Diffusion tensor imaging in attention deficit/hyperactivity disorder: A systematic review and meta-anlysis
ABSTRACT Diffusion tensor imaging (DTI) allows in vivo examination of the microstructural integrity of white matter brain tissue. A systematic review and quantitative meta-analysis using GingerALE were undertaken to compare current DTI findings in patients with ADHD and healthy controls to further unravel the neurobiological underpinnings of the disorder. Online databases were searched for DTI studies comparing white matter integrity between ADHD patients and healthy controls. Fifteen studies met inclusion criteria. Alterations in white matter integrity were found in widespread areas, most consistently so in the right anterior corona radiata, right forceps minor, bilateral internal capsule, and left cerebellum, areas previously implicated in the pathophysiology of the disorder. Current literature is critically discussed in terms of its important methodological limitations and challenges, and guidelines for future DTI research are provided. While more research is needed, DTI proves to be a promising technique, providing new prospects and challenges for future research into the pathophysiology of ADHD.
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- "The thalamocortical circuitry undergoes rapid morphological growth to adapt to the needs of numerous sensorimotor, cognitive, and attentional functions in early life (Gilmore et al., 2012; Holland et al., 2014; Qiu et al., 2013). Thalamocortical dysconnectivity, both structural and functional, has been implicated in children with autism spectrum disorder (Nair et al., 2013), attention deficit hyperactivity disorder (ADHD; Bush, 2011; Van Ewijka et al., 2012), and schizophrenia (Jones, 1997; Woodward et al., 2012). Abnormal thalamic development has also been found in preterm infants (Ball et al., 2012; Srinivasan et al., 2007), and survivors often suffer from cognitive and behavioral deficits and have an increased risk of developing autism and ADHD (D'Onofrio et al., 2013; Delobel-Ayoub et al., 2009). "
ABSTRACT: The thalamus is a deep gray matter structure and consists of axonal fibers projecting to the entire cortex, which provide the anatomical support for its sensorimotor and higher-level cognitive functions. There is limited in vivo evidence on the normal thalamocortical development, especially in early life. In this study, we aimed to investigate the developmental patterns of the cerebral cortex, the thalamic substructures, and their connectivity with the cortex in the first few weeks of the postnatal brain. We hypothesized that there is developmental synchrony of the thalamus, its cortical projections, and corresponding target cortical structures. We employed diffusion tensor imaging (DTI) and divided the thalamus into five substructures respectively connecting to the frontal, precentral, postcentral, temporal, and parietal, and occipital cortex. T2-weighted magnetic resonance imaging (MRI) was used to measure cortical thickness. We found age-related increases in cortical thickness of bilateral frontal cortex and left temporal cortex in the early postnatal brain. We also found that the development of the thalamic substructures was synchronized with that of their respective thalamocortical connectivity in the first few weeks of the postnatal life. In particular, the right thalamo-frontal substructure had the fastest growth in the early postnatal brain. Our study suggests that the distinct growth patterns of the thalamic substructures are in synchrony with those of the cortex in early life, which may be critical for the development of the cortical and subcortical functional specialization. Copyright © 2015 Elsevier Inc. All rights reserved.NeuroImage 03/2015; 116. DOI:10.1016/j.neuroimage.2015.03.039 · 6.36 Impact Factor
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- "Moreover, tractography algorithms can use diffusion tensor information to estimate the location and direction of fiber tracts. DTI has been used to characterize abnormal white matter diffusion properties in a range of diseases, including psychiatric disorders involving psychosis and disturbances in mood and attention [4,5,8,9]. "
ABSTRACT: Background Scientists are beginning to document abnormalities in white matter connectivity in major depressive disorder (MDD). Recent developments in diffusion-weighted image analyses, including tractography clustering methods, may yield improved characterization of these white matter abnormalities in MDD. In this study, we acquired diffusion-weighted imaging data from MDD participants and matched healthy controls. We analyzed these data using two tractography clustering methods: automated fiber quantification (AFQ) and the maximum density path (MDP) procedure. We used AFQ to compare fractional anisotropy (FA; an index of water diffusion) in these two groups across major white matter tracts. Subsequently, we used the MDP procedure to compare FA differences in fiber paths related to the abnormalities in major fiber tracts that were identified using AFQ. Results FA was higher in the bilateral corticospinal tracts (CSTs) in MDD (p’s < 0.002). Secondary analyses using the MDP procedure detected primarily increases in FA in the CST-related fiber paths of the bilateral posterior limbs of the internal capsule, right superior corona radiata, and the left external capsule. Conclusions This is the first study to implicate the CST and several related fiber pathways in MDD. These findings suggest important new hypotheses regarding the role of CST abnormalities in MDD, including in relation to explicating CST-related abnormalities to depressive symptoms and RDoC domains and constructs.09/2014; 4(1):8. DOI:10.1186/2045-5380-4-8
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- "Given that youths with ADHD tend to show EF deficits (Gau & Shang, 2010; Chamberlain et al. 2011), school adjustment problems (Sonuga-Barke, 2003; Biederman et al. 2004; Loe & Feldman, 2007; Wu & Gau, 2013) and disturbed white matter integrity (Liston et al. 2011; van Ewijk et al. 2012), we conducted this study not only to examine the degree of impairment in these aspects in youths with ADHD, as compared to TD youths, but also to investigate the linkage between frontostriatal tract integrity, EF, ADHD symptoms and school functioning . We focused on frontostriatal tracts because review studies have suggested that abnormalities in the structural and functional connectivity in the frontostriatal–cerebellar circuitry may be implicated in the pathophysiology of ADHD (Bush et al. 2005; Konrad & Eickhoff, 2010; Cubillo et al. 2012; van Ewijk et al. 2012) and that disturbed microstructural integrity in the frontostriatal network in ADHD represents one of the best-replicated findings (Ashtari et al. 2005; Silk et al. 2009; Davenport et al. 2010; Kobel et al. 2010; Li et al. 2010; Peterson et al. 2011; de Zeeuw et al. 2012; Tamm et al. 2012). Specifically, we hypothesized that ADHD symptoms and EF deficits may be the mechanisms linking disturbed frontostriatal tracts integrity and school dysfunctioning. "
ABSTRACT: Deficits in executive function (EF), impaired school functioning and altered white matter integrity in frontostriatal networks have been associated with attention-deficit/hyperactivity disorder (ADHD). However, relationships between impairments in these areas are unclear. Using a sample of youths with and without ADHD, this study examined the association between microstructural integrity of frontostriatal tracts and school dysfunction and the mediating roles of EF and ADHD symptoms in this association.Psychological Medicine 07/2014; 45(03):1-15. DOI:10.1017/S0033291714001664 · 5.43 Impact Factor