Ziskind-Somerfeld Research Award 1996. Medial and superior temporal gyral volumes and cerebral asymmetry in schizophrenia versus bipolar disorder

Similar effect of family history of psychosis on Sylvian fissure size and auditory P200 amplitude in schizophrenic and bipolar subjects

Several cerebral studies point to the non-specificity of structural and functional changes described in schizophrenia and bipolar disorders. Furthermore, the origin of these changes is still unclear. The present study investigated the effect of a family history (FH) of psychotic disorders in first-degree relatives on computed tomographic (CT) measures (ventricular, cerebral and Sylvian fissure size) and auditory event-related potentials (amplitudes and latencies of peak components in oddball paradigms) in 30 schizophrenic patients and 24 bipolar type I patients. We found a significant correlation between FH and the size of the right Sylvian fissure, and between FH and auditory P200 amplitude. More specifically, the schizophrenic and bipolar patients with negative FH (n=36) had larger right Sylvian fissures and smaller P200 amplitude than patients with positive FH (n=18). These findings were independent of the specific diagnosis, gender, and age of subjects. Our results suggest some underlying process common to schizophrenia and bipolar I disorder, and they provide support for the continuum view of the nosologic structure of psychotic illness.

Abnormal neurochemical asymmetry in the temporal lobe of schizophrenia

Neuroanatomical asymmetries are known to be present in the human brain, and loss of reversal of these asymmetries, particularly through changes in the left temporal lobe, have been found in the brains of patients with schizophrenia. In addition to disturbed neuroanatomical asymmetries, disturbed neurochemical asymmetries have also been reported in the brains of patients with schizophrenia. However, in the temporal lobe, the laterality of most of these neurochemical changes has not been specifically evaluated. Few neurochemical studies have addressed left-right differences in the superior temporal gyrus (STG). A deteriorated serotonin2A receptor-G protein qalpha (Gqalpha)-phosphoinositide-specific phospholipase C beta1(PLC beta1) cascade has been found in the left, but not right, STG of patients with schizophrenia. Not only neuroanatomical but also neurochemical evidence supports the loss or reversal of normal asymmetry of the temporal lobe in schizophrenia, which might be due to a disruption of the neurodevelopmental processes involved in hemispheric lateralization.

A review of MRI findings in schizophrenia

After more than 100 years of research, the neuropathology of schizophrenia remains unknown and this is despite the fact that both Kraepelin (1919/1971: Kraepelin, E., 1919/1971. Dementia praecox. Churchill Livingston Inc., New York) and Bleuler (1911/1950: Bleuler, E., 1911/1950. Dementia praecox or the group of schizophrenias. International Universities Press, New York), who first described 'dementia praecox' and the 'schizophrenias', were convinced that schizophrenia would ultimately be linked to an organic brain disorder. Alzheimer (1897: Alzheimer, A., 1897. Beitrage zur pathologischen anatomie der hirnrinde und zur anatomischen grundlage einiger psychosen. Monatsschrift fur Psychiarie und Neurologie. 2, 82-120) was the first to investigate the neuropathology of schizophrenia, though he went on to study more tractable brain diseases. The results of subsequent neuropathological studies were disappointing because of conflicting findings. Research interest thus waned and did not flourish again until 1976, following the pivotal computer assisted tomography (CT) finding of lateral ventricular enlargement in schizophrenia by Johnstone and colleagues. Since that time significant progress has been made in brain imaging, particularly with the advent of magnetic resonance imaging (MRI), beginning with the first MRI study of schizophrenia by Smith and coworkers in 1984 (Smith, R.C., Calderon, M., Ravichandran, G.K., et al. (1984). Nuclear magnetic resonance in schizophrenia: A preliminary study. Psychiatry Res. 12, 137-147). MR in vivo imaging of the brain now confirms brain abnormalities in schizophrenia. The 193 peer reviewed MRI studies reported in the current review span the period from 1988 to August, 2000. This 12 year period has witnessed a burgeoning of MRI studies and has led to more definitive findings of brain abnormalities in schizophrenia than any other time period in the history of schizophrenia research. Such progress in defining the neuropathology of schizophrenia is largely due to advances in in vivo MRI techniques. These advances have now led to the identification of a number of brain abnormalities in schizophrenia. Some of these abnormalities confirm earlier post-mortem findings, and most are small and subtle, rather than large, thus necessitating more advanced and accurate measurement tools. These findings include ventricular enlargement (80% of studies reviewed) and third ventricle enlargement (73% of studies reviewed). There is also preferential involvement of medial temporal lobe structures (74% of studies reviewed), which include the amygdala, hippocampus, and parahippocampal gyrus, and neocortical temporal lobe regions (superior temporal gyrus) (100% of studies reviewed). When gray and white matter of superior temporal gyrus was combined, 67% of studies reported abnormalities. There was also moderate evidence for frontal lobe abnormalities (59% of studies reviewed), particularly prefrontal gray matter and orbitofrontal regions. Similarly, there was moderate evidence for parietal lobe abnormalities (60% of studies reviewed), particularly of the inferior parietal lobule which includes both supramarginal and angular gyri. Additionally, there was strong to moderate evidence for subcortical abnormalities (i.e. cavum septi pellucidi-92% of studies reviewed, basal ganglia-68% of studies reviewed, corpus callosum-63% of studies reviewed, and thalamus-42% of studies reviewed), but more equivocal evidence for cerebellar abnormalities (31% of studies reviewed). The timing of such abnormalities has not yet been determined, although many are evident when a patient first becomes symptomatic. There is, however, also evidence that a subset of brain abnormalities may change over the course of the illness. The most parsimonious explanation is that some brain abnormalities are neurodevelopmental in origin but unfold later in development, thus setting the stage for the development of the symptoms of schizophrenia. Or there may be additional factors, such as stress or neurotoxicity, that occur during adolescence or early adulthood and are necessary for the development of schizophrenia, and may be associated with neurodegenerative changes. Importantly, as several different brain regions are involved in the neuropathology of schizophrenia, new models need to be developed and tested that explain neural circuitry abnormalities effecting brain regions not necessarily structurally proximal to each other but nonetheless functionally interrelated. (ABSTRACT TRUNCATED)

Handedness, language lateralisation and anatomical asymmetry in schizophrenia: meta-analysis

BACKGROUND

Cerebral lateralisation appears to be decreased in schizophrenia. Results of studies investigating this, however, are equivocal.

AIMS

To review quantitatively the literature on decreased lateralisation in schizophrenia.

METHOD

Meta-analyses were conducted on 19 studies on handedness, 10 dichotic listening studies and 39 studies investigating anatomical asymmetry in schizophrenia.

RESULTS

The prevalence of mixed- and left-handedness ('non-right-handedness') was significantly higher in patients with schizophrenia as compared to healthy controls, and also as compared to psychiatric controls. The analysis of dichotic listening studies revealed no significant difference in lateralisation in schizophrenia. However, when analysis was restricted to studies using consonant-vowel or fused word tasks, significantly decreased lateralisation in schizophrenia emerged. Asymmetry of the planum temporale and the Sylvian fissure was significantly decreased in schizophrenia, while asymmetry of the temporal horn of the lateral ventricle was not.

CONCLUSION

Strong evidence is provided for decreased cerebral lateralisation in schizophrenia.

A volumetric magnetic resonance imaging study of monozygotic twins discordant for bipolar disorder

Six monozygotic (MZ) twin pairs discordant for bipolar disorder were compared with normal MZ twins with magnetic resonance imaging (MRI) on volumes of basal ganglia (BG), amygdala-hippocampus (AH), and cerebral hemisphere. Caudate nuclei were larger in both affected and unaffected bipolar twins than in normal MZ twins. The right hippocampus was smaller in the sick vs. well bipolar twins. The hippocampus was also less asymmetric in the affected bipolar twins than in the well cotwins and the normal MZ twins. These anatomical structures continue to be of interest in bipolar disorder research.

Sylvian fissure and medial temporal lobe structures in patients with schizophrenia: a magnetic resonance imaging study

Volumes of the medial temporal lobe structures (i.e. the amygdala, hippocampus, and parahippocampal gyrus), Sylvian fissure, and inferior horn of the lateral ventricle relative to the cerebral hemisphere were measured in 24 patients with schizophrenia and 23 normal controls using magnetic resonance imaging. The patients had significantly larger Sylvian fissures and inferior horns bilaterally than the controls. In the patients the right Sylvian fissure size showed a significant positive correlation with the duration of illness. Moreover, earlier onset of illness was significantly correlated with decreased volume of the left medial temporal lobe structures. These results replicate previous finding of inferior horn enlargement and suggest the significance of the Sylvian fissure and the medial temporal lobe structures in pathophysiology of schizophrenia.

Neuroimaging studies of mood disorders

Neuroimaging studies of major depression have identified neurophysiologic abnormalities in multiple areas of the orbital and medial prefrontal cortex, the amygdala, and related parts of the striatum and thalamus. Some of these abnormalities appear mood state-dependent and are located in regions where cerebral blood flow increases during normal and other pathologic emotional states. These neurophysiologic differences between depressives and control subjects may thus implicate areas where physiologic activity changes to mediate or respond to the emotional, behavioral, and cognitive manifestations of major depressive episodes. Other abnormalities persist following symptom remission, and are found in orbital and medial prefrontal cortex areas where postmortem studies demonstrate reductions in cortex volume and histopathologic changes in primary mood disorders. These areas appear to modulate emotional behavior and stress responses, based upon evidence from brain mapping, lesion analysis, and electrophysiologic studies of humans and/or experimental animals. Dysfunction involving these regions is thus hypothesized to play a role in the pathogenesis of depressive symptoms. Taken together, these findings implicate interconnected neural circuits in which pathologic patterns of neurotransmission may result in the emotional, motivational, cognitive, and behavioral manifestations of primary and secondary affective disorders.

fMRI during affect discrimination in bipolar affective disorder

OBJECTIVE

It has been hypothesized that disturbances in affect may represent distinct etiologic factors for bipolar affective disorder. The neural mechanisms mediating affective processes and their relationship to brain development and the pathophysiology of bipolar affective disorder remain to be clarified. Recent advances in neuroimaging techniques have made possible the non-invasive examination of specific brain regions during cortical challenge paradigms. This study reports findings based on fMRI data acquired during fearful and happy affect recognition paradigms in patients with bipolar affective disorder and in healthy adult subjects.

METHODS

Prior to the scan, subjects were instructed to view the stimuli and to identify the type of facial expression presented. Echo planar scanning was performed on a 1.5 Tesla scanner which had been retrofitted with a whole body echo planar coil, using a head coil.

RESULTS

The data indicate that in adult subjects with bipolar affective disorder, there is a reduction in dorsolateral prefrontal cortex activation and an increase in amygdalar activation in response to fearful facial affect. In a healthy comparison group, signal intensity changes were not found in these regions. In addition, although the patients with bipolar affective disorder completed the task demands, they demonstrated an impaired ability to correctly identify fearful facial affect but not the happy facial affect displayed.

CONCLUSION

These findings are consistent with the hypothesis that in some patients with bipolar affective disorder, there may be a reduction of frontal cortical function which may be associated with affective as well as attentional processing deficits.

Neuroimaging in bipolar disorder

OBJECTIVE

The authors reviewed neuroimaging studies of bipolar disorder in order to evaluate how this literature contributes to the current understanding of the neurophysiology of the illness.

METHOD

Papers were reviewed as identified, using the NIMH PubMed literature search systems that reported results of neuroimaging studies involving a minimum of five bipolar disorder patients compared with healthy comparison subjects.

RESULTS

Structural neuroimaging studies report mixed results for lateral and third ventriculomegaly. Recent studies suggest subcortical structural abnormalities in the striatum and amygdala, as well as the prefrontal cortex. Proton spectroscopic studies suggest that abnormalities in choline metabolism exist in bipolar disorder, particularly in the basal ganglia. Additionally, phosphorous MRS suggests that there may be abnormalities in frontal phospholipid metabolism in bipolar disorder. Functional studies have identified affective state-related changes in cerebral glucose metabolism and blood flow, particularly in the prefrontal cortex during depression, but no clear abnormalities specific to bipolar disorder have been consistently observed.

CONCLUSIONS

The current literature examining the neurophysiology of bipolar disorder using neuroimaging is limited. Nonetheless, abnormalities in specific frontal-subcortical brain circuits seem likely. Additional targeted studies are needed to capitalize on this burgeoning technology to advance our understanding of the neurophysiology of bipolar disorder.

Evidence of a smaller left hippocampus and left temporal horn in both patients with first episode schizophrenia and normal control subjects

Findings from cerebral magnetic resonance imaging (MRI) studies in schizophrenia indicating temporal lobe involvement have been inconsistent and controversial. In a prospective study, we quantified the volumes of temporal lobe structures in 20 male patients with first episode schizophrenia (FES; mean+/-S.D.=27.4+/-4. 8 years) and 20 healthy age-matched male control subjects (27.7+/-3. 1 years). Measurements were performed on contiguous 2.2-mm coronal MRI slices, which included, as well as the temporal lobe, the amygdala, the hippocampal formation, and the temporal horn of the lateral ventricle. The definition of the borders of the structures relied on measurement guidelines derived from mutual comparisons of MRI and histological data. The definition of the hippocampus-amygdala interface was also validated in a correlated triplanar display. We did not detect any significant volume reductions of the measured structures in the FES group, as compared with healthy control subjects, on either side. Comparisons within groups, however, revealed that in both the patients and the healthy volunteers the hippocampal formations showed a significant right-sided bias (+9%, P=0.004, in the FES group; +12%, P=0.0003 in the control subjects). A significant volume difference in favor of the right hemisphere was also observed in the temporal horns of the lateral ventricles (+17%, P=0.02 in the patients with FES; +34%, P=0. 003, in the control group). There was only a nonsignificant trend for a larger temporal horn on the left side in patients with schizophrenia as compared with the control subjects. Our findings do not indicate a loss or reversal of the normal volume asymmetry pattern in the FES group.

An MRI study of temporal lobe structures in men with bipolar disorder or schizophrenia

BACKGROUND

Hippocampal atrophy has been described in postmortem and magnetic resonance imaging studies of schizophrenia. The specificity of this finding to schizophrenia remains to be determined. The neuropathology of bipolar disorder is understudied, and temporal lobe structures have only recently been evaluated.

METHODS

Twenty-four bipolar, 20 schizophrenic, and 18 normal comparison subjects were evaluated using magnetic resonance brain imaging. Image data were acquired using a three-dimensional spoiled GRASS sequence, and brain images were reformatted in three planes. Temporal lobe structures including the amygdala, hippocampus, parahippocampus, and total temporal lobe were measured to obtain volumes for each structure in the three subject groups. Severity of symptoms in both patient groups was assessed at the time the magnetic resonance images were obtained.

RESULTS

Hippocampal volumes were significantly smaller in the schizophrenic group than in both bipolar and normal comparison subjects. Further, amygdala volumes were significantly larger in the bipolar group than in both schizophrenic and normal comparison subjects.

CONCLUSIONS

The results suggest differences in affected limbic structures in patients with schizophrenia and bipolar disorder. These specific neuroanatomic abnormalities may shed light on the underlying pathophysiology and presentation of the two disorders.

Planum temporale and Heschl gyrus volume reduction in schizophrenia: a magnetic resonance imaging study of first-episode patients

BACKGROUND

Magnetic resonance imaging studies in schizophrenia have revealed abnormalities in temporal lobe structures, including the superior temporal gyrus. More specifically, abnormalities have been reported in the posterior superior temporal gyrus, which includes the Heschl gyrus and planum temporale, the latter being an important substrate for language. However, the specificity of the Heschl gyrus and planum temporale structural abnormalities to schizophrenia vs affective psychosis, and the possible confounding roles of chronic morbidity and neuroleptic treatment, remain unclear.

METHODS

Magnetic resonance images were acquired using a 1.5-T magnet from 20 first-episode (at first hospitalization) patients with schizophrenia (mean age, 27.3 years), 24 first-episode patients with manic psychosis (mean age, 23.6 years), and 22 controls (mean age, 24.5 years). There was no significant difference in age for the 3 groups. All brain images were uniformly aligned and then reformatted and resampled to yield isotropic voxels.

RESULTS

Gray matter volume of the left planum temporale differed among the 3 groups. The patients with schizophrenia had significantly smaller left planum temporale volume than controls (20.0%) and patients with mania (20.0%). Heschl gyrus gray matter volume (left and right) was also reduced in patients with schizophrenia compared with controls (13.1%) and patients with bipolar mania (16.8%).

CONCLUSIONS

Compared with controls and patients with bipolar manic psychosis, patients with first-episode schizophrenia showed left planum temporale gray matter volume reduction and bilateral Heschl gyrus gray matter volume reduction. These findings are similar to those reported in patients with chronic schizophrenia and suggest that such abnormalities are present at first episode and are specific to schizophrenia.

Hippocampal pathology in schizophrenia: magnetic resonance imaging and spectroscopy studies

The hippocampus is a site of previously reported structural and functional abnormalities in schizophrenia. We used magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) to measure gray matter volumes, the neuronal marker N-acetylaspartate (NAA), and the combination of glutamate (Glu), glutamine (Gln), and gamma-aminobutyric acid (GABA), designated Glx. Measurements were obtained of the medial temporal lobe, centered on the hippocampus, in 10 male patients with schizophrenia (3 neuroleptic-medicated and 7 medication-free), and 10 matched normal volunteers. MRI volumetric measurements and MRS data obtained with short echo time (TE=20 ms) one-dimensional STEAM chemical shift imaging (CSI) on a GE 1.5 Tesla Signa system were analyzed. A laterality index ¿(L-R)/(L+R) was generated from the ratio of Glx to choline-containing compounds (Cho) to test asymmetry changes. Reliability of the MRS measures was assessed with five test-retest studies of healthy volunteers and showed coefficients of variation (CV) in the range of 36-44% for the MRS ratios and standard deviations (S.D.) of 0.15-0.17 for the laterality indices. The Glx/Cho laterality index showed a relative right-sided excess in this region in the patients (-0.23+/-0.20) compared to the controls (+0.06+/-0.20), which was not confounded by tissue composition or placement variability of the MRS voxels. Hippocampal volume deficit and asymmetry were not significant, and other MRS measures showed no differences between patients and controls. The preliminary finding of a lateralized abnormality in Glx is consistent with postmortem findings of asymmetric neurochemical temporal lobe abnormalities in schizophrenia.

Superior temporal gyrus in schizophrenia: a volumetric magnetic resonance imaging study

The left superior temporal gyrus (STG) has been reported to be smaller in patients with schizophrenia. The volume of the STG has been found to correlate negatively with severity of hallucinations and thought disorder. In this study, we measured the STG volume of 20 normal controls and 20 patients with schizophrenia using 3 mm contiguous coronal T1 magnetic resonance images. We found that patients had a significantly smaller left anterior STG, and that the volume of this region negatively correlated with the severity of hallucinations. The left posterior STG was not significantly smaller in patients than in controls, but its volume negatively correlated with severity of thought disorder. We also found that the left anterior STG was smaller than the right STG in patients but not in controls. The STG has at least three histologically distinct areas, each with different connections to the rest of the brain. These data are consistent with the proposition that dysfunction of the primary auditory cortex in the anterior and middle STG and auditory association cortex in the posterior STG may play a role in the production of auditory perceptual abnormalities and poor organization of thought respectively.

Cortical gray matter deficit in patients with bipolar disorder

BACKGROUND

cortical gray matter volume deficit and ventricular enlargement are well documented in schizophrenia, but their presence in bipolar disorder is less well established.

METHODS

global cortical gray matter, white matter and sulcal CSF, as well as lateral and third ventricular volume measures, were derived from axial MRI brain images obtained on age-matched bipolar (n=9), schizophrenic (n=9), and control (n=16) subjects. All subjects were free of history of alcohol or other substance dependence.

RESULTS

relative to controls, bipolar patients had widespread volume deficits of cortical gray matter but not of cortical white matter. Schizophrenic patients had an even more severe cortical gray matter deficit and greater sulcal and lateral ventricular enlargement than the bipolar patients.

CONCLUSIONS

this group of patients with bipolar disorder had a widespread deficit of cortical gray matter similar to, but less pronounced than, that observed in patients with schizophrenia.

Brain event-related potentials (ERPs) in schizophrenia during a word recognition memory task

Impairments of recognition memory for words and attenuation of the ERP 'old-new' effect have been found in patients with left medial temporal lobe damage. If left temporal lobe dysfunction in schizophrenia involves medial structures (e.g. hippocampus), then schizophrenic patients might show similar abnormalities of verbal recognition memory. This study recorded ERPs from 30 electrode sites while subjects were engaged in a continuous word recognition memory task. Results are reported for 24 patients having a diagnosis of schizophrenia (n = 16) or schizoaffective disorder (n = 8) and 19 age-matched healthy controls. Both patients and controls showed the expected 'old-new' effect, with greater late positivity to correctly recognized old words at posterior sites, and there was also no significant difference between groups in P3 amplitude. However, accuracy of word recognition memory was poorer in patients than controls, and patients showed markedly smaller N2 amplitude. Reduced amplitudes of N2 and N2-P3 were associated with poorer performance, with highest correlations over the left inferior parietal (N2) and left medial parietal (N2-P3) region. Moreover, patients failed to show significantly greater left than right hemisphere amplitude of N2-P3 at posterior sites, which was seen for healthy controls. These findings suggest that impaired word recognition in schizophrenia may arise from a left lateralized deficit at an early stage of processing, beginning at 200-300 ms after word onset.

Lack of normal pattern of cerebral asymmetry in familial schizophrenic patients and their relatives--The Maudsley Family Study

Lack of the normal cerebral asymmetry has been reported in schizophrenia. We wished to test the hypothesis that this lack of the normal pattern of asymmetry is familial and that it can be found in both schizophrenic and non-schizophrenic family members. In particular, we wanted to know whether those relatives who appear to be transmitting liability to the illness also demonstrate the loss of normal asymmetry. We studied families with several members affected with schizophrenia. We carried out volumetric measurements of prefrontal, premotor, sensorimotor and occipitoparietal regions in each hemisphere using 3D reconstructed MRI images in 29 schizophrenic patients, 55 of their first degree relatives, and 39 unrelated control subjects on contiguous thin slices of the brain. Nine of the unaffected relatives appeared to be transmitting the liability for schizophrenia (e.g. the mother of a schizophrenic patient who, although not psychotic herself, had a schizophrenic parent or sibling). We termed them presumed obligate carriers and the remaining 46 relatives presumed non-obligate carriers. The healthy control subjects showed larger right than left prefrontal regions and larger left than right sensorimotor and occipitoparietal regions. The schizophrenic patients showed lack of this normal brain asymmetry in the prefrontal, sensorimotor and occipitoparietal cortical regions. The presumed obligate carriers were similar to the schizophrenic patients in exhibiting lack of asymmetries in these cortical regions, while the presumed non-obligate relatives showed lack of asymmetry only in the occipitoparietal region. There was no overall reduction in total or regional brain volumes among the groups. Our findings indicate that lack of the normal pattern of frontal and occipital asymmetry is a marker for genetic liability to schizophrenia in families multiply affected with schizophrenia.

PET imaging of serotonin 1A receptor binding in depression

BACKGROUND

The serotonin-1A (5HT1A) receptor system has been implicated in the pathophysiology of major depression by postmortem studies of suicide victims and depressed subjects dying of natural causes. This literature is in disagreement, however, regarding the brain regions where 5HT1A receptor binding differs between depressives and controls and the direction of such differences relative to the normal baseline, possibly reflecting the diagnostic heterogeneity inherent within suicide samples. PET imaging using the 5HT1A receptor radioligand, [11C]WAY-100635, may clarify the clinical conditions under which 5HT1A receptor binding potential (BP) is abnormal in depression.

METHODS

Regional 5HT1A receptor BP values were compared between 12 unmedicated depressives with primary, recurrent, familial mood disorders and 8 healthy controls using PET and [carbonyl-11C]WAY-100635. Regions-of-interest (ROI) assessed were the mesiotemporal cortex (hippocampus-amygdala) and midbrain raphe, where previous postmortem studies suggested 5HT1A receptor binding is abnormal in depression.

RESULTS

The mean 5HT1A receptor BP was reduced 41.5% in the raphe (p < .02) and 26.8% in the mesiotemporal cortex (p < .025) in the depressives relative to the controls. Post hoc comparisons showed the abnormal reduction in 5HT1A receptor BP was not limited to these regions, but extended to control ROI in the occipital cortex and postcentral gyrus as well. The magnitude of these abnormalities was most prominent in bipolar depressives (n = 4) and unipolar depressives with bipolar relatives (n = 4).

CONCLUSIONS

Serotonin-1A receptor BP is abnormally decreased in the depressed phase of familial mood disorders in multiple brain regions. Of the regions tested, the magnitude of this reduction was most prominent in the midbrain raphe. Converging evidence from postmortem studies of mood disorders suggests these reductions of 5HT1A receptor BP may be associated with histopathological changes involving the raphe.

Altered cerebral perfusion measured by SPECT in relatives of patients with schizophrenia. Correlations with memory and P300

BACKGROUND

Genetic studies in schizophrenia are hampered by the complex heterogeneous clinical phenotype. Biological variables identified as trait markers of risk could clarify the mode of inheritance, define clinical subgroups and provide clues about aetiology.

AIMS

To use single photon emission computed tomography (SPECT) to compare brain perfusion maps in patients with schizophrenia (n = 19), their asymptomatic 'high-risk' relatives (n = 36) and control subjects (n = 34) and to examine the relationships between imaging, memory and P300 event-related potential.

METHOD

SPECT, memory tests and P300 recording were carried out.

RESULTS

In the patients with schizophrenia and their relatives, perfusion was reduced in left inferior prefrontal and anterior cingulate cortex and increased bilaterally in a subcortical region. Perfusion significantly correlated with verbal memory and P300 amplitude in left inferior prefrontal cortex and with P300 latency in anterior cingulate cortex.

CONCLUSIONS

Medication- and symptom-free relatives had altered regional perfusion intermediate between subjects with schizophrenia and controls. Impaired perfusion, verbal memory and P300 appear to be related traits associated with an increased risk of illness.

Thalamic and amygdala-hippocampal volume reductions in first-degree relatives of patients with schizophrenia: an MRI-based morphometric analysis

BACKGROUND

Schizophrenia is characterized by subcortical and cortical brain abnormalities. Evidence indicates that some nonpsychotic relatives of schizophrenic patients manifest biobehavioral abnormalities, including brain abnormalities. The goal of this study was to determine whether amygdala-hippocampal and thalamic abnormalities are present in relatives of schizophrenic patients.

METHODS

Subjects were 28 nonpsychotic, and nonschizotypal, first-degree adult relatives of schizophrenics and 26 normal control subjects. Sixty contiguous 3 mm coronal, T1-weighted 3D magnetic resonance images of the brain were acquired on a 1.5 Tesla magnet. Cortical and subcortical gray and white matter and cerebrospinal fluid (CSF) were segmented using a semi-automated intensity contour mapping algorithm. Analyses of covariance of the volumes of brain regions, controlling for expected intellectual (i.e., reading) ability and diagnosis, were used to compare groups.

RESULTS

The main findings were that relatives had significant volume reductions bilaterally in the amygdala-hippocampal region and thalamus compared to control subjects. Marginal differences were noted in the pallidum, putamen, cerebellum, and third and fourth ventricles.

CONCLUSIONS

Results support the hypothesis that core components of the vulnerability to schizophrenia include structural abnormalities in the thalamus and amygdala-hippocampus. These findings require further work to determine if the abnormalities are an expression of the genetic liability to schizophrenia.

The pathomorphology of schizophrenia and mood disorders: similarities and differences

In this article, post-mortem neurohistological and structural imaging studies of schizophrenia and mood disorders are briefly reviewed. In contrast to the large number of post-mortem studies on schizophrenia published during the last 20 years, very few histological studies of affective disorders are available. After commenting on CT and MRI studies, as well as on neuropathological findings on whole-brain size, cortex, frontal and temporal lobes, limbic system, basal ganglia, thalamus, brain stem, and cortical asymmetry, it is concluded that despite a broad overlap in structural findings in the so-called endogenous psychoses, heteromodal association cortex, limbic system, and structural asymmetry are more affected in schizophrenia, while subtle structural abnormalities in the basal ganglia, especially in the nucleus accumbens and in hypothalamic areas, might play a crucial role in mood disorders.

Structural and functional brain changes in bipolar disorder: a selective review

The purpose of this paper is to provide a concise, selective review of the major issues and findings germane to structural and functional neuroimaging studies of bipolar affective disorder (BPD). In attempting to identify the brain changes associated with BPD, investigators have used neuroimaging techniques to focus on several interrelated questions. These are: What are the changes and where do they occur? Do their nature and location suggest a particular etiopathologic basis or have notable clinical correlates? With regard to specificity, are the changes unique to BPD, or do they overlap with those reported in other neuropsychiatric illnesses, especially schizophrenia? Do they occur in brain systems that normally play a role in modulating mood? Finally, how do the brain changes integrate with neurocognitive, neurogenetic, and neuropathologic data in the same patients? To date, these questions have been addressed only preliminarily. We outline some of the strategies used to pursue answers to these questions and review conclusions to date.

Structural brain imaging in schizophrenia: a selective review

Structural neuroimaging studies have provided some of the most consistent evidence for brain abnormalities in schizophrenia. Since the initial computed tomography study by Johnstone and co-workers, which reported lateral ventricular enlargement in schizophrenia, advances in brain imaging technology have enabled further and more refined characterization of abnormal brain structure in schizophrenia in vivo. This selective review discusses the major issues and findings in structural neuroimaging studies of schizophrenia. Among these are evidence for generalized and regional brain volume abnormalities, the specificity of anatomic findings to schizophrenia and to men versus women with schizophrenia, the contribution of genetic influences, and the timing of neuroanatomic pathology in schizophrenia. The second section reviews new approaches for examining brain structure in schizophrenia and their applications to studies on the pathophysiology of schizophrenia.

Schizotypal personality disorder and MRI abnormalities of temporal lobe gray matter

BACKGROUND

Structural MRI data indicate schizophrenics have reduced left-sided temporal lobe gray matter volumes, especially in the superior temporal gyrus (STG) and medial temporal lobe. Our data further suggest a specificity to schizophrenia spectrum disorders of STG volume reduction. Interpretation of research studies involving schizophrenics may be complicated by the effects of exposure to neuroleptics and chronic illness. Sharing the same genetic diathesis of schizophrenics, subjects with schizotypal personality disorder (SPD) offer a unique opportunity to evaluate commonalities between schizophrenia and SPD, particularly as SPD subjects are characterized by cognitive and perceptual distortions, an inability to tolerate close friendships, and odd behavior, but they are not psychotic and so have generally not been prescribed neuroleptics nor hospitalized. Evaluation of brain structure in SPD may thus offer insight into the "endophenotype" common to both disorders. In addition, differences between groups may suggest which are the brain structures of schizophrenics that contribute to the development of psychosis.

METHODS

To test the hypothesis of whether SPD subjects might show similar STG abnormalities, STG and medial temporal lobe regions of interest (ROI) were manually drawn on high resolution coronal MRI 1.5 mm thick slices. Images were derived from 16 right-handed male SPD subjects, without regard to family history, and 14 healthy, right-handed, comparison males who did not differ from the SPD group on parental socio-economic status, age, or verbal IQ.

RESULTS

As predicted, SPD subjects showed a reduction in left STG gray matter volume compared with age and gender matched comparison subjects. SPD subjects also showed reduced parahippocampal left/right asymmetry and a high degree of disordered thinking. Comparisons with chronic schizophrenics previously studied by us showed the SPD group had a similarity of left STG gray matter volume reduction, but fewer medial temporal lobe abnormalities.

CONCLUSIONS

These abnormalities strengthen the hypothesis of a temporal lobe abnormality in SPD, and the similarity of STG findings in schizophrenia and SPD suggest that STG abnormalities may be part of the spectrum "endophenotype." It is also possible that presence of medial temporal lobe abnormalities may help to differentiate who will develop schizophrenia and who will develop the less severe schizophrenia spectrum disorder, SPD.

Meta-analysis of brain size in bipolar disorder

A recent meta-analysis concluded that patients with schizophrenia have reduced cerebral volume, and this finding has been used to implicate neurodevelopmental events in the etiology of this disorder. Since bipolar-disorder patients and schizophrenia patients have some similar brain abnormalities, it was of interest to meta-analytically review the literature on brain size in bipolar disorder. Only seven studies met the inclusion/exclusion criteria for our meta-analysis, but none reported the brain size differences between the bipolar patients and the controls to be statistically significant. The composite effect size was a negligible 0.04 (95% CI: -0.17 to 0.25) and statistically not significantly different from 0.0 (no effect). Thus, it appears that bipolar disorder is not associated with the same cerebral volume reductions noted in schizophrenia. Implications for hypotheses regarding the etiology of the two disorders are discussed.

The neuropathology of schizophrenia. A critical review of the data and their interpretation

Despite a hundred years' research, the neuropathology of schizophrenia remains obscure. However, neither can the null hypothesis be sustained--that it is a 'functional' psychosis, a disorder with no structural basis. A number of abnormalities have been identified and confirmed by meta-analysis, including ventricular enlargement and decreased cerebral (cortical and hippocampal) volume. These are characteristic of schizophrenia as a whole, rather than being restricted to a subtype, and are present in first-episode, unmedicated patients. There is considerable evidence for preferential involvement of the temporal lobe and moderate evidence for an alteration in normal cerebral asymmetries. There are several candidates for the histological and molecular correlates of the macroscopic features. The probable proximal explanation for decreased cortical volume is reduced neuropil and neuronal size, rather than a loss of neurons. These morphometric changes are in turn suggestive of alterations in synaptic, dendritic and axonal organization, a view supported by immunocytochemical and ultrastructural findings. Pathology in subcortical structures is not well established, apart from dorsal thalamic nuclei, which are smaller and contain fewer neurons. Other cytoarchitectural features of schizophrenia which are often discussed, notably entorhinal cortex heterotopias and hippocampal neuronal disarray, remain to be confirmed. The phenotype of the affected neuronal and synaptic populations is uncertain. A case can be made for impairment of hippocampal and corticocortical excitatory pathways, but in general the relationship between neurochemical findings (which centre upon dopamine, 5-hydroxytryptamine, glutamate and GABA systems) and the neuropathology of schizophrenia is unclear. Gliosis is not an intrinsic feature; its absence supports, but does not prove, the prevailing hypothesis that schizophrenia is a disorder of prenatal neurodevelopment. The cognitive impairment which frequently accompanies schizophrenia is not due to Alzheimer's disease or any other recognized neurodegenerative disorder. Its basis is unknown. Functional imaging data indicate that the pathophysiology of schizophrenia reflects aberrant activity in, and integration of, the components of distributed circuits involving the prefrontal cortex, hippocampus and certain subcortical structures. It is hypothesized that the neuropathological features represent the anatomical substrate of these functional abnormalities in neural connectivity. Investigation of this proposal is a goal of current neuropathological studies, which must also seek (i) to establish which of the recent histological findings are robust and cardinal, and (ii) to define the relationship of the pathological phenotype with the clinical syndrome, its neurochemistry and its pathogenesis.

Multimodal imaging in psychiatry: the electroencephalogram as a complement to other modalities

The use of different imaging modalities provides the clinician and researcher with different views of anatomy and physiology at unprecedented levels of detail. Multimodal imaging allows for noninvasive measurement of structure and function in humans during complex behavior, and thus provides information about the inner workings of the brain previously unavailable. The present paper examines the various imaging techniques available, and describes their application to the clinic-in the case of epilepsy-and to research-in the case of schizophrenia. Because the electroencephalogram has a dynamic response in milliseconds, it provides the best temporal sensitivity of functional measures of brain activity. When coupled with high-resolution magnetic resonance imaging measures of brain structure, this multimodal approach provides a powerful tool for understanding brain activity. Clinically, the use of multimodal imaging has provided greater precision in localization of the epileptogenic focus. For researchers attempting to determine the underlying causes of schizophrenia, the use of multimodal imaging has helped lead the field away from a specific lesion view to a more distributed system abnormality view of this disorder.

Late paraphrenia: a variant of schizophrenia manifest in late life or an organic clinical syndrome? A review of recent evidence

A large amount of research has been devoted during the past 15 years to the clinical and neurobiological aspects of the disorder named as 'late paraphrenia' (LP) in 1955. The symptomatology and diagnosis of the disorder, its prognosis, the cognitive functioning of those affected, the structural changes in the brain as revealed by modern techniques of brain imaging and its postmortem neuropathology have all been submitted to investigation. The results have been widely regarded as consistent with the concept of LP as an organic disease of the brain, but increased knowledge of the neurobiology of schizophrenia and of the age-related changes that occur in the brains of elderly people casts doubt on the validity of this interpretation. The findings are consistent with the view that LP is the form in which schizophrenia is manifest in old age. The proposal that LP has a closer kinship with affective disorder than with schizophrenia is part of a general theory of the sex differences in schizophrenia. In LP it becomes entangled with the organicity hypothesis, suggesting that neither of these explanations is adequate, and most of the evidence points to a unitary concept which views LP as a variant of a single disorder, namely schizophrenia, which, however, requires a broad definition. This concept has implications for fresh paths of enquiry.

Temporal horn enlargement is present in schizophrenia and bipolar disorder

BACKGROUND

Ventricular enlargement and temporal lobe volume deficits have been demonstrated in patients with affective disorder as well as those with schizophrenia. This study compares quantitative measures of temporal lobe, hemispheric, and ventricular volumes in a group of patients with chronic schizophrenia and bipolar disorder and seeks to determine if the groups can be differentiated on the basis of measured brain abnormalities.

METHODS

A series of coronal magnetic resonance imaging sections were acquired and analyzed for each of 22 patients with chronic schizophrenia, 14 patients with bipolar disorder, and 15 community volunteers. Eleven regions of interest for each brain were defined, which included temporal lobe, superior temporal gyrus, hemisphere, lateral ventricle, third ventricle, and temporal horn measures. Tissue measures were obtained by tracing, and cerebrospinal fluid measures were obtained by fluid-tissue thresholding using specialized computer software.

RESULTS

Both patient groups had significantly larger temporal horn volumes in comparison with the control group both before and after correction for intracranial volume. The two patient groups did not differ from each other or controls on any other tissue or fluid measure.

CONCLUSIONS

This study confirms the findings of increased temporal horn volume in patients with schizophrenia and suggests that this structural abnormality does not differentiate the structural neuropathology of schizophrenia from that of bipolar disorder.

Mesial temporal lobe measurements on magnetic resonance imaging scans

Changes in the mesial temporal lobe, particularly in the hippocampus, amygdala, and entorhinal cortex, are reported to occur in several neuropsychiatric conditions. Neuroimaging provides a non-invasive means of studying these changes. We present a method for reliably measuring the hippocampus, amygdala, and entorhinal cortex on MRI. The advantages of our method include high reliability, the use of orthogonal views in delineating boundaries and circumscription of measurement such that no tissue of any one anatomic structure is included in the measurement of another structure.

Neuropsychological risk indicators for schizophrenia: a preliminary study of female relatives of schizophrenic and bipolar probands

Evidence of subtle neuropsychological deficits in relatives of schizophrenic probands (REL-SZs) suggests that these are risk indicators for schizophrenia, but little is known about whether neuropsychological performance in REL-SZs differs from that in other groups of relatives. We compared neuropsychological function in female REL-SZs (n = 39), relatives of primarily psychotic bipolar disorder probands (REL-BPs; n = 15), and a normal control group (n = 44). After adjustment for expected intellectual ability (based on reading recognition), REL-SZs showed deficits in verbal and visual memory (Wechsler Memory Scale-Revised logical memories, visual reproductions), and auditory attention (dichotic digits) compared with either REL-BPs or control subjects. Memory, but not dichotic listening differences remained significant after adjusting for current IQ; however, average effect sizes after controlling for either reading or IQ were roughly comparable for these three parameters (d = 0.80, 0.71, and 0.69, respectively). REL-BPs and control subjects showed little difference. Although both schizophrenic and bipolar patients often manifest neuropsychological dysfunction, these preliminary findings indicate subtle neuropsychological deficits only in REL-SZs. Such differences suggest different underlying processes; neuropsychological impairment may, in part, reflect an expression of genetic liability to schizophrenia but not bipolar disorder. Replication with a larger REL-BP sample and with male relatives is needed to evaluate the generalizability of the results.

Compartmental volumetry of the superior temporal gyrus reveals sex differences in schizophrenia--a post-mortem study

Brain imaging studies have shown superior temporal gyrus (STG) volume loss and abnormal patterns of asymmetry in schizophrenia; however, these are not consistent findings. Post-mortem volumetry of three different STG regions (defined by external landmarks) was used to compare 17 schizophrenics to 20 age- and sex-matched controls. Total STG volumes did not differ. A significant gray-matter volume reduction in schizophrenics was observed in the middle compartment (reaching from the mamillary body to the lateral geniculate body). This may have been related to reduced length of this region, particularly in schizophrenic females. These results reflect the problematic issue of defining boundaries of macroscopic brain structures.

Functional neuroimaging studies of depression: the anatomy of melancholia

Functional brain imaging techniques, which permit noninvasive measures of neurophysiology and neuroreceptor binding, are powerful and sensitive tools for research aimed at elucidating the pathophysiology of major depression. The application of these technologies in depression research has produced several studies of resting cerebral blood flow (BF) and glucose metabolism in subjects imaged during various phases of illness and treatment. This review examines these data and the principles relevant to their interpretation and discusses the insights they provide into the anatomical correlates of depression. Within the anatomical networks implicated in emotional processing by other types of evidence, these BF and metabolic data demonstrate that major depression is associated with reversible, mood state-dependent, neurophysiological abnormalities in some structures and irreversible, trait-like abnormalities in other structures. In some of the regions in which trait-like abnormalities appear, abnormal metabolic activity appears at least partly related to the anatomical abnormalities identified in magnetic resonance imaging (MRI) studies of depression.

Superior temporal gyrus and planum temporale in schizophrenia: a selective review

1. The normal structure of the superior temporal gyrus (STG) has been elucidated from human and non-human primate research. This brain region is structurally complex, contains several distinct cellular regions and the area known as the planum temporale. 2. The STG connects with heteromodal neocortical regions and temporolimbic areas. 3. Functional studies of the normal STG in animals and in humans, using electrophysiology and PET/fMRI, emphasize the STG's role as part of a cortical network important in the interpretation, production and self-monitoring of language. 4. There is evidence for structural abnormalities of the STG in schizophrenia including both volume reductions and disturbances of normal asymmetries. 5. Functional studies of this region in schizophrenic patients, including measurements of evoked potentials and of bloodflow, are abnormal, especially when patients perform language tasks or experience hallucinations. 6. This structural and functional pathology in the STG probably represents one example of a more general disruption in schizophrenia of the neocortical network of which this region is an essential part. This disturbance may be closely associated with the symptoms of formal thought disorder and of auditory hallucinations commonly seen in the disorder.

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 neuronanatomic studies of pediatric populations.

The functional neuroanatomy of mood disorders

Mood disorders may be associated with global and regional changes in cerebral blood flow and metabolism. The accumulated functional neuroimaging findings in mood disorders were reviewed in order to examine a proposed neuroanatomic model of pathophysiology. Global cerebral blood flow and glucose metabolism appear normal, but may be decreased in late-life depression. Regional cerebral blood flow and glucose metabolism deficits are present, and may be indicators of brain regions participating in neuroanatomic circuits involved in mood disorders. Decreased pre-frontal cortex blood flow and metabolism in depressed unipolar and bipolar patients are the most consistently replicated findings, and correlate with severity of illness. Basal ganglia abnormalities have been found in depressed unipolar and bipolar patients, involving decreased blood flow and metabolism. Temporal lobe abnormalities are present in bipolar disorder patients, and perhaps unipolar depression. There is conflicting evidence of abnormalities in other limbic regions. Cognitive impairment may correlate with decreased metabolism in frontal and cerebellar areas. The relationship between functional neuroimaging findings and clinical course, and therefore state and trait characteristics, has not been systematically investigated. Antidepressant medications, but not ECT, seem to reverse some of the identified functional brain changes in the depressed state. The structural, neurotransmitter and neuropathological correlates of these functional abnormalities are yet to be determined. Functional abnormalities in frontal, subcortical and limbic structures appear to be part of the pathophysiology of mood disorders.

Subgenual prefrontal cortex abnormalities in mood disorders

Pathological disturbances of mood may follow a 'bipolar' course, in which normal moods alternate with both depression and mania, or a 'unipolar' course, in which only depression occurs. Both bipolar and unipolar disorders can be heritable illnesses associated with neurochemical, neuroendocrine and autonomic abnormalities. The neurobiological basis for these abnormalities has not been established. Using positron emission tomographic (PET) images of cerebral blood flow and rate of glucose metabolism to measure brain activity, we have now localized an area of abnormally decreased activity in the prefrontal cortex ventral to the genu of the corpus callosum in both familial bipolar depressives and familial unipolar depressives. This decrement in activity was at least partly explained by a corresponding reduction in cortical volume, as magnetic resonance imaging (MRI) demonstrated reductions in the mean grey matter volume in the same area of 39 and 48% in the bipolar and unipolar samples, respectively. This region has previously been implicated in the mediation of emotional and autonomic responses to socially significant or provocative stimuli, and in the modulation of the neurotransmitter systems targeted by antidepressant drugs.

Quantitative MRI volume changes in late onset schizophrenia and Alzheimer's disease compared to normal controls

Volumes of medial and lateral temporal lobe structures were assessed using magnetic resonance imaging (MRI) in 11 patients with late-life onset schizophrenia (LOS), 18 normal elderly controls and 12 patients with moderate cognitive impairment due to Alzheimer's disease (AD) who had no non-cognitive symptoms. While both patient groups had smaller volumes of several medial temporal regions (e.g. entorhinal cortex, left hippocampus), schizophrenics had significantly smaller anterior superior temporal gyri (STG) than normal controls, but AD patients did not. We have previously demonstrated anterior STG volume to be reduced in early life onset schizophrenia.