Event-related potentials in different subtypes of multiple sclerosis--a cross-sectional study

BACKGROUND: Neurodegenerative and cerebrovascular diseases show a distinct distribution of regional atrophy and subcortical lesions. OBJECTIVE: To develop an easily applicable landmark-based method for segmentation of the brain into the four cerebral lobes from MRI images. METHOD: The segmentation method relies on a combination of anatomical landmarks and geometrical definitions. It is applied on the surface reconstruction of the MRI volume. The internal borders between the lobes are defined on the axial slices of the brain. The reliability of this method was determined from MRI scans of 10 subjects. To illustrate the use of the method, it was applied to MRI scans of an independent group of 10 healthy elderly subjects and 10 patients with vascular dementia to determine the regional distribution of white matter hyperintensities (WMH). RESULTS: The intra-rater relative error (and intra-class correlation coefficient) of the lobe segmentation ranged from 1.6% to 6.9% (from 0.91 to 0.99). The inter-rater relative error (and intra-class correlation coefficient) ranged from 1.4% to 5.2% (from 0.96 to 0.99). Density of WMH was significantly higher in all four lobes in VD patients compared to controls (p<0.05). Within each group, WMH density was significantly higher in frontal and parietal than in temporal and occipital lobes (p<0.05). CONCLUSION: This landmark based method can accommodate age and disease-related changes in brain morphology. It may be particularly useful for the study of neurodegenerative and cerebrovascular disease and for the validation of template-based automated techniques.     

Frontal and temporal volume size of grey and white matter in patients with schizophrenia

We previously performed a magnetic resonance imaging (MRI) parcellation study that showed smaller grey and white matter volumes of the temporal lobes and increased CSF volumes in the frontal and temporal lobe in men with schizophrenia. One question that arose from this earlier study was whether similar structural changes in the brain are found in a large group of schizophrenic patients consisting of both men and women. In the present study, MRI scans were acquired from 94 patients of both genders with schizophrenia and 101 healthy subjects. After the automatic segmentation of grey matter, white matter, and cerebrospinal fluid, the frontal, temporal, parietal, and occipital lobes were automatically parcellated according to the Talairach atlas. Compared with healthy subjects, schizophrenic patients showed significantly smaller volumes of grey matter in the temporal lobe and white matter in the frontal lobe. Schizophrenic patients had a greater CSF volume in the frontal and temporal lobes. These results suggest that volume reduction in the cerebrum is prominent in the frontal and temporal lobes in both men and women with schizophrenia.     

MRI volumetric study of dementia with Lewy bodies: a comparison with AD and vascular dementia

OBJECTIVE: To compare global and regional atrophy on MRI in subjects with dementia with Lewy bodies (DLB), AD, vascular dementia (VaD), and normal aging. In addition, the relationship between APOE-epsilon4 genotype and volumetric indices was examined. METHOD: MRI-based volume measurements of the whole-brain, ventricles, frontal lobe, temporal lobe, hippocampus, and amygdala were acquired in elderly subjects with DLB (n = 27; mean age = 75.9 years), AD (n = 25; 77.2 years), VaD (n = 24; 76.9 years), and normal control subjects (n = 26; 76.2 years). RESULTS: Subjects with DLB had significantly larger temporal lobe, hippocampal, and amygdala volumes than those with AD. No significant volumetric difference between subjects with DLB and VaD was observed. Compared with control subjects, ventricular volumes were increased in all patients with dementia, though those with DLB showed a relative preservation of whole-brain volume. There were no significant differences in frontal lobe volumes between the four groups. APOE-epsilon4 status was not associated with volumetric indices. CONCLUSION: The findings support the hypothesis that DLB is associated with a relative preservation of temporal lobe structures. In the differentiation of DLB and AD, this may have important implications for diagnosis.     

Single Photon Emission Computed Tomography, Magnetic Resonance Imaging Hyperintensity, and Cognitive Impairments in Patients With Vascular Dementia

BACKGROUND: The relationship between subcortical hyperintensity (SH) on magnetic resonance imaging (MRI), cortical perfusion on single photon emission computed tomography (SPECT), and cognitive function is not well understood. The authors examined these relationships in individuals with vascular dementia (VaD), paying particular attention to frontal lobe function to determine whether the presence of SH on MRI was associated with frontal hypoperfusion on SPECT, which in turn would be associated with impairments of executive-attention function. METHODS: Patients with vascular dementia (n = 26) were assessed on neurocognitive tests and brain MRI and SPECT. SH volume was quantified from the axial T2-weighted fluid attenuated inversion recovery MRI. Total counts of activation across voxels for 12 cortical regions of interest were determined from SPECT. Perfusion ratios of both total cortical and frontal activation relative to cerebellum activation were derived, and regression analyses were performed to determine the relationships between cognitive, MRI, and SPECT indices. RESULTS: SH volume on MRI was significantly associated with frontal lobe perfusion, but not with global cortical perfusion as measured by SPECT. Frontal lobe perfusion did not consistently correlate with performance on measures of executive-attention function, although both total and frontal perfusion ratios were significantly associated with other cognitive functions. CONCLUSIONS: These results suggest that a functional "disconnection" between the frontal lobes and subcortical structures does not fully account for the magnitude of global cognitive impairment in VaD. Cortical perfusion as measured by SPECT appears to be associated with cognitive performance, but not specifically executive-attention dysfunction. Additional studies are needed to further examine the relationship between subcortical and cortical function in VaD.     

APOE ε4 and risk for Alzheimer's disease: Do regionally distributed white matter hyperintensities play a role?

BackgroundWe previously demonstrated that parietal lobe white matter hyperintensities (WMH) increase the risk for Alzheimer's disease (AD). Here, we examined whether individuals with apolipoprotein E gene (APOE ε4) have increased parietal WMH volume.MethodsParticipants were from the Washington Heights-Inwood Columbia Aging Project (WHICAP; n = 694, 47 with dementia) in northern Manhattan and the Etude Santé Psychologique Prévalence Risques et Traitement study (ESPRIT; n = 539, 8 with dementia) in Montpellier. The association between regional WMH and APOE ε4 was examined separately in each group and then in a combined analysis.ResultsIn WHICAP, ε4 carriers had higher WMH volume particularly in parietal and occipital lobes. In ESPRIT, ε4 carriers had elevated WMH particularly in parietal and temporal lobes. In the combined analysis, ε4 carriers had higher WMH in parietal and occipital lobes. Increased WMH volume was associated with increased frequency of dementia irrespective of APOE ε4 status; those with the ε4 were more likely to have dementia if they also had increased parietal WMH.ConclusionsAPOE ε4 is associated with increased parietal lobe WMH.     

阿尔茨海默病脑白质葡萄糖代谢异常分析

目的探讨阿尔茨海默病(AD)脑白质葡萄糖代谢异常的意义。方法纳入33例符合美国精神障碍诊断与统计手册-第四版(DSM-IV)AD诊断标准的患者和健康对照20名,进行脑正电子发射断层成像(PET)检查。应用SPM软件对PET图像进行分析。结果①与健康对照相比,AD患者有广泛的白质葡萄糖代谢减低,减低较为明显的区域有右侧额叶皮质下白质、左侧额叶上中回皮质下白质(P<0.001);另外,AD患者左侧额叶内侧回皮质下白质、左侧枕叶楔回皮质下白质葡萄糖代谢增强(P<0.001);②与不伴有精神行为症状(BPS)的AD患者(16例)相比,伴有BPS的AD患者(17例)在左右枕叶中回、右侧枕叶楔回、右侧顶下小叶、左侧颞叶梭形回、左侧额叶内侧回等脑区的皮质下白质葡萄糖代谢增强(P<0.001);而左右额叶中央旁回、右侧额叶上回和中回、左侧颞叶上回等脑区的皮质下白质葡萄糖代谢减低(P<0.001)。结论AD有广泛的白质脑葡萄糖代谢异常,有无BPS的AD白质代谢异常不同。     

Association of regional white matter hyperintensities with hypertension and cognition in the population-based 1000BRAINS study

Background

White matter hyperintensities of presumed vascular origin (WMH) are frequent in cerebral magnetic resonance imaging of older people. They are promoted by vascular risk factors, especially hypertension, and are associated with cognitive deficits at the group level. It has been suggested that not only the severity, but also the location, of lesions might critically influence cognitive deficits and represent different pathologies.

Methods

In 560 participants (65.2 ± 7.5 years, 51.4% males) of the population-based 1000BRAINS study, we analyzed the association of regional WMH using Fazekas scoring separately for cerebral lobes, with hypertension and cognition.

Results

WMH most often affected the frontal lobe (83.7% score >0), followed by the parietal (75.8%), temporal (32.7%), and occipital lobe (7.3%). Higher Fazekas scores in the frontal, parietal, and temporal lobe were associated with higher blood pressure and antihypertensive treatment in unadjusted ordinal regression models and in models adjusted for age, sex, and vascular risk factors (e.g., age- and sex-adjusted odds ratio = 1.14, 95% confidence interval = 1.03–1.25 for the association of frontal lobe WMH Fazekas score with systolic blood pressure [SBP] [per 10 mm Hg]; 1.13 [1.02–1.23] for the association of parietal lobe score with SBP; 1.72 [1.19–2.48] for the association of temporal lobe score with antihypertensive medications). In linear regressions, higher frontal lobe scores were associated with lower performance in executive function and non-verbal memory, and higher parietal lobe scores were associated with lower performance in executive function, verbal-, and non-verbal memory.

Conclusions

Hypertension promotes WMH in the frontal, parietal, and temporal lobe. WMH in the frontal and parietal lobe are associated with reduced executive function and memory.     

皮质下缺血性血管性认知损害扩散张量成像研究

目的通过扩散张量成像(DTI)探讨皮质下缺血性血管性认知损害患者白质微结构变化及其与认知功能之间的相关性。方法采集49例皮质下缺血性脑血管病患者[轻度血管性痴呆(VaD)10例、非痴呆型血管性认知损害(VCIND)20例、认知功能正常19例]DTI数据并观察皮质下白质微结构改变,分析VaD组患者DTI参数与认知功能间的相关性。结果与对照组相比,VaD组内侧前额叶、前扣带回、胼胝体干、双侧顶叶、右侧颞叶、双侧眶额叶,以及VCIND组右侧额下回、右侧海马、双侧楔前叶FA值减低(均P=0.000);与VCIND组比较,VaD组内侧前额叶、前扣带回、胼胝体、双侧顶叶、右侧颞叶FA值减低(P=0.000)。与对照组相比,VaD组内侧前额叶、胼胝体、双侧顶叶、双侧颞叶、前扣带回,以及VCIND组双侧楔前叶、右侧海马MD值升高(均P=0.000);与VCIND组相比,VaD组右侧内侧前额叶、前扣带回、胼胝体干、双侧顶叶、双侧颞叶MD值升高(均P=0.000)。VaD组内侧前额叶FA值与数字连线测验A时呈显著负相关(r=-0.782,P=0.007),双侧额下回MD值与数字连线试验A时程呈显著正相关(r=0.877,P=0.001)。结论 DTI对皮质下缺血性认知损害患者白质微结构改变更敏感,能够反映患者认知功能早期异常改变;内侧前额叶白质微结构的改变是影响患者执行能力的重要因素。     

White matter hyperintensities and within-person variability in community-dwelling adults aged 60-64 years

Estimates of white matter hyperintensities (WMH) derived from T2-weighted MRI were investigated in relation to cognitive performance in 469 healthy community-dwelling adults aged 60-64 years. Frontal lobe WMH but not WMH from other brain regions (temporal, parietal, and occipital lobes, anterior and posterior horn, periventricular body) were associated with elevated within-person reaction time (RT) variability (trial to trial fluctuations in RT performance) but not performance on several other cognitive tasks including psychomotor speed, memory, and global cognition. The findings are consistent with the view that elevated within-person variability is related to neurobiological disturbance, and that attentional mechanisms supported by the frontal cortex play a key role in this type of variability.     

Volumetric comparisons of supratentorial white matter hyperintensities on FLAIR MRI in patients with migraine and multiple sclerosis

Migraine and multiple sclerosis (MS) can both cause white matter lesions that appear similar on conventional MRI. This study aimed to compare these abnormalities, and to find anatomical biomarkers specific for migraine. Supratentorial white matter hyperintensities (WMH) of 17 migraineurs and 15 patients with MS were counted, volumetrically analyzed, and their lobar distribution assessed on fluid-attenuated inversion recovery MRI. We found that migraine WMH affected mainly the deep white matter and subcortical U-fibers, belonged to the anterior circulation, appeared more frequently in the frontal and parietal lobes, showed no difference in average size between lobes, and were smaller and fewer than in MS. Most of the MS WMH were in the frontal lobe and were the smallest average size, while the fewest WMH with the largest size were in the occipital lobe. The pattern of supratentorial WMH appearance differs between the two groups; however, accurate differential diagnosis of WMH by conventional MRI is probably not possible in individual patients.     

阿尔茨海默病的脑血流灌注研究

目的探讨AD患者脑血流灌注的特征性变化。方法选择20例确诊AD患者和10例认知正常者,对所有入组对象行SPECT脑血流灌注显像检查,对所得图像进行视觉分析和半定量分析,比较两组对象各脑区血流灌注情况的差异,并比较AD患者左、右脑叶脑血流灌注的差异。结果 (1)视觉分析结果显示,AD组以颞叶或顶叶脑血流灌注减低为主,各占55%,其中双侧颞顶叶血流灌注减低者占15%,单侧颞顶叶血流灌注减低占20%。正常认知组SPECT影像学表现各异,额叶、颞叶、顶叶、枕叶、丘脑、基底节血流灌注减少情况均存在,各占10%。但无双侧颞顶叶血流灌注减少者,40%表现完全正常。(2)半定量分析结果显示,AD组在右额叶、双侧颞顶叶、右枕叶血流灌注显著低于正常认知组(P<0.05),以右侧颞叶血流灌注降低最明显,左右颞顶叶血流低灌注程度对比无显著性差异。结论 AD患者的SPECT特征性表现为双侧对称性颞顶叶血流低灌注,其中右侧颞叶血流灌注下降最严重。     

Regional white matter hyperintensities in normal aging, single domain amnestic mild cognitive impairment, and mild Alzheimer’s disease

Few studies have examined white matter hyperintensities (WMH) along the cognitive continuum between single-domain amnestic mild cognitive impairment (sd-aMCI) and Alzheimer’s disease (AD). The aims of our study were to explore relationships between the extent and location of WMH and disease severity along the cognitive continuum and to determine whether differences in the distribution of WMH could be predictive of specific patterns of cognitive impairment. We compared cognitive function, vascular risk factors, and regional (frontal lobe, parieto-occipital [PO] lobe, temporal lobe, periventricular [PV] white matter and deep white matter) WMH volume in 37 patients with mild AD, 23 patients with sd-aMCI, and 24 age-matched and education-matched normal controls. A quantitative volumetric method was applied to measure WMH burden. Total and regional WMH burdens, except for those in the temporal lobe, were significantly correlated with age (p < 0.01). We found a trend toward increasing WMH volume with disease severity, higher in AD than in sd-aMCI and lowest in the controls. Total WMH volume was associated with the global cognitive test score. In multiple linear regression analysis, PV WMH volume, but not deep WMH volume, strongly predicted performances on the Controlled Oral Word Association test and the Color Word Stroop test after adjusting for important demographic variables. Only PO WMH volume was a significant predictor of a cognitive test score when frontal and temporal WMH volumes were simultaneously entered into the regression model. The extent and distribution of WMH, especially in the PV and PO regions, were associated with disease severity and reduced cognition.     

18F-FDG PET/CT脑显像评价认知障碍患者中的脑小血管病变对皮层功能的影响

目的 探讨18氟代脱氧葡萄糖（18F-fluorodeoxyglucose,18F-FDG）正电子发射断层成像/计算机断层扫
描（positron emission tomography/computed tomography,PET/CT）脑显像评价认知障碍患者中的脑小血
管病变对皮层功能的影响。
方法 本研究为回顾性研究,纳入2009年1月～2010年12月北京协和医院PET中心行18F-FDG PET/CT
脑显像且颅脑磁共振成像（magnetic resonance imaging,MRI）提示存在小血管病变的认知障碍患者21例,
其中临床诊断血管性痴呆（vascular dementia,VaD）10例,阿尔茨海默病（Alzheimer’s disease,AD）或混
合型痴呆（mixed dementia,MD）11例。首先目测两组患者的18F-FDG PET/CT脑显像皮层及皮层下核团代
谢减低特点,并结合颅脑MRI判断病变血管对脑代谢的影响。使用NeuroQ软件和Scenium软件对18F-FDG
PET/CT脑图像在像素基础上进行定量分析比较两组患者的皮层代谢情况。
结果 通过目测和NeuroQ软件分析发现VaD组患者18F-FDG PET/CT脑显像图像特点为无规律,不对
称皮层或皮层下核团代谢减低,其中额叶皮层代谢减低范围最广,程度最重。结合颅脑MRI改变,考
虑皮层和皮层下核团代谢减低主要为小血管病变引起。AD或MD组患者脑代谢均呈现双侧颞顶叶代谢
减低,其中8例出现皮层代谢减低不对称表现,6例出现基底节丘脑不对称代谢减低表现,与典型AD
的表现不符,结合颅脑MRI表现,考虑为病变血管所致,小血管病变可能导致相应皮层代谢减低。通
过定量分析发现两组患者的SUV比值在左右顶叶、内外颞叶和枕叶差异具有显著性。
结论 18F-FDG PET/CT脑显像作为功能影像可以推断小血管病变与皮层及皮层下核团代谢的关系。     

White matter lesions impair initiation of FAS flow

Word fluency performance is known to rely on left frontal cortical regions and has also been shown to be affected by lesions in the white matter, which may be seen as white matter hyperintensities (WMH) on magnetic resonance imaging. However, word fluency may be divided into two independent components, initial and late performance, separated in time [J Clin Exp Neuropsychol 1998;20:137-143]. The purpose of the current study was to investigate the relationship between the two components of FAS fluency performance and WMH. Patients varying in degree of memory impairment participated: Alzheimer's disease, mild cognitive impairment and subjective memory disorder. WMH were rated with the Scheltens scale in the periventricular and deep subcortical areas. Results demonstrated that WMH in this sample of patients may be summarized in two indices according to a principal factor analysis, one anterior factor mainly related to WMH in the frontal lobes and adjacent to ventricles, and a second posterior factor related to parietal and occipital WMH. The initial FAS performance was related to anterior WMH, in particular left frontal or lateral periventricular hyperintensities, whereas the late FAS performance was not related to any index of WMH.     

Anatomical and functional correlates of human hippocampal volume asymmetry

Hemispheric asymmetry of the human hippocampus is well established, but poorly understood. We studied 110 healthy subjects with 3-Tesla MRI to explore the anatomical and functional correlates of the R>L volume asymmetry. We found that the asymmetry is limited to the anterior hippocampus (hemisphere×region interaction: F(1,109)=42.6, p<.001). Anterior hippocampal volume was correlated strongly with the volumes of all four cortical lobes. In contrast, posterior hippocampal volume was correlated strongly only with occipital lobe volume, moderately with the parietal and temporal lobe volumes and not with the frontal lobe volume. The degree of R>L anterior hippocampal volume asymmetry predicted performance on a measure of basic cognitive abilities. This provides evidence for regional specificity and functional implications of the well-known hemispheric asymmetry of hippocampal volume. We suggest that the developmental profile, genetic mechanisms and functional implications of R>L anterior hippocampal volume asymmetry in the human brain deserve further study.     

Topographical patterns of lobar atrophy in frontotemporal dementia and Alzheimer's disease

BACKGROUND/AIMS: Fronto-temporal dementia (FTD) designates a group of relatively common neurodegenerative disorders. The aim of this study was to characterize the patterns of brain atrophy in FTD compared to Alzheimer's disease (AD). METHODS: A novel semiautomatic volumetric MRI analysis method was applied to measure regional brain volumes in FTD (n = 15; behavioural variant n = 9, language variant n = 6) in contrast with AD patients (n = 15) and age-matched controls (NC) (n = 15). FTD and AD patients were matched on demographic measures and Mini Mental State Examination scores. RESULTS: Significant atrophy was present in the frontal and anterior temporal lobes of subjects with FTD compared to AD (p = 0.02; effect size = 1.11) and compared to NC (p < 0.001; effect size = 1.86). Severe atrophy of the left anterior temporal region distinguished the language variant. AD patients, by contrast, did not differ from NC for frontal lobe volume but had smaller anterior temporal lobes (p = 0.03). Both dementia groups had medial temporal lobe atrophy of similar magnitude. A logistic regression model including 4 regional measures correctly classified 100% of subjects. CONCLUSION: FTD can be reliably differentiated from AD by virtue of a topographical pattern of atrophy involving the frontal lobes and anterior temporal regions. Medial temporal lobe volumes do not distinguish FTD from AD.     

Combined magnetic resonance imaging and single-photon emission tomography scanning in the discrimination of Alzheimer's disease from age-matched controls

OBJECTIVE: To compare the utility of temporal lobe magnetic resonance imaging (MRI) and single-photon emission tomography (SPET) scanning in discriminating between subjects with Alzheimer's disease (AD) and age-matched controls. METHODS: Thirty subjects with NINCDS-ADRDA AD (23 probable AD, 5 possible AD, 2 definite AD) and 22 age- and sex-matched controls underwent T1-weighted coronal MRI scanning (0.3 T) and technetium 99m-HMPAO SPET scanning. MRI scans were analyzed using a digitizer system with volumes of hippocampus, amygdala, entorhinal cortex, parahippocampal gyrus, and whole cerebral cortex calculated. From SPET scans, regional cerebral blood flow (rCBF) was assessed in anterior and posterior frontal, parietal, occipital, and mesial temporal cortex using a region of interest analysis with the cerebellum as a reference area. RESULTS: Using MRI, the areas that best separated groups were left hippocampal and left amygdala volume, resulting in correct classification (patient vs. control) in 79% of cases (sensitivity 77%, specificity 82%). Exactly the same proportion of subjects were correctly classified by SPET, with the most discriminating rCBF changes being left parietal and right posterior frontal. Combining information from both scans improved the proportion of correctly classified subjects in a discriminant function to 90% (sensitivity 93%, specificity 86%; only 2 AD and 3 controls misclassified). All AD subjects had abnormalities on MRI and/or SPET (sensitivity for combined examinations 100%), while abnormalities on both MRI and SPET had a positive predictive value of 100% for dementia (including the detection of one control subject who later had dementia). Significant correlations between MRI and SPET measures were seen in control subjects but not in patients. CONCLUSION: Both 0.3 T MRI and single rotating gamma camera SPET were equally useful in separating AD subjects from age-matched controls, although the combination of both significantly enhanced discrimination. In particular, all AD subjects had abnormalities on either MRI or SPET and both techniques may have an important role in assisting with clinical diagnosis, though replication in other centers and examination of differentiation of AD from other causes of dementia need to be examined.     

Regional quantification of white matter hyperintensity in normal aging, mild cognitive impairment, and Alzheimer's disease

BACKGROUND/AIMS: A quantitative method was applied to measure the volume of white matter hyperintensity (WMH) in different brain regions of subjects with Alzheimer's disease (AD), mild cognitive impairment (MCI) and normal healthy age-matched controls, and the relationship between regional WMH and age and cognitive function was investigated. METHODS: Fifty-six subjects were included in this study, 27 AD, 15 MCI and 14 normal age-matched controls. A user-friendly software was developed for WMH quantification in frontal, temporal, and parieto-occipital lobes. Mini-Mental State Examination and cognitive scores in performing naming, language fluency, and memory tasks were obtained for correlation analysis. RESULTS: AD patients had the greatest total WMH volume, followed by MCI, then controls. However, there was a large variation within each group, and the difference did not reach a significant level. There was a positive linear correlation between the total WMH (p = 0.031) and the frontal WMH (p = 0.006) vs. age. After age correction the Boston Naming Test scores were negatively correlated with the total WMH volume in the AD (p = 0.03) and the control (p = 0.03) groups, and with the frontal WMH in controls (p = 0.01). CONCLUSION: We demonstrated a quantitative analysis method to measure regional WMH. Although WMH was not strongly associated with disease severity or cognition, it may provide a characteristic neuroimaging parameter in the study of AD development.     

Topography of callosal atrophy reflects distribution of regional cerebral volume reduction in Alzheimer's disease.

It has been suggested that regional corpus callosum atrophy in Alzheimer's disease (AD) may serve as an in vivo index of neuronal loss in the neocortex. In this study total and regional size of the corpus callosum was evaluated with respect to the volumes of the frontal, temporal, and parietal lobes in 38 patients with AD (NINCDS-ADRDA criteria) using quantitative magnetic resonance imaging. Twenty healthy subjects matched for age and gender served as a control group. All quantitative measurements were performed by manual tracing using personal computer-based software. Both total size and the five measured regional subsections were significantly smaller in AD when compared to the control subjects. The severity of dementia was significantly correlated with the size of the middle sections of the corpus callosum (rostral body and midbody). Within the AD group, the rostral body of the corpus callosum was significantly correlated with the frontal lobe volumes, the midbody was correlated with the temporal lobe volumes, and size of the splenium was correlated with the parietal lobe volumes. We conclude that callosal atrophy in AD reflects the severity and pattern of cortical neuronal damage. Correlations between regional callosal atrophy and severity of dementia indicate that interhemispheric cortico-cortical disconnection may contribute to the dementia syndrome.     

Gyrification abnormalities in childhood- and adolescent-onset schizophrenia.

BACKGROUND: Gyrification is an important index of brain development. We used magnetic resonance scanning technology to compare brain surface morphology and measures of gyrification in children and adolescents with a schizophrenia spectrum disorder and in age-equivalent healthy controls. METHODS: Magnetic resonance scans were obtained from 42 patients and 24 healthy controls, mean age 17.7 years for both groups. We employed novel quantitative measures of brain morphology, including cortical thickness and a variety of indices of sulcal and gyral curvature. We examined these measures in the whole brain and in the frontal, temporal, parietal, and occipital lobes. RESULTS: There were significant decreases in cortical thickness in the patients. This was most pronounced in the cortical tissue that underlies the sulci. The patient group had significantly more flattened curvature in the sulci and more steeped or peaked curvature in the gyri. CONCLUSIONS: This study quantitatively examines cortical thickness and surface morphology in children and adolescents with schizophrenia. Patients with schizophrenia demonstrated patterns of brain morphology that were distinctly different from healthy controls. In light of current theories of the formation of gyri and sulci, these changes may reflect aberrations in cerebral and subcortical connectivity.