Attention and Executive Systems Abnormalities in Adults with Childhood ADHD: A DT-MRI Study of Connections

Abstract

Attention-deficit/hyperactivity disorder (ADHD) is hypothesized to be due, in part, to structural defects in brain networks influencing cognitive, affective, and motor behaviors. Although the current literature on fiber tracts is limited in ADHD, gray matter abnormalities suggest that white matter (WM) connections may be altered selectively in neural systems. A prior study (Ashtari et al. 2005), using diffusion tensor magnetic resonance imaging (DT-MRI), showed alterations within the frontal and cerebellar WM in children and adolescents with ADHD. In this study of adults with childhood ADHD, we hypothesized that fiber pathways subserving attention and executive functions (EFs) would be altered. To this end, the cingulum bundle (CB) and superior longitudinal fascicle II (SLF II) were investigated in vivo in 12 adults with childhood ADHD and 17 demographically comparable unaffected controls using DT-MRI. Relative to controls, the fractional anisotropy (FA) values were significantly smaller in both regions of interest in the right hemisphere, in contrast to a control region (the fornix), indicating an alteration of anatomical connections within the attention and EF cerebral systems in adults with childhood ADHD. The demonstration of FA abnormalities in the CB and SLF II in adults with childhood ADHD provides further support for persistent structural abnormalities into adulthood.

Overflow movements and white matter abnormalities in ADHD

“…WM signal intensities may also show differences that indicate abnormal cerebral myelination. The demonstration of FA abnormalities in adults who had ADHD in childhood provides further support for the persistence of structural abnormalities into adulthood (Makris et al, 2008).…”

“…One of the most replicated alterations is a significantly smaller CC, and there are conflicting reports regarding the affected callosal segments (Luders et al, 2009). Moreover, recent magnetic resonance imaging (MRI) structural investigations show that WM alterations are present in children, adolescents and adults with ADHD (Makris et al, 2008). Table 1 presents an overview of white matter abnormalities in ADHD patients from the literature.…”

“…It has been hypothesized that Attention Deficit/Hyperactivity Disorder (ADHD) is due to structural defects in the brain networks that influence cognitive, affective and motor behaviours (Makris et al, 2008). In addition to the main symptoms of inattention, impulsiveness and hyperactivity, neurological soft signs (NSS) are often associated with ADHD (Pasini and D'Agati, 2009).…”

Double-dissociation between the mechanism leading to impulsivity and inattention in Attention Deficit Hyperactivity Disorder: A resting-state functional connectivity study

“…One of the most consistent findings from studies of anatomical connectivity, in children and adolescents with ADHD, is reduced fractional anisotropy (Hamilton et al 2008;Makris et al 2008;Luders et al 2009;Konrad et al 2010) of fronto-striatal tracts (within the cortico-striatal network) and fronto-parietal tracts (within the ventral and dorsal attention network). These findings have been supported by some (Dickstein et al 2006;Rubia 2011;Cubillo et al 2012) but not all studies of functional connectivity (Tian et al 2006;Uddin et al 2008).…”

Attention-Deficit/Hyperactivity Disorder and Attention Networks

“…Further, prefrontal fiber tract measures were associated between ADHD parents and their children, suggesting disruption of frontostriatal connections has a role in ADHD. Makris et al (2008) showed that abnormalities of the cingulum bundle and superior longitudinal fascicle IIFconnection pathways that subserve attention and executive functionsFare evident in adults with ADHD. Lower corticospinal tract and superior longitudinal fasciculus FA (Hamilton et al, 2008) similarly suggested disruption of motor and attention networks in ADHD children, whereas the study by Silk et al (2008) indicated that fronto-striatal and fronto-parietal circuitry abnormalities exist in children with ADHD.…”