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

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)

Enlargement of the fornix in early-onset schizophrenia: a quantitative MRI study

Abnormalities of temporal lobe structure and frontal lobe function occur in schizophrenia. There have been few studies of young people with schizophrenia and little is known about temporo-frontal connectivity in the disease. Therefore, the cross-sectional area of the body of the fornix was measured on MR images from 17 young people with schizophrenia, nine with other serious psychiatric illnesses and eight without illness. The mean age of each group was 16-17 years. The mean cross-sectional fornix area in subjects with schizophrenia was significantly larger than that in subjects without illness ( approximately 40%) and psychiatric controls ( approximately 26%). There was no such significant difference between subjects without illness and psychiatric controls. The nature of the larger fornix in early-onset schizophrenia, whether it persists and whether it occurs in schizophrenia presenting in adulthood, remain to be elucidated.

Oxidative stress and role of antioxidant and omega-3 essential fatty acid supplementation in schizophrenia

1. Schizophrenia is a major mental disorder that has a lifetime risk of 1% and affects at young age (average age at the onset 24 +/- 4.6 years) in many cultures around the world. The etiology is unknown, the pathophysiology is complex, and most of the patients need treatment and care for the rest of their lives. 2. Cellular oxidative stress is inferred from higher tissue levels of reactive oxygen species (ROS, e.g., O2*-, OH*, OH-, NO* and ONOO--) than its antioxidant defense that cause peroxidative cell injury, i.e., peroxidation of membrane phospholipids, particularly esterified essential polyunsaturated fatty acids (EPUFAS), proteins and DNA. 3. Oxidative stress can lead to global cellular with predominantly neuronal peroxidation, since neurons are enriched in highly susceptible EPUFAs and proteins, and damages DNA is not repaired effectively. 4. Such neuronal peroxidation may affect its function (i.e., membrane transport, loss of mitochondrial energy production, gene expression and therefore receptor-mediated phospholipid-dependent signal transduction) that may explain the altered information processing in schizophrenia. 5. It is possible that the oxidative neuronal injury can be prevented by dietary supplementation of antioxidants (e.g., vitamins E, C and A; beta-carotene, Q-enzyme, flavons, etc.) and that membrane phospholipids can be corrected by dietary supplementation of EPUFAs. 6. It may be that the oxidative stress is lower in populations consuming a low caloric diet rich in antioxidants and EPUFAs, and minimizing smoking and drinking. 7. Oxidative stress exists in schizophrenia based on altered antioxidant enzyme defense, increased lipid peroxidation and reduced levels of EPUFAs. The life style of schizophrenic patients is also prooxidative stress, i.e., heavy smoking, drinking, high caloric intake with no physical activity and treatment with pro-oxidant drugs. 8. The patients in developed countries show higher levels of lipid peroxidation and lower levels of membrane phospholipids as compared to patients in the developing countries. 9. Initial observations on the improved outcome of schizophrenia in patients supplemented with EPUFAs and antioxidants suggest the possible beneficial effects of dietary supplementation. 10. Since the oxidative stress exists at or before the onset of psychosis the use of antioxidants from the very onset of psychosis may reduce the oxidative injury and dramatically improve the outcome of illness.

Evidence for a mitochondrial oxidative phosphorylation defect in brains from patients with schizophrenia

In-vivo imaging studies and post-mortem studies have demonstrated an impairment of energy metabolism in brains of patients with schizophrenia. Decreased oxidative metabolism has been consistently documented in the frontal lobes. However, the biochemical basis of these changes is unclear. The changes could be caused by reduced requirement of the cells for metabolic energy or an abnormality in energy generation. Neurons generate energy through the respiratory chain in the mitochondria. The respiratory chain consists of five enzyme complexes (I-V). The purpose of the present study was to assess mitochondrial function and test the hypothesis of an underlying oxidative phosphorylation defect in schizophrenia. We analysed spectrophotometrically post-mortem brain specimens of frontal cortex, temporal cortex, basal ganglia, and cerebellum of 12 patients who met the DSM-IV criteria for schizophrenia and of 13 healthy controls for the specific activities of respiratory chain enzymes in the mitochondria. The major finding was that the activity of complex IV was significantly reduced in the frontal cortex (40.9+/-6.7 vs. 87.3+/-12, P=0.003) and in the temporal cortex (39.5+/-6.8 vs. 78+/-10.8, P=0.006) of schizophrenics. In addition, the activity of complexes I+III was significantly reduced in the temporal cortex (2.2+/-0.6 vs. 4.4+/-0.5, P=0.01) and basal ganglia (1.6+/-0.5 vs. 3.4+/-0.3, P=0.015) in schizophrenia. All other enzyme activities showed no differences to healthy controls. The results confirm a defect of oxidative phosphorylation in brains from patients with schizophrenia, which may contribute to impaired energy generation.

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.

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

OBJECTIVES

Compare MRI scans of patients with late-onset schizophrenia, late-life depression and late-life bipolar disorder to age- and gender-matched controls. MRI head scans of 14 patients in each diagnostic group and 21 patients in the normal control group were compared. Subjects were recruited from inpatient and outpatient services.

MEASURES

The CERAD MRI rating algorithm was used to rate degree of atrophy.

RESULTS

Patients with bipolar and unipolar disorder had greater left sylvian fissure and left and right temporal sulcal enlargement, and more bilateral cortical atrophy than normals. Patients with late-onset schizophrenia had larger right temporal horns and larger third ventricles. These findings validate the distinctions between late-life affective disorder and late-onset schizophrenia and mirror changes reported in younger individuals. They may reflect underlying structural and functional abnormalities found in neuropathologic and functional imaging studies.

Brain weight in suicide. An exploratory study

BACKGROUND

There is little available literature on the effect of suicide methods on brain weight.

AIMS

To explore variations in post-mortem brain weight in different methods of fatal self-harm (FSH) and in deaths from natural causes.

METHOD

A review of a sample of coroners' records of elderly persons (60 and above). Verdicts of suicide, misadventure and open verdicts were classified as FSH. Post-mortem brain weight for 142 FSH victims and 150 victims of unexpected, sudden or unexplained death due to natural causes, and from various methods of FSH, were compared.

RESULTS

Brain weight of victims of FSH was significantly higher than of those who died of natural causes (P < 0.01); brain weights in both groups were within the normal range for this age group. There was no significant difference in brain weight between different methods of FSH (P > 0.05).

CONCLUSIONS

The findings require critical examination and further research, to include data from younger age groups. A regional or national suicide neuropathological database could be set up if all victims of FSH underwent routine neurohistochemical post-mortem examination.

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.

Cerebral ventricular enlargement as a generalized feature of schizophrenia: a distribution analysis on 502 subjects

Enlargement of cerebral ventricles is one of the most replicated biological features, and the one quantitatively most deviant in schizophrenia. It occurs in the early phases of the disease and may have pathogenetic relevance. Whether this abnormality is limited to a specific subgroup of patients or is a common feature to most or all patients affected by schizophrenia, however, is still a matter of debate. The answer to this question would improve our comprehension of the nature of this abnormality and contribute to the debate between the competing hypotheses of biological homogeneity vs heterogeneity of schizophrenia.We performed a distribution analysis of lateral ventricular dimensions of 340 schizophrenic patients and 162 non-psychiatric controls. All subjects underwent cerebral computerized tomographic scan, and ventricular dimensions were expressed as ventricular brain ratio (VBR). After removing the effect of confounding variables (age, sex and type of scanner) on individual VBR, data were power-transformed and different distribution hypotheses were tested by means of the maximum log-likelihood ratio method. Our findings indicate that, in the mixed sample of patients and controls, a mixture of two gaussian curves represents the distribution better than a single gaussian curve, but no evidence emerged leading to rejection of the normality hypothesis in the schizophrenic patients sample. Lateral ventricular enlargement in schizophrenia is not a marker of a discrete subgroup of schizophrenia, but occurs in most, if not all, schizophrenic patients. This supports the hypothesis of biological homogeneity of the disease, at least relative to its major brain morphological abnormality.

Properties of entorhinal cortex projection cells to the hippocampal formation

There are multiple connections from the entorhinal cortex (EC) to the hippocampus that carry the information from the EC to the hippocampus. Layer II cells of the medial EC innervating the dentate gyrus (DG)-molecular layer possess K(+)-outward currents and inward rectifier currents that are potentially modulated by changes in intracellular second messengers. Layer II cells responded to synaptic stimulation with a rather flat input-output curve, and much stronger stimuli are required to generate action potentials in these neurons than in EC layer III cells. During repetitive stimulation at frequencies of 10 Hz and more, EC layer II cells respond with increased likelihood to generate action potentials. Two different NMDA conductances can be demonstrated in these neurons. A slow, less Mg, less voltage-dependent component is responsible for the transient depolarization between the fast and slow IPSP. A second group of neurons also projects to the DG. These are either pyramidal or nonpyramidal cells in the deep layers of the EC. At least part of these neurons also possess rhythmogenic properties. In contrast to layer II cells, layer III neurons have a steep input-output curve and show during repetitive synaptic activation a tendency to repolarize and to display long-lasting inhibitions dependent on GABAB-, atropine-, and naloxone-sensitive components. As a consequence, they are readily activated during low frequency stimulation, but project only a few action potentials to area CA1 initially during higher (more than 10 Hz) frequency synaptic stimulation.

Molecular effects of the psychotropic NMDA receptor antagonist MK-801 in the rat entorhinal cortex: increases in AP-1 DNA binding activity and expression of Fos and Jun family members

Noncompetitive NMDA receptor antagonists such as phencyclidine and MK-801 produce psychotropic symptoms that closely resemble schizophrenic psychosis and induce the expression of immediate early genes in limbic cortical areas. We are concentrating on analyzing molecular and physiological effects that these drugs produce in the entorhinal cortex and on the potential connection between these effects and the psychotic symptoms. We show here that MK-801 increases the DNA binding activity of the activator protein-1 (AP-1) complex in the entorhinal cortex. We also observed increased expression of mRNAs for Fos and Jun transcription factor family members c-Fos, FosB, Fra-2, and JunB, as well as Fos family proteins in the entorhinal cortex after MK-801 administration. This suggests that the activated AP-1 complex consists of these transcription factors. Genes regulated by the AP-1 complex in the entorhinal cortex might be involved in the pathophysiology of psychotic behavior and are potential targets for new antipsychotic drugs.

Cellular and molecular neuropathology of the parahippocampal region in schizophrenia

The entorhinal cortex, subiculum, and hippocampus have been regions of great interest in both clinical and neuropathological investigations of schizophrenia. Postmortem studies have identified numerous abnormalities, although many remain controversial or unconfirmed. Among the cellular and molecular neuropathological findings are (1) abnormal cytoarchitecture of the entorhinal cortex characterized by poorly formed layer II neuron clusters and laminar disorganization; (2) normal neuron density but smaller neuron size in the superficial lamina of the entorhinal cortex and subiculum; (3) abnormal expression of the microtubule-associated protein MAP2 in the entorhinal cortex and subiculum; (4) aberrant glutamatergic and catecholaminergic innervation of the entorhinal cortex; (5) abnormal mRNA expression of various transcription factors, ion channels, and neurosecretory pathway-related proteins in entorhinal stellate neurons; and (6) an absence of any neurodegeneration. Altogether, these findings suggest that aberrant neurodevelopmental processes play a key role in the pathobiology of schizophrenia and provide a neuroanatomic basis for understanding many of the clinical and neuropsychological abnormalities in the disorder.

Neonatal lesions of the left entorhinal cortex affect dopamine metabolism in the rat brain

The present study was performed to determine the effects of neonatal excitotoxic lesions of the left entorhinal cortex on dopamine (DA) metabolism and release in limbic regions of the rat brain. Quinolinic acid or phosphate buffered saline was infused into the left entorhinal cortex of rat pups on postnatal day 7 (PD7). Concentrations of DA,3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the lateral amygdala, nucleus accumbens, caudate-putamen, and medial prefrontal cortex were determined in the postmortem brains of lesioned and sham-operated rats on PD35 and PD56. On PD35, concentrations of DA in the bilateral lateral amygdala and HVA in the left lateral amygdala were significantly increased in lesioned rats compared with sham-operated animals, while no significant change was observed in the other three brain areas. On PD56, in addition to the increased concentration of DA in the left lateral amygdala, those of DA, DOPAC and HVA in the caudate-putamen, and DA in the nucleus accumbens were found to be increased, but DA concentrations in the right medial prefrontal cortex were decreased. The DOPAC/DA concentration ratio was, however, decreased in the amygdala and nucleus accumbens of the lesioned rats. In an in vivo microdialysis study, methamphetamine (MAP: 2 mg/kg, i.p.)-induced DA release in the amygdala of lesioned rats was significantly enhanced compared with sham-operated rats on both PD35 and PD56. There were no significant differences in MAP-induced DA release in the caudate-putamen between the sham-operated and lesioned rats at any time point. These findings provide evidence that neonatally induced structural abnormalities in the entorhinal cortex affect DA transmission in the limbic regions at the adolescent stage.

Invited commentary on: functional anatomy of verbal fluency in people with schizophrenia and those at genetic risk. The genetics of asymmetry and psychosis

Spence et al (2000, this issue) describe an original and incisive approach to the genetics of psychosis – an attempt to define brain connectivity in patients and family members closest to the genetic risk (‘obligate carriers’) by comparison with those remote from familial risk. Their findings are potentially important but I suggest an alternative interpretation: that words are simply less lateralised in those genetically predisposed to suffer from schizophrenic symptoms. This conclusion has, I believe, implications for understanding the organisation of the human brain.

Changes in adult brain and behavior caused by neonatal limbic damage: implications for the etiology of schizophrenia

We tested the hypothesis that limbic damage in early development can cause aberrant maturation of brain structures known to be abnormal in adult schizophrenics: the hippocampus, prefrontal cortex, ventricles, and forebrain dopamine systems. We measured brain morphology, locomotor response to apomorphine, and cognitive processes in adult rats which received electrolytic damage to amygdala or hippocampus 48 h after birth. The behavioral measurements involved tasks which depend upon the integrity of the hippocampus or prefrontal cortex, and a task sensitive to forebrain dopamine system activation. The tasks included place navigation, egocentric spatial ability, and apomorphine-induced locomotion. The rats with lesions showed poor performance on the place navigation and egocentric spatial tasks and more apomorphine-induced locomotion after puberty than the sham lesion group. Regardless of lesion location, the adult rats showed smaller amygdalae and hippocampi, and larger lateral ventricles. Analyzing the lesion and sham rats together, adult amygdala volume was found to be positively correlated with cerebral cortex, prefrontal cortex, and hippocampal volumes and place navigation performance, and was negatively correlated with lateral ventricle volume. This study contributes to our understanding of the pathogenesis of schizophrenia by showing that early damage to limbic structures produced behavioral, morphological, and neuropharmacological abnormalities related to pathology in adult schizophrenics.

Interruptions of early cortical development affect limbic association areas and social behaviour in rats; possible relevance for neurodevelopmental disorders

Deficits in social behaviour are found in several neuropsychiatric disorders with a presumed developmental origin. Adequate social behaviour may rely importantly on the associative integration of new stimuli with previously stored, related information. The limbic allocortex, in particular the entorhinal region, is thought to support this kind of processing. Therefore, in the present study, gestating dams were treated with methylazoxymethanol acetate (MAM) on one of gestational days nine to twelve, to interrupt neuronal proliferation in the entorhinal region of the developing foetuses. Effects of prenatal MAM administration on social behaviour were evaluated in adult animals. As the entorhinal cortex has been implicated by some studies in spatial memory, effects on this function were also investigated. Following the behavioural studies, brain morphology was screened for effects of MAM. Our results show moderate to severe social impairment in MAM-treated animals, depending on the exact timing of prenatal exposure. By contrast, spatial reference and working memory were not importantly affected in any group. Analysis of brain morphology in the MAM-treated offspring supported maldevelopment of the entorhinal cortex and revealed mild abnormalities also in some connected limbic and limbic affiliated structures, such as the perirhinal and ectorhinal cortex, the anterior cingulate cortex and the medial septum-diagonal band region. Findings are discussed with respect to entorhinal cortex function, and with regard to their relevance for psychiatric disorders with a putatively neurodevelopmental pathogenesis, such as schizophrenia.

Is the course of brain development in schizophrenia delayed? Evidence from onsets in adolescence

A degree of ventricular enlargement, together with a reduction of total cortical mass and loss of asymmetry is reported in schizophrenia, but the meaning is obscure. These changes may reflect an anomaly of brain development. Brain structure was assessed on a 1.5-Tesla MRI scan in a series of 29 adolescents at the time of a first episode of schizophrenia and compared with 15 adolescents with other serious psychiatric disturbance (mostly psychotic) and 20 normal adolescent controls. The age at scan ranged between 13 and 20 years. In the adolescents with a diagnosis of schizophrenia, total brain volume increased with age in a way that differed significantly (p=0.007) from that seen in patients with other psychiatric disturbance and normal controls. Thus, brain growth, as assessed by this index, had reached a plateau in the control group by the age of 13 years, but this was not true of patients with schizophrenia. The measure that most clearly distinguished the groups (p<0.001 after co-varying for height and sex) was the volume of the left lateral ventricle the ventricle was significantly larger in patients with schizophrenic illness, and ventricular size increased with age to a greater extent in the patient group, although not significantly so, than in normal controls. Thus, aspects of brain growth are delayed in patients with early onset schizophrenia, and the greatest severity of illness is reflected in a component of growth that is lateralized to the dominant hemisphere. Individuals who develop serious psychiatric illness, including schizophrenia, represent a fraction of the population in whom a component of the relative development of the cerebral hemispheres occurs late.

Subtype-associated metabolite differences in the temporal lobe in schizophrenia detected by proton magnetic resonance spectroscopy

Brain imaging studies have indicated that the medial temporal lobe functions aberrantly in schizophrenic patients. Both diagnostic subtype and gender may affect functional and morphologic abnormalities in this region. We investigated subtype- and gender-associated differences in metabolites in the left medial temporal lobe in 40 medicated schizophrenic patients by proton magnetic resonance spectroscopy and compared findings with those in 40 healthy control subjects. Peaks corresponding to N-acetylaspartate (NAA), choline-containing compounds (Cho), creatine-phosphocreatine (Cr), and inositol were measured. Schizophrenic patients showed a decrease in the NAA/Cr ratio in the left medial temporal lobe, and patients with the disorganized subtype of illness showed significantly lower NAA/Cr and Cho/Cr ratios than those with paranoid schizophrenia. The NAA/Cr ratio in patients with the undifferentiated subtype also was significantly lower than in the paranoid subtype. No significant associations were observed between metabolite ratios and clinical symptom scores, age at onset of illness, or gender. These findings suggest that patients with the disorganized and undifferentiated subtypes have greater impairments in neuronal integrity or function in the left medial temporal lobe than patients with other subtypes of schizophrenia.

Commentary on Annett, Yeo et al., Klar, Saugstad and Orr: cerebral asymmetry, language and psychosis--the case for a Homo sapiens-specific sex-linked gene for brain growth

Annett, Yeo et al. and Klar have each proposed theories that relate the genetics of cerebral lateralization to predisposition to psychosis. These theories are considered in relation to the central paradox that psychosis is associated with a substantial biological disadvantage. Annett's heterozygote advantage hypothesis critically identified lateralization as a major determinant of ability, but it appears that what is inherited is degrees (as suggested by Yeo et al.) rather than (or as well as) direction of lateralization. Relative hand skill has been shown (Crow, T.J., Crow, L.R., Done, D.J., Leask, S.J., 1998. Relative hand skill predicts academic ability: global deficits at the point of hemispheric indecision. Neuropsychologia 36, 1275-1282.) to be a powerful predictor (interacting with sex) of academic ability but the greatest region of vulnerability (that includes reading disability and predisposition to psychosis) is close to the point of equal hand skill ('hemispheric indecision'). In contrast with Annett's single locus, Yeo's polygenic and Klar's strand-segregation hypotheses, each of which postulates an autosomal locus or loci, the hypothesis of a single gene for asymmetry located in a sex-specific region of homology on both X and Y chromosomes can account for sex differences, as observed in age of onset, and premorbid precursors of psychosis, as well as differences in the general population in relation to degrees of hand skill, verbal ability and cerebral asymmetry. The evolutionarily recent transposition to, and subsequent paracentric inversion in, the Y chromosome short arm of a 4-Mb block from Xq21.3 (the proximal long arm of the X) are candidates for speciation events in the lineage that led to Homo sapiens. A gene associated with a range of variation (that may be due to a high mutation site, or perhaps to epigenetic modification) on the Y that overlaps with, but differs quantitatively from, that on the X may explain the sex differences associated with psychosis, and may be relevant to its persistence. Such a gene could be the principal determinant in Man of the rate of brain growth, as suggested by Saugstad and by the findings of a recent study of adolescent onset psychosis (James, A., Crow, T.J., Renowden, S., Wardell, M., Smith, D.M., Anslow, P., in press. Is the course of brain development in schizophrenia delayed? Evidence from onsets in adolescence. Schizophr. Res.).

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.

Schizophrenia and temporal lobe asymmetry. A post-mortem stereological study of tissue volume

BACKGROUND

A previous report by Crow of a left-sided increase in temporal horn volume in schizophrenia implies a left-sided loss of tissue.

AIMS

To elucidate the structural nature of schizophrenia.

METHOD

The volume of grey matter in the temporal pole and inferior, middle and superior temporal gyri was measured, in addition to the total volume of grey and white matter, in the temporal lobes of the brains of 29 patients with schizophrenia and 27 controls.

RESULTS

We found a significant left-sided reduction in the superior temporal gyrus in both males and females with schizophrenia, which was related to increasing age of onset in the males. The total volume of temporal lobe grey and white matter was also significantly reduced. Although being more marked on the left than the right, the lateralisation for these total grey and white measures (by contrast with the superior temporal gyrus alone) did not attain formal statistical significance.

CONCLUSIONS

Confirmation of a lateralised reduction in the superior temporal gyrus, which is differentially related to age of onset according to gender, adds to evidence that the changes in schizophrenia are in systems that are lateralised. The findings implicate language as the relevant function.

Prenatal ethanol effects on NGF level, NPY and ChAT immunoreactivity in mouse entorhinal cortex: a preliminary study

It has been reported that maternal ethanol consumption leads to deficits in the limbic areas involved in cognitive functions and interferes with synthesis and utilization of neurotrophins. In the present study, it was hypothesized that prenatal alcohol intake might induce neuroanatomical alterations in the entorhinal cortex (EC). We also investigated the possible EC involvement of brain nerve growth factor (NGF), the first neurotrophin to be isolated, during such pathological events. To test this hypothesis, we used pregnant mice exposed to ethanol during EC neurogenesis (starting about gestational day 8). Our data show that prenatal alcohol intake in male mice alters the EC neuronal growth and differentiation. These morphological alterations are accompanied by an altered NGF level in the EC of prenatal alcohol-treated mice. We also found a decrease in choline acetyltransferase- and neuropeptide Y-immunopositive neurons in the EC of alcohol-exposed mice. However, the relationship between neuronal damage induced in the EC by ethanol, low presence of NGF, and the possible functional and behavioral consequences remains to be elucidated.

Prenatal methylazoxymethanol acetate alters behavior and brain NGF levels in young rats: a possible correlation with the development of schizophrenia-like deficits

It has been hypothesized that a deleterious key contribution to schizophrenia (SZ) development is a failure of migration and setting of young neurons into their appropriate cortical target sites, particularly in the entorhinal cortex (EC). To test this hypothesis in an animal model, we injected, in pregnant rats, on gestational day (GD) 9, or 10, or 11, or 12, the antimitotic compound methylazoxymethanolacetate (MAM) known to cause EC neuronal loss. We investigated whether or not EC disruption during prenatal development is able to affect behavior, including memory and learning, and brain nerve growth factor (NGF). Prenatally MAM treated young rats didn't display gross behavioral changes in social interaction, open-field and novel object investigation tests. By contrast, GD11 and GD12 MAM treated rats had a retardation in passive avoidance acquisition, while, in GD12 animals, pain sensitivity was reduced. GD12 animals also showed increased NGF in the EC and remaining cortex. MAM treated animals showed no changes in paw NGF or substance P levels suggesting that the altered nociceptive response is not related to local downregulation of these two molecules. The possibility that these behavioral and biochemical alterations might be associated with the onset of SZ is discussed.

Reduction of the parahippocampal gyrus and the hippocampus in patients with chronic schizophrenia

BACKGROUND

There have been many studies reporting reduced volume of the hippocampus or other limbic structures in patients with schizophrenia, but the literature is inconsistent.

AIMS

To compare patients with either first-episode or chronic schizophrenia with controls using high-resolution volumetric magnetic resonance imaging (MRI) scans.

METHOD

Thirteen patients with first-episode schizophrenia, 27 with chronic schizophrenia and 31 controls had 1.5 mm coronal slices taken through the whole brain using a spoiled-grass MRI acquisition protocol.

RESULTS

The parahippocampal gyrus was reduced significantly on the left side in patients with chronic schizophrenia compared with controls for both male and female patients, whereas the hippocampus was reduced significantly on both sides only in female patients. There were no significant reductions in any structure between patients with first-episode schizophrenia and controls.

CONCLUSIONS

Volumetric reduction seen in patients with chronic schizophrenia may be due to an active degenerative process occurring after the onset of illness.

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.

The size and fibre composition of the corpus callosum with respect to gender and schizophrenia: a post-mortem study

In this study the cross-sectional area (in n = 14 female controls, 15 male controls, 11 female patients with schizophrenia, 15 male patients with schizophrenia) and fibre composition (in n = 11 female controls, 10 male controls, 10 female patients with schizophrenia, 10 male patients with schizophrenia) of the corpus callosum in post-mortem control and schizophrenic brains was examined. A gender x diagnosis interaction (P = 0.005) was seen in the density of axons in all regions of the corpus callosum except the posterior midbody and splenium. Amongst controls, females had greater density than males; in patients with schizophrenia this difference was reversed. A reduction in the total number of fibres in all regions of the corpus callosum except the rostrum was observed in female schizophrenic patients (P = 0.006; when controlling for brain weight, P = 0.053). A trend towards a reduced cross-sectional area of the corpus callosum was seen in schizophrenia (P = 0.098); however, this is likely to be no more than a reflection of an overall reduction in brain size. With age, all subregions of the corpus callosum except the rostrum showed a significant reduction in cross-sectional area (P = 0.018) and total fibre number (P = 0.002). These findings suggest that in schizophrenia there is a subtle and gender-dependent alteration in the forebrain commissures that may relate to the deviations in asymmetry seen in other studies, but the precise anatomical explanation remains obscure.

The reduced neuropil hypothesis: a circuit based model of schizophrenia

In recent years, quantitative studies of the neuropathology of schizophrenia have reignited interest in the cerebral cortex and focused attention on the cellular and subcellular constituents that may be altered in this disease. Findings have ranged from compromised circuitry in prefrontal areas to outright neuronal loss in temporal and cingulate cortices. Herein, we propose that a reduction in interneuronal neuropil in the prefrontal cortex is a prominent feature of cortical pathology in schizophrenia and review the growing evidence for this view from reports of altered neuronal density and immunohistochemical markers in various cortical regions. The emerging picture of neuropathology in schizophrenia is one of subtle changes in cellular architecture and brain circuity that nonetheless have a devastating impact on cortical function.

Alteration of dopamine metabolites in CSF and behavioral impairments induced by neonatal hippocampal lesions

Alterations of monoamine metabolites in CSF and behavioral abnormalities were studied in rats with neonatal hippocampal lesions and controls. Lesions of the ventral hippocampus were produced bilaterally by ibotenic acid on postnatal day 7. Lesion-induced neurochemical alterations and behavioral impairments were examined concurrently when rats were 12 weeks old. CSF from the cisterna magna was sampled repeatedly from freely moving rats. The levels of free 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in CSF were determined. An exposure to a novel environment induced hyperexploratory behavior and elevated the level of free DOPAC in CSF in lesioned rats. Although a swim stress increased the levels of free DOPAC and 5-HIAA in CSF in both control and lesioned groups, rats with hippocampal lesions had a further elevation of free DOPAC in CSF and greater spontaneous activity relative to controls shortly after stress. Amphetamine (1.5 mg/kg, i.p.) induced hyperlocomotion in lesioned rats compared to controls. For the control group, the levels of the three monoamine metabolites in CSF were not significantly influenced by amphetamine. However, for the lesioned group, the level of DOPAC significantly decreased compared to preinjection of amphetamine. The results indicate that neonatal hippocampal lesion-induced impairments can be manifested by behavioral and neurochemical abnormalities. Alterations of monoamine metabolites in CSF may be determined quantitatively and used as indices for monitoring lesion-impaired monoaminergic function in the central nervous system.

Forgetting rates in neuropsychiatric disorders

OBJECTIVE

Previous studies have attributed accelerated forgetting rates on recognition memory tasks to temporal lobe pathology, but findings in some patient groups may have been attributable to metabolic disruption. Findings in psychiatric disorders such as schizophrenia are conflicting. The purpose of the present study was to compare forgetting rates in patients with confusional states (post-electroconvulsive therapy (post-ECT), delirium), with those obtained in schizophrenic patients (with putative temporal lobe pathology), non-ECT depressed patients, and healthy controls. The findings could also be compared with previous reports in patients with head injury, focal structural lesions, and Alzheimer's dementia.

METHODS

Two studies employed a picture recognition task to examine forgetting rates, the first between delays of 1 minute, 15 minutes, and 30 minutes, and the second between delays of 10 minutes, 2 hours, and 24 hours.

RESULTS

There were no significant differences in forgetting rates between 1 minute and 30 minutes, but the ECT group showed accelerated forgetting between 10 minutes and 2 hours compared with healthy controls, associated with a rapid decline in "hit rate". This was not attributable to differential changes in either depression or severity of memory impairment. There were no differences in forgetting rates across the other subject groups.

CONCLUSION

Post-ECT confusional state patients (similarly to "within post-traumatic amnesia" patients with head injury) show accelerated forgetting on a recognition memory task and, in this, they contrast with patients who have focal structural lesions or widespread cortical atrophy. Accelerated forgetting may reflect the effect of disrupted cerebral metabolism on either "consolidation" or memory "binding" processes.

In vivo neurochemistry of the brain in schizophrenia as revealed by magnetic resonance spectroscopy

Magnetic resonance spectroscopy (MRS), an application of the methods of nuclear magnetic resonance (NMR), is a functional imaging modality that provides a view of localized biochemistry in vivo. A number of studies applying MRS to the neurochemistry of schizophrenia have been reported, which encompass a range of patient populations, states of medication, anatomic regions, nuclear species, and MRS techniques. A brief review of the history and methodology of NMR and MRS is presented. Comparison is made of MRS capabilities with other functional imaging modalities. Aspects of the neurochemistry of schizophrenia relevant to MRS studies are reviewed, as are the reported MRS studies involving patients with schizophrenia. Areas of consistent findings include decreased phosphomonoesters and increased phosphodiesters in frontal lobes, and decreases in the putative neuronal cell marker, N-acetylaspartate, in temporal lobes. Studies of neurotransmitters such as glutamate, gamma-aminobutyric acid, and glutamine have generated inconsistent results. New insights into alterations in neurochemistry in schizophrenia have been provided by MRS. Studies of neurotransmitters have future potential with improvements in field strength and in spectral editing techniques. MRS has the potential to measure brain medication levels and simultaneous effects on neurochemistry. MRS may assist in characterizing high-risk populations, and ultimately guide medication use.

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.

Left nostril olfactory identification impairment in a subgroup of male patients with schizophrenia

Abnormal structural brain asymmetries have been reported in schizophrenia in brain areas which overlap with olfactory processing regions, with abnormalities more often described within the left hemisphere. We attempted to determine whether the olfactory agnosia observed in some male patients with schizophrenia was more likely left-hemisphere based. We assessed unirhinal (single nostril) olfactory identification and detection threshold in 65 male patients who met DSM-IV criteria for the diagnosis of schizophrenia and 59 healthy male control subjects. A two-way, mixed-design ANCOVA with diagnosis as the between-group factor, nostril as the within-subject factor and age as covariate was used to compare olfactory identification ability. This analysis demonstrated that patients with schizophrenia performed more poorly than the healthy controls across nostrils, but no differences were observed in either group between nostrils. However, when patients were classified according to unirhinal olfactory status (impaired left < right, impaired right < left, normosmic left < right, normosmic right < left), impaired patients were more than twice as likely to be classified as having a left nostril disadvantage than right nostril disadvantage. In contrast, within the normosmic group of patients, this pattern was reversed. Moreover, when those patients whose unirhinal olfactory scores differed by less than two points were removed from the analysis, a 2:1 ratio of left < right versus right < left was observed in the impaired patients. These results suggest that for impaired male patients with schizophrenia, olfactory identification deficits are more likely found for the left nostril, perhaps indicative of abnormalities in olfactory processing within the left hemisphere.

Ventricular enlargement in poor-outcome schizophrenia

BACKGROUND

A subset of patients with schizophrenia, defined on the basis of longitudinal deficits in self-care, may show a classic ("Kraepelinian") degenerative course. An independent validator of the phenomenologically defined Kraepelinian subtype might be provided by a structural indicator of possible brain degeneration: ventricular size as measured by computed tomography (CT).

METHODS

To examine whether Kraepelinian patients would show a differential increase in ventricular size over time, two CT scans were conducted at intervals separated by > 4 years, an average of 5 years. Fifty-three male patients with DSM-III-R diagnoses of chronic schizophrenia were subdivided into Kraepelinian (n = 22; mean age = 42 +/- 6 years) and non-Kraepelinian (n = 31; mean age = 38 +/- 12.2 years) subgroups. Kraepelinian patients were defined on the basis of longitudinal criteria: > 5 years of complete dependence on others for life necessities and care, lack of employment, and sustained symptomatology. Thirteen normal elderly volunteers (mean age = 60 +/- 17.8) were also scanned at 4-year intervals. CT measurements were made by raters without knowledge of subgroup membership. A semiautomated computer program was used to trace the anterior horn, lateral ventricles, and temporal horns for each slice level on which they were clearly seen.

RESULTS

The ventricles showed a bilateral increase in size over the 4-year interval in the Kraepelinian subgroup, more marked in the left hemisphere than the right. By contrast, neither the non-Kraepelinian subgroup nor the normal volunteers showed significant CT changes from scan 1 to scan 2.

CONCLUSIONS

Thus, the longitudinal dysfunctions in self-care that characterize the Kraepelinian patients were associated with an independent indicator of brain abnormality.

Methylazoxymethanol acetate-induced abnormalities in the entorhinal cortex of the rat; parallels with morphological findings in schizophrenia

It has been suggested repeatedly that the non-heritable factors in the pathogenesis of schizophrenia involve abnormalities of prenatal neurodevelopment. Furthermore, post-mortem studies show neuropathology of apparently developmental origin in the entorhinal cortex and other brain regions of schizophrenic subjects. In an attempt to model a developmental defect of the entorhinal region in the rat, cerebrocortical proliferation was briefly interrupted during its earliest stages, when the entorhinal area is thought to undergo major cell division. Specifically, the experimental set-up involved the administration of methylazoxymethanol acetate (MAM) on 1 of 4 consecutive days of embryonal development, from E9 to E12. Analysis of the forebrain in adult animals shows reduction of the entorhinal cortex in rats treated on each of these days. This effect shifts from lateral to medial divisions of the entorhinal cortex with later administration of MAM, following a known developmental gradient. Morphological consequences of MAM administration appear to be largely confined to the entorhinal cortex in the groups treated on E9 to E11, although slight reductions of the frontal and occipital neocortex were also observed in these animals. MAM treatment on E12 produces relatively more widespread damage, as reflected among other in a small reduction of brain weight. The described brain abnormalities are not accompanied by obvious phenotypical changes in any, but the E12-treated group. They, moreover, involve cortical thinning, disorganised cortical layering, and abnormal temporal asymmetries. These finding bare some similarity to observations in brains of schizophrenic subjects. The possible relevance of this approach in modeling neurodevelopmental aspects of schizophrenia is discussed.

Chemical and physiologic brain imaging in schizophrenia

Technologic advances in functional brain imaging have provided exciting and informative insights into the functional neuroanatomy and neurochemistry of schizophrenia. Using MR spectroscopy, it has been possible to examine in vivo brain metabolism and to relate observed changes to physiological processes occurring at a cellular level. Positron emission tomography and single photon emission computed tomography have revealed disturbances of cerebral blood flow and glucose metabolism in patients with schizophrenia. More recently, these tools have also proved most useful in studying the relative receptor occupancy of typical and atypical antipsychotic medications.

The neuroanatomy and neurochemistry of schizophrenia

Substantial progress, in part owing to recent refinements in methodology, has been made in unraveling the anatomic correlates of schizophrenia. Subtle pathomorphologic changes, distinct from those of well-known degenerative brain disorders, have been observed. Neurochemical characterization has illuminated the nature of these morphologic abnormalities and has pointed to complex dysregulation of neurotransmitters and G proteins. New biochemical hypotheses such as the glutamate hypothesis have replaced and revitalized more established concepts in the neurochemistry of schizophrenia.

Asymmetrical changes in the fodrin alpha subunit in the superior temporal cortices in schizophrenia

BACKGROUND

We examined possible abnormalities in neural structural proteins that may underlie morphometric changes reported in the left superior temporal cortices (Brodmann's area 22) of schizophrenics.

METHODS

Particulate proteins of the superior temporal cortices taken at autopsy from 11 schizophrenic and 9 control brains were fractionated by gel electrophoresis. Target proteins, identified by reading their amino acid sequences, were immunoquantified using the specific antibody.

RESULTS

Amino acid sequences of the 150-kDa proteins on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, which were significantly increased on the left side of schizophrenic superior temporal cortices, revealed that they were proteolytic fragments of the alpha subunit of fodrin, a major cytoskeletal protein underlying the plasma membrane. Immunoquantification using the specific antibodies against alpha and beta subunits of fodrin indicated that there exist concomitant decreases in the full-length 240-kDa form and increases in the 150-kDa form of alpha-fodrin with no changes of the 235-kDa form of beta-fodrin in the left superior temporal cortices of the schizophrenic brains.

CONCLUSIONS

The findings may be a possible molecular basis for linking morphometric changes to neurochemical pathophysiology in schizophrenia.

Neuropathology of suicide. A review and an approach

Neuropathology is one approach to the effort to elucidate the pathophysiology of suicide. Initial neurochemical studies focusing on the roles of serotonin (5-HT) and noradrenaline (NE) abnormalities in brains of suicide victims have been somewhat inconsistent. More recently developed methodologies, including quantitative receptor autoradiography, immunoblotting, immunohistochemistry, cell morphometry, in situ hybridization, Northern analysis, solution hybridization/RNase protection assay, reverse transcriptase polymerase chain reaction, and genotyping, which have already been applied successfully in studies of other disorders of brain structure or function, are now increasingly being adopted for postmortem studies of suicide. These new strategies are adding convergent evidence for brain 5-HT and NE dysfunction in the etiology of suicide susceptibility, refining the neuroanatomical localization of this dysfunction, and in addition, implicating heretofore unsuspected candidate neurotransmitter systems in the neuropathological substrates of suicide susceptibility. It is argued here that the confluence of the availability of suitable postmortem samples and this augmentation of our armamentarium of techniques promises the attainment of important new insights into the biological underpinnings of suicide from postmortem research. It is to be hoped that this new knowledge might inspire novel pharmacotherapeutic strategies for the prevention of suicide.

The dysplastic net hypothesis: an integration of developmental and dysconnectivity theories of schizophrenia

Two separate theories that attempt to explain different aspects of schizophrenia have recently attracted much attention. The first, the neurodevelopmental hypothesis, postulates that deviations in early development establish a neuronal phenotype that predisposes to, or, in some versions, determines the later onset of schizophrenia. The second theory proposes that schizophrenic symptoms arise from abnormalities in neuronal connectivity. Here, we suggest that the findings from these two separate lines of inquiry can be integrated into a unitary framework: the dysplastic net hypothesis. In essence, this proposes that anatomical and physiological dysconnectivity of the adult schizophrenic brain is determined by dysplastic fetal brain development. We also indicate how abnormal connectivity between brain regions constituting large-scale neurocognitive networks is expressed in both the prepsychotic and psychotic phases of schizophrenia, and we examine possible risk factors (genetic and environmental) for dysplastic formation of these networks.

Schizophrenia, psychosis, and the basal ganglia

Schizophrenia is one of the most common and perhaps the most disabling of mental disorders, for which effective forms of treatment have not yet been established definitively. The findings reviewed in this article strongly suggest that basal ganglia abnormalities are involved in the pathophysiology of psychotic syndromes in general, and schizophrenia in particular.

The Maudsley Family Study. I: Structural brain changes on magnetic resonance imaging in familial schizophrenia

1. The authors investigated the prevalence of qualitatively rated structural brain abnormalities in schizophrenic probands and their first-degree relatives from families multiply affected with schizophrenia. 2. Magnetic resonance imaging was used to evaluate brain morphology in 33 schizophrenic probands, 54 of their non-schizophrenic first-degree relatives (including 11 presumed obligate carriers) and 37 unrelated control subjects. Structural images were examined by a neuroradiologist who was blind to diagnostic and family status. 3. 52% of the schizophrenic subjects were rated as showing abnormalities compared with 27% of presumed obligate carriers, 16% of their non-schizophrenic relatives and 11% of unrelated controls. 4. Brain abnormalities were more frequent in schizophrenic subjects from multiplex families than in their first-degree relatives and controls. Abnormalities were also found in unaffected relatives particularly those who appear to be transmitting the disorder.