抑郁症首次发病患者静息态脑功能局部一致性的研究

目的 利用功能磁共振(fMRI)和局部一致性(regional homogeneity,ReHo)探讨抑郁症首次发病(以下简称首发)患者在静息态脑功能是否存在异常及异常部位.方法 对34例符合美国精神疾病诊断与统计手册第4版诊断标准的首发抑郁症患者(抑郁症组)和34名性别、年龄、文化程度匹配的健康志愿者(对照组)进行静息态fMRI扫描.结果 抑郁症组静息态脑血氧水平依赖信号的ReHo高于对照组的脑区有左侧额叶眶回、顶下小叶、颞上回,右侧额内侧回、顶下小叶、小脑后叶;低于对照组的脑区有左颞下回、右颞上同和胼胝体、双侧后扣带回(P＜0.005,K≥10).结论首发抑郁症患者在静息态存在多个腩区功能活动的异常,并可能和抑郁症的病理机制有关.     

MRI findings differentiate between late-onset schizophrenia and late-life mood disorder

OBJECTIVES: Compare MRI scans of patients with late-onset schizophrenia, late-life depression and late-life bipolar disorder to age- and gender-matched controls. MRI head scans of 14 patients in each diagnostic group and 21 patients in the normal control group were compared. Subjects were recruited from inpatient and outpatient services. MEASURES: The CERAD MRI rating algorithm was used to rate degree of atrophy. RESULTS: Patients with bipolar and unipolar disorder had greater left sylvian fissure and left and right temporal sulcal enlargement, and more bilateral cortical atrophy than normals. Patients with late-onset schizophrenia had larger right temporal horns and larger third ventricles. These findings validate the distinctions between late-life affective disorder and late-onset schizophrenia and mirror changes reported in younger individuals. They may reflect underlying structural and functional abnormalities found in neuropathologic and functional imaging studies.     

抑郁症患者局部脑血流的研究

目的：了解抑郁症患者局部脑血流灌注的特点：方法：应用单光子发射计算机断层扫描对20例抑郁症患者及18例正常对照者局部脑血流灌注进行对比分析。结果：抑郁症组双侧基底核、双侧额叶、左颞叶及左枕叶局部血流低灌注；抑郁症组与对照组左右大脑半球局部血流灌注无显著性差异：结论：抑郁症患者局部脑血流存在低灌注，但未发现局部脑血流低灌注有侧化现象。     

Alteration of functional neuroanatomy of simple object memory in medial temporal lobe epilepsy patients

Using H2 15O PET, we examined the neuroanatomy associated with a simple form of episodic memory in patients with right or left medial temporal lobe epilepsy and normal healthy controls. When line drawings of common objects were memorized and tested after a 30 min delay, no behavioral difference was found between the patient groups and the controls. However, the patients with epilepsy showed greater cortical activations than the control group on the side ipsilateral to the epileptic focus. rCBF in the anterior thalamic region was enhanced in patients relative to the control group. The results showed that long-term dysfunction of the medial temporal lobe might reinforce alternative memory pathways and recruit a distributed cortical network ipsilateral to their epilepsy focus.     

Perfusion MRI and computerized cognitive test abnormalities in abstinent methamphetamine users

This study aims to determine possible persistent abnormalities in regional cerebral blood flow (relative rCBF) and cognitive function in abstinent methamphetamine (METH) users. Twenty METH-dependent subjects (abstinent for 8+/-2 months) and 20 age- and gender-matched controls were evaluated with perfusion magnetic resonance imaging (pMRI) and neuropsychological tests. METH users showed decreased relative rCBF bilaterally in putamen/insular cortices (right: -12%; left: -10%) and the right lateral parietal brain region (-11%), but increased relative rCBF bilaterally in the left temporoparietal white matter (+13%), the left occipital brain region: (+10%) and the right posterior parietal region (+24%). Interaction effects were observed between METH and gender in the right occipital cortex and a midline brain region; female METH users showed increased relative rCBF (+15% both regions) whereas the male METH users had decreased relative rCBF (-10% and -18%, respectively). METH users performed within normal ranges on standard neuropsychological tests; however, they were slower on several tasks on the California Computerized Assessment Package (CalCAP), especially tasks that required working memory. These findings suggest that METH abuse is associated with persistent physiologic changes in the brain, and these changes are accompanied by slower reaction times on computerized measures of cognitive function.     

P300 in schizophrenia: confirmation and statistical validation of temporal region deficit in P300 topography

Comparison of normal and medicated schizophrenic groups on the auditory P300 component of the event-related potential confirmed our earlier finding of a left temporal deficit in P300 amplitude in schizophrenia. A difference in P300 topography between groups was evident in both color mapping and in grand-averaged waveforms, which was statistically validated by the presence of a group-by-scalp region interaction (p less than 0.05). The left temporal area in schizophrenics was denoted as the region of greatest deficit and of maximal statistical separation (p less than 0.05) relative to normals by t statistic mapping (SPM), Hotelling's T-squared "protected" contrasts of individual scalp regions, and the relative ratio of left scalp amplitudes to right scalp amplitudes. The left temporal scalp region yielding maximal group separation in the previous study also statistically separated the schizophrenic group from the normal group. This feature correctly differentiated 9 of 11 schizophrenics and 7 of 9 controls. These findings are compatible with other histological, metabolic, and electrophysiological studies suggesting temporal lobe abnormality in schizophrenia.     

Correlations between cerebral blood flow variations and clinical parameters in temporal lobe epilepsy: an interictal study.

Regional cerebral blood flow (rCBF) measurements were determined by the intravenous Xenon 133 technique in 80 patients suffering from temporal lobe epilepsy. All the patients had a normal CT scan. Three subgroups were differentiated, according to EEG and all-night polygraphic recordings: temporal lobe epilepsy with left (N = 25) or right (N = 25) EEG epileptic abnormalities and temporal lobe epilepsy with EEG abnormalities in both temporal regions with asynchronous occurrence (n = 30). In comparison with a control group (n = 20), there was (1) a marked reduction of blood flow in the temporal region corresponding to the site of the epileptic focus and (2) a reduction in blood flow in distant brain areas and the contralateral hemisphere. The rCBF decrease was highly correlated (p less than 0.001) with the disease severity (taking into account the complex partial seizure frequency and the number of secondary generalised seizures). Differences were found in the rCBF decrease between left and right temporal lobe epilepsy.     

Voxel-based analyses of gray/white matter volume and diffusion tensor data in major depression

The purpose of this study is to use voxel-based analysis to simultaneously elucidate regional changes in gray/white matter volume, mean diffusivity (MD), and fractional anisotropy (FA) in patients with unipolar major depressive disorder. We studied 21 right-handed patients and 42 age- and gender-matched right-handed normal subjects. Local areas showing significant gray matter volume reduction in depressive patients compared with controls were observed in the right parahippocampal gyrus, hippocampus, bilateral middle frontal gyri, bilateral anterior cingulate cortices, left parietal and occipital lobes, and right superior temporal gyrus. Local areas showing an increase of MD in depressive patients were observed in the bilateral parahippocampal gyri, hippocampus, pons, cerebellum, left frontal and temporal lobes, and right frontal lobe. There was no significant difference between the two groups for FA and white matter volume in the entire brain. Although there was no local area where brain volume and MD were significantly correlated with disease severity, FA tended to correlate negatively with total days depressed in the right anterior cingulate and the left frontal white matter. These results suggest that the frontolimbic neural circuit might play an important role in the neuropathology of patients with major depressive disorder.     

An MRI study of the superior temporal subregions in patients with current and past major depression

The superior temporal gyrus (STG), especially its lateral portion, and temporal pole (TP) both play a central role in emotional processing, but it remains largely unknown whether patients with major depressive disorder (MDD) exhibit morphologic changes in these regions. We delineated the STG subregions [planum polare (PP), Heschl gyrus (HG), planum temporale (PT), rostral STG, and caudal STG] and TP using magnetic resonance imaging in 29 currently depressed patients (mean age = 32.5 years, 7 males), 27 remitted depressed patients (mean age = 35.1 years, 9 males), and 33 age- and gender-matched healthy control subjects (mean age = 34.0 years, 12 males). Both current and remitted MDD patients showed a significant volume reduction of the left PT and bilateral caudal STG as compared with healthy controls. The TP volume did not differ between the groups. The right PT volume was negatively correlated with total score on the Beck Depression Inventory in the MDD patients as a whole. Medication, presence of melancholia, and comorbidity with anxiety disorders did not affect the TP and STG volumes. These findings suggest that the volume reduction of the STG, but not the TP, may represent enduring brain changes in MDD even after recovery from depression, but right STG volume may also be related to the severity of depressive symptoms.     

Glucose utilization in the temporal cortex of affectively ill patients: positron emission tomography

As temporal lobe dysfunction has been postulated in the affective disorders, the authors investigated glucose utilization in the temporal lobes of 13 affectively ill patients in comparison with 18 normal volunteer controls and 17 previously reported schizophrenic patients, following injections of fluorine 18-2-deoxy-D-glucose (FDG) during somatosensory stimulation to the right forearm. Using a boundary-finding algorithm to outline each temporal lobe, maximum glucose use relative to maximums elsewhere in the same positron emission tomography (PET) slice were calculated. In a small group of moderately to severely depressed patients, this relative measure was significantly reduced in the right (with a similar trend in the left) temporal lobe compared to normal volunteers and the other comparison groups. The lack of a significant increase in glucose utilization, measured either as a maximum or in relation to other areas in the PET scan slice, suggests that a temporal lobe activation or a seizure-like process is not generally occurring during active depressive phases of the illness.     

The investigation of Alzheimer''s disease with single photon emission tomography.

Twenty patients satisfying standard clinical criteria for Alzheimer's disease (AD) and six age-matched normal controls were studied using 99mTc hexamethyl-propyleneamine oxime and single photon emission tomography. The AD patients had lower regional cerebral blood flow (rCBF) in the temporal and posterior parietal lobes compared to controls. AD patients with apraxia and aphasia had lower rCBF in the lateral temporal and posterior parietal lobes than AD patients without these features. Within the AD group, correlations were found between neuropsychological tests and rCBF: praxis correlated with posterior parietal activity, memory with left temporal lobe activity and language with activity throughout the left hemisphere.     

Brain perfusion in autism varies with age

Our subjects consisted of 14 autistic individuals and 14 controls ranging in age from 3 to 37 years. A (99m)Tc HMPAO single photon emission computed tomogram (SPECT) was used to examine blood flow variations between autistic subjects, compared to an age- and gender-matched control group. We found significant hypoperfusion in the prefrontal areas of autistic individuals as compared to normals in every case (p < 0.01). As the age of the autistic individuals increased the hypoperfusion of verbal-associated areas in the left temporal lobe and frontal areas became more evident. The findings were significant at the p < 0.001 level. The changes in perfusion over time correlated with language development and acquisition as individuals matured. We conclude that autistic individuals have a deficiency in prefrontal areas associated with word identification and language formation skills. This subsequently prevents development of true verbal fluency and development in the temporal and frontal areas associated with speech and communication.     

Abnormalities of P300 cortical current density in unmedicated depressed patients revealed by LORETA analysis of event-related potentials

The purpose of the present study was to investigate the neural substrates underlying event-related potential (ERP) abnormalities, with respect to the generators of the ERP components in depressed patients. Using an oddball paradigm, ERP from auditory stimuli were recorded from 22 unmedicated patients with current depressive episodes and compared with those from 22 age- and gender-matched normal controls. Cortical current densities of the N100 and P300 components were analyzed using low-resolution electromagnetic tomography (LORETA). Group differences in cortical current density were mapped on a 3-D cortex model. The results revealed that N100 cortical current densities did not differ between the two groups, while P300 cortical current densities were significantly lower in depressed patients over the bilateral temporal lobes, the left frontal region, and the right temporal-parietal area. Furthermore, the cortical area in which the group difference in P300 current density had been identified was remarkably larger over the right than the left hemisphere, thus supporting the hypothesis of right hemisphere dysfunction in depression.     

抑郁症患者静息状态的功能磁共振成像研究

目的 了解在静息状态下抑郁症患者脑区的局部一致性特点.方法 采用功能磁共振成像(fMRI)技术,检测静息状态下27例抑郁症患者(患者组)和性别、年龄、受教育程度均与患者相匹配的27名正常人(对照组)的脑功能活动,并对两组进行比较.利用局部一致性方法 分析fMRI数据,用SPM2软件进行配对t检验(P＜0.005).结果 与对照组相比,患者组双侧额中回、右额下回、右颞上回、左前扣带回、右后扣带回、右岛叶、双侧豆状核、双侧屏状核、左尾状核局部一致性显著增高(P＜0.005,未校正,体素值＞10);未显示脑区有明显的局部一致性减低.结论 抑郁症患者神经环路脑区局部在静息状态下具有很高的一致性,其局部一致性的增高可能参与了抑郁症的代偿机制.     

抑郁症患者识别负性表情的脑磁源性影像动态变化

目的 利用磁源性影像技术以及表情事件相关识别实验范式探讨抑郁症患者识别负性动态表情的神经网络磁源性影像动态变化的特点.方法 利用脑磁图检测12例抑郁症患者(患者组)及12名年龄、性别、受教育年限近似匹配的健康对照者(对照组)识别负性动态表情视频时的脑部反应.设P＜0.01时,差异均具有统计学意义.结果 与对照组相比,患者组识别负性面部表情时,活动异常主要出现在双侧钩回、双侧颞上回、右额中回、右杏仁核、右颞回下、左梭状回、左枕下回、右海马旁回、左枕舌回、双侧楔前叶、左楔叶等脑区,这些脑区组成的神经网络在识别负性动态表情过程有相应脑区激活异常.结论 抑郁症患者识别负性表情的功能网络的脑磁源性影像动态变化特点与正常人比较差异有统计学意义.     

Regional cerebral blood flow during interictal state: differences between temporal lobe epilepsy and primary generalized epilepsy

Regional cerebral blood flow (rCBF) was investigated during interictal state by 133Xenon intravenous clearance technique in two groups of epileptic patients: group I (n = 28) having partial complex seizures (temporal lobe epilepsy); group II (n = 14) having generalized seizures (primary generalized epilepsy). Mean hemispheric CBF was decreased in group I and unchanged in group II compared to normal controls. Modifications in rCBF pattern were observed in group I but not in group II. A marked hypoperfusion of one temporal region was found in patients from group I showing a unilateral and fixed epileptic focus. Hypoperfusion of other cerebral areas at a distance from the epileptic focus was greater for patients with a left epileptic focus than for those with a right epileptic focus. Patients with the same severity of disease and bilateral and variable foci had no significant modification of mean hemispheric CBF and rCBF distribution. These observations indicate that interictal investigations of rCBF may be of interest for a differential classification of epilepsy.     

Voxel-based morphometry in adolescents with bipolar disorder: first results

Bipolar disorder is an increasingly recognized cause of significant morbidity in the pediatric age group. However, there is still a large degree of uncertainty regarding the underlying neurobiological deficits. In this preliminary study, we performed automated volumetric studies and whole-brain voxel-based morphometry (VBM) on gray matter. Imaging data from 10 adolescents with bipolar disorder were compared with data from 52 age- and gender-matched healthy controls. Previously defined brain parcellations and optimized VBM protocols were used, based on custom-made pediatric reference data. An additional, exploratory whole-brain comparison was also implemented. The volumetric region-of-interest study revealed significantly greater gray matter volume in central gray matter structures bilaterally (including the basal ganglia and the thalamus) and the left temporal lobe in the bipolar group. VBM confirmed bilaterally larger basal ganglia. Localized gray matter deficits in bipolar subjects were found in the medial temporal lobe, orbito-frontal cortex, and the anterior cingulate, confirming and extending earlier studies.     

Abnormalities of cortical thickness in postictal psychosis

Postictal psychosis (PIP), the occurrence of psychotic episodes following a seizure, is a common and serious comorbidity in patients with epilepsy. Yet, the anatomical correlates remain poorly defined. Here, we used quantitative MRI morphometry to identify structural abnormalities in the cortex of patients with PIP relative to patients with epilepsy without PIP and age- and gender-matched normal healthy controls. Comparison of patients with epilepsy and PIP with patients with epilepsy without PIP revealed increased cortical thickness in the right lateral prefrontal cortex, right anterior cingulate cortex, and right middle temporal gyrus. The PIP group was distinguished from the EC and NC groups by thicker cortex in the right rostral anterior cingulate cortex and thinner cortex in the right angular gyrus and the left middle temporal region. Findings indicate that PIP is associated with thickening of the right anterior cingulate cortex, which may serve as a marker for patients at risk for developing PIP.     

Prefrontal-subcortical and limbic circuit mediation of major depressive disorder

Substantial progress has been made in elucidating the pathophysiology of major depressive disorder (MDD) using functional and structural brain imaging. In functional imaging studies comparing MDD subjects to normal controls at baseline, dorsolateral prefrontal cortex (DLPFC) activity has been found to be decreased and ventrolateral prefrontal cortex (VLPFC) activity has been found to be increased in MDD. Other regions found abnormal in baseline studies include the anterior cingulate gyrus (AC), temporal lobe, and basal ganglia. Studies examining mood state change (using sleep deprivation, sadness-induction, and tryptophan depletion) and changes from pre- to posttreatment have generally shown improvement of these abnormalities with improved MDD symptoms and worsening of these abnormalities with worsening symptoms. In structural imaging studies, decreased frontal lobe, hippocampal, and basal ganglia volumes are the most commonly reported findings. Several associations can be made between clinical features of MDD and brain function: (1) active sad thoughts/sadness with both decreased DLPFC and dorsal AC activity and increased VLPFC and ventral AC activity (2) psychomotor retardation with decreased left prefrontal activity (3) anxiety with increased left AC activity (4) impaired episodic memory with left prefrontal and medial temporal dysfunction and (5) impaired sustained attention with right prefrontal and parietal dysfunction.     

The regional cerebral blood flow changes in major depressive disorder with and without psychotic features

Depressive patients with psychotic features demonstrate distinct biological abnormalities in the hypothalamic-pituitary-adrenal axis (HPA), dopaminergic activity, electroencephalogram sleep profiles and measures of serotonergic function when compared to nonpsychotic depressive patients. However, very few functional neuroimaging studies were specifically designed for studying the effects of psychotic features on neuroimaging findings in depressed patients. The objective of the present study was to compare brain Single Photon Emission Tomography (SPECT) images in a group of unmedicated depressive patients with and without psychotic features. Twenty-eight patients who fully met DSM-IV criteria for major depressive disorder (MDD, 12 had psychotic features) were included in the study. They were compared with 16 control subjects matched for age, gender and education. Both psychotic and nonpsychotic depressed patients showed significantly lower regional cerebral blood flow (rCBF) values in the left and right superior frontal cortex, and left anterior cingulate cortex compared to those of controls. In comparison with depressive patients without psychotic features (DwoPF), depressive patients with psychotic features (DwPF) showed significantly lower rCBF perfusion ratios in left parietal cortex, left cerebellum but had higher rCBF perfusion ratio in the left inferior frontal cortex and caudate nucleus. The present study showed that DwPF have a different rCBF pattern compared to patients without psychotic features. Abnormalities involving inferior frontal cortex, striatum and cerebellum may play an important role in the generation of psychotic symptoms in depression.