The brain anatomy of attention-deficit/hyperactivity disorder in young adults – a magnetic resonance imaging study

Abstract

BackgroundThis is one of the first studies to examine the structural brain anatomy and connectivity associated with an ADHD diagnosis and child as well as adult ADHD symptoms in young adults. It was hypothesized that an adult ADHD diagnosis and in particular childhood symptoms, are associated with widespread changes in the brain macro- and microstructure, which can be used to develop a morphometric biomarker for ADHD.MethodsVoxel-wise linear regression models were used to examine structural and diffusion-weighted MRI data in 72 participants (31 young adults with ADHD and 41 controls without ADHD) in relation to diagnosis and the number of self-reported child and adult symptoms.ResultsFindings revealed significant associations between ADHD diagnosis and widespread changes to the maturation of white matter fiber bundles and gray matter density in the brain, such as structural shape changes (incomplete maturation) of the middle and superior temporal gyrus, and fronto-basal portions of both frontal lobes. ADHD symptoms in childhood showed the strongest association with brain macro- and microstructural abnormalities. At the brain circuitry level, the superior longitudinal fasciculus (SLF) and cortico-limbic areas are dysfunctional in individuals with ADHD. The morphometric findings predicted an ADHD diagnosis correctly up to 83% of all cases.ConclusionAn adult ADHD diagnosis and in particular childhood symptoms are associated with widespread micro- and macrostructural changes. The SLF and cortico-limbic findings suggest complex audio-visual, motivational, and emotional dysfunctions associated with ADHD in young adults. The sensitivity of the morphometric findings in predicting an ADHD diagnosis was sufficient, which indicates that MRI-based assessments are a promising strategy for the development of a biomarker.

Maturation changes the excitability and effective connectivity of the frontal lobe: A developmental TMS–EEG study

“…Exploring how frontal activation and connectivity develop with age can provide insight into why children and adults differ in complex cognitive functions (Stiles & Jernigan, 2010). Moreover, the characterization of frontal lobe development offers the promise of understanding the origins of developmental disorders, since the frontal lobe is the primary candidate for dysfunction in many neurological and psychiatric disorders that appear in childhood and adolescence (Gehricke et al, 2017;Lesh, Niendam, Minzenberg, & Carter, 2011;Mitchell et al, 2009;Schubert, Martens, & Kolk, 2015;Solomon et al, 2014). Thus, it is of particular interest to understand how the frontal lobe and its connections change with development.…”

Neurobiological support to the diagnosis of ADHD in stimulant‐naïve adults: pattern recognition analyses of MRI data

“…Such MRI findings have been interpreted as reflecting a delay in brain maturation processes underlying ADHD symptoms in children and adolescents . Preliminary MRI studies of modestly sized adult ADHD samples have suggested the presence of mean gray matter (GM) and WM volume abnormalities, reported as more subtle than those found in children with ADHD . Yet, some of these brain abnormalities, for instance in regard to striatal volumes, appear to lose its significance in the transition to adulthood .…”

“…Yet, some of these brain abnormalities, for instance in regard to striatal volumes, appear to lose its significance in the transition to adulthood . DTI studies have also shown anisotropy and diffusivity alterations in WM tracts in symptomatic ADHD adults compared to HC ; however, microstructural WM abnormalities seem to be more strongly associated with ADHD symptoms in childhood than in adulthood .…”

Interactions between the neural correlates of dispositional internally directed thought and visual imagery

“…Previous studies have shown that brainstem abnormalities can support increased accuracy of diagnostic classification in ADHD [78]. Decreased axial diffusivity (a marker of axonal degeneration in clinical cases, [79]) in the occipital lobe and brainstem has also been associated with an ADHD diagnosis [80]. In addition, processes within the brainstem have been related to rumination, worry and anxiety by influencing heart rate variability [81] and by its functional interactions with the limbic network in anxiety disorders [82].…”