OBJECTIVES:Temporomandibular disorders (TMD) are characterized by sensorimotor and psychological dysfunction, with evidence revealing the implication of a dysfunctional central nervous system. Previous magnetic resonance imaging (MRI) studies have reported brain alterations in TMD, but most studies focused on either structure or function by a single modality of MRI and investigated static functional connectivity (FC) in TMD. By combining structural and functional MRI data, the present study aimed to identify brain regions with structural abnormalities in TMD patients and examine static and dynamic FC seeded by these regions to investigate structural brain alterations and related disrupted FC underlying the pathophysiology of TMD. METHODS:We recruited 30 TMD patients and 20 healthy controls who underwent 3.0 T MRI scanning with T1-weighted images using a three-dimensional magnetization-prepared rapid gradient-echo sequence and resting state functional images using a gradient-echo echo-planar imaging sequence. Cortical thickness, volume, surface area, and subcortical volume were calculated, where brain areas with significant structural between-group differences were treated as seeds for static and dynamic FC analyses. RESULTS:In this preliminary study, we found between-group alterations in sensorimotor regions including decreased cortical thickness in the right sensorimotor cortex as well as decreased volume in the left putamen and associated reduced dynamic FC with the anterior midcingulate cortex; and alterations in emotion processing and regulation regions including decreased volume/surface area in the left posterior superior temporal gyrus and associated increased dynamic FC with the precuneus in TMD patients than controls, having all p < 0.05 with corrections for multiple comparisons. CONCLUSION:Our findings of structural and functional abnormalities in brain regions implicated in sensorimotor and emotional functions provided evidence for the biopsychosocial model of TMD and facilitated our understanding of the pathophysiological mechanism underlying TMD. The associations between neuroimaging results and clinical measurements of TMD warrant further exploration.

Alzheimer’s disease (AD) and mild cognitive impairment (MCI) both show abnormal resting-state functional connectivity (rsFC) of default mode network (DMN), but it is unclear to what extent these abnormalities are shared. Therefore, we performed a comprehensive meta-analysis, including 31 MCI studies and 20 AD studies. MCI patients, compared to controls, showed decreased within-DMN rsFC in bilateral medial prefrontal cortex/anterior cingulate cortex (mPFC/ACC), precuneus/posterior cingulate cortex (PCC), right temporal lobes, and left angular gyrus and increased rsFC between DMN and left inferior temporal gyrus. AD patients, compared to controls, showed decreased rsFC within DMN in bilateral mPFC/ACC and precuneus/PCC and between DMN and left inferior occipital gyrus and increased rsFC between DMN and right dorsolateral prefrontal cortex. Conjunction analysis showed shared decreased rsFC in mPFC/ACC and precuneus/PCC. Compared to MCI, AD had decreased rsFC in left precuneus/PCC and between DMN and left inferior occipital gyrus and increased rsFC in right temporal lobes. MCI and AD share a decreased within-DMN rsFC likely underpinning episodic memory deficits and neuropsychiatric symptoms, but differ in DMN rsFC alterations likely related to impairments in other cognitive domains such as language, vision, and execution. This may throw light on neuropathological mechanisms in these two stages of dementia.

Background Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) are neurodevelopmental disorders with overlapping behavioral features and genetic etiology. While brain cortical thickness (CTh) alterations have been reported in ASD and ADHD separately, the degree to which ASD and ADHD are associated with common and distinct patterns of CTh changes is unclear. Methods We searched PubMed, Web of Science, Embase, and Science Direct from inception to 8 December 2023 and included studies of cortical thickness comparing youth (age less than 18) with ASD or ADHD with typically developing controls (TDC). We conducted a comparative meta-analysis of vertex-based studies to identify common and distinct CTh alterations in ASD and ADHD. Results Twelve ASD datasets involving 458 individuals with ASD and 10 ADHD datasets involving 383 individuals with ADHD were included in the analysis. Compared to TDC, ASD showed increased CTh in bilateral superior frontal gyrus, left middle temporal gyrus, and right superior parietal lobule (SPL) and decreased CTh in right temporoparietal junction (TPJ). ADHD showed decreased CTh in bilateral precentral gyri, right postcentral gyrus, and right TPJ relative to TDC. Conjunction analysis showed both disorders shared reduced TPJ CTh located in default mode network (DMN). Comparative analyses indicated ASD had greater CTh in right SPL and TPJ located in dorsal attention network and thinner CTh in right TPJ located in ventral attention network than ADHD. Conclusions These results suggest shared thinner TPJ located in DMN is an overlapping neurobiological feature of ASD and ADHD. This alteration together with SPL alterations might be related to altered biological motion processing in ASD, while abnormalities in sensorimotor systems may contribute to behavioral control problems in ADHD. The disorder-specific thinner TPJ located in disparate attention networks provides novel insight into distinct symptoms of attentional deficits associated with the two neurodevelopmental disorders. Trial registration PROSPERO CRD42022370620. Registered on November 9, 2022.

BACKGROUND:Attention-deficit/hyperactivity disorder (ADHD) is a clinically heterogeneous neurodevelopmental disorder defined by characteristic behavioral and cognitive features. Abnormal brain dynamic functional connectivity (dFC) has been associated with the disorder. The full spectrum of ADHD-related variation of brain dynamics and its association with behavioral and cognitive features remain to be established. METHODS:We sought to identify patterns of brain dynamics linked to specific behavioral and cognitive dimensions using sparse canonical correlation analysis across a cohort of children with and without ADHD (122 children in total, 63 with ADHD). Then, using mediation analysis, we tested the hypothesis that cognitive deficits mediate the relationship between brain dynamics and ADHD-associated behaviors. RESULTS:We identified four distinct patterns of dFC, each corresponding to a specific dimension of behavioral or cognitive function (r = 0.811-0.879). Specifically, the inattention/hyperactivity dimension was positively associated with dFC within the default mode network (DMN) and negatively associated with dFC between DMN and the sensorimotor network (SMN); the somatization dimension was positively associated with dFC within DMN and SMN; the inhibition and flexibility dimension and fluency and memory dimensions were both positively associated with dFC within DMN and between DMN and SMN, and negatively associated with dFC between DMN and the fronto-parietal network. Furthermore, we observed that cognitive functions of inhibition and flexibility mediated the relationship between brain dynamics and behavioral manifestations of inattention and hyperactivity. CONCLUSIONS:These findings document the importance of distinct patterns of dynamic functional brain activity for different cardinal behavioral and cognitive features related to ADHD.

BACKGROUND:Obsessive-compulsive disorder (OCD) and schizophrenia have distinct but also overlapping symptoms. Few studies have examined the shared and disorder-specific disturbances in dynamic brain function in the 2 disorders. STUDY DESIGN:Resting-state functional magnetic resonance imaging data of 31 patients with OCD and 49 patients with schizophrenia, all untreated, and 45 healthy controls (HCs) were analyzed using spatial group independent component (IC) analysis. Time-varying degree centrality patterns across the whole brain were clustered into 3 reoccurring states, and state transition metrics were obtained. We further explored regional temporal variability of degree centrality for each IC across all time windows. STUDY RESULTS:Patients with OCD and patients with schizophrenia both showed decreased occurrence of a state having the highest centrality in the sensorimotor and auditory networks. Additionally, patients with OCD and patients with schizophrenia both exhibited reduced dynamics of degree centrality in the superior frontal gyrus than controls, while dynamic degree centrality of the cerebellum was lower in patients with schizophrenia than with OCD and HCs. Altered dynamics of degree centrality nominally correlated with symptom severity in both patient groups. CONCLUSIONS:Our study provides evidence of transdiagnostic and clinically relevant functional brain abnormalities across OCD and schizophrenia in neocortex, as well as functional dynamic alterations in the cerebellum specific to schizophrenia. These findings add to the recognition of overlap in neocortical alterations in the 2 disorders, and indicate that cerebellar alterations in schizophrenia may be specifically important in schizophrenia pathophysiology via impact on cerebellar thalamocortical circuitry.

Neuroimaging studies have revealed functional brain network abnormalities in attention deficit hyperactivity disorder (ADHD), but the results have been inconsistent, potentially related to confounding medication effects. Furthermore, specific topological alterations in functional networks and their role in behavioral inhibition dysfunction remain to be established. Resting-state functional magnetic resonance imaging was performed on 51 drug-naive children with ADHD and 55 age-matched healthy controls. Brain functional networks were constructed by thresholding the partial correlation matrices of 90 brain regions, and graph theory was used to analyze network topological properties. The Stroop test was used to assess cognitive inhibitory abilities. Nonparametric permutation tests were used to compare the topological architectures in the two groups. Compared with healthy subjects, brain networks in ADHD patients demonstrated altered topological characteristics, including lower global (FDR q = 0.01) and local efficiency (p = 0.032, uncorrected) and a longer path length (FDR q = 0.01). Lower nodal efficiencies were found in the left inferior frontal gyrus and anterior cingulate cortex in the ADHD group (FDR both q < 0.05). Altered global and nodal topological efficiencies were associated with the severity of inhibitory cognitive control deficits and hyperactivity symptoms in ADHD (p <0 .05). Alterations in network topologies in drug-naive ADHD patients indicate weaker small-worldization with decreased segregation and integration of functional brain networks. Deficits in the cingulo-fronto-parietal attention network were associated with inhibitory control deficits.

Background: Attention Deficit Hyperactivity Disorder (ADHD) is a common neurodevelopmental disorder in childhood characterized by multiple behavioral problems and executive dysfunctions. Neuroimaging studies revealed a variety of abnormalities, but the results were inconsistent, partly owing to confounding medication effects and psychiatric comorbidities. Thus, studies of drug- naïve ADHD with limited comorbidities is needed to better define disorder-related abnormalities in brain networks.

Diffusion tensor imaging (DTI) studies that use tract-based spatial statistics (TBSS) have demonstrated the microstructural abnormalities of white matter (WM) in patients with attention-deficit/hyperactivity disorder (ADHD); however, robust conclusions have not yet been drawn. The present study integrated the findings of previous TBSS studies to determine the most consistent WM alterations in ADHD via a narrative review and meta-analysis. The literature search was conducted through October 2015 to identify TBSS studies that compared fractional anisotropy (FA) between ADHD patients and healthy controls. FA reductions were identified in the splenium of the corpus callosum (CC) that extended to the right cingulum, right sagittal stratum, and left tapetum. The first two clusters retained significance in the sensitivity analysis and in all subgroup analyses. The FA reduction in the CC splenium was negatively associated with the mean age of the ADHD group. We hypothesize that, in addition to the fronto-striatal-cerebellar circuit, the disturbed WM matter tracts that integrate the bilateral hemispheres and posterior-brain circuitries play a crucial role in the pathophysiology of ADHD.

Background Attention-deficit/hyperactivity disorder (ADHD) is an early-onset neurodevelopmental disorder with multiple behavioural problems and executive dysfunctions for which neuroimaging studies have reported a variety of abnormalities, with inconsistencies partly owing to confounding by medication and concurrent psychiatric disease. We aimed to investigate the microstructural abnormalities of white matter in unmedicated children and adolescents with pure ADHD and to explore the association between these abnormalities and behavioural symptoms and executive functions.Methods We assessed children and adolescents with ADHD and healthy controls using psychiatric interviews. Behavioural problems were rated using the revised Conners' Parent Rating Scale, and executive functions were measured using the Stroop Colour-Word Test and the Wisconsin Card Sorting test. We acquired diffusion tensor imaging data using a 3 T MRI system, and we compared diffusion parameters, including fractional anisotropy (FA) and mean, axial and radial diffusivities, between the 2 groups.Results Thirty-three children and adolescents with ADHD and 35 healthy controls were included in our study. In patients compared with controls, FA was increased in the left posterior cingulum bundle as a result of both increased axial diffusivity and decreased radial diffusivity. In addition, the averaged FA of the cluster in this region correlated with behavioural measures as well as executive function in patients with ADHD.Limitations This study was limited by its cross-sectional design and small sample size. The cluster size of the significant result was small.Conclusion Our findings suggest that white matter abnormalities within the limbic network could be part of the neural underpinning of behavioural problems and executive dysfunction in patients with ADHD.

Previous structural imaging studies have revealed gray matter volume abnormalities to reflect the etiology of attention deficit hyperactivity disorder (ADHD), however, which are confounded by age, medication and comorbidity and also ignore the core feature of brain structure in the executive impairments of ADHD. In the present study, we explored gray matter volume abnormalities in male children and adolescents with ADHD who were drug-naive and without comorbidities, and tried to connect structural data and behavioral executive dysfunction to provide more information regarding the brain-behavior relationships in ADHD. Seventy-two male subjects (37 patients and 35 controls) underwent three-dimensional high-resolution structural magnetic resonance imaging and executive function assessments, including the Stroop Color-Word Test and Wisconsin Card Sorting Test (WCST). Voxel-based morphometry with diffeomorphic anatomical registration through exponentiated Lie algebra was used to identify gray matter volume differences between the ADHD and controls. Correlation analyses were performed to identify neuroanatomical deficits that were associated with executive dysfunctions. Significantly reduced gray matter volumes were identified in the right orbitofrontal cortex, right primary motor/premotor cortex, left anterior cingulate cortex and left posterior midcingulate cortex of ADHD patients compared with controls (P<0.05, corrected for family-wise errors). In patients group, the gray matter volumes of the right orbitofrontal cortex and left posterior midcingulate cortex were positively correlated with the completed categories on the WCST, and the gray matter volume of the left posterior midcingulate cortex was negatively correlated with the total and non-perseverative errors on the WCST (P<0.05). The present findings show gray matter volume reductions in motor regions as well as the orbitofrontal and cingulate cortex; this evidence supports theories that suggest frontal abnormalities in children and adolescents with ADHD at early illness stage. The correlations between structural abnormalities and executive dysfunction suggest that neuroanatomical substrate deficits are implicated in the pathophysiology of ADHD.

The involvement of the central nervous system in the pathophysiology of temporomandibular disorders (TMD) has been noticed. TMD patients have been shown dysfunction of motor performance and reduced cognitive ability in neuropsychological tests. The aim of this study is to explore the spontaneous neural activity in TMD patients with centric relation (CR)-maximum intercuspation (MI) discrepancy before and after stabilization splint treatment. Twenty-three patients and twenty controls underwent clinical evaluations, including CR-MI discrepancy, Helkimo indices and chronic pain, and resting state functional magnetic resonance imaging scans at baseline. Eleven patients repeated the evaluations and scanning after the initial wearing (T1) and 3months of wearing (T2) of the stabilization splint. The fractional amplitude of low-frequency fluctuation (fALFF) was calculated to compare the neural functions. At baseline, the patients showed decreased fALFF in the left precentral gyrus, supplementary motor area, middle frontal gyrus and right orbitofrontal cortex compared with the controls (P<0.05, AlphaSim corrected). Negative correlations were found between the fALFF in the left precentral gyrus and vertical CR-MI discrepancy of bilateral temporomandibular joints of patients (P<0.05, two-tailed). At T2, the symptoms and signs of the patients were improved, and a stable condylar position on the CR was recovered, with increased fALFF in the left precentral gyrus and left posterior insula compared with pretreatment. The fALFF decrease in the patients before treatment was no longer evident at T2 compared with the controls. The results suggested that TMD patients with CR-MI discrepancy showed significantly decreased brain activity in their frontal cortexes. The stabilization splint elicited functional recovery in these cortical areas. These findings provided insight into the cortical neuroplastic processes underlying TMD with CR-MI discrepancy and the therapeutic mechanisms of stabilization splint.

Background: Impaired working memory is thought to be a core feature of attention deficit hyperactivity disorder (ADHD). Previous imaging studies investigating working memory in ADHD have used tasks involving different cognitive resources and ignoring the categorical judgments about objects that are essential parts of performance in visual working memory tasks, thus complicating the interpretation of their findings. In the present study, we explored differential neural activation in children and adolescents with ADHD and in healthy controls using functional magnetic resonance imaging (fMRI) with the categorical n-back task (CN-BT), which maximized demands for executive reasoning while holding memory demands constant.Methods: A total of 33 drug-naive, right-handed male ADHD without comorbidity (mean age 9.9 +/- 2.4 years) and 27 right-handed, healthy male controls (mean age 10.9 +/- 2.7 years) were recruited in the present study. Event-related fMRI was used to study differences in brain activity during the CN-BT between the two groups.Results: The two groups did not differ in their accuracy in the CN-BT, although the ADHD patients showed significantly shorter reaction times to correct responses than did the controls. During the CN-BT, both ADHD patients and controls showed significant positive and negative activations by the correct responses, mainly in the sensory-motor pathways and the striato-cerebellum circuit. Additionally, the ADHD patients showed significantly higher activation in the bilateral globus pallidus and the right hippocampus compared with the controls. There was also a positive correlation between hyperactivation of the left globus pallidus and the reaction time to correct responses in ADHD.Conclusions: In contrast to controls, ADHD patients showed neural hyperactivation in the striatum and mediotemporal areas during a working memory task involving categorization. Hyperfunction in these areas might be the pathophysiological foundation of ADHD, related to the deficits of working memory and the impulsive symptoms. (C) 2014 Elsevier Inc. All rights reserved.

Purpose: To explore alterations of regional and network-level neural function using resting-state functional magnetic resonance (MR) imaging in children and adolescents with attention deficit hyperactivity disorder (ADHD) and to assess the association between these alterations of intrinsic neural activity and executive dysfunction in ADHD.Materials and Methods: This prospective study was approved by the local ethical committee, and written informed consent was obtained from guardians of all participants. Thirty-three boys with ADHD who were not receiving medication and who were without comorbidity (aged 6-16 years) and 32 healthy control subjects (aged 8-16 years) underwent imaging by using resting-state functional MR imaging. Amplitude of low-frequency fluctuation (ALFF) and seed-based functional connectivity (FC) were calculated to examine regional neural function and functional integration, respectively, and were compared between patients and control subjects by using the voxel-based two-sample t test, while Pearson correlation analyses were performed to identify neural correlates of executive function measured with the Wisconsin Card Sorting Test and the Stroop Color-Word Test.Results: Relative to healthy control subjects, patients with ADHD showed impaired executive function (P < .05), along with the following: lower ALFF in the left orbitofrontal cortex (P = .004) and the left ventral superior frontal gyrus (P = .003); higher ALFF in the left globus pallidus (P = .004), the right globus pallidus (P = .002), and the right dorsal superior frontal gyrus (P = .025); lower long-range FC in the frontoparietal and frontocerebellar networks; and higher FC in the frontostriatal circuit that correlated across subjects with ADHD with the degree of executive dysfunction (P < .05).Conclusion: These findings of focal spontaneous hyper- and hypofunction, together with altered brain connectivity in the large-scale resting-state networks, which correlates with executive dysfunction, point to a connectivity-based pathophysiologic process in ADHD. (C) RSNA, 2014

Abnormal grey matter volume correlates with executive dysfunction in attention deficit hyperactivity disorder Fei Li, Ning He, Yuanyuan Li, Xiaoqi Huang, Su Lui, Lanting Guo, and Qiyong Gong Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China, Department of Psychiatry, West China Hospital of Sichuan University, Chengdu, Sichuan, China

PURPOSE: Attention Deficit/Hyperactivity Disorder (ADHD) is a common childhood-onset neurodevelopmental disorder with higher prevalence in boys. Although gray matter volume (GMV) deficits have been frequently reported in ADHD children via structural magnetic resonance imaging, few of them had specifically focused on male patients. Even fewer studies had explored the development trajectory of age effect or the relationship between structural abnormalities and cognitive functions. So present study aimed to apply the relatively new VBM technique with Diffeomorphic Anatomic Registration Through Exponentiated Lie (DARTEL) algebra algorithm to investigate the neuroanatomical differences of GMV between ADHD boys and controls, and further analyzed the affected areas for changes with age and their correlation between neuropsychological measurements.

PURPOSE: Attention deficit/hyperactivity disorder (ADHD) is one common neurodevelopmental disorder characterized as behavioral problems as well as damaged cognitive functions. White matter (WM) abnormality had been studied with diffusion tensor imaging (DTI) in the past with small sample size and inconsistent results in various brain regions with underlying mechanism remaining unclear. Present study aims to explore microscopic WM alternations in drug-naïve ADHD children in a relatively large sample size, more importantly, apart from the commonly used water diffusion parameters such as fractional anisotropy (FA), we also calculated radial diffusivity (RD) and axial diffusivity (AD) to help elucidate the possible mechanism of FA changes underlie pathophysiology of ADHD.

Introduction: Attention deficit hyperactivity disorder (ADHD) is a disorder of inattention, impulsivity and hyperactivity that affects 8-12% of children worldwide (1), which also has a primary deficit in executive functions (EF). Recent advances in resting-state functional magnetic resonance imaging (rfMRI) have facilitated the models of ADHD pathophysiology that encompass a number of different large-scale resting-state networks (2). And the amplitude of low-frequency fluctuations (ALFF) and functional connectivity (FC) of blood oxygen level-dependent (BOLD) signal of rfMRI can reflect the intrinsic neural activity and temporal correlation (3). However, there’s no research to explore the relationship between the altered spontaneous brain activity and executive dysfunction of ADHD patients. In this study, changes in ALFF and FC were examined to characterize the multi-systemic underlying pathophysiology in ADHD and try to find the association between the executive dysfunction.