Structural changes in the gray matter of unmedicated patients with obsessive-compulsive disorder: a voxel-based morphometric study

The aim of the current study was to use whole brain voxel-based morphometry（VBM）to assess the gray matter（GM）changes in unmedicated patients with obsessive-compulsive disorder（OCD）compared with normal controls.We compared the GM volumes in28 patients with 22 matched healthy controls using a1.5T MRI.Three-dimensional T1-weighted magnetic resonance images were obtained from all participants.VBM was performed to detect GM volume differences between the two groups.We detected increased regional GM volumes in the bilateral middle temporal gyri,bilateral middle occipital gyri,bilateral globus pallidus,right inferior parietal gyrus,left superior parietal gyrus,right parahippocampus,right supramarginal gyrus,right medial superior frontal gyrus,and left inferior frontal opercular cortex in the OCD patients relative to controls（P〈0.001,uncorrected,cluster size〉100 voxels）.No decreased GM volume was found in the OCD group compared with normal controls.Our findings suggest that structural changes in the GM are not limited to fronto-striato-thalamic circuits in the pathogenesis of OCD.Temporo-parietal cortex may also play an important role.     

A Comparative Multimodal Meta-analysis of Anisotropy and Volume Abnormalities in White Matter in People Suffering From Bipolar Disorder or Schizophrenia

Schizophrenia (SZ) and bipolar disorder (BD) share some similarities in terms of genetic-risk genes and abnormalities of gray-matter structure in the brain, but white matter (WM) abnormalities have not been studied in depth. We undertook a comparative multimodal meta-analysis to identify common and disorder-specific abnormalities in WM structure between SZ and BD. Anisotropic effect size-signed differential mapping software was used to conduct a comparative meta-analysis of 68 diffusion tensor imaging (DTI) and 34 voxel-based morphometry (VBM) studies comparing fractional anisotropy (FA) and white matter volume (WMV), respectively, between patients with SZ (DTI: N = 1543; VBM: N = 1068) and BD (DTI: N = 983; VBM: N = 518) and healthy controls (HCs). The bilateral corpus callosum (extending to the anterior and superior corona radiata) showed shared decreased WMV and FA in SZ and BD. Compared with BD patients, SZ patients showed remarkable disorder-specific WM abnormalities: decreased FA and increased WMV in the left cingulum, and increased FA plus decreased WMV in the right anterior limb of the internal capsule. SZ patients showed more extensive alterations in WM than BD cases, which may be the pathophysiological basis for the clinical continuity of both disorders. The disorder-specific regions in the left cingulum and right anterior limb of the internal capsule provided novel insights into both disorders. Our study adds value to further understanding of the pathophysiology, classification, and differential diagnosis of SZ and BD.     

Asymmetric Gray Matter Volume Changes Associated with Epilepsy Duration and Seizure Frequency in Temporal-Lobe-Epilepsy Patients with Favorable Surgical Outcome

MethodsVBM analysis of brain MRI using statistical parametric mapping 8 (SPM8) was performed for 30 left MTLE (LMTLE) and 30 right MTLE (RMTLE) patients and 30 age- and sex-matched healthy controls. We also analyzed the correlations between GMV changes and clinical features of MTLE patients.ResultsIn SPM8-based analyses, MTLE patients showed significant GMV reductions in the hippocampus ipsilateral to the epileptic focus, bilateral thalamus, and contralateral putamen in LMTLE patients. The GMV reductions were more extensive in the ipsilateral hippocampus, thalamus, caudate, putamen, uncus, insula, inferior temporal gyrus, middle occipital gyrus, cerebellum, and paracentral lobule in RMTLE patients. These patients also exhibited notable reductions of GMV in the contralateral hippocampus, thalamus, caudate, putamen, and inferior frontal gyrus. We observed that GMV reduction was positively correlated with several clinical features (epilepsy duration and seizure frequency in RMTLE, and history of febrile seizure in LMTLE) and negatively correlated with seizure onset age in both the RMTLE and LMTLE groups.ConclusionsOur study revealed GMV decreases in the hippocampus and extrahippocampal regions. Furthermore, the GMV reduction was more extensive in the RMTLE group than in the LMTLE group, since it included the contralateral hemisphere in the former. This difference in the GMV reduction patterns between LMTLE and RMTLE may be related to a longer epilepsy duration and higher seizure frequency in the latter.     

Frontal and cingulate gray matter volume reduction in heroin dependence: Optimized voxel-based morphometry

Aims:  Repeated exposure to heroin, a typical opiate, causes neuronal adaptation and may result in anatomical changes in specific brain regions, particularly the frontal and limbic cortices. The volume changes of gray matter (GM) of these brain regions, however, have not been identified in heroin addiction.
Methods:  Using structural magnetic resonance imaging and an optimized voxel-based morphometry approach, the GM volume difference between 15 Chinese heroin-dependent and 15 healthy subjects was tested.
Results:  Compared to healthy subjects, the heroin-dependent subjects had reduced GM volume in the right prefrontal cortex, left supplementary motor cortex and bilateral cingulate cortices.
Conclusion:  Frontal and cingulate atrophy may be involved in the neuropathology of heroin dependence.     

Frontal lobe gray matter density decreases in bipolar I disorder.

BACKGROUND: This study was conducted to explore differences in gray and white matter density between bipolar and healthy comparison groups using voxel-based morphometry (VBM). METHODS: Brain magnetic resonance imaging was performed for 39 subjects with bipolar I disorder and 43 comparison subjects. Images were registered into a proportional stereotaxic space and segmented into gray matter, white mater, and cerebrospinal fluid. Statistical parametric mapping was used to calculate differences in gray and white matter density between groups. RESULTS: Bipolar subjects had decreased gray matter density in left anterior cingulate gyrus (Brodmann's area [BA] 32, 7.3% decrease), an adjacent left medial frontal gyrus (BA 10, 6.9% decrease), right inferior frontal gyrus (BA 47, 9.2% decrease), and right precentral gyrus (BA 44, 6.2% decrease), relative to comparison subjects. CONCLUSIONS: The observation of a gray matter density decrease in the left anterior cingulate, which processes emotions, in bipolar subjects is consistent with prior reports that used region-of-interest analytic methods. Decreased gray matter density in the right inferior frontal gyrus, which processes nonverbal and intrinsic functions, supports nondominant hemisphere dysfunction as a component of bipolar disorder.     

Structural neuroimaging in schizophrenia: from methods to insights to treatments

Historically, Kraepelin speculated that dementia praecox resulted from damage to the cerebral cortex, most notably the frontal and temporal cortices. It is only recently, however, that tools have been available to test this hypothesis. Now, more than a century later, we know that schizophrenia is a brain disorder. This knowledge comes from critical advances in imaging technology--including computerized axial tomography, magnetic resonance imaging, and diffusion imaging--all of which provide an unprecedented view of neuroanatomical structures, in vivo. Here, we review evidence for structural neuroimaging abnormalities, beginning with evidence for focal brain abnormalities, primarily in gray matter, and proceeding to the quest to identify abnormalities in brain systems and circuits by focusing on damage to white matter connections in the brain. We then review future prospects that need to be explored and pursued in order to translate our current knowledge into an understanding of the neurobiology of schizophrenia, which can then be translated into novel treatments.     

Brain maturation in adolescence: concurrent changes in neuroanatomy and neurophysiology

Adolescence to early adulthood is a period of dramatic transformation in the healthy human brain. However, the relationship between the concurrent structural and functional changes remains unclear. We investigated the impact of age on both neuroanatomy and neurophysiology in the same healthy subjects (n = 138) aged 10 to 30 years using magnetic resonance imaging (MRI) and resting electroencephalography (EEG) recordings. MRI data were segmented into gray and white matter images and parcellated into large-scale regions of interest. Absolute EEG power was quantified for each lobe for the slow-wave, alpha and beta frequency bands. Gray matter volume was found to decrease across the age bracket in the frontal and parietal cortices, with the greatest change occurring in adolescence. EEG activity, particularly in the slow-wave band, showed a similar curvilinear decline to gray matter volume in corresponding cortical regions. An inverse pattern of curvilinearly increasing white matter volume was observed in the parietal lobe. We suggest that the reduction in gray matter primarily reflects a reduction of neuropil, and that the corresponding elimination of active synapses is responsible for the observed reduction in EEG power.     

动脉自旋标记技术在血管源性脑白质高信号中的研究进展

脑小血管病（CSVD）是指累及脑的小动脉、穿支动脉、毛细血管及小静脉等小血管的各种结构或功能性的病变,导致相应临床、认知、影像及病理表现的综合征。血管源性脑白质高信号（WMH）是当前最为广泛认可的CSVD影像学标志物,多数研究认为慢性脑血流低灌注是WMH潜在病理机制之一。该文介绍磁共振成像的一个新的技术——动脉自旋标记技术（ASL）的基本原理,重点介绍ASL技术在WMH中的应用进展,对单一ASL及ASL联合多模态磁共振技术,如弥散张量成像（DTI）、血氧水平依赖磁共振（BOLD）、基于体素的形态学分析（VBM）、动态对比增强磁共振（DCE）在WMH中的应用进行综述,为进一步了解WMH相关机制、早期诊断和早期干预等提供依据。     

Smoking and structural brain deficits: a volumetric MR investigation

Growing evidence from animal studies indicates brain-damaging properties of nicotine exposure. Investigations in humans found a wide range of functional cerebral effects of nicotine and cigarette smoking, but studies focusing on brain damage are sparse. In 22 smokers and 23 never-smokers possible differences of the cerebral structures were investigated using magnetic resonance imaging and voxel-based morphometry. Significantly smaller grey matter volume and lower grey matter density (P = 0.05, corrected) were observed in the frontal regions (anterior cingulate, prefrontal and orbitofrontal cortex), the occipital lobe and the temporal lobe including parahippocampal gyrus, in smokers than in never-smokers. Group differences of either grey matter volume or grey matter density were also found in the thalamus, cerebellum and substantia nigra, among other regions. Smokers did not show greater volumes than never-smokers in any cerebral region. Magnitude of lifetime exposure to tobacco smoke (pack-years) was inversely correlated with volume of frontal and temporal lobes and cerebellum (P = 0.001, uncorrected). The data indicate structural deficits of several cortical and subcortical regions in smokers relative to never-smokers. The topographic profile of the group differences show some similarities to brain networks known to mediate drug reinforcement, attention and working memory processing. The present findings may explain in part the frequently reported cognitive dysfunctions in chronic cigarette consumers.     

Non-participation may bias the results of a psychiatric survey

Objective A major reason for limited validity of research is non-participation. Subjects with severe mental illness tend to cumulate in the group of non-participants, causing selection bias. We tested the hypothesis that severe psychosis is linked to non-participation in a field survey including magnetic resonance imaging (MRI) of the brain, psychiatric interviews and cognitive testing among subjects with psychosis. Furthermore, we wanted to explore other associative factors expected to affect non-participation. Methods Members of the Northern Finland 1966 Birth Cohort with a lifetime diagnosis of psychosis (N = 145) were invited to participate in the survey conducted in 1999–2001. Non-participation was determined by refusal or loss of contact. Data were gathered in earlier phases of the follow-up study or using register data. Results Ninety-one (63%) subjects attended the study. Compared to participants, non-participants were more often patients with schizophrenia and had more psychiatric hospitalisations, they had more positive psychosis symptoms during their illness course and they were more often on disability pension. Married subjects participated more often than those who were not married. Conclusion This study suggests that among subjects with psychosis, particularly those subjects who have the most severe course of illness are less willing to participate. This may lead to biased estimates when studying subjects with severe mental disorders.