Attentional Deficit in Individuals with ADHD Is Modality-Specific

Attention-deficit/hyperactivity disorder or ADHD is a neurodevelopmental disorder characterized by a pattern of hyperactivity, impulsivity, and attention deficits in different sensory modalities. In particular, many studies have been done to understand attention deficits associated with ADHD by contrasting attentional performance between individuals with and without ADHD. For example, “Top-down attention modulates auditory-evoked neural responses in neurotypical, but not ADHD, young adults” provides insight into auditory attention deficits in individuals with ADHD by comparing top-down attentional control in young adults with and without ADHD (Kwasa et al. 2021); Dr. Kwasa and colleagues looked at differences in both behavior as well as neural responses measured by electroencephalogram (EEG), while both groups of subjects completed auditory selective attention tasks. Specifically, they looked at N1 and P3 event-related potentials in EEG to determine how each individual’s top-down attention and bottom-up attention modulate in response to different auditory stimuli, respectively. The auditory tasks required participants to pay attention only to target syllables and ignore interrupters (FOCAL trials), or to pay attention to target syllables and interrupters as they show up (BROAD trials). Overall, they found that performance was significantly better in the FOCAL trials than in BROAD in both groups, as subjects did not have to anticipate potential distractions. They also found that attention modulated N1 more weakly in ADHD subjects than did subjects without ADHD, suggesting weaker top-down control attention in ADHD subjects. Finally, individual differences in top-down control of attention directly relate to differences in performance, but ADHD status did not have a significant effect on performance. 

As sensory information overlaps with different modalities, it is fair to assume that the degree of attention deficit in each modality within an individual should be correlated as well. However, little is known about the interaction between attention deficits in different sensory modalities prior to the paper “Relationship between intraindividual auditory and visual attention in children with ADHD” (Lin et al. 2021). In this paper, Lin and colleagues examined two dimensions of attention, vision and sound, in children with and without ADHD. Each participant underwent two tests of variables of attention (visual version and auditory version), from which anticipatory responses (ANTI) were calculated and a higher number indicated greater deficit. Overall, they found a higher ANTI on the vision version than the auditory version in subjects with ADHD compared to controls, suggesting that visual attention is more impaired than auditory attention in the ADHD group. Most importantly, when they looked at ANTI within each ADHD subject, they found little correlation between vision and auditory attention, indicating that the mechanism of attentional deficits in individuals with ADHD is modality-specific; In other words, one could have visual attentional deficits (high ANTI) and not auditory attentional deficits (low ANTI), and vice versa.

Together, these two papers are important as they deepen our understanding of attention deficit in individuals with and without ADHD by highlighting its manifestation in one specific modality and the (lack of) relationship between two different modalities, respectively: Kwasa et al. specifically investigated the role of top-down control in modulating auditory attention in adults, whereas Lin et al’s study discovered separate mechanisms of visual and auditory attention deficits in children. A future experiment combining results from these two studies could look at how top-down attentional control modulates both modalities simultaneously in children with ADHD. 

References

Kwasa, Jasmine A. C. et al. “Top-down attention modulates auditory-evoked neural responses in neurotypical, but not ADHD, young adults.” bioRxiv (2021): n. Pag.

Lin, Hung-Yu, et al. "Relationship between intraindividual auditory and visual attention in children with ADHD." Research in Developmental Disabilities 108 (2021): 103808.