T2 ∗ magnetic resonance imaging: A non-invasive biomarker of brain iron content in children with attention-deficit/hyperactivity disorder

Brain tissue iron neurophysiology and its relationship with the cognitive effects of dopaminergic modulation in children with and without ADHD

“…Few studies to date have leveraged brain tissue iron measurements to probe dopaminergic function in individuals with ADHD. These studies have found that individuals with ADHD exhibit reduced brain tissue iron levels in the basal ganglia and thalamus relative to their age- and sex-matched TD peers ( Adisetiyo et al, 2014 , Cortese et al, 2012 , Hasaneen et al, 2017 ), which is in line with other neuroimaging work finding reduced midbrain dopamine activity in ADHD ( Volkow et al, 2009 ). None of these studies have examined the relationship between dopamine-related brain tissue iron neurophysiology and response inhibition performance in individuals with ADHD.…”

“…Here, ‘dopaminergic modulation’ refers to reward reinforcement or administration of MPH, and responsivity to this modulation will be operationalized as improvement on tasks probing response inhibition. As prior work has found that individuals with ADHD have lower basal ganglia and thalamic tissue iron levels relative to their TD peers ( Adisetiyo et al, 2014 , Cortese et al, 2012 , Hasaneen et al, 2017 ), we predict that individuals with ADHD will have higher nT2*w signal, reflecting reduced brain tissue iron levels, in these regions. Based on previous work in TD individuals ( Hect et al, 2018 , Larsen et al, 2020 , Parr et al, 2022 ), we hypothesize that individuals with lower nT2*w signal, reflecting greater tissue iron levels, will exhibit better response inhibition, as well as greater improvements in response inhibition following the administration of rewards and MPH.…”

“…First, they are dopamine rich, and iron is colocalized with dopamine in the brain ( Beard, 2003 , Haber and Knutson, 2010 , Schipper, 2012 ). Second, reduced brain tissue iron has been observed in each of these regions in children with ADHD relative to age- and sex-matched TD peers ( Adisetiyo et al, 2014 , Cortese et al, 2012 , Hasaneen et al, 2017 ).…”

“…Replication analysis – comparing nT2*w signal in children with ADHD and TD children : We first replicated previous work and examined whether there were group differences between children with ADHD and TD children in nT2*w signal in the whole basal ganglia and thalamus ( Adisetiyo et al, 2014 , Cortese et al, 2012 , Hasaneen et al, 2017 ). We used separate linear regression models covarying for age and sex for each of the two ROIs, as follows: nT2*w signal ∼ group + age + sex …”

Predictive Modelling of The Dynamic Patterns of Thinking in Attention-Deficit/Hyperactivity Disorder: Diagnostic Accuracy of Spatiotemporal Fractal Measures

“…This review included other existing methods proposed to diagnose ADHD, that were not covered in the former systematic review. To make the indirect comparison possible, this in-house scoping review included only diagnostic accuracy studies that reported the chosen metrics of diagnostic for methods based on; electroencephalography and eventrelated potentials (Marcano et al, 2017;Loo et al, 2016;Snyder et al, 2015;Mohammadi et al, 2016;Gloss et al, 2016;Biederman et al, 2017;Gamma and Kara, 2016;Marcano et al, 2018;Manouilenko et al, 2017), structural and functional neuroimaging (Iannaccone et al, 2015;Rangarajan et al, 2014;de Celis Alonso et al, 2017;Qureshi et al, 2017;Serrallach et al, 2016;Hasaneen et al, 2017;Tan et al, 2017b;Uddin et al, 2017), simulated virtual reality and computer games (Negut et al, 2017(Negut et al, , 2016Berger et al, 2017;Faraone et al, 2016), and peripheral biochemical markers (Faraone et al, 2014;Scassellati and Bonvicini, 2015;Scassellati et al, 2012;Thome et al, 2012). According with this complementary "scoping review", the method presented in this research, seems to outperforms all the diagnostic accuracy metrics reported in the trials scrutinised in the aforementioned review.…”