Meta‐analysis of structural MRI studies in children and adults with attention deficit hyperactivity disorder indicates treatment effects

Abstract

Basal ganglia regions like the right globus pallidus, the right putamen, and the nucleus caudatus are structurally affected in children with ADHD. These changes and alterations in limbic regions like ACC and amygdala are more pronounced in non-treated populations and seem to diminish over time from child to adulthood. Treatment seems to have positive effects on brain structure.

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“…13 Two of the VBM meta-analyses mentioned previously found that subcortical volume differences between patients with ADHD and controls were smaller when the patients had taken medication. 6,7 Further, increasing age was found to be associated with smaller brain volume differences 6,7 between participants with ADHD and controls, which is in line with the findings of studies reporting delayed brain maturation in participants with ADHD. 2,14 As previous MRI studies of ADHD included mostly children or adults, 5-7 the present study adds to the literature by focusing on adolescents and young adults.…”

“…21 Subtyping of ADHD has been proposed based on dorsalfrontostriatal, orbitofrontal-striatal and fronto-cerebellar circuits involved in cognitive control, reward and motivation, and timing and building temporal expectations, respectively. 29,30 While meta-analyses of VBM studies have shown corresponding subcortical regions to be altered in individuals with ADHD [5][6][7] and while cerebellar volume differences have been reported, 3,31 our study did not reveal structural differences in these regions. Possible explanations for this might be the adolescent age range of our sample and the previously reported normalization of differences in caudate nucleus volume …”

“…28 However, findings in the prefrontal cortex have been inconsistent and are not supported by meta-analyses. [5][6][7] A possible contributing factor is the heterogeneity in age among studies, as development of the prefrontal cortex is late and protracted. 21 Subtyping of ADHD has been proposed based on dorsalfrontostriatal, orbitofrontal-striatal and fronto-cerebellar circuits involved in cognitive control, reward and motivation, and timing and building temporal expectations, respectively.…”

“…Three meta-analyses of VBM studies reporting on partly the same samples have investigated the most prominent volumetric differences between participants with ADHD and controls. [5][6][7] The first meta-analysis (114 children with ADHD and 143 controls) reported smaller grey matter volume in the right putamen and globus pallidus in children with ADHD than in controls. 5 A more recent meta-analysis (202 children and adolescents and 176 adults with ADHD and 344 controls) confirmed the reduced localized subcortical grey matter findings in the right globus pallidus and putamen and also reported on a smaller right caudate nucleus, whereas larger local grey matter volume was found in the left posterior cingulate cortex.…”

“…6 The most recent study (175 children and adolescents and 145 adults with ADHD plus 288 controls) found reduced right globus pallidus and putamen volumes in children with ADHD, whereas the adult samples were characterized by anterior cingulate cortex volume reductions. 7 However, studies used to generate the meta -analyses showed strong heterogeneity among samples and methods; reliability analysis revealed inconsistency in findings in 50%-75% of the studies. 6 Given these limitations, investigating local volume differences within a single large sample has substantial added value over existing meta-analyses.…”