Neuroimaging of Inhibitory Control Areas in Children With Attention Deficit Hyperactivity Disorder Who Were Treatment Naive or in Long-Term Treatment

University of Nottingham, Nottigham, England, United Kingdom
American Journal of Psychiatry (Impact Factor: 12.3). 07/2006; 163(6):1052-60. DOI: 10.1176/appi.ajp.163.6.1052
Source: PubMed


Difficulty with response inhibition is a cardinal symptom of attention deficit hyperactivity disorder (ADHD), combined type. Prefrontal and cingulate brain regions are known to be involved in inhibitory control. Event-related functional magnetic resonance imaging (fMRI) might establish if these regions differ in their activity in ADHD children relative to healthy comparison subjects.
Fifteen healthy comparison subjects and 17 children with ADHD, combined type, completed fMRI studies while performing the Stop Signal Task. Eight ADHD subjects were treatment naive; the remainder had a history of long-term treatment with stimulants, but they were medication free at the time of the fMRI. No subject had a learning disorder or a comorbid psychiatric condition (other than oppositional defiant disorder in the ADHD subjects).
Both the ADHD and comparison subjects activated the right dorsolateral prefrontal cortex on "stop" trials relative to "go" trials; this increase was greater in ADHD subjects. When inhibition was unsuccessful (relative to successful inhibition), healthy comparison subjects strongly activated the anterior cingulate cortex and the left ventrolateral prefrontal cortex. In contrast, the ADHD subjects did not show these differences. Activations in treatment-naive and ADHD subjects treated in the long term did not differ significantly in any brain regions.
In relation to comparison subjects, ADHD subjects failed to activate the anterior cingulate cortex and the left ventrolateral prefrontal cortex after unsuccessful inhibition. These findings appear in treatment-naive ADHD individuals and are unlikely to be an artifact of long-term treatment with stimulants or of abrupt termination of stimulants before imaging.

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Available from: Mario Liotti, Oct 21, 2015
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    • "These observations were further supported by structural (Shaw et al., 2009) and functional (Pliszka et al., 2006) neuroimaging studies comparing medication-naïve children (Pliszka et al., 2006) and adolescents (Shaw et al., 2009) to their treated counterparts. In a prospective study, Bush et al. (2008) also found increased left IFG activation after treatment with methylphenidate for 6 weeks in adults with ADHD. "
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    • "From a neuropsychological perspective, ADHD is associated with deficits in well-defined cognitive domains, including sustained attention and executive functioning (Barkley, 1998; Pennington & Ozonoff, 1996). Some theorists focus on executive deficits (Shallice et al., 2001); children with ADHD show deficits in executive functions, including response inhibition, working memory, and conflict resolution (Bush et al., 1999; Casey et al., 1997; Doyle, 2006; Pliszka et al., 2006; Rubia, Smith, Brammer, Toone & Taylor, 2005; Vaidya et al., 2005); other theorists recognize a difficulty in ADHD in the automatic processing of basic skills (Ackerman, Anhalt, Holcomb, & Dykman, 1986; Fabio, 2001, 2009) or in the modality of stimulus presentation (Fabio & Antonietti, 2012). Moreover, Hazell et al. (1999) suggested that participants affected by ADHD show, along with a deficit in the central controlled processes, a deficit in the encoding and in the automaticity of processes. "
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    • "Previous ERP studies indicated that behavioral inhibition is associated to the N2 component, whose amplitude increases in Nogo trials according to the response inhibition requirements [26], [42]–[44], as compared to Go trials where no RI activity is needed [15]. "
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