title: Working memory-related functional brain patterns in never medicated children with ADHD.
abstract: Attention Deficit/Hyperactivity Disorder (ADHD) is a pervasive neurodevelopmental disorder characterized by 3 clusters of age-inappropriate cardinal symptoms: inattention, hyperactivity and impulsivity. These clinical/behavioural symptoms are assumed to result from disturbances within brain systems supporting executive functions including working memory (WM), which refers to the ability to transiently store and flexibly manipulate task-relevant information. Ongoing or past medications, co-morbidity and differences in task performance are potential, independent confounds in assessing the integrity of cerebral patterns in ADHD. In the present study, we recorded WM-related cerebral activity during a memory updating N-back task using functional Magnetic Resonance Imaging (fMRI) in control children and never medicated, prepubescent children with ADHD but without comorbid symptoms. Despite similar updating performance than controls, children with ADHD exhibited decreased, below baseline WM-related activation levels in a widespread cortico-subcortical network encompassing bilateral occipital and inferior parietal areas, caudate nucleus, cerebellum and functionally connected brainstem nuclei. Distinctive functional connectivity patterns were also found in the ADHD in these regions, with a tighter coupling in the updating than in the control condition with a distributed WM-related cerebral network. Especially, cerebellum showed tighter coupling with activity in an area compatible with the brainstem red nucleus. These results in children with clinical core symptoms of ADHD but without comorbid affections and never treated with medication yield evidence for a core functional neuroanatomical network subtending WM-related processes in ADHD, which may participate to the pathophysiology and expression of clinical symptoms.
authors.affiliation: UR2NF - Neuropsychology and Functional Neuroimaging Research at CRCN- Center for Research in Cognition and Neurosciences and UNI - ULB Institute for Neurosciences, Université Libre de Bruxelles (ULB), Bruxelles, Belgium.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Massat
authors.forename: Hichem
authors.initials: H
authors.lastname: Slama
authors.forename: Martin
authors.initials: M
authors.lastname: Kavec
authors.forename: Sylvie
authors.initials: S
authors.lastname: Linotte
authors.forename: Alison
authors.initials: A
authors.lastname: Mary
authors.forename: Daniele
authors.initials: D
authors.lastname: Baleriaux
authors.forename: Thierry
authors.initials: T
authors.lastname: Metens
authors.forename: Julien
authors.initials: J
authors.lastname: Mendlewicz
authors.forename: Philippe
authors.initials: P
authors.lastname: Peigneux
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D001530:Belgium; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D002648:Child; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*