative to not taking a test. These testing benefits were diminished in participants with ADHD, who did not show any advantage of testing over either restudying or no test. The absence of testing benefits in the ADHD group is likely due in part to decreased recall on the initial test. These findings have implications for improving educational practices among individuals with ADHD and also speak to the need to examine individual differences in the effectiveness of testing as a learning strategy.

Age-related changes in visual pseudoneglect

Pseudoneglect is a slight but consistent leftward attentional bias commonly observed in healthy young populations, purportedly explained by right hemispheric dominance. It has been suggested that normal aging might be associated with a decline of the right hemisphere. According to this hypothesis, a few studies have shown that elderly tend to exhibit a rightward attentional bias in line bisection. In the present study, we tested this hypothesis in young and older participants using a perceptual landmark task. Results yield evidence for an age-related shift, from a strong attentional leftward bias in young adults toward a suppressed or even a reversed bias in the elderly. Right hemisphere impairment coupled to a left hemispheric compensation might explain the perceptual shift observed in older adults. However, a decline in corpus callosum function cannot be excluded. Alternatively, these results may be in agreement with the hypothesis of an age-related specific inhibition of return dysfunction, an overt attentional orienting mechanism, and/or a decrease of dopamine.

Do low-effort learning strategies mediate impaired memory in ADHD?

As a group, participants with attention-deficit/hyperactivity disorder (ADHD) are impaired in academic performance and learning. This may be due to a mild intellectual impairment, impaired attention, or inability to allocate sufficient effort. If the latter is the case, this should be evident in the learning strategies applied. Four indices of learning strategy, considered to measure degree of effort, were analyzed from 67 participants with ADHD and 67 age-matched normal controls between 9 and 16 years of age. The participants with ADHD were impaired with regard to semantic clustering, retroactive interference, and percentage items reported from the middle section of the list even when controlling for IQ and comorbid conduct or oppositional defiant disorders symptoms. In addition, participants with combined ADHD (ADHD-C) did not display the normal proactive interference effect. The four effort indices explained 39% and 35% of the variance in free recall among participants with inattentive ADHD (ADHD-I) and ADHD-C, respectively. IQ was still significant when the effect of strategy measures were accounted for, whereas diagnosis was no longer significant when entered into the regression analysis after the effort indices. The study shows that participants with ADHD employ less effortful learning strategies than healthy controls and that low effort to a large degree can account for diagnosis related variance in memory performance.