Medial frontal and dorsal cortical morphometric abnormalities are related to obsessive-compulsive disorder

Whole-brain voxel-based morphometry (VBM) studies provide support for orbitofrontal, medial frontal as well as for dorsal cortical volumetric alteration in obsessive-compulsive disorder (OCD). However, there is still a need to replicate a priori unpredicted findings and to elucidate white matter volumetric abnormalities and relationships between grey (GM) and white (WM) matter volume and clinical characteristics of OCD. We compared GM and WM volume in a group of 14 patients with OCD and 15 healthy controls using a 3 T MRI scanner and an optimized VBM protocol. Regression analysis was used to examine relationships between GM and WM volume and clinical variables. In OCD we have found total WM volume reduction and marked mediofrontal, right temporo-parieto-occipital, right precentral, left middle temporal, left cerebellar and bilateral pons and mesencephalon GM volume reduction in the voxel-based analysis (p ≤ 0.05, FDR corrected, extent threshold 100 voxels). Regression analysis indicated a positive relationship between left orbitofrontal GM volume and severity of obsessive-compulsive symptoms and a negative relationship between symptom severity and GM volume in supramarginal gyri. Earlier age of OCD onset and longer illness duration were associated with smaller left occipital GM and right parietal WM and with greater left medial frontal GM and left frontal WM (p ≤ 0.001, uncorrected, extent threshold 50 voxels). Our results confirm volumetric abnormalities in the medial frontal and dorsal cortical areas in OCD. The relationships between OCD and clinical variables provide further evidence that frontal, parietal and occipital structures play a role in the disorder.     

Pediatric OCD structural brain deficits in conflict monitoring circuits: a voxel-based morphometry study

The aim of this study is to use a voxel-based morphometry protocol to compare the brains of 18 children with obsessive-compulsive disorder (OCD) with those of a healthy group matched for gender and handedness. Images were acquired with a 1.5-T MRI scanner, spatially normalized, and segmented with an optimized voxel-based morphometry protocol. OCD children presented a 5.93% reduction of gray matter (GM) total volume in comparison with control brains. We identified OCD brain volume reductions in regions that have been extensively related to action monitoring and error signaling processes. Specifically, we found decreased bilateral GM in frontal (significant after Family Wise Error (FEW), multiple comparisons correction) and cingulate regions as well as decreased white matter (WM) in bilateral frontal and right parietal (p<0.001 uncorrected). Additionally, we found a negative correlation between symptom severity and bilateral hippocampal GM-volume (p<0.001uncorrected) as well as a positive correlation between age and GM left caudate volume (p=0.037 FWE small volume corrected) in the OCD group. As a conclusion, our results point to conflict monitoring structural brain regions as primary deficits in pediatric OCD, and to striatal abnormalities as age-related deficits.     

强迫症患者大脑灰质体积变化——基于体素的形态学分析

目的 探讨强迫症（OCD）患者大脑灰质体积的变化,并分析其在发病过程中可能存在的相关机制。 方法 选择31例年龄17~47岁重度强迫症患者和31例正常对照被试者,获取脑结构磁共振T1图像,使用基于体素的形态学测量（VBM）方法,比较强迫症组和对照组大脑灰质体积的差异,并将患者灰质体积差异区与其临床评分进行相关分析。 结果 与对照组相比,OCD患者在左侧壳核、岛叶、运动前区、顶上小叶以及右侧角回处体积显著减小。左侧壳核和岛叶的体积与患者贝克焦虑量表（BAI）评分成显著负相关。 结论 左侧壳核、岛叶、运动前区、顶上小叶以及右侧角回的灰质体积变化影响了该脑区功能,从而导致了OCD患者的部分症状。其中左侧壳核以及岛叶的损伤与患者焦虑情绪的异常密切相关。     

首发抽动障碍儿童基底节结构异常的磁共振成像研究

目的:探讨抽动障碍(TD)儿童基底节结构异常特点及其与病程、疾病严重程度之间的相关性。方法:对9例符合美国精神障碍诊断与统计手册第4版(DSM-Ⅳ)中TD标准的首发未用药6～14岁TD儿童,采用耶鲁综合抽动严重程度量表(YGTSS)对TD儿童进行临床评估,同时收集9例8～10岁健康儿童,对受试者进行脑结构磁共振扫描,采用感兴趣区法对基底节及其亚区尾状核、壳核、苍白球分别进行测量,比较两组上述脑区的原始体积、相对体积(原始体积/颅内总体积)、左右不对称性指数(AI)的差异,分析基底节及其各亚区体积与患者病程、YGTSS总分之间相关性。结果:患儿组右侧苍白球原始体积[(1.4±0.2)mL vs.(1.1±0.1)mL]及其相对体积[(0.9±0.1)×10-3vs.(0.7±0.2)×10-3]均高于对照组(均P0.01);其他各结构原始体积及其相对体积组间差异均无统计学意义(均P0.05)。患儿组尾状核体积[(4.9±0.4)mL vs.(4.7±0.5)mL]和对照组尾状核体积两组组内左右侧比较[(4.7±0.5)mL vs.(4.5±0.5)mL],结果显示左侧均高于右侧(均P0.05);其他各结构组内左右侧体积的比较,差异均无统计学意义(均P0.05)。两组间基底节及其各亚区AI值差异无统计学意义(P0.05);患儿组各结构相对体积与YGTSS总分(r=-0.08～0.63)和病程(r=-0.09～0.59)均无明显相关(均P0.05)。结论:抽动障碍儿童脑右侧苍白球体积明显大于健康儿童,可能为该症的异常脑结构之一;抽动障碍儿童基底节及各亚区结构体积大小与病程、疾病严重程度无明显相关。     

Subcortical and deep cortical atrophy in Frontotemporal Lobar Degeneration

Though neuroimaging, pathology and pathophysiology suggest a subcortical and deep cortical involvement in Frontotemporal Lobar Degeneration (FTLD), no studies have comprehensively assessed the associated gray matter (GM) volume changes. We measured caudate, putamen, thalamus, and amygdala GM volume using probabilistic a-priori regions of interest (ROIs) in 53 early FTLD patients (38 behavioral variant FTD [bvFTD], 9 Semantic Dementia [SD], 6 Progressive Non-Fluent Aphasia [PNFA]), and 25 age-matched healthy controls (HC). ANOVA showed significant (P < 0.001) main effect of diagnosis, and significant interactions for diagnosis and region, and diagnosis and hemisphere. Post-hoc comparisons with HC showed bilateral GM atrophy in the caudate, putamen and thalamus, in bvFTD; a left-confined GM reduction in the amygdala in SD; and bilateral GM atrophy in the caudate and thalamus, and left-sided GM reduction in the putamen and amygdala in PNFA. Correlation analyses suggested an association between GM volumes and language, psychomotor speed and behavioral disturbances.This study showed a widespread involvement of subcortical and deep cortical GM in early FTLD with patterns specific for clinical entity.     

Anatomical measurements of the orbitofrontal cortex in child and adolescent patients with bipolar disorder

Imaging studies indicate smaller orbitofrontal cortex (OFC) volume in mood disorder patients compared with healthy subjects. We sought to determine whether child and adolescent patients with bipolar disorder have smaller OFC volumes than healthy controls. Fourteen children and adolescents meeting DSM-IV criteria for bipolar disorder (six males and eight females with a mean age+/-S.D.=15.5+/-3.2 years) and 20 healthy controls (11 males and nine females with mean age+/-S.D.=16.9+/-3.8 years) were studied. Orbitofrontal cortex volume was measured using magnetic resonance imaging. Male bipolar patients had smaller gray matter volumes in medial (p=0.044), right medial (0.037) and right (p=0.032) lateral OFC subdivisions compared to male controls. In contrast, female patients had larger gray matter volumes in left (p=0.03), lateral (p=0.012), left lateral (p=0.007), and trends for larger volumes in right lateral and left medial OFC subdivisions compared with female controls. Male patients exhibit smaller gray matter volumes, while female patients exhibit larger volumes in some OFC sub-regions. Gender differences in OFC abnormalities may be involved in illness pathophysiology among young bipolar patients.     

Thalamocortical circuits: fMRI assessment of the pulvinar and medial dorsal nucleus in normal volunteers

This fMRI study investigates the activation of the thalamic nuclei in a spatial focusing-of-attention task previously shown to activate the pulvinar with FDG-PET and assesses the connectivity of the thalamic nuclei with cortical areas. Normal right-handed subjects (eight men, eight women, average age=32 years) viewed four types of stimuli positioned to the right or left of the central fixation point (left hemifield-large letter, left hemifield-small letter display with flanking letters; right hemifield-large letter, right hemifield-small letter display with flankers). BOLD responses to small letters surrounded by flankers were compared with responses to large isolated letters. To examine maximum functional regional connectivity, we modeled "subject" as a random effect and attained fixed effect parameter estimates and t-statistics for functional connectivity between each of the thalamic nuclei (pulvinar, medial dorsal, and anterior) as the seed region and each non-seed voxel. Greater BOLD activation for letters surrounded by flankers than for large letters was observed in the pulvinar as anticipated and was also marked in the medial dorsal nucleus (MDN), anterior and superior cingulate (BA24 and BA24'), dorsolateral prefrontal cortex, and frontal operculum and insula. For the MDN, maximal functional connectivity was with the dorsolateral prefrontal cortex; correlations with left superior temporal, parietal, posterior frontal, and occipital regions were also observed. For the pulvinar, maximal functional connectivity was with parietal BA39; for anterior thalamus, with anterior cingulate.     

Changes in grey matter development in autism spectrum disorder

Results on grey matter (GM) structural alterations in autism spectrum disorder (ASD) are inconclusive. Moreover, little is known about age effects on brain-structure abnormalities in ASD beyond childhood. Here, we aimed to examine regional GM volumes in a large sample of children, adolescents, and adults with ASD. Magnetic resonance imaging scans were obtained in 47 male ASD subjects and 51 matched healthy controls aged 8–50 years. We used whole-brain voxel-based morphometry to first assess group differences in regional GM volume across age. Moreover, taking a cross-sectional approach, group differences in age effects on regional GM volume were investigated. Compared to controls, ASD subjects showed reduced GM volumes in the anterior cingulate cortex, posterior superior temporal sulcus, and middle temporal gyrus. Investigation of group differences in age effects on regional GM volume revealed complex, region-specific alterations in ASD. While GM volumes in the amygdala, temporoparietal junction, septal nucleus and middle cingulate cortex increased in a negative quadratic fashion in both groups, data indicated that GM volume curves in ASD subjects were shifted to the left along the age axis. Moreover, while GM volume in the right precentral gyrus decreased linearly with age in ASD individuals, GM volume development in controls followed a U-shaped pattern. Based on a large sample, our voxel-based morphometry results on group differences in regional GM volumes help to resolve inconclusive findings from previous studies in ASD. Results on age-related changes of regional GM volumes suggest that ASD is characterized by complex alterations in lifetime trajectories of several brain regions that underpin social-cognitive and motor functions.     

Identification of the cerebral loci processing human swallowing with H2(15)O PET activation

Lesional and electrophysiological data implicate a role for the cerebral cortex in the initiation and modulation of human swallowing, and yet its functional neuroanatomy remains undefined. We therefore conducted a functional study of the cerebral loci processing human volitional swallowing with 15O-labeled water positron emission tomography (PET) activation imaging. Regional cerebral activation was investigated in 8 healthy right handed male volunteers with a randomized 12-scan paradigm of rest and water swallows (5 ml/bolus, continuous infusion) at increasing frequencies of 0.1, 0.2, and 0.3 Hz, which were visually cued and monitored with submental electromyogram (EMG). Group and individual linear covariate analyses were performed with SPM96. In five of eight subjects, the cortical motor representation of pharynx was subsequently mapped with transcranial magnetic stimulation (TMS) in a posthoc manner to substantiate findings of hemispheric differences in sensorimotor cortex activation seen with PET. During swallowing, group PET analysis identified increased regional cerebral blood flow (rCBF) (P < 0.001) within bilateral caudolateral sensorimotor cortex [Brodmann's area (BA) 3, 4, and 6], right anterior insula (BA 16), right orbitofrontal and temporopolar cortex (BA 11 and 38), left mesial premotor cortex (BA 6 and 24), left temporopolar cortex and amygdala (BA 38 and 34), left superiomedial cerebellum, and dorsal brain stem. Decreased rCBF (P < 0.001) was also observed within bilateral posterior parietal cortex (BA 7), right anterior occipital cortex (BA 19), left superior frontal cortex (BA 8), right prefrontal cortex (BA 9), and bilateral superiomedial temporal cortex (BA 41 and 42). Individual PET analysis revealed asymmetric representation within sensorimotor cortex in six of eight subjects, four lateralizing to right hemisphere and two to left hemisphere. TMS mapping in the five subjects identified condordant interhemisphere asymmetries in the motor representation for pharynx, consistent with the PET findings. We conclude that volitional swallowing recruits multiple cerebral regions, in particular sensorimotor cortex, insula, temporopolar cortex, cerebellum, and brain stem, the sensorimotor cortex displaying strong degrees of interhemispheric asymmetry, further substantiated with TMS. Such findings may help explain the variable nature of swallowing disorders after stroke and other focal lesions to the cerebral cortex.     

Gray matter differences between pediatric obsessive-compulsive disorder patients and high-risk siblings: A preliminary voxel-based morphometry study

Neuroimaging studies have identified alterations in frontostriatal circuitry in obsessive-compulsive disorder (OCD). Voxel-based morphometry (VBM) allows for the assessment of differences in gray matter density across the whole brain. VBM has not previously been used to examine regional gray matter density in pediatric OCD patients and the siblings of pediatric OCD patients. Volumetric magnetic resonance imaging (MRI) studies were conducted in 10 psychotropic naïve pediatric patients with OCD, 10 unaffected siblings of pediatric patients with OCD, and 10 healthy controls. VBM analysis was conducted using SPM2. Statistical comparisons were performed with the general linear model, implementing small volume random field corrections for a priori regions of interest (anterior cingulate cortex or ACC, striatum and thalamus). VBM analysis revealed significantly lower gray matter density in OCD patients compared to healthy in the left ACC and bilateral medial superior frontal gyrus (SFG). Furthermore, a small volume correction was used to identify a significantly greater gray matter density in the right putamen in OCD patients as compared to unaffected siblings of OCD patients. These findings in patients, siblings, and healthy controls, although preliminary, suggest the presence of gray matter structural differences between affected subjects and healthy controls as well as between affected subjects and individuals at risk for OCD.     

基于磁共振T1成像的帕金森病相关脑结构体积差异性分析

目的 应用3.0T磁共振T1成像分析帕金森病（PD）患者脑结构如尾状核、壳核、苍白球、中脑、背侧丘脑、海马、杏仁核体积的变化,探讨MRI体积测量在PD引起形态学改变的应用及在早期诊断上的意义。 方法 采用3.0T MRI对40例早中期PD患者和年龄匹配的32名正常人进行扫描,分别测量出全脑体积、双侧尾状核、双侧壳核、双侧苍白球、中脑、双侧背侧丘脑、双侧海马、双侧杏仁核的体积,对体积值标准化处理后,使用SPSS 22.0软件对数据进行统计学分析。 结果 比较早中期PD患者和正常对照组发现, PD患者的全脑、双侧尾状核、双侧海马、双侧杏仁核的标准化体积和正常人比较差异无显著性（P>0.05）;双侧壳核、双侧苍白球、双侧背侧丘脑、中脑标准化体积差异有显著性（P<0.05）。 结论 基于MRI测量尾状核、壳核、苍白球、中脑、背侧丘脑、海马与杏仁核的体积的变化能为PD的辅助诊断提供一定帮助。     

Depression with late onset is associated with right frontal lobe atrophy

BACKGROUND: The objective of this study was to determine whether older adults with first-ever onset of depression after age 60 years (late onset depression, LOD) have smaller frontal lobes than elderly patients with early-onset depression (EOD) and aged controls. METHOD: Twenty-seven subjects with LOD, 24 with EOD and 37 controls underwent volumetric MRI to determine right and left frontal lobe volumes and total brain volume. RESULTS: The right frontal volume of subjects with LOD was 8.0% and 5.6% smaller than that of patients with EOD (P < 0.01) and controls (NS) respectively. Volume of the left frontal lobe was not significantly different from EOD or controls. All analyses were adjusted for age, gender and total brain volume. Unlike controls and those with EOD, patients with LOD did not display a significant positive correlation between cognitive scores and total brain, left frontal or right frontal volumes. CONCLUSION: LOD is associated with right frontal lobe atrophy and loss of the correlation between cognitive performance and brain volume. This adds support to the fronto-striatal hypothesis of depression and suggests that structural brain changes have a particular role in cases of LOD.     

Voxel-based morphometry study of gray matter abnormalities in obsessive-compulsive disorder

To examine regional abnormalities in the brains of patients with obsessive-compulsive disorder (OCD), we assessed the gray matter (GM) density using voxel-based morphometry (VBM). We compared magnetic resonance images (MRIs) acquired from 71 OCD patients and 71 age- and gender-matched normal controls and examined the relationship between GM density and various clinical variables in OCD patients. We also investigated whether GM density differs among the subtypes of OCD compared to healthy controls. We detected significant reduction of GM in the inferior frontal gyrus, the medial frontal gyrus, the insula, the cingulate gyrus, and the superior temporal gyrus of OCD patients. A significant increase in GM density was observed in the postcentral gyrus, the thalamus, and the putamen. Some of these regions, including the insular and postcentral gyrus, were also associated with the severity of obsessive- compulsive symptoms. These findings indicate that the frontal-subcortical circuitry is dysfunctional in OCD, and suggest that the parietal cortex may play a role in the pathophysiology of this disease.     

健康人大脑和小脑空间记忆认知功能的fMRI研究

本研究应用功能磁共振成像(functional magnetic resonance imaging,fMRI)技术,检测了健康人大脑和小脑参与空间记忆的认知过程。通过对10名右利手健康志愿者进行一项短时空间记忆任务作业的同时进行脑功能磁共振扫描,实验采用组块设计,任务与对照任务交替进行,数据采用SPM99软件进行数据分析和脑功能区定位。结果显示:当统计阈值设定为P<0.0001时,大脑皮层和右侧小脑一起被显著激活;大脑皮层所激活的脑区有双侧顶叶的楔前叶、顶上小叶、缘上回(BA7/40,BA:Brodma-nn Area),双侧前额上、中、下回(BA6/9/47),双侧枕叶和枕颞交界处(BA18/19/37),右侧海马回;左侧中脑黑质及被盖部也被激活。上述结果提示:小脑和大脑皮层一起参与了空间记忆的认知过程。     

Functional connectivity reveals load dependent neural systems underlying encoding and maintenance in verbal working memory

One of the main challenges in working memory research has been to understand the degree of separation and overlap between the neural systems involved in encoding and maintenance. In the current study we used a variable load version of the Sternberg item recognition test (two, four, six, or eight letters) and a functional connectivity method based on constrained principal component analysis to extract load-dependent neural systems underlying encoding and maintenance, and to characterize their anatomical overlap and functional interaction. Based on the pattern of functional connectivity, constrained principal component analysis identified a load-dependent encoding system comprising bilateral occipital (Brodmann's area (BA) 17, 18), bilateral superior parietal (BA 7), bilateral dorsolateral prefrontal (BA 46), and dorsal anterior cingulate (BA 24, 32) regions. For maintenance, in contrast, constrained principal component analysis identified a system that was characterized by both load-dependent increases and decreases in activation. The structures in this system jointly activated by maintenance load involved left posterior parietal (BA 40), left inferior prefrontal (BA 44), left premotor and supplementary motor areas (BA 6), and dorsal cingulate regions (BA 24, 32), while the regions displaying maintenance-load-dependent activity decreases involved bilateral occipital (BA 17, 18), posterior cingulate (BA 23) and rostral anterior cingulate/orbitofrontal (BA 10, 11, 32) regions. The correlation between the encoding and maintenance systems was strong and negative (Pearson's r = -.55), indicting that some regions important for visual processing during encoding displayed reduced activity during maintenance, while subvocal rehearsal and phonological storage regions important for maintenance showed a reduction in activity during encoding. In summary, our analyses suggest that separable and complementary subsystems underlie encoding and maintenance in verbal working memory, and they demonstrate how constrained principal component analysis can be employed to characterize neuronal systems and their functional contributions to higher-level cognition.     

完全性生长激素缺乏患儿大脑皮质形态变化的3.0 T MRI研究

目的 探讨完全性生长激素缺乏(CGHD)患儿与特发性矮小(ISS)患儿大脑结构的灰质体积、皮层表面积及皮层厚度的差异。方法 回顾性队列研究。纳入2015年1月—2019年1月山东省立医院确诊的12例CGHD患儿(男8例、女4例,年龄5~14岁,生长激素刺激释放试验峰值小于5.0 μg/L)与12例ISS患儿(男9例、女3例,年龄5~14岁,生长激素刺激释放试验峰值大于10.0 μg/L)。在首次就诊时采集患者高分辨率、高信噪比三维T₁WI MRI。利用FreeSurfer软件图像后处理方法获得两组患儿左右大脑半球及全脑灰质体积、皮层表面积与皮层厚度值,统计分析组间的差异情况。将每组患儿的上述形态学参数值分别进行平均以获得该组患儿的均值分布图。将两组患儿的测量均值进行相减,即获得两组患儿该测量均值的差异值分布图。结果 CGHD患儿左、右侧大脑半球的灰质体积分别为(228.50±36.72)cm³、 (229.10±34.95)cm³;皮层表面积分别为(737.02±140.48)cm²、(738.68±135.26)cm²;皮层厚度分别为(2.43±0.09)mm、(2.44±0.09)mm。ISS患儿左、右侧大脑半球的灰质体积分别为(272.36±34.77)cm³、 (272.54±32.76)cm³;皮层表面积分别为(841.88±141.75)cm²、(839.98±135.69)cm²;皮层厚度分别为(2.55±0.18)mm、(2.57±0.17)mm。CGHD患儿与ISS患儿的双侧半球与全脑的灰质体积(F_左=17.884, F_右=20.115, F_全=19.009)、皮层表面积(F_左=11.105, F_右=11.453, F_全=11.337)及皮层厚度(F_左=5.907, F_右=6.109, F_全=6.066)的差异均有统计学意义(P值均<0.05)。测量值的均值分布图与均值的差异值分布图显示两组患儿的灰质体积、皮层表面积与皮层厚度在诸多脑区存在差异。结论 CGHD患儿较ISS患儿的大脑灰质体积、皮层表面积与皮层厚度均较小,这可能与其智力、运动或其它功能发育相对落后相关。     

Peer Victimization in Children With Obsessive–Compulsive Disorder: Relations With Symptoms of Psychopathology

This study examined the frequency of peer victimization and psychological symptom correlates among youth with obsessive-compulsive disorder (OCD). The Schwartz Peer Victimization Scale, Children's Depression Inventory, and Asher Loneliness Scale were administered to 52 children and adolescents diagnosed with OCD. The child's parent or guardian completed the Child Behavior Checklist, and a trained clinician administered the Children's Yale-Brown Obsessive–Compulsive Scale (CY– BOCS). Fifty-two healthy controls and 52 children with Type 1 diabetes (T1D) who were administered the Schwartz Peer Victimization Scale as part of another study were included for comparison purposes. Greater rates of peer victimization were reported in youth with OCD relative to healthy controls and children with Type 1 diabetes (T1D). Peer victimization in the OCD sample was positively related to loneliness, child-reported depression, parent-reported internalizing and externalizing symptoms, and clinician-rated OCD severity. Peer victimization fully mediated the relation between OCD severity and both depression and parent reports of child externalizing behaviors and partially mediated the relation between OCD severity and loneliness. Recognition of the magnitude of the problem and contribution problematic peer relations may play in comorbid psychological conditions is important for clinicians who see children with OCD.     

Quantitative MRI of the hippocampus and amygdala in severe depression

BACKGROUND: There is little evidence to support possible structural changes in the amygdala and hippocampus of patients with severe depression. METHODS: Quantitative MRI of the amygdala and hippocampus, as well as proton spectroscopy (MRS) of mesial temporal structures were studied in 34 drug-resistant in-patients with major depression and compared with 17 age-matched controls. Volumetric MRI data were normalized for brain size. RESULTS: The volume of the left hippocampus was significantly smaller in the patients compared with the controls. Both groups exhibited similar significant hippocampal asymmetry (left smaller than right). The patients, but not the controls, had significant asymmetry of the amygdalar volumes (right smaller than left). No differences were observed between the patients and controls in the T2 relaxation times for the hippocampus and amygdala. Mesial temporal lobe MRS revealed a significantly elevated choline/creatine ratio in the patients compared with the controls. CONCLUSIONS: This quantitative MRI study provides support for a possible association between structural and biochemical substrates and severe drug-resistant major depression.     

Association between symptom severity and internal capsule volume in obsessive-compulsive disorder

Neurobiological models support an involvement of white matter tracts in the pathophysiology of obsessive-compulsive disorder (OCD), but there has been little systematic evaluation of white matter volumes in OCD using magnetic resonance imaging (MRI). We investigated potential differences in the volume of the cingulum bundle (CB) and anterior limb of internal capsule (ALIC) in OCD patients (n = 19) relative to asymptomatic control subjects (n = 15). White matter volumes were assessed using a 1.5T MRI scanner. Between-group comparisons were carried out after spatial normalization and image segmentation using optimized voxel-based morphometry. Correlations between regional white matter volumes in OCD subjects and symptom severity ratings were also investigated. We found significant global white matter reductions in OCD patients compared to control subjects. The voxel-based search for regional abnormalities (with covariance for total white matter volumes) showed no specific white matter volume deficits in brain portions predicted a priori to be affected in OCD (CB and ALIC). However, large clusters of significant positive correlation with OCD severity scores were found bilaterally on the ALIC. These findings provide evidence of OCD-related ALIC abnormalities and suggest a connectivity dysfunction within frontal-striatal-thalamic-cortical circuits. Further studies are warranted to better define the role of such white matter alterations in the pathophysiology of OCD, and may provide clues for a more effectively targeting of neurosurgical treatments for OCD.     

Fractal dimension of cerebral cortical surface in schizophrenia and obsessive-compulsive disorder

Schizophrenia and obsessive-compulsive disorder (OCD) are assumed to be neurodevelopmental disorders. To examine the cortical patterns in the two disorders, three-dimensional fractal dimension (FD) of skeletonized cerebral cortical surface was estimated from magnetic resonance (MR) images of 50 patients with schizophrenia, 45 patients with OCD and 26 healthy normal controls. The schizophrenic group had a significantly smaller mean FD than OCD group, and the OCD group than normal controls. The FD revealed a significant interaction effect of group-by-hemisphere, and the FD asymmetry index distinguished the schizophrenic group from normal controls. In logistic regression models, the FD and CSF volume correctly classified 95.6% of the schizophrenics from the controls and 88.0% of the patients with OCD from the controls. In the control and schizophrenic groups, the FD was not associated with any of tissue volume measures. In the OCD group, however, the FD was significantly correlated with gray matter tissue volume and intracranial volume (ICV). The results of the present study suggest that three-dimensional FD of cortical surface may be a sensitive indicator for investigation of the structural brain abnormalities in mental disorders, especially those developmentally disturbed. Further studies to explore regional FD changes in mental disorders and clinical implications of the FD including diagnostic value should be performed in the future.