Article

Meta-Analysis of Structural Imaging Findings in Attention-Deficit/Hyperactivity Disorder

Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.
Biological Psychiatry (Impact Factor: 10.26). 06/2007; 61(12):1361-9. DOI: 10.1016/j.biopsych.2006.06.011
Source: PubMed

ABSTRACT

Although there are many structural neuroimaging studies of attention-deficit/hyperactivity disorder (ADHD) in children, there are inconsistencies across studies and no consensus regarding which brain regions show the most robust area or volumetric reductions relative to control subjects. Our goal was to statistically analyze structural imaging data via a meta-analysis to help resolve these issues.
We searched the MEDLINE and PsycINFO databases through January 2005. Studies must have been written in English, used magnetic resonance imaging, and presented the means and standard deviations of regions assessed. Data were extracted by one of the authors and verified independently by another author.
Analyses were performed using STATA with metan, metabias, and metainf programs. A meta-analysis including all regions across all studies indicated global reductions for ADHD subjects compared with control subjects, standardized mean difference=.408, p<.001. Regions most frequently assessed and showing the largest differences included cerebellar regions, the splenium of the corpus callosum, total and right cerebral volume, and right caudate. Several frontal regions assessed in only two studies also showed large significant differences.
This meta-analysis provides a quantitative analysis of neuroanatomical abnormalities in ADHD and information that can be used to guide future studies.

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    • "Various structural neuroimaging studies have lent support to this theory showing volumetric differences in subcortical regions , including the caudate, putamen and globus pallidus (e.g. Aylward et al. 1996; Castellanos et al. 1996; Frodl and Skokauskas 2012; Hynd et al. 1993; Qiu et al. 2009; Valera et al. 2007) and components of the prefrontal cortex, including dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex (VLPFC) and the orbitofrontal cortex (OFC) (e.g. Bush 2011; Castellanos et al. 2002; Garrett et al. 2008; McAlonan et al. 2007; Overmeyer et al. 2001; Shaw et al. 2006; Wang et al. 2007). "
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    • "It has been proposed that the cerebellum is involved in the time dependent perception of a delayed reward (Rubia et al. 2009). Additionally, a meta-analysis of structural MRI studies in ADHD has shown abnormal cerebellar structure with the largest differences observed in the right lobe (Valera et al. 2007). An altered perception of time in the context of a delayed reward is a potential mechanism for more impulsive discounting. "
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    • "Moreover, there is evidence that abnormal brain lateralization might be a core component underlying dysfunctions in ADHD (Hale et al., 2008, 2009). At the structural and neuroimaging level, studies have reported atypical right hemisphere structure (Valera et al., 2007; Frodl and Skokauskas, 2012); in particular, smaller size of right frontal and prefrontal cortex were found in subjects with ADHD (Hill et al., 2003; Almeida et al., 2010). Atypical right hemisphere structure may affect attentional processing and response inhibition (Stefanatos and Wasserstein, 2001; Hart et al., 2013). "
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