Structural white matter abnormalities in patients with idiopathic dystonia

We investigated whether structural white matter abnormalities, in the form of disruption of axonal coherence and integrity as measured with diffusion tensor imaging (DTI), constitute an underlying pathological mechanism of idiopathic dystonia (ID), independent of genotype status. We studied seven subjects with ID: all had cervical dystonia as their main symptom (one patient also had spasmodic dysphonia and two patients had concurrent generalized dystonia, both DYT1‐negative). We compared DTI MR images of patients with 10 controls, evaluating differences in mean diffusivity (MD) and fractional anisotropy (FA). ID was associated with increased FA values in the thalamus and adjacent white matter, and in the white matter underlying the middle frontal gyrus. ID was also associated with increase in MD in adjacent white matter to the pallidum and putamen bilaterally, left caudate, and in subcortical hemispheric regions, including the postcentral gyrus. Abnormal FA and MD in patients with ID indicate that abnormal axonal coherence and integrity contribute to the pathophysiology of dystonia. These findings suggest that ID is not only a functional disorder, but also associated with structural brain changes. Impaired connectivity and disrupted flow of information may contribute to the impairment of motor planning and regulation in dystonia. © 2006 Movement Disorder Society     

皮质下血管性认知障碍患者弥散张量成像和脑血流量的研究

目的明确脑小血管病(cerebral small vessel disease,CSVD)患者白质完整性、脑血流量及其认知障碍之间的关系。方法连续招募严格定义的CSVD患者58例,分为无认知障碍(no cognitive impairment,NCI)11例、血管性轻度认知障碍(vascular mild cognitive impairment,VaMCI)29例和血管性痴呆(vascular dementia,VaD)18例三组,评定脑室旁(periventricular,PV)及放射冠(corona radiate,CR)白质的弥散张量成像(diffusion tensor imaging,DTI)参数,即平均弥散率(mean diffusivity,MD)和各向异性分数(fractional anisotropy,FA)。应用CT灌注(CT perfusion,CTP)成像对PV和CR区进行脑血流量(cerebral blood flow,CBF)测定。对DTI参数、CBF和认知评分进行相关性分析。结果 1三组间PV区的CBF及MD值比较,差异均有显著性(P0.01),其中MD值与CBF以及注意执行功能间均呈显著相关性(P0.01),但CBF和认知功能间未见相关性。三组间FA值比较,差异均无显著性,FA值亦未显示与CBF以及认知功能的相关性。2三组间CR区的CBF和MD、FA值比较,差异均无显著性,仅CR区MD和注意执行功能有一定相关性(P0.05),CBF与DTI参数以及认知功能间均未见相关性。结论脑室旁白质完整性的破坏是CSVD患者认知损害的重要影像学标志,且与低灌注密切相关。     

皮质下缺血性血管病患者联络纤维的扩散张量成像分析和认知功能相关研究

【摘要】 目的 运用磁共振成像（magnetic resonance imaging,MRI）基于白质地图的扩散张量成像（diffusion tensor imaging,DTI）技术研究皮质下缺血性血管病（subcortical ischemic vascular disease,SIVD）患者联络纤维的超微结构改变,并分析DTI参数与认知功能的关系。 方法 连续入选40例SIVD患者,分为血管性认知障碍组18例,无认知障碍组22例,另设立20例正常老年人为对照组。对三组进行MRI检查并对其白质改变进行评分,对联络纤维进行基于白质地图分析（atlase based analysis,ABA）DTI成像,比较组间部分各向异性指数（fractional anisotrophy,FA）、平均扩散率（mean diffusivity,MD）差异,并对SIVD患者DTI参数与蒙特利尔认知评估量表（Montreal Cognitive Assessment,MoCA）得分进行相关性分析。 结果 无认知障碍组较正常组在右侧矢状层（下纵束/下额枕束）、右侧扣带（海马部）及左侧上额枕束的FA值减低;认知障碍组较正常组存在广泛的联络纤维FA值降低,差异均具有显著性。无认知障碍组与正常组比较,仅左侧扣带海马部及左侧上纵束MD值无显著差异,余联络纤维的MD值均显著增高;认知障碍组较正常组存在广泛的联络纤维MD值增高,差异均具有显著性。与无认知功能障碍组比较,认知功能障碍组在双侧矢状层（下纵束/下额枕束）、双侧扣带扣带回部、海马部、双侧上纵束、双侧上额枕束及双侧钩束的FA值减低,MD值增高,差异具有显著性。SIVD患者双侧矢状层（下纵束/下额枕束）、扣带扣带回部、上纵束、上额枕束及钩束和左侧扣带海马部的FA值与MoCA评分呈正相关,MD值与MoCA评分呈负相关。 结论 SIVD患者联络纤维的FA值减低,MD值增高,且DTI参数与其认知功能密切相关。     

The relationship between white matter abnormalities and cognitive functions in new-onset juvenile myoclonic epilepsy

Diffusion tensor imaging (DTI) has revealed evidence of subcortical white matter abnormalities in the frontal area in juvenile myoclonic epilepsy (JME). Decreased fractional anisotropy (FA) and increased mean diffusivity (MD) in the corticothalamic pathway have been detected in adult patients with JME. It has been demonstrated that, in adult patients with JME, frontal dysfunction is related to subcortical white matter damage and decreased volume in frontal cortical gray matter and the thalamus. Many studies have focused on adult patients.Twenty-four patients and 28 controls were evaluated. The group with JME had significantly worse results for the word fluency, trail-B, and Stroop tests that assessed executive functions. A significant decrease in FA values in the dorsolateral prefrontal cortex (DLPFC), the supplementary motor area (SMA), the right thalamus, the posterior cingulate, the corpus callosum anterior, the corona radiata, and the middle frontal white matter (MFWM) and an increase in ADC values in patients with JME were detected. The correlation between FA values in DLPFC and the letter fluency test results was positive, and the correlation with the Stroop and trail-B test results was negative. We found a negative correlation between SMA, anterior thalamus, and MFWM FA values and the trail-B test results and a positive correlation between the SMA, anterior thalamus, and MFWM FA values and the letter fluency test results.We detected white matter and gray matter abnormalities in patients with new-onset JME using DTI. In addition, we determined the relationship between cognitive deficit and microstructural abnormalities by evaluating the correlation between the neuropsychological test battery results and DTI parameters. We evaluated newly diagnosed patients with JME in our study. That leads us to believe that microstructural abnormalities exist from the very beginning of the disease and that they result from the genetic basis of the disease.     

Diffusion tensor imaging of subcortical brain injury in patients infected with human immunodeficiency virus

Diffusion tensor imaging (DTI) was used to derive in vivo tissue status measurements of subcortical brain regions that are vulnerable to injury in human immunodeficiency virus (HIV)-infected patients. Quantitative measurements, including the mean diffusivity (MD) and fractional anisotropy (FA), were determined in lateralized basal ganglia (caudate and putamen) and centrum semiovale in 11 well-characterized HIV patients and in 11 control subjects. DTI measurements were examined for patterns of relationship with markers of clinical and cognitive progression. DTI measures acquired in subcortical regions were significantly correlated with loss of function in specific cognitive domains. Significant relationships were identified between measures for putamen and verbal memory (MD), visual memory (FA), working memory (FA), and overall cognitive impairment (MD). Measures for caudate (FA) were significantly correlated with visual memory. Measures for centrum semiovale were significantly correlated with visual memory deficits (MD) and visuoconstruction (FA). Relationships between anisotropy measures and anemia (basal ganglia) and CD4 counts (centrum semiovale) were also observed. Findings from this investigation indicate that DTI is a sensitive tool for correlating neuroanatomic pathologic features with specific cognitive deficits in patients with HIV infection.     

Difference of the hippocampal and white matter microalterations in MCI patients according to the severity of subcortical vascular changes: neuropsychological correlates of diffusion tensor imaging

OBJECTIVES: Most imaging studies of mild cognitive impairment (MCI) have focused on gray matter alterations, although many MCI patients demonstrate subcortical vascular changes. We investigated the changes of the hippocampal area and various white matter areas in MCI patients with using diffusion tensor imaging (DTI), according to the severity of subcortical vascular changes, and we then correlated the DTI findings with the neuropsychological results. PATIENTS AND METHODS: Among the 40 MCI patients, the 21 non-vascular MCI (nvMCI) and 19 vascular MCI (vMCI) patients were subdivided according to Erkinjuntti's imaging criteria. The mean diffusivity (MD) and fractional anisotropy (FA) were compared in the bilateral temporal, frontal, parietal and occipital white matter regions, as well as in the bilateral hippocampi, centrum semiovale, and the midline genu and splenum of the corpus callosum among the nvMCI and vMCI patients and the 17 controls. The neuropsychological findings were also compared between the subgroups. RESULTS: All the MCI patients showed decreased FA and increased MD in all the regions except the occipital areas. In the parietal regions and centrum semiovale, the vMCI patients had a greater FA decrease than the nvMCI patients and controls. In the hippocampi, the FA was lowest in the nvMCI patients. The memory function in the nvMCI patients was more impaired than that in the vMCI patients. The vMCI patients showed impairment of the visuospatial and frontal executive functions. CONCLUSION: We were able to correlate the microstructural alterations with the neuropsychological findings in the MCI subgroups.     

皮质下缺血性血管性痴呆患者脑白质损害的磁共振弥散张量成像研究

目的:应用磁共振弥散张量成像技术(DTI)观察皮质下缺血性血管性痴呆(SIVD)患者脑白质损害程度,探讨DTI对SIVD白质损害的评估及与阿尔茨海默病(AD)鉴别诊断价值。方法:研究对象分为3组,分别是健康老年人(NC)、皮质下缺血性血管性痴呆(SIVD)患者、AD患者,每组各20例。行常规MR I和DTI扫描后,测定相同感兴趣区(RO I)的各向异性分数(FA)值和表观扩散系数(ADC)值进行比较。结果:SIVD组下额枕束、胼胝体膝部、胼胝体压部、上纵束等部位FA值下降,ADC值升高,与NC、AD组比较差异有统计学意义(P<0.05)。与NC组比较,AD组前额叶、颞叶、海马、下额枕束、胼胝体膝部和扣带束等部位FA值降低,颞叶、海马等部位ADC值升高,两组差异具有显著性(P<0.05);结论:DTI可以用来评估痴呆患者白质损害的程度,SIVD患者以下额枕束、胼胝体膝部、胼胝体压部、上纵束等部位受累为主,可作为与AD鉴别的客观指标。     

A primary study of diffusion tensor imaging-based histogram analysis in vascular cognitive impairment with no dementia

Purpose

This study performed diffusion tensor imaging (DTI) histogram analysis and voxel-based analysis (VBA) to detect white matter (WM) damage in patients with vascular cognitive impairment with no dementia (VCIND) and to determine correlations between DTI histogram-derived measures and cognitive dysfunction in these patients.

Materials and methods

Among patients with subcortical ischemic vascular disease, 18 patients with VCIND were selected along with 18 age- and sex-matched cognitive-normal subjects. Both groups underwent magnetic resonance and DTI scans, and fractional anisotropy (FA) changes in VBA between the two groups were assessed. Further, mean diffusivity (MD) and FA histograms of WM and normal-appearing WM (NAWM) in each subject were evaluated.

Results

Compared to control, the VCIND group showed lower FA values throughout the brain. FA and MD histogram patterns of WM and NAWM were significantly different between the groups. Significant differences were found in all DTI histogram-derived measures, except in the mean FA peak height of WM and mean MD peak location of NAWM. Neuropsychological results (z-scores) were found to be significantly correlated with mean FA peak location, average MD, mean MD peak location of WM, and mean FA peak height, average MD, mean MD peak location of NAWM.

Conclusions

Results of VBA and diffusion tensor imaging-based histogram analysis suggest that VCIND patients have more severe damage in WM and NAWM than the control. Thus, the severity of damage in WM and NAWM may be related with cognitive dysfunction in VCIND patients, and DTI histogram analysis can help in further understanding VCIND.     

Involvement of motor pathways in corticobasal syndrome detected by diffusion tensor tractography

Corticobasal syndrome (CBS) is a progressive parkinsonian disease characterized by cortical and subcortical neuronal loss. Although motor disabilities are a core feature of CBS, the involvement of motor pathways in this condition has not been completely clarified. We used magnetic resonance diffusion tensor imaging (DTI) to study corticospinal and transcallosal motor projections in CBS, and applied fiber tractography to analyze the axonal integrity of white matter projections. Ten patients with CBS were compared with 10 age‐matched healthy controls. Fiber tracts were computed using a Monte‐Carlo simulation approach. Tract‐specific mean values of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were determined. CBS patients showed a reduction of corticospinal tract (CST) fibers on the first affected side with significantly increased ADC and reduced FA values. In the corpus callosum (CC), particularly in the posterior trunk, patients also had significantly reduced fiber projections, with a higher ADC and lower FA than controls. This pattern indicates changes of the white matter integrity in both CST and CC. Thus, magnetic resonance DTI can be used to assess motor pathway involvement in CBS patients. © 2008 Movement Disorder Society     

Diffusion tensor imaging in presymptomatic and early Huntington's disease: Selective white matter pathology and its relationship to clinical measures.

Atrophy of cortical and subcortical gray matter is apparent in Huntington's disease (HD) before symptoms manifest. We hypothesized that the white matter (WM) connecting cortical and subcortical regions must also be affected early and that select clinical symptoms were related to systems degeneration. We used diffusion tensor magnetic resonance imaging (DTI) to examine the regional nature of WM abnormalities in early HD, including the preclinical period, and to determine whether regional changes correlated with clinical features. We studied individuals in early stages (HD), presymptomatic individuals known to carry the genetic mutation that causes HD (Pre-HD), and matched healthy controls. DTI indices of tissue integrity were obtained from several regions of interest, including the corpus callosum (CC), internal capsule (IC), and basal ganglia, were compared across groups by t tests, and were correlated to cognitive and clinical measures. WM alterations were found throughout the CC, in the anterior and posterior limbs of the IC, and in frontal subcortical WM in HD subjects, supporting the selective involvement of the pyramidal tracts in HD; a similar distribution of changes was seen in Pre-HD subjects, supporting presymptomatic alterations. There was a significant relationship between select DTI measures and cognitive performance. Alterations in diffusion indices were also seen in the striatum that were independent of atrophy. Our findings support that WM alterations occur very early in HD. The distribution of the changes suggests that these changes contribute to the disruption of pyramidal and extrapyramidal circuits and also support a role of compromised cortical circuitry in early cognitive and subtle motor impairment during the preclinical stages of HD.     

弥散张量成像对意识障碍患者诊断与预后评估的作用

目的探讨弥散张量成像（DTI）对意识障碍（DOC）患者的临床应用价值及其各指标变化规律。 方法选取自2014年1月至2015年12月陆军总医院附属八一脑科医院临床诊断为DOC的患者[植物状态（VS）患者56例,微意识状态（MCS）患者19例]进行弥散张量扫描,分别收集脑干、丘脑、皮层下三个相关的感兴趣区域评价FA、MD等指标数据。对不同意识状态的两组的参数值进行统计学分析,并将感兴趣区的各向异性（FA）、平均弥散率（MD）均值与临床昏迷恢复量表（CRS-R）评分进行相关性分析。 结果VS组FA值明显低于MCS组,差异具有统计学意义（P<0.05）;MD值则高于MCS组,差异具有统计学意义（P<0.05）;感兴趣区（脑干、皮层下,丘脑）FA值和MD值与CRS-R评分具有较好相关性,尤其是丘脑部。 结论DTI对于DOC影像学分级具有一定的临床参考价值。意识障碍程度越重,MD值越高,FA值越低。     

Diffusion tensor imaging in patients with primary cervical dystonia and in patients with blepharospasm

Diffusion tensor imaging (DTI) analyses the movement of water molecules within the cerebral white matter thus providing information on ultrastructural brain changes. We studied 18 patients with cervical dystonia (CD), 16 with blepharospasm (BSP) and 35 years age-matched healthy controls. DTI data were obtained with a Philips 1.5 Tesla scanner and then processed to obtain maps of fractional anisotropy (FA) and mean diffusivity (MD). Twenty-three square regions of interest of uniform size were positioned on the FA maps and then automatically transferred to the MD maps. FA and MD values in the corpus callosum, left and right putamen, right caudate, left and right pre-frontal cortical area and left supplementary motor area in CD patients differed significantly from those in healthy controls. No significant regional differences were found between patients with BSP and healthy controls. In the CD group, age, duration and severity of dystonia did not correlate with regional FA/MD values, whereas the duration of botulinum toxin treatment correlated significantly with the MD value in the right-pre-frontal cortex. The abnormal DTI findings in patients with CD suggest the presence of brain ultrastructural changes in adult-onset primary CD.     

Diffusion tensor imaging measures of normal appearing white matter in patients who are aging,or have amnestic mild cognitive impairment,or Alzheimer’s disease

To evaluate whether cerebral white matter integrity is related to cognitive function, and whether diffusion tensor imaging (DTI) could differentiate amnestic mild cognitive impairment (aMCI) from Alzheimer’s disease (AD), 12 patients with AD, 12 with aMCI, and 12 controls were recruited for this study. Cognitive functions of all subjects were assessed using the Mini-Mental State Examination (MMSE) and AD Assessment Scale – Cognitive Subscale (ADAS-Cog). DTI studies were acquired, and fractional anisotropy (FA) and mean diffusivity (MD) values of normal-appearing white matter (NAWM) in multiple brain regions were obtained. Results showed that MMSE and ADAS-Cog subscores were significantly associated with white matter integrity of the temporal-parietal lobes. A decrease in FA values and an increase in MD values in multiple cortical regions were confirmed in patients with AD compared to controls. MD values in the posterior region of the corpus callosum in aMCI differed from those of early AD. Significant reductions of FA values in the NAWM of the parietal lobe was observed in aMCI compared to controls. Our data indicate that the microstructural white matter integrity in the temporal-parietal lobes is gradually impaired in the progressive process of AD, and that splenium MD values could be used as a biomarker differentiating aMCI from AD.     

DTI correlates of distinct cognitive impairments in Parkinson's disease

The spectrum of cognitive symptoms in Parkinson's disease (PD) can span various domains, including executive function, language, attention, memory, and visuospatial skills. These symptoms may be attributable to the degradation of projection fibers associated with the underlying neurodegenerative process. The primary purpose of this study is to find microstructural correlates of impairments across these cognitive domains in PD using diffusion tensor imaging (DTI). Sixteen patients with PD with comprehensive neuropsychological evaluation and DTI data were retrospectively studied. Fractional anisotropy (FA) and mean diffusivity (MD) were assessed using regions‐of‐interest (ROI) analysis and confirmed with a voxel‐based approach. Executive function directly correlated with FA and inversely correlated with MD in mostly frontal white matter tracts, especially the anterior limb of the internal capsule and genu of the corpus callosum. Likewise, language and attentional performance demonstrated correlations with DTI parameters in the frontal regions, but the attention domain additionally recruited regions widespread throughout the brain, with the most significant correlation identified in cingulate gyrus (cingulum). Lastly, memory impairment mainly involved MD alterations within the fornix. No significant correlations were found between visuospatial skills and DTI measures. Despite some overlap, unique patterns of white matter diffusivity underlie impairments in distinct cognitive domains in patients with PD. DTI combined with neurocognitive tests may be a valuable biomarker for identifying cognitive impairments in PD. Hum Brain Mapp 35:1325–1333, 2014. © 2013 Wiley Periodicals, Inc.     

Retrograde Wallerian degeneration of cranial corticospinal tracts in cervical spinal cord injury patients using diffusion tensor imaging

Diffusion tensor imaging (DTI) has the potential to reveal disruption of white matter microstructure in chronically injured spinal cords. We quantified fractional anisotropy (FA) and mean diffusivity (MD) to demonstrate retrograde Wallerian degeneration (WD) of cranial corticospinal tract (CST) in cervical spinal cord injury (SCI). Twenty-two patients with complete cervical SCI in the chronic stage were studied with DTI along with 13 healthy controls. Mean FA and MD values were computed for midbrain, pons, medulla, posterior limb of internal capsule, and corona radiata. Significant reduction in the mean FA and increase in MD was observed in the cranial CST in patients with SCI compared with controls, suggesting retrograde WD. Statistically significant inverse FA and MD changes were noted in corona radiata, indicating some restoration of spared white matter tracts. Temporal changes in the DTI metrics suggest progressing degeneration in different regions of CST. These spatiotemporal changes in DTI metrics suggest continued WD in injured fibers along with simultaneous reorganization of spared white matter fibers, which may contribute to changing neurological status in chronic SCI patients.     

Diffusion imaging in dementia with Lewy bodies: Associations with amyloid burden,atrophy, vascular factors and clinical features

IntroductionWhite matter disruption in dementia has been linked to a variety of factors including vascular disease and cortical pathology. We aimed to examine the relationship between white matter changes on diffusion tensor imaging (DTI) in DLB and factors including vascular disease, structural atrophy and amyloid burden.MethodsParticipants with DLB (n = 29), Alzheimer's disease (AD, n = 17) and healthy controls (n = 20) had clinical and neuropsychological assessments followed by structural and diffusion tensor 3T MRI and ¹⁸F-Florbetapir PET-CT imaging. Voxelwise statistical analysis of white matter fractional anisotropy (FA) and mean diffusivity (MD) was carried out using Tract-Based Spatial Statistics with family-wise error correction (p < 0.05).ResultsDLB and AD groups demonstrated widespread increased MD and decreased FA when compared with controls. There were no differences between the DLB and AD groups. In DLB, increased MD and decreased FA correlated with decreased grey matter and hippocampal volumes as well as vascular disease. There was no correlation with cortical florbetapir SUVR. The relationship between DTI changes and grey matter/hippocampal volumes remained after including Cumulative Illness Rating Scale-Geriatric vascular score as a covariate.ConclusionsWidespread disruption of white matter tracts is present in DLB and is associated with vascular disease, reduced hippocampal volume and reduced grey matter volume, but not with cortical amyloid deposition. The mechanism behind the correlation observed between hippocampal volume and white matter tract disruption should be investigated in future cohorts using tau imaging, as hippocampal atrophy has been shown to correlate with tau deposition in DLB.     

White matter integrity linked to functional impairments in aging and early Alzheimer's disease

BackgroundAlzheimer's disease (AD) is associated with changes in cerebral white matter (WM), but the functional significance of such findings is not yet established. We hypothesized that diffusion tensor imaging (DTI) might reveal links between regional WM changes and specific neuropsychologically and psychophysically defined impairments in early AD.MethodsOlder adult control subjects (OA, n = 18) and mildly impaired AD patients (n = 14) underwent neuropsychological and visual perceptual testing along with DTI of cerebral WM. DTI yielded factional anisotropy (FA) and mean diffusivity (〈D〉) maps for nine regions of interest in three brain regions that were then compared with the performance measures.ResultsAD patients exhibited nonsignificant trends toward lower FAs in the posterior region's callosal and subcortical regions of interest. However, posterior callosal FA was significantly correlated with verbal fluency and figural memory impairments, whereas posterior subcortical FA was correlated with delayed verbal memory, figural memory, and optic flow perceptual impairments.ConclusionsWM changes in early AD are concentrated in posterior cerebral areas, with distributions that correspond to specific functional impairments. DTI can be used to assess regional pathology related to individual's deficits in early AD.     

Microstructural white matter abnormality and frontal cognitive dysfunctions in juvenile myoclonic epilepsy

Purpose: Previous neuroimaging studies provide growing evidence that patients with juvenile myoclonic epilepsy (JME) have both structural and functional abnormalities of the thalamus and frontal lobe gray matter. However, limited data are available regarding the issue of white matter (WM) involvement, making the microstructural WM changes in JME largely unknown. In the present study we investigated changes of WM integrity in patients with JME, and their relationships with cognitive functions and epilepsy-specific clinical factors. Methods: We performed diffusion tensor imaging (DTI) and neuropsychological assessment in 25 patients with JME and 30 control subjects matched for age, gender, and education level. Between-group comparisons of fractional anisotropy (FA) and mean diffusivity (MD) were carried out in a whole-brain voxel-wise manner by using tract-based spatial statistics (TBSS). In addition, both FA and MD were correlated with cognitive performance and epilepsy-specific clinical variables to investigate the influence of these clinical and cognitive factors on WM integrity changes. Key Findings: Neuropsychological evaluation revealed that patients with JME had poorer performance than control subjects on most of the frontal function tests. TBSS demonstrated that, compared to controls, patients with JME had significantly reduced FA and increased MD in bilateral anterior and superior corona radiata, genu and body of corpus callosum, and multiple frontal WM tracts. Disease severity, as assessed by the number of generalized tonic-clonic seizures in given years, was negatively correlated with FA and positively correlated with MD extracted from regions of significant differences between patients and controls in TBSS. Significance: Our findings of widespread disturbance of microstructural WM integrity in the frontal lobe and corpus callosum that interconnects frontal cortices could further support the pathophysiologic hypothesis of thalamofrontal network abnormality in JME. These WM abnormalities may implicate frontal cognitive dysfunctions and disease progression in JME.     

White matter abnormalities and their impact on attentional performance in adult attention-deficit/hyperactivity disorder

Inattention is the most important behavioral feature of adult patients with attention-deficit/hyperactivity disorder (ADHD). Neuroimaging studies in ADHD have demonstrated abnormalities primarily in the frontostriatal circuitry and were mostly conducted in children. We investigated white matter (WM) integrity in adult ADHD patients and the correlation of WM microstructure and neuropsychological parameters in 37 (21 men) never-medicated adult ADHD patients and 34 age- and gender-matched healthy controls. All subjects underwent clinical interviews, rating scales, and neuropsychological tests of attentional performance. Diffusion tensor imaging (DTI) was acquired, and 12 WM regions-of-interest (ROIs) within the attentional network were chosen. Group differences of mean fractional anisotropy (FA) and mean diffusivity (MD) values were calculated for each ROI, and patients' DTI measures were then correlated with measures of attentional performance. FA values in ADHD patients were significantly reduced in the left inferior longitudinal fasciculus (ILF), while MD values were significantly increased in ADHD patients in the frontal portion of the left frontooccipital fasciculus (IFO). In ADHD patients, MD values were negatively correlated with attentional performance in the left ILF. Our findings provide further support for disturbed frontostriatal structural connectivity and also point to an involvement of the left temporal white matter with an impact on attentional performance.