Objectively-Measured Impulsivity and Attention-Deficit/Hyperactivity Disorder (ADHD): Testing Competing Predictions from the Working Memory and Behavioral Inhibition Models of ADHD

Abstract

Impulsivity is a hallmark of two of the three DSM-IV ADHD subtypes and is associated with myriad adverse outcomes. Limited research, however, is available concerning the mechanisms and processes that contribute to impulsive responding by children with ADHD. The current study tested predictions from two competing models of ADHD-working memory (WM) and behavioral inhibition (BI)-to examine the extent to which ADHD-related impulsive responding was attributable to model-specific mechanisms and processes. Children with ADHD (n = 21) and typically developing children (n = 20) completed laboratory tasks that provided WM (domain-general central executive [CE], phonological/visuospatial storage/rehearsal) and BI indices (stop-signal reaction time [SSRT], stop-signal delay, mean reaction time). These indices were examined as potential mediators of ADHD-related impulsive responding on two objective and diverse laboratory tasks used commonly to assess impulsive responding (CPT: continuous performance test; VMTS: visual match-to-sample). Bias-corrected, bootstrapped mediation analyses revealed that CE processes significantly attenuated between-group impulsivity differences, such that the initial large-magnitude impulsivity differences were no longer significant on either task after accounting for ADHD-related CE deficits. In contrast, SSRT partially mediated ADHD-related impulsive responding on the CPT but not VMTS. This partial attenuation was no longer significant after accounting for shared variance between CE and SSRT; CE continued to attenuate the ADHD-impulsivity relationship after accounting for SSRT. These findings add to the growing literature implicating CE deficits in core ADHD behavioral and functional impairments, and suggest that cognitive interventions targeting CE rather than storage/rehearsal or BI processes may hold greater promise for alleviating ADHD-related impairments.

Prevalence and diagnostic validity of motivational impairments and deficits in visuospatial short-term memory and working memory in ADHD subtypes

“…Further, it supports the assumption that WM is crucial for the mental activities basic to children's intelligence [59], and is consistent with the idea that neuropsychological impairments (e.g., in WM) are responsible for the lower level of intellectual performance typically found in children with ADHD [1]. 11 …”

Sleep disorder investigation might be considered to be mandatory in attention deficit/hyperactivity disorder guideline

“…Therefore, it seems that the presence of OSA causes alterations in latency, prolonging it, with a cascade effect on brain areas used for abstraction, including the frontal (Fz), central (Cz) and parietal (Pz). The same was observed by Huang et al 20 Another possible explanation is related to the fact that attention disorder can also cause abnormalities in working memory, which uses attention to follow its function 21,22 . A study focusing on an analysis of working memory related to attention could better define the relationship between attention deficit and sleep disorders, and changes in working memory due to altered latencies.…”

“…This can be associated with cognitive deficits other than those described above and changes in IQ 26 . The functional impairment of the frontal cortex can cause low performance of superior mental executive functions and lack of behavioural inhibition, which are essential for the development of other mental functions such as verbal and nonverbal memory, self-regulation of affect and motivation 22 . Imaging studies are other sources of evidence that suggest the possibility of neuronal damage in patients with apnea and hypoxemia, as was observed in our study.…”

Visuospatial working memory underlies choice-impulsivity in boys with attention-deficit/hyperactivity disorder

“…Moreover, these findings build on a growing body of research that suggests WM impairments underlie DSM-5-defined core ADHD-related hyperactivity (Alderson, Rapport, Kasper, Sarver, & Kofler 2012;Rapport et al, 2009), rapid-response impulsivity (Raiker et al, 2012), inattention (Kofler, Rapport, Bolden, Sarver, & Raiker, 2010), and disinhibition (Alderson et al, 2010), as well as secondary symptoms commonly associated with the disorder, such as social deficits (Kofler et al, 2011) and academic difficulties (Rennie, Beebe-Frankenberger, & Swanson, 2014). Alternative models, (Sonuga-Barke, 2003;Halperin & Schulz, 2006) have suggested that identification of a single-core neurocognitive deficit of ADHD is overly simplistic and point to the high degree of within-and between-study variability in neurocognitive task performance by affected children.…”

“…Moreover, the correlational nature of previous studies preclude interpretations about the directional relationship between the choice-impulsivity and WM constructs. That is, although findings from recent mediation-model studies suggest that ADHD-related WM impairments are upstream of behavioral inhibition deficits (Alderson, Rapport, Hudec, Sarver, & Kofler, 2010) and rapid-response impulsivity (Raiker, Rapport, Kofler, & Sarver, 2012), no studies to date have examined the directional relationship between WM and choiceimpulsivity in children diagnosed with ADHD. Findings that explicate the directional relationship between WM and choice-impulsivity are expected to have strong heuristic (e.g., informing model development and refinement) and applied (e.g., clarify appropriate targets for ADHD treatments) implications.…”