Differential Brain Activation Patterns in Adult Attention-Deficit Hyperactivity Disorder (ADHD) Associated With Task Switching

Department of Clinical Psychological Science, Faculty of Psychology and Neuroscience, Maastricht University, the Netherlands.
Neuropsychology (Impact Factor: 3.27). 07/2010; 24(4):413-23. DOI: 10.1037/a0018997
Source: PubMed


The main aim of the study was to examine blood oxygen level-dependent response during task switching in adults with attention-deficit/hyperactivity disorder (ADHD).
Fifteen male adults with ADHD and 14 controls participated and performed a task-switching paradigm.
Behaviorally, no specific executive control problems were observed in the ADHD participants, although they did display more errors in general. The neuroimaging data did show remarkable differences between the ADHD and control adults: Adults with ADHD engaged more strongly the dorsal anterior cingulate cortex, middle temporal gyrus, precuneus, lingual gyrus, precentral gyrus, and insula than did the healthy controls during task switching. Controls displayed more task-related activity in the putamen, posterior cingulate gyrus, medial frontal gyrus, thalamus, orbitofrontal cortex, and postcentral gyrus.
ADHD adults did not display specific executive control problems at a behavioral level, but did engage different brain areas during task switching compared with healthy controls. The results are discussed in the framework of the executive frontostriatal circuitry, conflict detection, and attentional networks.

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Available from: Pauline Dibbets, Dec 19, 2013
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    • "Of the studies that have been conducted, several have shown decreased activation as well as functional connectivity in frontostriatal, frontocerebellar and frontoparietal networks (Bush et al. 1999, Valera et al. 2005, Wolf et al. 2009). Conversely, there are other studies in adults that show increased activation throughout the frontal, parietal and occipital lobes during tasks of executive function (Hale et al. 2007, Banich et al. 2009, Dibbets et al. 2010). It has been hypothesized that inconsistencies across studies of adult ADHD, as compared to child/adolescent ADHD, may be due to confounding factors such as the need for retrospective diagnoses, medication effects, symptom remission and comorbid disorders (Cubillo and Rubia 2010). "
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    ABSTRACT: An important characteristic of childhood attention-deficit/hyperactivity disorder (ADHD) is a bias towards small immediate versus larger delayed rewards, but it is not known if this symptom is also a feature of adult ADHD. A delay-discounting task was administered to participants with adult ADHD and a comparison group in conjunction with functional magnetic resonance imaging. Participants responded to a series of questions that required judgments between small sums of money available immediately and larger sums obtained after a temporal delay. Question parameters were adjusted by an adaptive algorithm designed to converge on each participant’s discounting indifference point, an individual set point at which there is equal valuation of both choices. In all participants, robust task activation was observed in regions previously identified in functional imaging studies of delay discounting. However, adults with ADHD showed less task activation in a number of regions including the dorsolateral prefrontal cortex, superior frontal gyrus, anterior cingulate, caudate nucleus and declive of the cerebellum. Additionally, the degree to which a participant discounted delayed rewards was inversely related to task activation in the cerebellum. The results suggest that the bias towards immediate rewards in childhood ADHD may not persist behaviorally, but instead present in adulthood as alterations in frontostriatal and frontocerebellar networks.
    Acta neurobiologiae experimentalis 10/2015; 75(3):2015. · 1.29 Impact Factor
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    • "We did not find much evidence for attentional shifting abnormalities in ADHD in behavior or BOLD signal. Few studies have examined shifting or cognitive flexibility in adults, with two studies using traditional task switching paradigms reporting inconsistent results, possibly due to different comorbidity and medication status [Cubillo et al., 2010; Dibbets et al., 2010]. It is difficult to interpret the present findings within the context of these studies as task requirements were very different, with infrequent shifting requiring no change in overt responding [Dodds et al., 2011]. "
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    ABSTRACT: Adult ADHD has been linked to impaired motor response inhibition and reduced associated activation in the right inferior frontal cortex (IFC). However, it is unclear whether abnormal inferior frontal activation in adult ADHD is specifically related to a response inhibition deficit or reflects a more general deficit in attentional processing. Using functional magnetic resonance imaging, we tested a group of 19 ADHD patients with no comorbidities and a group of 19 healthy control volunteers on a modified go/no-go task that has been shown previously to distinguish between cortical responses related to response inhibition and attentional shifting. Relative to the healthy controls, ADHD patients showed increased commission errors and reduced activation in inferior frontal cortex during response inhibition. Crucially, this reduced activation was observed when controlling for attentional processing, suggesting that hypoactivation in right IFC in ADHD is specifically related to impaired response inhibition. The results are consistent with the notion of a selective neurocognitive deficit in response inhibition in adult ADHD associated with abnormal functional activation in the prefrontal cortex, whilst ruling out likely group differences in attentional orienting, arousal and motivation. Hum Brain Mapp, 2014. © 2014 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.
    Human Brain Mapping 10/2014; 35(10). DOI:10.1002/hbm.22539 · 5.97 Impact Factor
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    • "Psychiatry Research: Neuroimaging revealed an energy deficiency in the thalamus in children and adolescents with ADHD (Ferreira et al., 2009; Cortese et al., 2012). Task-based fMRI studies have demonstrated reduced blood– oxygen-level dependent (BOLD) activation in the thalamus during tasks of motor inhibition and cognitive switching in adults with ADHD, which are persistent from childhood (Cubillo et al., 2010), and reduced BOLD activation in the thalamus during task switching in adults with ADHD (Dibbets et al., 2011). Resting-state fMRI studies have reported abnormal functional connectivity between thalamus and striatum, hippocampus and amygdala within CSTC loops in children with ADHD (Cao et al., 2009; Qiu et al., 2011). "
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    ABSTRACT: Attention-deficit/hyperactivity disorder (ADHD) is characterized by widespread structural and functional abnormalities in the cortico-striato-thalmo-cortical (CSTC) loops that subserve attention and executive functions. In this study, we analyzed thalamic shape and its white matter connections using structural MRI and diffusion tensor imaging (DTI) data acquired from children with ADHD (n=19) and controls (n=19). Shape morphology of the thalamus was assessed using shape-based analysis, while connectivity between the thalamus and other brain regions was determined using probabilistic diffusion tractography. Shape-based analysis indicated significant regional atrophy in the left thalamus in children with ADHD compared to controls. Group analyses of white matter connectivity measures showed significantly decreased mean fractional anisotropy (FA) and volume of the tracts between thalamus and striatum, hippocampus, and prefrontal lobe in children with ADHD compared to controls. The structural abnormalities within the thalamus and the reduced integrity of the white matter tracks between thalamus and other brain regions, as shown from the results of this study, may be the anatomical bases of the impaired cognitive performances in the attention and executive function domains in ADHD.
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