Postmortem evidence of structural brain changes in schizophrenia. Differences in brain weight, temporal horn area, and parahippocampal gyrus compared with affective disorder

Effect of chronic antipsychotic treatment on brain structure: a serial magnetic resonance imaging study with ex vivo and postmortem confirmation

BACKGROUND

There is increasing evidence that antipsychotic (APD) may affect brain structure directly. To examine this, we developed a rodent model that uses clinically relevant doses and serial magnetic resonance imaging (MRI), followed by postmortem histopathological analysis to study the effects of APD on brain structures.

METHODS

Antipsychotic , haloperidol, and olanzapine were continuously administered to rats via osmotic minipumps to maintain clinic-like steady state levels for 8 weeks. Longitudinal in vivo MRI scanning (T₂-weighted) was carried out at baseline, 4 weeks, and 8 weeks, after which animals were perfused and their brains preserved for ex vivo MRI scanning. Region of interest analyses were performed on magnetic resonance images (both in vivo as well as ex vivo) along with postmortem stereology using the Cavalieri estimator probe.

RESULTS

Chronic (8 weeks) exposure to both haloperidol and olanzapine resulted in significant decreases in whole-brain volume (6% to 8%) compared with vehicle-treated control subjects, driven mainly by a decrease in frontal cerebral cortex volume (8% to 12%). Hippocampal, corpus striatum, lateral ventricles, and corpus callosum volumes were not significantly different from control subjects, suggesting a differential effect of APD on the cortex. These results were corroborated by ex vivo MRI scans and decreased cortical volume was confirmed postmortem by stereology.

CONCLUSIONS

This is the first systematic whole-brain MRI study of the effects of APD, which highlights significant effects on the cortex. Although caution needs to be exerted when extrapolating results from animals to patients, the approach provides a tractable method for linking in vivo MRI findings to their histopathological origins.

Behavioral and molecular biomarkers in translational animal models for neuropsychiatric disorders

Modeling neuropsychiatric disorders in animals poses a significant challenge due to the subjective nature of diverse often overlapping symptoms, lack of objective biomarkers and diagnostics, and the rudimentary understanding of the pathophysiology. Successful translational research requires animal models that can inform about disease mechanisms and therapeutic targets. Here, we review behavioral and neurobiological findings from selected animal models, based on presumed etiology and risk factors, for schizophrenia, bipolar disorder, and major depressive disorder. We focus on the use of appropriate statistical tools and newly developed Research Domain Criteria (RDoC) to link biomarkers from animal models with the human disease. We argue that this approach will lead to development of only the most robust animal models for specific psychiatric disorders and may ultimately lead to better understanding of the pathophysiology and identification of novel biomarkers and therapeutic targets.

Neuropathology of epilepsy and psychosis: the contributions of J.A.N. Corsellis

Professor J.A.N. Corsellis, whose life and work is recalled here, gained great insight into the meaning of morphological cerebral aberrations found in neuropsychiatric disease through exact neuropathological investigations of tissue specimens obtained from patients with distinct syndromes. He was a leading authority in the field. We have searched and compiled resources relating to J.A.N. Corsellis' life and work, including personal memories from colleagues and data from scientific publications. J.A.N. Corsellis made seminal contributions to the understanding of neuropsychiatric disease; his works substantially added to the understanding of the dementias, schizophrenia and the psychoses, and morphological sequelae of boxing. In seizure disorders, his name is linked to the first description of focal cortical dysplasia and limbic encephalitis, the pathology of status epilepticus and Ammon's horn sclerosis, and the systematic investigation of epilepsy surgery specimens in general. Both his life and work are closely linked to Runwell Hospital, Wickford, Essex and the Maudsley Hospital. During his professional life he established a large brain bank, now known as the Corsellis Collection. J.A.N. Corsellis had significant impact on neuroscience; many of his observations were groundbreaking and are still valid.

Inverse relationship between adult hippocampal cell proliferation and synaptic rewiring in the dentate gyrus

Adult neurogenesis is a key feature of the hippocampal dentate gyrus (DG). Neurogenesis is accompanied by synaptogenesis as new cells become integrated into the circuitry of the hippocampus. However, little is known to what extent the embedding of new neurons rewires the pre-existing network. Here we investigate synaptic rewiring in the DG of gerbils (Meriones unguiculatus) under different rates of adult cell proliferation caused by different rearing conditions as well as juvenile methamphetamine treatment. Surprisingly, we found that an increased cell proliferation reduced the amount of synaptic rewiring. To help explain this unexpected finding, we developed a novel model of dentate network formation incorporating neurogenesis and activity-dependent synapse formation and remodelling. In the model, we show that homeostasis of neuronal activity can account for the inverse relationship between cell proliferation and synaptic rewiring.

Schizophrenia and the normal functional development of the prefrontal cortex

Schizophrenia is being increasingly viewed as a neurodevelopmental disorder, that is, one in which early, fixed pathology becomes manifest clinically during the normal course of maturation of the brain. Evidence for this position comes first from neuroimaging research, such as (1) studies that demonstrate morphologic brain changes (such as ventriculomegaly on CT scans) even in first break patients; and (2) a lack of correlation between these morphologic changes and duration of illness. Another source of evidence is studies of normal brain development in rodents and primates, including research that shows (1) the prefrontal cortex is a late maturing part of the brain, and (2) lesions of the prefrontal cortex may be initially silent and show delayed onset of dysfunction as the brain matures. A neurodevelopmental approach to schizophrenia, in turn, has stimulated further work into the normal development of brain regions implicated in the illness, such as the frontal cortex. Thus, the fields of neuropsychiatry and neurodevelopment have been mutually stimulated during the course of this work. In addition, viewing schizophrenia in developmental terms may have implications for the understanding of changes in cognition and behavior during normal adolescence.

Middle-ear disease and schizophrenia: case-control study

BACKGROUND

One hundred years ago psychiatrists thought that ear disease could cause insanity by irritation of the brain. Current understanding of the role of the temporal lobes in schizophrenia and their proximity to the middle ear supports this hypothesis.

AIMS

To establish the rate of middle-ear disease pre-dating the onset of schizophrenia.

METHOD

Eighty-four patients with schizophrenia were each matched to four non-psychiatric controls by age, gender and season of birth. History of ear disease was obtained from general practice records. Additional information on symptoms was collected for participants in the case group, who also had audiometry.

RESULTS

The odds ratio of recorded middle-ear disease pre-dating schizophrenia was 3.68 (95% CI 1.86-7.28). This excess was particularly marked on the left (OR=4.15, 95% CI 2.08-8.29). Auditory hallucinations were associated with middle-ear disease but not with hearing loss.

CONCLUSIONS

There is an association between middle-ear disease and schizophrenia which may have aetiological significance.

What happens after the first episode? A review of progressive brain changes in chronically ill patients with schizophrenia

Numerous imaging studies have revealed structural brain changes in schizophrenia. Decreases in brain tissue are accompanied by increases in ventricle volumes and cerebrospinal fluid. Whether or not these brain changes are progressive beyond the first episode is subject to debate. To assess if progressive brain changes occur in chronically ill patients, 11 longitudinal magnetic resonance imaging and computed tomography studies were reviewed. Patients were ill for on average 10 years at their initial scan. Follow-up intervals varied between 1 and 10 years. Overall, the findings suggest continuous progressive brain tissue decreases and lateral ventricle volume increases in chronically ill patients, up to at least 20 years after their first symptoms. The extent of progressive brain tissue decrease in patients (-0.5% per year) is twice that of healthy controls (-0.2% per year). These findings are consistent with the extent of postmortem brain tissue loss in schizophrenia. Progressive volume loss seems most pronounced in the frontal and temporal (gray matter) areas. Progressive lateral ventricle volume increases are also found. More pronounced progressive brain changes in patients is associated with poor outcome, more negative symptoms, and a decline in neuropsychological performance in one or some of the studies, but not consistently so. Higher daily cumulative dose of antipsychotic medication intake is either not associated with brain volume changes or with less prominent brain volume changes. The progressive brain changes present in chronic schizophrenia may represent a continuous pathophysiological process taking place in the brains of these patients that warrants further study.

Limbic structures and networks in children and adolescents with schizophrenia

Studies of adults with schizophrenia provide converging evidence for abnormalities in the limbic system. Limbic structures that show consistent patient/control differences in both postmortem and neuroimaging studies include the anterior cingulate and hippocampus, although differences in the amygdala, parahippocampal gyrus, and fornix have also been observed. Studies of white matter in children and adolescents with schizophrenia tend to show findings that are more focal than those seen in adults. Interestingly, these focal abnormalities in early-onset schizophrenia tend to be more localized to limbic regions. While it is unclear if these early limbic abnormalities are primary in the etiology of schizophrenia, there is evidence that supports a developmental progression with early limbic abnormalities evolving over time to match the neuroimaging profiles seen in adults with schizophrenia. Alternatively, the aberrations in limbic structures may be secondary to a more widespread or global pathological processes occurring with the brain that disrupt neural transmission. The goal of this article is to provide a review of the limbic system and limbic network abnormalities reported in children and adolescents with schizophrenia. These findings are compared with the adult literature and placed within a developmental context. These observations from neuroimaging studies enrich our current understanding of the neurodevelopmental model of schizophrenia and raise further questions about primary vs secondary processes. Additional research within a developmental framework is necessary to determine the putative etiologic roles for limbic and other brain abnormalities in early-onset schizophrenia.

Brain metabolite abnormalities in the white matter of elderly schizophrenic subjects: implication for glial dysfunction

BACKGROUND

Abnormalities in the white matter of the brain may occur in individuals with schizophrenia as well as with normal aging. Therefore, elderly schizophrenic patients may suffer further cognitive decline as they age. This study determined whether elderly schizophrenia participants, especially those with declined cognitive function (Clinical Dementia Rating score > 1), show white matter metabolite abnormalities on proton magnetic resonance spectroscopy and whether there are group differences in age-dependent changes in these brain metabolites.

METHOD

Twenty-three elderly schizophrenia and twenty-two comparison participants fulfilling study criteria were enrolled. Localized, short echo-time (1)H MRS at 4 Tesla was used to assess neurometabolite concentrations in several white matter regions.

RESULTS

Compared with healthy subjects, schizophrenia participants had lower N-acetyl compounds (-12.6%, p = .0008), lower myo-inositol (-16.4%, p = .026), and higher glutamate + glutamine (+28.7%, p = .0016) concentrations across brain regions. Schizophrenia participants with Clinical Dementia Rating >/= 1 showed the lowest NA in the frontal and temporal regions compared with control subjects. Interactions between age and schizophrenia status on total creatine and choline-containing compounds were observed; only schizophrenia participants showed age-related decreases of these metabolites in the right frontal region.

CONCLUSIONS

Decreased NA in these white matter brain regions likely reflects reduced neuronal content associated with decreased synapses and neuronal cell volumes. The elevated glutamate + glutamine, if reflecting elevated glutamate, could result from excess neuronal glutamate release or glial dysfunction in glutamate reuptake. The decreased myo-inositol in participants with schizophrenia suggests decreased glial content or dysfunctional glia, which might result from glutamate-mediated toxicity.

Asymmetries of cerebral neuroanatomy

The mammalian cerebral cortex is asymmetrical. One hemisphere does not contain cortical areas or architectonic patterns, histological features, ultrastructural characteristics, or connectivities of the neurons that are not present in the other: homologous areas on the two sides may differ only in size. Asymmetry has directionality: two-thirds of human brains have plana temporale that are larger on the left. Conversely, roughly the same number of non-human brains show asymmetry in one direction as in the other. Asymmetry has magnitude: some brains show a large asymmetry, others show no asymmetry in a given area. Symmetrical areas are larger than their asymmetrical counterparts, which reflects fewer neurons in the latter. Indirect evidence points to variable asymmetry in the germinal zones in the production of symmetrical or asymmetrical cortical areas. These areas differ in their patterns of callosal connections. Fewer connections are seen in the asymmetrical cases, paralleling the smaller number of neurons. The symmetrical cases contain connections that are more widely distributed. These findings of different numbers of neurons and different proportions of callosal connections suggest that symmetrical and asymmetrical cortical areas may have different functional properties.

Pathology of cortical development and neuropsychiatric disorders

Epilepsy is a well-documented consequence of about 150 rare genetic syndromes and malformations of the central nervous system. These syndromes are generally associated with fairly gross defects within the central nervous system and they were thought to be responsible for a small minority of cases. However, improved methods of neuropathological investigations and extensive magnetic resonance imaging studies have revealed a range of disturbances in cortical cytoarchitecture in patients with epileptic seizures previously considered as idiopathic (up to 70% of epilepsy). Structural abnormalities have also been demonstrated in the brain in schizophrenia. These consist of disturbed cortical cytoarchitecture (best described in the temporal lobe) and a diffuse loss of grey matter. The absence of the pathological stigma characteristic of degenerative processes indicates that these structural changes are the result of an abnormal pattern of brain development. The relationship between the type and location of developmental abnormality and the subsequent clinical syndrome (e.g. generalized or localized epilepsy) and the effects of aberrant cortical development on the functional integrity of the adult brain require definition.

Fetal brain development and later schizophrenia

Computed tomography and magnetic resonance imaging studies have shown cerebral ventricular enlargement and a decreased volume of temporal lobe structures in a proportion of schizophrenic patients. Neuropathological investigations confirm these findings and also show diminished volume of the hippocampus and abnormal pre-alpha cell clusters in the parahippocampal gyrus. Compared with controls, schizophrenic patients are more likely to have minor physical anomalies, to have a history of obstetric complications, and to have been born in the late winter. Together the evidence regarding structural brain abnormalities and epidemiology suggests that a significant proportion of cases of schizophrenia have their origins in fetal or neonatal life. The mechanisms involved in the aberrant neurodevelopment remain obscure but some impairment of neuronal migration is an appealing hypothesis.

Callosal misconnectivity and the sex difference in psychosis

The sex difference in age of onset in schizophrenia is paradoxical in the sense that the brain is developing faster in females but onsets are earlier in males. Therefore if schizophrenia, as widely believed, is a disorder of development, the difference is in the wrong direction. Here we attempt to resolve the paradox with the hypothesis that psychosis is an anomaly of development of cerebral asymmetry and the following assumptions: (1) asymmetry (the torque) confers directionality on the 'language circuit'--failure to develop asymmetry leads to the risk of reverse transmission, a putative mechanism of psychotic symptoms; (2) the corpus callosum goes on developing in an antero-posterior direction into the third and fourth decades of life; (3) a sex difference in structure and development of the corpus callosum (with some anterior components greater in males and posterior components greater in females) reflects stronger, faster lateralization in females; (4) because of the inverse relationship between asymmetry and interhemispheric connections, females, by developing faster, avoid the misconnectivity phenomena in the frontal lobes that males, developing more slowly, may encounter at a younger age with particular risk of negative symptoms.

The dementias of schizophrenia

Cases of “adolescent insanity” were known to Kraepelin’s forerunners and lay at the core of his concept of dementia præcox. In the post-neuroleptic era it became clear that dementia may also occur in schizophrenia as a fully reversible state depending on psychopathological status. In the present review we discuss the validity of applying the concept of dementia to schizophrenia. We concur with the view that schizophrenia may lead to a true dementia both (i) as a fixed end-stage consequence of the disease process itself, or (ii) as a drug-responsive reversible state. There is an urgent need to examine the patterns of dementia in other common neuropsychiatric disorders, employing current methods of neurobehavioral investigation.

Hippocampal and parahippocampal volumes in schizophrenia: a structural MRI study

Smaller medial temporal lobe volume is a frequent finding in studies of patients with schizophrenia, but the relative contributions of the hippocampus and three surrounding cortical regions (entorhinal cortex, perirhinal cortex, and parahippocampal cortex) are poorly understood. We tested the hypothesis that the volumes of medial temporal lobe regions are selectively changed in schizophrenia. We studied 19 male patients with schizophrenia and 19 age-matched male control subjects. Hippocampal and cortical volumes were estimated using a three-dimensional morphometric protocol for the analysis of high-resolution structural magnetic resonance images, and repeated measures ANOVA was used to test for region-specific differences. Patients had smaller overall medial temporal lobe volumes compared to controls. The volume difference was not specific for either region or hemisphere. The finding of smaller medial temporal lobe volumes in the absence of regional specificity has important implications for studying the functional role of the hippocampus and surrounding cortical regions in schizophrenia.

Variations in differential gene expression patterns across multiple brain regions in schizophrenia

Large-scale gene expression studies in schizophrenia (SZ) have generally focused on the dorsolateral prefrontal cortex. Despite a wealth of evidence implicating multiple other brain regions in the disease, studies of other brain regions have been less frequent and have rarely been performed in the same subjects. We analyzed postmortem gene expression in the frontal, cingulate, temporal, parietal and occipital cortices (Brodmann areas 8, 10, 44, 46, 23/31, 24/32, 20, 21, 22, 36/28, 7 and 17, respectively) as well as in the hippocampus, caudate nucleus and putamen of persons with schizophrenia and control subjects (N's = 13) using Affymetrix GeneChip microarrays. Under identical data filtering conditions, the superior temporal cortex (BA22) of schizophrenia subjects showed the maximal number of altered transcripts (approximately 1200) compared to controls. Anterior and posterior cingulate cortices (BA23/31, 24/32) and the hippocampus followed the superior temporal cortex with two-times lower numbers of altered transcripts. The dorsolateral prefrontal cortex (BA46), a frequent target of SZ-associated studies, showed substantially fewer altered transcripts (approximately 33). These regional differences in differentially expressed genes could not be accounted for by factors such as total numbers of genes expressed or the filtering conditions and criteria used for identification of differentially expressed genes. These findings suggest that the temporal and cingulate cortices and the hippocampal formation represent brain regions of particular abnormality in SZ and may be more susceptible to the disease process(es) than other regions thus far studied.

Face emotion perception and executive functioning deficits in depression

Frontal, limbic and temporal regions of the brain important in emotion perception and executive functioning also have been implicated in the etiology and maintenance of depression; yet, the relationships among these topics remain poorly understood. The present study evaluated emotion perception and executive functioning among 21 depressed women and 20 nondepressed women controls. Depressed women performed significantly worse than controls in emotion perception accuracy and in inhibitory control, an aspect of executive functioning, whereas the groups did not differ in other cognitive tests assessing memory, visual-spatial, motor, and attention skills. The findings suggest that emotion perception and executive functioning are disproportionately negatively affected relative to other cognitive functions, even in a high-functioning group of mildly depressed women. Measures of emotion perception and executive functioning may be of assistance in objectively measuring functional capability of the ventral and dorsal neural systems, respectively, as well as in the diagnosis of depression.

Increased proportion of high-affinity dopamine D2 receptors in rats with excitotoxic damage of the entorhinal cortex, an animal model of schizophrenia

Excitotoxic lesions of the left entorhinal cortex (EC) cause dopamine supersensitivity. In order to determine if these lesions selectively alter the high-affinity state of dopamine D2 receptors (D2(High)), these high-affinity states were measured by competition between dopamine and [3H]domperidone in striata from lesioned rats and sham-operated animals. The proportion of D2(High) sites was significantly elevated by 200% in the EC-lesioned rats while that of the D1(High) sites, measured by dopamine/[3H]SCH23390 competition, was unaltered. These results provide a biochemical basis for behavioral supersensitivity in rats with EC lesions.

Tonic modulation of inhibition by dopamine D4 receptors in the rat hippocampus

Dopaminergic pathways have been recognized to play a critical role in cognition and emotion. Dopamine D2 and D4 receptors are the target for most common antipsychotics and their activation, particularly those in the medial temporal lobe structures, has been associated with their beneficial actions. The entorhinal cortex, which is the cortical area most consistently and severely affected in schizophrenia constitutes the main input to the hippocampus. Since the D4 receptor is highly concentrated in the hippocampus, and the effects of the selective activation of D4 receptors on the input/output function of the hippocampal formation are poorly understood, we sought to investigate the role of these receptors in the synaptic transmission and paired-pulse inhibition from the perforant path to area CA1 and the dentate gyrus. The D4 receptor antagonist, clozapine, translated paired-pulse inhibition into paired-pulse potentiation in both perforant path targets. By contrast, the D2/D3 antagonist quinpirole had no effect. The blockade of the D2/3 receptors with sulpiride, and of D1/5 receptors with SCH-23390, has no effect on paired-pulse inhibition, suggesting that these receptors are not involved in feedforward inhibition in these hippocampal areas. Interestingly, the perfusion of the D4 selective antagonist, L-745,870 (Patel et al., 1997: J Pharmacol Exp Ther 283:636-647) during the blockade of D2/3 and D1/5 receptors produces a reversible decrease in paired-pulse inhibition in CA1, but not in the DG. Our results show that endogenous DA tonically modulates feedforward inhibition in area CA1 and the dentate gyrus through the activation of D4 receptors located in the interneuronal population of these hippocampal regions. Since activation of the D4 receptor inhibits GABA release and GABAergic synaptic transmission, we suggest that the perforant path stimulates interneurons that have the D4 receptor and that, in turn, contact other interneurons that synapse onto pyramidal cells. (c) 2004 Wiley-Liss, Inc.

BDNF in schizophrenia, depression and corresponding animal models

Understanding the etiology and pathogenesis schizophrenia and depression is a major challenge facing psychiatry. One hypothesis is that these disorders are secondary to a malfunction of neurotrophic factors. Inappropriate neurotrophic support during brain development could lead to structural disorganisation in which neuronal networks are established in a nonoptimal manner. Inadequate neurotrophic support in adult individuals could ultimately be an underlying mechanism leading to decreased capacity of brain to adaptive changes and increased vulnerability to neurotoxic damage. Brain-derived neurotrophic factor (BDNF) is a mediator involved in neuronal survival and plasticity of dopaminergic, cholinergic, and serotonergic neurons in the central nervous system (CNS). In this review, we summarize findings regarding altered BDNF in schizophrenia and depression and animal models, as well as the effects of antipsychotic and antidepressive treatments on the expression of BDNF.

Enhanced locomotor activity in rats with excitotoxic lesions of the entorhinal cortex, a neurodevelopmental animal model of schizophrenia: Behavioral and in vivo microdialysis studies

In order to examine the construct validity of rats with excitotoxic damage of the left entorhinal cortex (EC) as an animal model of schizophrenia, we measured dopamine (DA)-related behaviors and methamphetamine (MAP)-induced DA release in the accumbens nucleus (NAC) in these animals. Quinolinic acid (lesion group) or phosphate buffer (sham group) was infused into the left EC of adolescent (postnatal 7 weeks) male Wistar rats. On the 14th and 28th postoperative day, spontaneous and MAP (1 mg/kg, i.p.)-induced locomotor activities, as well as MAP-induced stereotypy, were measured. The lesioned rats exhibited significantly greater spontaneous or MAP-induced locomotor activity on both of the postoperative days than did sham-operated animals, while EC lesions did not affect MAP-induced stereotypy on either occasion. MAP (1 mg/kg, i.p.)-induced DA release in NAC was measured by in vivo microdialysis on the 28th postoperative day. Lesioned rats did not show a significant change in MAP (1 mg/kg, i.p.)-induced DA release in NAC compared to sham-operated animals. These results suggest that excitotoxic damage of the left EC produces behavioral changes consistent with altered mesolimbic dopaminergic transmissions, possibly mediated by postsynaptic supersensitivity.

The hippocampus in schizophrenia: a review of the neuropathological evidence and its pathophysiological implications

This paper puts the case for the hippocampus as being central to the neuropathology and pathophysiology of schizophrenia. The evidence comes from a range of approaches, both in vivo (neuropsychology, structural and functional imaging) and post mortem (histology, morphometry, gene expression, and neurochemistry). Neuropathologically, the main positive findings concern neuronal morphology, organisation, and presynaptic and dendritic parameters. The results are together suggestive of an altered synaptic circuitry or "wiring" within the hippocampus and its extrinsic connections, especially with the prefrontal cortex. These changes plausibly represent the anatomical component of the aberrant functional connectivity that underlies schizophrenia. Glutamatergic pathways are prominently but not exclusively affected. Changes appear somewhat greater in the left hippocampus than the right, and CA1 is relatively uninvolved compared to other subfields. Hippocampal pathology in schizophrenia may be due to genetic factors, aberrant neurodevelopment, and/or abnormal neural plasticity; it is not due to any recognised neurodegenerative process. Hippocampal involvement is likely to be associated with the neuropsychological impairments of schizophrenia rather than with its psychotic symptoms.

Meta-analysis of brain weight in schizophrenia

Brain weight is often said to be decreased in schizophrenia, but a reduction has only been found in a minority of studies. We have therefore carried out a meta-analysis to answer this basic neuropathological question. Data were identified from literature searches and from contacting researchers in the field who were invited to submit unpublished data. Inclusion criteria were: an operational diagnosis of schizophrenia, or comparison subjects with no neurological or psychiatric history, aged 18 or over, for whom brain weight, age and sex were known. Exclusion criteria were: a history of head injury, epilepsy, substance dependence or leucotomy; neuropathological evidence of neurodegenerative disorder or focal brain lesion. Results were analysed by multilevel modelling. Brain weight was, as expected, related to age and sex (both p<0.0001). After control for these factors, there was an effect of diagnosis, with brains from the 540 schizophrenia subjects being 2% lighter than from the 794 controls (weighted mean difference=24 g [95% confidence interval, 1-47 g]; p=0.04). The difference was similar in male and female patients. There was no correlation with duration of illness. In conclusion, brain weight is slightly but significantly reduced in schizophrenia, consistent in direction and magnitude with MRI volumetric findings. The result encourages a continuing search for the histological and molecular correlates of schizophrenia.

Ventricular enlargement in schizophrenia: a primary change in the temporal lobe?

BACKGROUND

The anatomical origin of the enlargement of the cerebral ventricles in schizophrenia is obscure.

METHODS

In this study, the volumes of the hemispheres and lateral ventricles were assessed in MRI scans of 43 formalin-fixed brains (23 from patients and 19 comparison subjects) using a spline 'snake' segmentation method.

RESULTS

A bilateral ventricular volume increase was found in schizophrenia. Whereas enlargement of the lateral ventricle (mean: 54%) as a whole was related to age of onset and was greater in females than in males, enlargement of the temporal horn (mean: 54%) was not strongly related to age of onset or sex. Lateral ventricle volume was negatively correlated with STG, fusiform and parahippocampal volume in schizophrenia. Hemispheric volumes were unchanged.

CONCLUSIONS

The differing correlates of the components of ventricular enlargement suggest a degree of selectivity of the disease process with a focus in the temporal lobe.

Regional specificity of brain glucocorticoid receptor mRNA alterations in subjects with schizophrenia and mood disorders

Glucocorticoid receptors (GR) mediate the direct effects of glucocorticoids released in response to stress and the regulation of the hypothalamic-pituitary-adrenocortical (HPA) system through a negative feedback mechanism. Individuals with major mental illness, who often exhibit hypercortisolemia, may have down-regulated levels of GR mRNA. In situ hybridization for GR mRNA was performed on post-mortem specimens from patients suffering from depression, bipolar disorder, schizophrenia and from normal controls (n = 15 per group). In frontal cortex, GR mRNA levels were decreased in layers III-VI in the subjects with depression and schizophrenia. In inferior temporal cortex, GR mRNA levels were decreased in layer IV in all three diagnostic groups. In the entorhinal cortex, GR mRNA levels were decreased in layers III and VI in the bipolar group. In hippocampus, GR mRNA levels were reduced in the dentate gyrus, CA(4), CA(3) and CA(1) in the schizophrenia group. In the subiculum, GR mRNA levels were reduced in the bipolar group. These results suggest that GR dysregulation occurs in all three major psychiatric illnesses with variability according to anatomical site. The severity and heterogeneity of this reduction may underlie some of the clinical heterogeneity seen in these disorders.

Biochemical and molecular studies using human autopsy brain tissue

The use of human brain tissue obtained at autopsy for neurochemical, pharmacological and physiological analyses is reviewed. RNA and protein samples have been found suitable for expression profiling by techniques that include RT-PCR, cDNA microarrays, western blotting, immunohistochemistry and proteomics. The rapid development of molecular biological techniques has increased the impetus for this work to be applied to studies of brain disease. It has been shown that most nucleic acids and proteins are reasonably stable post-mortem. However, their abundance and integrity can exhibit marked intra- and intercase variability, making comparisons between case-groups difficult. Variability can reveal important functional and biochemical information. The correct interpretation of neurochemical data must take into account such factors as age, gender, ethnicity, medicative history, immediate ante-mortem status, agonal state and post-mortem and post-autopsy intervals. Here we consider issues associated with the sampling of DNA, RNA and proteins using human autopsy brain tissue in relation to various ante- and post-mortem factors. We conclude that valid and practical measures of a variety of parameters may be made in human brain tissue, provided that specific factors are controlled.

Schizophrenia: from phenomenology to neurobiology

Schizophrenia is a common and debilitating illness, characterized by chronic psychotic symptoms and psychosocial impairment that exact considerable human and economic costs. The literature in electronic databases as well as citations and major articles are reviewed with respect to the phenomenology, pathology, treatment, genetics and neurobiology of schizophrenia. Although studied extensively from a clinical, psychological, biological and genetic perspective, our expanding knowledge of schizophrenia provides only an incomplete understanding of this complex disorder. Recent advances in neuroscience have allowed the confirmation or refutation of earlier findings in schizophrenia, and permit useful comparisons between the different levels of organization from which the illness has been studied. Schizophrenia is defined as a clinical syndrome that may include a collection of diseases that share a common presentation. Genetic factors are the most important in the etiology of the disease, with unknown environmental factors potentially modulating the expression of symptoms. Schizophrenia is a complex genetic disorder in which many genes may be implicated, with the possibility of gene-gene interactions and a diversity of genetic causes in different families or populations. A neurodevelopmental rather than degenerative process has received more empirical support as a general explanation of the pathophysiology, although simple dichotomies are not particularly helpful in such a complicated disease. Structural brain changes are present in vivo and post-mortem, with both histopathological and imaging studies in overall agreement that the temporal and frontal lobes of the cerebral cortex are the most affected. Functional imaging, neuropsychological testing and clinical observation are also generally consistent in demonstrating deficits in cognitive ability that correlate with abnormalities in the areas of the brain with structural abnormalities. The dopamine and other neurotransmitter systems are certainly involved in the treatment or modulation of psychotic symptoms. These broad findings represent the distillation of a large body of disparate data, but firm and specific findings are sparse, and much about schizophrenia remains unknown.

Boundaries of schizophrenia

The frontiers of schizophrenia are being increasingly challenged from several directions. In addition to ongoing debate as to divisions between schizophrenia and disorders of the schizophrenic spectrum, including schizotypal personality disorder and schizophreniform disorder, it has been suggested that obsessive-compulsive disorder might overlap phenomenologically with schizophrenia. There has been a long debate around the relationship of schizophrenia to affective disorders, particularly bipolar and schizoaffective disorder. The evidence suggests that although schizotypal personality and schizophreniform disorders are not homogeneous syndromes, they are related to or represent milder forms of schizophrenia. Obsessive-compulsive disorder seems to involve pathology in many of the same regions as observed in some patients with schizophrenia, which may account for the significant incidence of obsessive-compulsive symptoms in a subset of patients with schizophrenia. Despite similarities between schizophrenia and bipolar disorder, significant differences extend across suggested causes, phenomenology, and pathophysiology. These findings support the current conceptualization that the two disorders represent distinct disorders, probably with heterogeneous causes, rather than the ends of a spectrum of symptoms comprising a single syndrome. Schizoaffective disorder likely is made up of patients from the schizophrenic and bipolar cluster of illnesses. The long-standing debate as to the boundaries of schizophrenia is ultimately must await the eventual further elaboration of the underlying causes of schizophrenia and other psychotic disorders.

The relationship between predisposing factors, premorbid function and symptom dimensions in psychosis: an integrated approach

BACKGROUND

Increasing evidence suggests psychosis may be more meaningfully viewed in dimensional terms rather than as discrete categorical states and that specific symptom clusters may be identified. If so, particular risk factors and premorbid factors may predict these symptom clusters.

AIMS

(i) To explore, using principal component analysis, whether specific factors for psychotic symptoms can be isolated. (ii) To establish the predictors of the different symptom factors using multiple regression techniques.

METHOD

One hundred and eighty-nine inpatients with psychotic illness were recruited and information on family history, premorbid factors and current symptoms obtained from them and their mothers.

RESULTS

Seven distinct symptom components were identified. Regression analysis failed to identify any developmental predictors of depression or mania. Delusions/hallucinations were predicted by a family history of schizophrenia and by poor school functioning in spite of normal premorbid IQ (F = 6.5; P < 0.001); negative symptoms by early onset of illness, developmental delay and a family history of psychosis (F = 4.1; P = 0.04). Interestingly disorganisation was predicted by the combination of family history of bipolar disorder and low premorbid IQ (F = 4.9; P = 0.003), and paranoia by obstetric complications (OCs) and poor school functioning (F = 4.2; P = 0.01).

CONCLUSION

Delusions and hallucinations, negative symptoms and paranoia all appeared to have a developmental origin though they were associated with different childhood problems. On the other hand, neither mania nor depression was associated with childhood dysfunction. Our most striking finding was that disorganisation appeared to arise when a familial predisposition to mania was compounded by low premorbid IQ.

Amygdala-hippocampal shape differences in schizophrenia: the application of 3D shape models to volumetric MR data

Evidence suggests that some structural brain abnormalities in schizophrenia are neurodevelopmental in origin. There is also growing evidence to suggest that shape deformations in brain structure may reflect abnormalities in neurodevelopment. While many magnetic resonance (MR) imaging studies have investigated brain area and volume measures in schizophrenia, fewer have focused on shape deformations. In this MR study we used a 3D shape representation technique, based on spherical harmonic functions, to analyze left and right amygdala-hippocampus shapes in each of 15 patients with schizophrenia and 15 healthy controls matched for age, gender, handedness and parental socioeconomic status. Left/right asymmetry was also measured for both shape and volume differences. Additionally, shape and volume measurements were combined in a composite analysis. There were no differences between groups in overall volume or shape. Left/right amygdala-hippocampal asymmetry, however, was significantly larger in patients than controls for both relative volume and shape. The local brain regions responsible for the left/right asymmetry differences in patients with schizophrenia were in the tail of the hippocampus (including both the inferior aspect adjacent to parahippocampal gyrus and the superior aspect adjacent to the lateral geniculate nucleus and more anteriorly to the cerebral peduncles) and in portions of the amygdala body (including the anterior-superior aspect adjacent to the basal nucleus). Also, in patients, increased volumetric asymmetry tended to be correlated with increased left/right shape asymmetry. Furthermore, a combined analysis of volume and shape asymmetry resulted in improved differentiation between groups. Classification function analyses correctly classified 70% of cases using volume, 73.3% using shape, and 87% using combined volume and shape measures. These findings suggest that shape provides important new information toward characterizing the pathophysiology of schizophrenia, and that combining volume and shape measures provides improved group discrimination in studies investigating brain abnormalities in schizophrenia. An evaluation of shape deformations also suggests local abnormalities in the amygdala-hippocampal complex in schizophrenia.

Sudden death and suicide: a comparison of brain weight

BACKGROUND

Recent evidence suggests that the brain weight of individuals over the age of 60 who commit suicide is significantly higher than in those who die of natural causes.

AIMS

To ascertain whether brain weight is different in people of a younger age who commit suicide than in those who die accidentally.

METHOD

A retrospective review of post-mortem reports collecting height, weight and brain weight in 100 suicide victims (87 males, mean age 38.5 years) and 100 age/gender-matched controls who died accidentally or of natural causes (87 males, mean age 38.7 years). Comparison by t-test was made of brain weight in isolation as well as brain weight corrected for height, weight and body mass index.

RESULTS

These results reveal no significant difference in brain weight in suicide cases compared to the general population (P > 0.05). The brain weight of those who died by hanging was significantly higher than of those who died by overdose.

CONCLUSIONS

Whatever the significant neuropsychiatric elements are that influence suicidal behaviour, they do not consistently affect brain weight in the population studied.

Hippocampal dysfunction in schizophrenia

Although not necessarily primary to the disease, hippocampal dysfunction in schizophrenia is suggested by morphological changes in the hippocampal formation reported in schizophrenic patients. This notion receives additional support from studies showing that 1) similar behavioral deficits are exhibited by both schizophrenics and animals with hippocampal lesions, and 2) some of these behavioral deficits are reversed by neuroleptics in both schizophrenics and lesioned animals. A brain-mapped neural network model is used to explain how some impairments in attention can be caused by hippocampal dysfunction and ameliorated by dopaminergic blockers.

Shape distortion of the hippocampus: a possible explanation of the pyramidal cell disarray reported in schizophrenia

The finding of pyramidal cell disarray in the hippocampus of patients with schizophrenia has been disputed by several groups. Conflicting results have been attributed to differences in the subtype of patients used, staining method, the side of the hippocampus studied and the way cellular disarray has been measured. In the present study, we correct for these confounds by using a well-defined population of schizophrenic patients (n = 14) and controls (n = 10) in which Golgi impregnated material was available. Measurements were performed manually according to the method of Kovelman and Scheibel (1984). Pyramidal cell disarray for the CA1/prosubicular interface indicated significant differences between patients and controls (p = 0.0183). The findings were attributed to a bias accrued to referencing measurements in schizophrenics to the distorted circumventricular surface of the temporal horn.

Amygdala volume in schizophrenia: post-mortem study and review of magnetic resonance imaging findings

BACKGROUND

Claims that schizophrenia is a disease of the limbic system have been strengthened by meta-analyses of magnetic resonance imaging (MRI) studies finding reduced hippocampus and amygdala volumes. Some post-mortem studies do not find these abnormalities.

AIMS

To assess the volume of the amygdala in a series of brains post-mortem.

METHOD

Amygdala volume was estimated using point-counting in both hemispheres of the brains of 10 male and 8 female patients with schizophrenia, and a comparison group of 9 males and 9 females.

RESULTS

No significant reduction of amygdala volume was found.

CONCLUSIONS

Significant volume reduction of the amygdala is not a consistent feature of schizophrenia; findings from early MRI studies using coarse delineation methods may introduce bias to subsequent meta-analyses.

The relationship between regional cerebral blood flow and the Wisconsin Card Sorting Test in negative schizophrenia

The purpose of this study was to explore the relationship between regional cerebral blood flow (rCBF) and problem-solving thinking in negative schizophrenia. Twenty-one negative schizophrenic patients and 12 normal controls were studied with single photon emission computed tomography (SPECT). Measures of regional cerebral blood flow (rCBF) were taken both at rest and during a prefrontal activation task using Wisconsin Card Sorting Test (WCST). Compared with controls, poor performances on the WCST of total trials category (TT), perseverative errors (PE) and non-perseverative errors (NE) were found in negative schizophrenic (P < 0.05). During WCST activation, patients showed interhemispheric differences in the prefrontal region, but under rest conditions, no such differences manifested. The negative schizophrenia group had a significantly lower rCBF change rate in profrontal lobe during stimulant WCST than those in normal controls (P < 0.05). The negative schizophrenic patient has executive function deficits and lower rCBF perfusion in left profrontal lobes, which suggest that the negative schizophrenic patient has dysfunction of the left profrontal region.

Structural brain abnormalities in patients with schizophrenia, epilepsy, and epilepsy with chronic interictal psychosis

Chronic interictal psychotic syndromes, often resembling schizophrenia, develop in some patients with epilepsy. Although widespread brain abnormalities are recognized as characteristic of schizophrenia, prevailing but controversial hypotheses on the co-occurrence of epilepsy and psychosis implicate left temporal lobe pathology. In this study, quantitative MRI methods were used to address the regional specificity of structural brain abnormalities in patients with epilepsy plus chronic interictal psychosis (E+PSY, n=9) relative to three comparison groups: unilateral temporal lobe epilepsy without chronic psychosis (TLE, n=18), schizophrenia (SCZ, n=46), and healthy control subjects (HC, n=57). Brain measures, derived from a coronal spin-echo MRI sequence, were adjusted for age and cerebral volume. Relative to HC, all patient groups had ventricular enlargement and smaller temporal lobe, frontoparietal, and superior temporal gyrus gray matter volumes, with the extent of these abnormalities greatest in E+PSY. Only TLE had temporal lobe white matter deficits, as well as smaller hippocampi, which were ipsilateral to the seizure focus. Structural brain abnormalities in E+PSY are not restricted to the left temporal lobe. The confluence of cortical gray matter deficits in E+PSY and SCZ suggests salience to chronic psychosis.

Medial temporal lobe in childhood-onset schizophrenia

The majority of anatomic and neuroimaging studies in adult-onset schizophrenia demonstrate decreased volumes of the medial temporal lobe when compared with findings in normal individuals. The goal of this study was to investigate the hypothesis that subjects with childhood-onset schizophrenia would show decreased volumes of the medial temporal lobe when compared to normal children. Thirteen children meeting DSM-III-R criteria for schizophrenia (mean age 14.2+/-3.8 years) and 20 normal children (mean age 12.0+/-2.8 years) were investigated. MRI scans were performed on a 1.5-T GE Signa MR scanner using a coronal plane SPGR at 1.4-mm slice thickness. Volumes were assessed by manually tracing bilateral hippocampus, amygdala and temporal lobes. After adjustment for age and total brain volume, the amygdala was significantly larger in the schizophrenics than in the control subjects, and this volume increase was more pronounced on the left side. Hippocampus volumes did not differ significantly across groups. There was a nearly significant left-greater-than-right asymmetry of the amygdala in the schizophrenic group but not in the normal group. A nearly significant right-greater-than-left asymmetry was found in the anterior hippocampus for both schizophrenic and control groups. These findings are consistent with previous reports of at least initial sparing of temporal lobe regions in childhood-onset schizophrenia.

MRI correlates of suicide attempt history in unipolar depression

BACKGROUND

Suicide represents a major health problem in the United States, and prediction of suicide attempts is difficult. No structural neuroimaging studies have been done to specifically examine findings in patients who have attempted suicide. The objective of this study was to compare MRI findings in unipolar patients with and without a history of a suicide attempt.

METHODS

In this post hoc analysis, 20 unipolar subjects with a history of a suicide attempt were matched by age and gender to unipolar subjects without a history of an attempt. Subjects were also matched on parameters such as cardiovascular history, electroconvulsive treatment history, and history of psychosis. Subjects with a history of any neurologic condition were excluded. There were no significant differences in age of onset of depression, number of episodes of depression, and Hamilton Depression scores between the two groups. T2-weighted magnetic resonance imaging (MRI) scans were rated using the Coffey and Boyko rating scales.

RESULTS

Unipolar patients with a history of a suicide attempt demonstrated significantly more subcortical gray matter hyperintensities compared with patients without such a history.

CONCLUSIONS

Patients with abnormal MRI findings may be at higher risk for mood disorders and suicide attempts because of disruption of critical neuroanatomic pathways. Gray matter hyperintensities in the basal ganglia may be especially associated with risk for suicide attempts.

A quantitative immunohistochemical study of astrocytes in the entorhinal cortex in schizophrenia, bipolar disorder and major depression: absence of significant astrocytosis

A number of macroscopic changes have been reported in the temporal lobe in schizophrenia. We have evaluated the density of glial fibrillary acidic protein (GFAP)-positive astrocytes in cortical layers 2 through 6 in the intermediate subarea of entorhinal cortex in two cohorts: the first, 15 cases, made up of schizophrenic (n = 7) and normal nonpsychiatric control subjects (n = 8), and the second, 56 cases, composed of schizophrenic (n = 14), bipolar disorder (n = 13), major depressive (n = 14) and normal control subjects (n = 15). No significant difference in density of GFAP-positive astrocytes was detected between the psychiatric diagnostic groups and the normal controls in either of the two cohorts. In both cohorts there was a positive correlation between increasing age and astrocytic density which reached statistical significance in only the larger cohort (r = 0.38, p = 0.004). Our results find no evidence for astrocytosis in the entorhinal cortex in several mental illnesses. Although other studies have reported macroscopic and other structural abnormalities in this region, we have not detected astrocytic proliferation, which is a typical hallmark of atrophy and/or progressive neuronal loss.

The neuropsychology and neuroanatomy of bipolar affective disorder: a critical review

Bearden CE, Hoffman KM, Cannon TD. The neuropsychology and neuroanatomy of bipolar affective disorder: a critical review. Bipolar Disord 2001: 3: 106 150. C Munksgaard, 2001

OBJECTIVES

To present a comprehensive review of the existing neuropsychological and neuroimaging literature on bipolar affective disorder. This review critically evaluates two common conceptions regarding the neuropsychology of bipolar disorder: 1) that, in contrast to schizophrenia, bipolar affective disorder is not associated with general cognitive impairment independent of illness episodes, and 2) relative right hemisphere (RH) dysfunction is implicated in bipolar illness patients, supported by reports of relatively greater impairment in visuospatial functioning, lateralization abnormalities, and mania secondary to RH lesions.

METHODS

The major computerized databases (Medline and PSYCInfo) were consulted in order to conduct a comprehensive, integrated review of the literature on the neuropsychology and neuroanatomy of bipolar disorder. Articles meeting specified criteria were included in this review.

RESULTS

In a critical evaluation of the above notions, this paper determines that: 1) while there is little evidence for selective RH dysfunction, significant cognitive impairment may be present in bipolar illness, particularly in a subgroup of chronic, elderly or multiple-episode patients, suggesting a possible toxic disease process, and 2) the underlying functional correlate of these cognitive deficits may be white matter lesions ('signal hyperintensities') in the frontal lobes and basal ganglia, regions critical for executive function, attention, speeded information processing, learning and memory, and affect regulation. While this hypothesized neural correlate of cognitive impairment in bipolar disorder is speculative, preliminary functional neuroimaging evidence supports the notion of frontal and subcortical hypometabolism in bipolar illness.

CONCLUSIONS

The etiology of the structural brain abnormalities commonly seen in bipolar illness, and their corresponding functional deficits, remains unknown. It is possible that neurodevelopmental anomalies may play a role, and it remains to be determined whether there is also some pathophysiological progression that occurs with repeated illness episodes. More research is needed on first-episode patients, relatives of bipolar probands, and within prospective longitudinal paradigms in order to isolate disease-specific impairments and genetic markers of neurocognitive function in bipolar disorder.

Cerebral gray and white matter reductions and clinical correlates in patients with early onset schizophrenia

Few magnetic resonance imaging studies of schizophrenia have investigated brain tissue volumes and their relation to clinical symptoms in patients with an early age at illness onset. The twofold purpose of the study was to investigate both gray and white matter volumes in schizophrenic men with an early age at illness onset, and to determine whether clinical features correlated with tissue volume changes, using an automated voxel-by-voxel image analysis procedure. Twenty male patients with DSM-IV diagnoses of schizophrenia, and an early age at onset (m+/-SD=19+/-2) were compared with 20 age-matched health men. Magnetic resonance (1.5-T) scans were obtained with an Inversion-Recovery prepared fast gradient echo sequence enhancing gray and white matter contrast. Statistical Parametric Mapping was used for image segmentation and comparison. Patients had significant gray matter reductions in medial frontal gyri, left insula, left parahippocampus, and left fusiform gyrus; bilateral white matter reductions in frontal lobes, and increased total cerebrospinal fluid volume were also observed. Negative symptom scores were negatively related to white matter volumes in cingulate regions, and in the right internal capsule. These findings emphasize a pattern of left-hemisphere gray matter abnormalities, and suggest that fronto-paralimbic connectivity may be altered in men with early onset schizophrenia.

Synaptophysin and GAP-43 mRNA levels in the hippocampus of subjects with schizophrenia

Synaptophysin and growth associated protein-43 (GAP-43) are synaptic proteins colocalized to the presynaptic terminal, and involved in regulating transmitter release and synaptic plasticity. Recent studies have proposed an alteration in the number of synapses in the brains of individuals with schizophrenia. As a corollary, we hypothesized that there may be an alteration in the level of mRNAs that code for synaptic proteins in brains of patients with schizophrenia. Using in situ hybridization, we investigated the levels of synaptophysin and GAP-43 mRNA in the medial temporal lobe of 10 normal subjects, 11 subjects with schizophrenia and 10 psychiatric control subjects. Synaptophysin mRNA levels were significantly reduced in several hippocampal subfields in both the schizophrenic and psychiatric control groups. GAP-43 mRNA levels were not significantly reduced in either group. The implications of these findings are discussed in relation to neuroleptic treatment and the pathophysiology of mental illness.