Structural Magnetic Resonance Imaging Studies Research Articles

Brain morphology in antipsychotic-naïve schizophrenia: a study of multiple brain structures.

Although brain volume changes are found in schizophrenia, only a limited number of structural magnetic resonance imaging studies have exclusively examined antipsychotic-naïve patients. To comprehensively investigate multiple brain structures in a single sample of patients who were antipsychotic-naïve. Twenty antipsychotic-naïve patients with first-episode schizophrenia and 20 healthy comparison subjects were included. Intracranial, total brain, frontal lobe, grey and white matter, cerebellar, hippocampal, parahippocampal, thalamic, caudate nucleus and lateral and third ventricular volumes were measured. Repeated-measures analyses of (co)variance were conducted with intracranial volume as covariate. Third ventricle volume enlargement was found in patients compared with the healthy subjects. No differences were found in other brain regions. These findings suggest that some brain abnormalities are present in the early stages of schizophrenia. Moreover, it suggests that brain abnormalities reported in patients with chronic schizophrenia develop in a later stage of the disease and/or are medication induced.

The neurobiological basis of autism from a developmental perspective.

Autism is a neurobiological disorder that is diagnosed through careful behavioral assessment in early childhood. In this paper, we review recent studies that have attempted to reveal the underlying causes of autism using a variety of techniques. Particular emphasis is placed on techniques that have been used by a number of different laboratories, including structural magnetic resonance imaging and postmortem studies of neuroanatomy. Neurobiological and neuropsychological data from individuals across a wide age range are examined from a neurodevelopmental perspective. We discuss how these recent advances have led us to develop a growth dysregulation hypothesis of autism. Finally, we discuss how this hypothesis may lead to new innovations in autism research.

Clinical use of structural magnetic resonance imaging in the diagnosis of dementia in adults with Down's syndrome

AbstractObjectives:Magnetic Resonance Imaging (MRI) has been used to assist the diagnosis of Alzheimer's Disease (AD) in adults with Down's syndrome (DS). However, the interpretation of the scans is difficult and clinical usefulness is uncertain. We aimed to summarise the current knowledge of MRI studies in adults with Down's syndrome with and without dementia and to discuss its implications for clinical practice.Method:We identified MRI studies in DS by a computerised literature search with Medline, Embase, and Psychlit from 1986 to 2001. We examined the references of identified articles and hand searched relevant journals. Structural MRI studies were selected as this type of imaging is most frequently used in clinical practice.Results:We included eight volumetric studies in adults with DS. Four of these included adults with DS and dementia. Overall, the size of brain structures such as cerebellum, hippocampus and cortex of adults with DS without dementia was significantly smaller than in normal controls. The basal ganglia were similar in size, and ventricles were enlarged. Furthermore, the size of brain structures in adults with DS and dementia was significantly different than in DS without dementia. In particular, ventricular and hippocampal volumes were affected.Conclusions:The change in brain structure associated with dementia can be detected on MRI of adults with DS. However, these may be difficult to interpret given the extent to which brain appearance in DS differs from that in the general population. Implications for clinical practice and future research directions are discussed.

Anatomical MRI findings in mood and anxiety disorders.

In vivo structural magnetic resonance imaging (MRI) studies have evaluated the brain anatomy of various psychiatric disorders, allowing the investigation of putative abnormal brain circuits possibly involved in the patophysiology of psychiatric disorders. Here we reviewed the structural MRI literature in mood and anxiety disorders. All anatomical MRI studies evaluating mood and anxiety disorder patients were identified through a comprehensive Medline search conducted for the period from 1966 to January 2002, and a manual search of bibliographic cross-referencing complemented the Medline search. Differential patterns of anatomical brain abnormalities appear to be involved in subtypes of mood disorders, with hippocampus and basal ganglia being abnormal in unipolar disorder, and amygdala and cerebellum in bipolar disorders, suggesting that these two mood disorders are biologically distinct. As for anxiety disorders, orbital frontal regions and basal ganglia have been reported to be anatomically abnormal in obsessive-compulsive disorder, temporal lobe was found to be abnormally reduced in panic disorder, and abnormal hippocampus shrinkage was shown in posttraumatic stress disorder. The structural MRI findings reviewed here suggest abnormalities in specific brain regions participating in proposed neuroanatomic models possibly involved in the pathophysiology of mood disorders and anxiety disorders. Nonetheless, available MRI studies have suffered from limitations related to relatively small patient samples and involvement of medicated patients, and were largely cross-sectional investigations. Therefore, longitudinal MRI studies involving more sizeable samples of drug-free patients, patients at first episode of illness or at high risk for mood or anxiety disorders, associated to genetic studies, are likely to be extremely valuable to separate state from trait brain abnormalities and to characterize further the pathophysiology of these disorders.

Supporting evidence for the model of cognitive dysmetria in schizophrenia — a structural magnetic resonance imaging study using deformation-based morphometry

The aim of the study was to investigate whether there is any structural evidence for the model of ‘cognitive dysmetria’ in schizophrenia if an automatic whole-brain analysis method is used. High-resolution magnetic resonance scans were obtained for 75 schizophrenic patients and 75 controls. These data were analysed using the recently developed deformation-based morphometry allowing the assessment of volumetric differences without a priori definition of regions of interest. When compared with controls, we found reduced volumes in patients with schizophrenia in the frontal lobe (gyrus frontalis superior, medius and medialis), the temporal lobe (gyrus temporalis superior and inferior), the thalamus, the left cerebellar hemisphere and the right cerebellar vermis. There was an increase in volume in the right putamen. To date, this is the first structural magnetic resonance imaging study to demonstrate that the three key-elements of the model of cognitive dysmetria — frontal lobe, thalamus, and cerebellum — are reduced in volume in schizophrenic patients. This highlights the importance of this concept for future investigations.

Insular cortex abnormalities in schizophrenia: a structural magnetic resonance imaging study of first-episode patients

The insular cortex is a limbic integration region that is engaged in emotional and cognitive functions. To investigate possible insular cortex abnormalities in schizophrenia, we measured insular gray matter volume and cortical surface size in drug-naive first-episode patients. Magnetic resonance images were used to explore the morphology of the insular cortex of 25 healthy male volunteers, and 25 male schizophrenic patients. Groups were matched for age, sex, height, and parental socio-economic status. Clinical dimension scores were correlated with insular gray matter volume and cortical surface area. Patients had a significant reduction in cortical surface area [patients=2020 (206); controls=2142 (204); F=5.83, df=1,47; P=0.01] and gray matter volume [patients=8.12 (0.77); controls=8.57 (0.94); F=3.93, df=1,47; P=0.05] in the left insular cortex. Insular gray matter volume and cortical surface size correlated negatively and significantly with the psychotic symptom dimension. Schizophrenic patients show morphological abnormalities in the insular cortex at early stages of the illness. These abnormalities are related to the severity of psychotic symptoms. Further investigations are needed to evaluate the role of the insula in the pathophysiology of schizophrenia.

Features of structural brain abnormality detected in first-episode psychosis.

Structural magnetic resonance imaging (MRI) studies that focus on first-episode psychosis avoid some common confounds, such as chronicity of illness, treatment effects, and long-term substance abuse. However, such studies may select subjects with poor short-term treatment response or outcome. In this study, the authors focus on structural brain abnormalities in never or minimally treated patients who underwent MRI scanning early in their first episode of psychosis. The authors examined 37 patients (13 medication naive, 24 previously treated) who were experiencing their first episode of psychosis; the mean duration of symptoms was short (31 weeks). These patients were comparable in age, gender, handedness, ethnicity, and parental socioeconomic status to a group of 25 healthy comparison subjects. A three-dimensional, inversion recovery prepared, fast spoiled gradient/recall in the steady state scan of the whole brain that used 1.5-mm contiguous sections was performed to acquire a T(1)-weighted data set. Human ratings of volumetric measurement of brain structures were performed with stereological techniques on three-dimensional reconstructed MRIs. The patient group had significant deficits in cortical gray matter, temporal lobe gray matter, and whole brain volume as well as significant enlargement of the lateral and third ventricles. Structural deviations were found in both treatment-naive and minimally treated subjects. No relationships were found between any brain matter volumes and positive or negative symptoms. Structural brain abnormalities were distributed throughout the cortex with particular decrement evident in gray matter. This feature is consistent with altered cell structure and disturbed neuronal connectivity, which accounts for the functional abnormality of psychosis.

A structural magnetic resonance imaging (MRI) study of adults with Asperger's syndrome

A structural magnetic resonance imaging (MRI) study of adults with Asperger's syndrome

Apolipoprotein E epsilon4 allele, temporal lobe atrophy, and white matter lesions in late-life dementias.

To examine the relationship between the apolipoprotein E (APOE) epsilon4 genotype, medial temporal lobe atrophy, and white matter hyperintensities on magnetic resonance imaging in late-life dementias. Structural magnetic resonance imaging study using T2-weighted and proton density-weighted axial scans and T1-weighted coronal scans. Community-dwelling population of elderly patients prospectively chosen from a clinical case register of consecutive referrals to old age psychiatry services. Twenty-five subjects with Alzheimer disease (by criteria of the National Institute of Neurological and Communication Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association; mean age, 77.8 years), 22 subjects with dementia with Lewy bodies (consensus criteria; mean age, 77.2 years), and 24 subjects with vascular dementia (by criteria of the National Institute of Neurological Disorders and Stroke and the Association International pour la Recherche et l'Enseignement en Neurosciences; mean age, 76.9 years) were selected. Subjects were well matched for age, sex, duration of illness, and cognitive function. The APOE genotype was determined using the polymerase chain reaction method, and medial temporal lobe atrophy and white matter hyperintensities (periventricular and deep white matter) were visually rated using standardized scales. In all subjects with dementia, no significant associations were noted between APOE epsilon4 status and medial temporal lobe atrophy (mean score: 0 epsilon4 = 4.5, 1 epsilon4 = 4.5, and 2 epsilon4 = 4.3; P = .90), periventricular hyperintensities (0 epsilon4 = 3.3, 1 epsilon4 = 3.1, and 2 epsilon4 = 2.9; P = .83), and white matter hyperintensities (0 epsilon4 = 5.3, 1 epsilon4 = 4.9, and 2 epsilon4 = 4.9; P = .79). The APOE epsilon4 allele does not determine medial temporal lobe atrophy or white matter lesions, as measured by magnetic resonance imaging in patients with Alzheimer disease, vascular dementia, or dementia with Lewy bodies. Although APOE epsilon4 may modify the risk for acquiring dementia, this finding provides further evidence that APOE epsilon4 does not influence pathological processes thereafter.

Volumetric Evaluation of the Thalamus in Schizophrenic Male Patients Using Magnetic Resonance Imaging

Background: The thalamus, an important subcortical brain region connecting limbic and prefrontal cortices, has a significant role in sensory and cortical processing. Although inconsistently, previous studies have demonstrated neuroanatomical abnormalities in the thalamus of schizophrenic patients. Methods: This structural magnetic resonance imaging study, based on segmentation of contiguous coronal 1.5-mm images, compared thalamic brain volumes of 15 chronic, male schizophrenic patients with 15 normal controls matched on age, sex, handedness, and parental socioeconomic status. Results: There were no significant differences between patients and controls in thalamic volumes, right or left, adjusted for total brain volume; however, there were significantly different correlations of thalamic volumes with prefrontal white matter and lateral ventricles among patients, but not among controls. Thalamic volumes among patients were also significantly correlated with bizarre behavior, hallucinations, and thought disorder. Conclusions: Findings suggest that connectivity between thalamic nuclei and prefrontal cortical areas are abnormal in chronic male schizophrenic patients. In addition, ventricular enlargement may be, in part, due to subtle reduction in thalamic volume and/or in volume of thalamocortical and corticothalamic fibers secondary to thalamic abnormalities. Finally, correlations with positive symptomatology underscore the role of the thalamus in gating or filtering of sensory information and coordination of cortical processing.

Reliability and validity of MRI measurement of the amygdala and hippocampus in children with fragile X syndrome

Evidence from numerous structural magnetic resonance imaging (MRI) studies has converged to implicate mesial temporal lobe structures in the pathophysiology of several developmental and psychiatric disorders. Efforts to integrate the results of these studies are challenged, however, by the lack of consistency, detail and precision in published protocols for the manual measurement of the amygdala and hippocampus. In this study, we describe a highly detailed, standardized protocol for measuring the amygdala and the hippocampus. Within the context of this protocol, we tested the inter- and intra-rater reliability of two frequently cited methods for normalizing the anatomical position of the amygdala and hippocampus prior to measurement. One method consisted of creating a coronal data set in which images are rotated in a plane perpendicular to the long axis of the hippocampus. The second method consisted of creating a coronal data set in which images are rotated in a plane perpendicular to the axis connecting the anterior and posterior commissures. Inter- and intra-rater reliability coefficients (using the intraclass correlation) ranged from 0.80 to 0.98, indicating that both methods for positional normalization are highly reliable. In addition, we tested the validity of each method by comparing the temporal lobe anatomy of children with fragile X syndrome to a group of unaffected children matched by age and gender. We found that hippocampal volumes in children with fragile X were significantly increased when either rotational method was used. These results replicated previous findings, suggesting that either method can be validly applied to neuroanatomic studies of pediatric populations.

On- and offline Talairach registration for structural and functional MRI studies

We present a method for registering a brain in the Talairach coordinate system that can be performed either "online," i.e., in real time while a subject is in a magnetic resonance scanner, or "offline" on a previously acquired three-dimensional (3D) data set. The method is applicable to functional magnetic resonance imaging (MRI) studies because slices can be specified in Talairach coordinates and acquired in Talairach planes. Once functional data are obtained, pixels in a functional map can then be converted into Talairach coordinates, thereby facilitating brain averaging and communication of results. The method can also be used to align 3D data sets and perform volumetric analyses of regions of interest after correcting for head tilt, or to compute averaged structural brain images. Online and offline registration can be combined such that a series of sections can be interactively selected and visualized ahead of time using offline analyses and then replicated online at a later time. Hum. Brain Mapping 5:58-73, 1997. (c) 1997 Wiley-Liss, Inc.

Sex and brain abnormalities in schizophrenia: fact or fiction?

Evidence is growing from studies in our laboratory and others'-' that there are significant differences between males and females in cognition, brain structure, and neural function in schizophrenia. However, an understanding of the sexual dimorphism of the human brain is still in its infancy. Evidence for these differences has previously been derived from animal studies,B'g postmortem pathology,'0* and cognitive studies of brain function. Recently, researcher~'~'' have become interested in identifying sex differences in the normal brain using in vivo structural and functional imaging techniques. They have demonstrated sex differences in the volume of specific brain regions, in brain blood flow and glucose metabolism in the resting state and during cognitive challenge, and in lateralization of specific verbal functions. Further, some evidence suggests that sex differences in cognition in normals vary according to the sensory modality of the cognitive stimuli (e.g., visual versus auditory).''* Thus, identifying normal sex differences in brain function and structure is critical in understanding how these interact with the pathological processes involved in schizophrenia to produce sex differences in the expression of the disorder. SEX AND THE NORMAL BRAIN Several animal studies have shown that estrogens and androgens have specific effects on fetal brain development. Sexually dimorphic areas of the brain include the preoptic area of the hypothalamus,'8 the massa intermedia, the anterior commissure, the stria terminalis,l' the corpus callosum,20 and the hippocampus.' lho recent structural magnetic resonance imaging (MRI) studies in normal humans have found that compared to men, women have a greater ratio of gray matter volume to total volume in the

Imaging studies and APOE genotype in persons at risk for Alzheimer’s disease

Many studies have investigated APOE-related differences in cerebral structure, blood flow, metabolism, and activation in an attempt to detect early brain changes in subjects at risk for Alzheimer’s disease (AD). Structural magnetic resonance imaging studies have produced conflicting results, with some failing to detect APOE-related differences and others suggesting that ε4 carriers have more pronounced atrophy, particularly at medial temporal structures. All functional imaging studies done during rest in middle-aged and elderly subjects have found decreased cerebral metabolism for ε4 carriers (mostly in areas that usually are affected by AD), and some have reported faster cerebral metabolic reductions over time. Areas with decreased resting cerebral perfusion and metabolism, in addition to other areas with increased perfusion, have been reported in young ε4 carriers. Imaging studies done during the performance of various cognitive tasks in middle-aged and elderly subjects, and a single study in young subjects, have produced mixed results with regionally nonspecific increased, decreased, or nondifferential APOE-related activations depending on the cognitive task used. APOE-related findings in imaging studies of nondemented subjects may be the result of incipient AD pathologic changes or of genetic heterogeneity in brain structure and function.

Frontal-subcortical circuits and neuropsychiatric disorders.

Five parallel anatomic circuits link regions of the frontal cortex to the striatum, globus pallidus/substantia nigra, and thalamus. The circuits originate in the supplementary motor area, frontal eye fields, dorsolateral prefrontal region, lateral orbito-frontal area, and anterior cingulate cortex. Open loop structures that provide input to or receive output from specific circuits share functions, cytoarchitectural features, and phylogenetic histories with the relevant circuits. The circuits mediate motor and oculomotor function as well as executive functions, socially responsive behavior, and motivation. Neuropsychiatric disorders of frontal-subcortical circuits include impaired executive function, disinhibition, and apathy; indicative mood disorders include depression, mania, and lability. Transmitters, modulators, receptor subtypes, and second messengers within the circuits provide a chemoarchitecture that can inform pharmacotherapy.