Schizophrenia as an anomaly of development of cerebral asymmetry. A postmortem study and a proposal concerning the genetic basis of the disease

Volume reduction of the right anterior limb of the internal capsule in patients with schizotypal disorder

We have previously reported bilateral volume reductions in the anterior limb of the internal capsule (ALIC) in patients with schizophrenia. The purpose of this study was to extend the volumetric measurements of ALIC to subjects with schizotypal features to explore the neurobiology underlying schizophrenia-spectrum disorders in view of the fronto-thalamic connectivity. Three-dimensional magnetic resonance images were acquired from 24 patients with schizotypal disorder (ICD-10) and 47 healthy volunteers matched for age, gender, handedness, and parental education. Volumetric analyses of the ALIC and anterior parts of the caudate and lentiform nuclei were conducted using consecutive 1-mm thick coronal slices rostral to the anterior commissure. Compared with the comparison subjects, the schizotypal patients had significantly decreased volume in the right ALIC, but there was no significant group difference in the left ALIC volume. Volumes of the anterior part of the caudate or lentiform nucleus did not differ between groups. Volume deficit confined to the right ALIC suggests that limited involvement of the fronto-thalamic connectivity may have some relevance to the sparing of schizotypal patients from the development of overt psychosis.

3D morphometrics of craniofacial dysmorphology reveals sex-specific asymmetries in schizophrenia

Over early fetal life cerebral and craniofacial morphogenesis proceed in embryological intimacy. Therefore, craniofacial shape differences between schizophrenia patients and controls are informative of developmental disturbance(s) in cerebral-craniofacial morphogenesis. 3D craniofacial coordinates were calculated from interlandmark distances for 169 patients with DSM-III-R schizophrenia and 78 matched normal controls. These were analysed using geometric morphometrics with visualisation of the resultant statistical models. Patients of both sexes were characterised by an intricate topography of 3D shape change involving lengthened lower mid-facial height, shortened upper mid-facial height, nasion located posteriorly and a wider face posteriorly; there was sex-specific rotation of the midface such that the base of the nose is more anterior in female patients but more posterior in male patients. Importantly, there were sex-specific asymmetries: in males, controls evidenced marked directional asymmetry while patients showed reduced directional asymmetry; conversely, in females controls evidenced little directional asymmetry while patients showed marked directional asymmetry. In schizophrenia, the topography of craniofacial dysmorphology appears to reflect subtle disruption to a critical 3D trajectory of embryonic-fetal craniofacial growth, particularly along the midline, with disturbance to the establishment of normal asymmetries in a sex-related manner.

Measurement of lateral preferences and schizophrenia: results of the Edinburgh High-Risk Study and methodological issues

The assessment and measurement of handedness has varied across studies, limiting the comparability of results. Data from the Edinburgh High Risk for Schizophrenia Study were analyzed to investigate the effect of different methods of assessment and scoring of hand preferences on the prevalence of handedness type and on between-group differences in handedness. Handedness was measured using both the Edinburgh Handedness Inventory and the Annett Handedness Scale in 143 subjects at high risk for schizophrenia, 31 control subjects, and 27 patients with a first episode of schizophrenia. Hand preferences were identified through demonstration of items and by verbal report. No group differences were found, although the prevalence of hand preferences changed substantially depending on the definition used. Significant correlations with socio-demographic factors were found in some instances, but these correlations depended on the definition of handedness. No sex differences were identified. The magnitude of group differences remained similar, although the prevalence of handedness types varied greatly with changes in definition of handedness. Care should be taken in correlation studies to avoid spurious relationships between handedness and other factors. To allow for comparability of results across studies, researchers should adopt a standard definition of handedness.

Inhibition of dopamine synthesis with alpha-methyl-p-tyrosine abolishes the enhancement of methamphetamine-induced extracellular dopamine levels in the amygdala of rats with excitotoxic lesions of the entorhinal cortex

This study was performed to investigate the mechanisms underlying the augmentation of methamphetamine (MAP)-induced dopamine (DA) release in the entorhinal cortex-lesioned rats. Quinolinic acid or phosphate buffered saline was infused into the left entorhinal cortex of adolescent rats (postnatal day 7 weeks). After 4 weeks of lesioning, acute MAP (2 mg/kg, i.p.)-induced DA release in the amygdala was significantly enhanced in lesioned rats compared to sham operated rats. Inhibition of DA synthesis by alpha-methyl-p-tyrosine, an inhibitor of catecholamine synthesis, resulted in abolishment of the enhancement of MAP (2 or 5 mg/kg, i.p.)-induced DA release in the amygdala of lesioned rats. These results suggest that excessive DA pool in nerve terminals underlies the augmentation of MAP-induced DA release in the amygdala of the lesioned rats.

Cerebral ventricular change over the first 10 years after the onset of schizophrenia

Whether the brain structural abnormalities seen in schizophrenia are progressive is controversial. We previously reported on a longitudinal study of 50 first-episode patients with schizophrenia and 20 controls who had serial MRI scans during the first 5 years of illness. Greater enlargement of lateral ventricles and reduction of hemispheric volume was observed over time in the patients compared with controls. The present study obtained MRI scans from 26 of these patients and 10 controls at a follow-up 10 years subsequent to their first evaluations. The initial, 4-5th and 10th year scans were examined for the degree of change in ventricular and hemispheric volume. Significantly greater ventricular enlargement during the second 5 years was detected in the patient cohort compared with controls (P<0.05) with nine of the patients having ventricular enlargement (as measured by percent change) occurring at a rate exceeding that of any of the controls from years 1 through 10. The rate of ventricular change during the first 5 years was significantly correlated with age at first hospitalization, and ventricular enlargement in years 5-10 was correlated with the amount of time spent in hospital. Paradoxically, greater change in ventricles over time was correlated with better, not worse, outcome at the 10th year of follow-up with regard to the presence of symptoms. These data suggest heterogeneity in the course of brain change whereby some patients may exhibit active structural brain change only early in their illness or not at all after their first episode, while others continue to exhibit ventricular change spanning the decade subsequent to their first episode. Despite these differences among patients, the present study fails to detect any relationship of ventricular enlargement to poorer outcome as has been reported by other investigators.

Dopamine transporter change in drug-naive schizophrenia: an imaging study with 99mTc-TRODAT-1

The aim of this study was to use a specific dopamine transporter (DAT) ligand, 99mTc-TRODAT-1 with single photon emission computed tomography (SPECT) to investigate the densities of DAT in the striatal dopaminergic system in patients with schizophrenia. Striatal DAT uptakes were measured in 12 drug-nai;ve schizophrenic patients and 12 age- and sex-matched healthy volunteers. The psychometric tools included the Standardized Clinical Assessment for Neuropsychiatry (SCAN) and the Positive and Negative Syndrome Scale (PANSS). Semiquantitative analyses using the ratio of uptake in caudate, putamen, and striatum to occipital lobe, and left-right asymmetry were performed. Decreased TRODAT uptake in the right striatum and increased uptake in the left striatum were found in the schizophrenics. However, there is no overall difference in the average striatum uptake. The right-left asymmetry of the caudate and putamen DAT binding seen in the healthy control group disappeared in the schizophrenia group. The decreased right uptake and increased left uptake in the striatum might lead to the lack of right-left asymmetry in neuroleptic-nai;ve schizophrenia patients, confirming that the disorder could be due to a disruption in brain lateralization. This is the first report on the use TRODAT to evaluate the DAT density in schizophrenia patients and shows lack of asymmetry in striatal uptake of TRODAT in schizophrenics. The findings also suggest that TRODAT SPECT may be a useful technique to measure dopamine transmission in the human brain and for understanding the pathophysiology of neuropsychiatric disorders.

The causes of schizophrenia: neurodevelopment and other risk factors

Understanding the etiology of schizophrenia has been a considerable challenge. The neurodevelopmental hypothesis has held sway in recent years, focusing our attention on biological causes acting in early life. Much evidence supports this hypothesis and risk factors operating in early life (e.g., obstetric complications) have been shown to be associated with the later development of schizophrenia. Indicators of abnormal neurodevelopment that characterize individuals vulnerable to later developing schizophrenia have also been identified. For example, as a group, children who will later develop schizophrenia subtly differ from their peers in terms of their motor, cognitive, and social functioning. However, there is much that cannot be explained in purely neurodevelopmental terms. There is growing evidence of associations between the risk of schizophrenia and factors such as drug misuse, ethnicity/migration, life events, and urbanicity. A multifactorial model of causation that encompasses biological, social, and psychological elements is arguably both a better representation of current research findings and a more appropriate model for clinical practice.

Chronic schizophrenia as a brain misconnection syndrome: a white matter voxel-based morphometry study

It has been hypothesized that schizophrenia could be due to a defect of neural circuitry, that is a misconnection between different cerebral areas, particularly those involved in language processing and production. A group of 28 patients with chronic schizophrenia were investigated in order to detect differences in locations of white matter voxel signal intensity in comparison with a control group of 28 normal subjects matched for age, gender and educational level. Voxel-based morphometry was used to assess the white matter of the brain. Significant voxel signal hypointensity was identified in schizophrenic patients bilaterally (mainly in the left hemisphere) in the post-central gyrus and superior temporal gyrus and unilaterally (in the left hemisphere) in the inferior frontal gyrus-pars triangularis and pars pretriangularis, the medial orbital gyrus, the lateral orbital gyrus and the rectus gyrus. Thus, the white matters of these cerebral areas were structurally modified particularly in the left hemisphere and in those structures that control language and hearing processes.

Decreased volume and increased asymmetry of the anterior limb of the internal capsule in patients with schizophrenia

BACKGROUND

The anterior limb of the internal capsule (ALIC) contains the anterior thalamic peduncle connecting the medial and anterior thalamic nuclei with the prefrontal cortex and the cingulate gyrus. The purpose of this study was to detect the volumetric changes in the ALIC in view of the putative abnormal frontothalamic connectivity in schizophrenia.

METHODS

High-resolution, three-dimensional magnetic resonance imaging was acquired from 53 schizophrenia patients and 48 age- and gender-matched control subjects. Volumetric analysis was performed using consecutive 1-mm-thick coronal slices rostral to the anterior commissure, on the ALIC, caudate nucleus, and lentiform nucleus. White matter concentration over the whole brain was compared using the voxel-based morphometry (VBM) with Statistical Parametric Mapping 99.

RESULTS

The patients had significantly decreased volumes in the bilateral ALIC and showed significantly increased right-greater-than-left asymmetry of the ALIC; VBM revealed a reduction in white matter concentration of the bilateral internal capsule in patients. No volumetric difference was found in the rostral part of the caudate and lentiform nucleus between groups.

CONCLUSIONS

Decreased volume found in the ALIC supports the hypothesis of abnormal frontothalamic connectivity in schizophrenia. Increased asymmetry of the internal capsule seems consistent with the notion of predominantly left-side pathology 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.

Does schizophrenia result from developmental or degenerative processes?

The debate as to whether schizophrenia is a neurodevelopmental or a neurodegenerative disorder has its roots in the latter part of the 19th century when authorities such as Clouston (1891) posited that at least some insanities were "developmental" in origin. These views were soon eclipsed by Kraepelin's (1896) concept of dementia praecox as a degenerative disease, and the latter view carried not only the day but also much of the 20th century. Then, in the 1980s several research groups again began to speculate that schizophrenia might have a significant developmental component (Feinberg, 1982-1983; Schulsinger et al., 1984; Murray et al., 1985; Murray and Lewis, 1987; Weinberger et al., 1987). What became known as the "neurodevelopmental hypothesis" received support from neuropathological studies implicating anomalies in early brain development such as aberrant migration of neurons. Unfortunately, these studies proved difficult, if not impossible, to replicate (Harrison, 1999). The pendulum, therefore, began to swing again, and in the latter part of the 1990s came renewed claims that the clinical progression of the illness was accompanied by continued cerebral ventricular enlargement and reduction in the volumes of certain brain structures. Nevertheless, since few doubt that there is a developmental component to schizophrenia, the question which we will address in this paper is whether schizophrenia is a) simply the final consequence of a cascade of increasing developmental deviance (Bramon et al., 2001), or b) whether there is an additional brain degeneration following onset of psychosis which is superimposed on the developmental impairment (Lieberman, 1999).

Engagement of brain areas implicated in processing inner speech in people with auditory hallucinations

BACKGROUND

The neurocognitive basis of auditory hallucinations is unclear, but there is increasing evidence implicating abnormalities in processing inner speech. Previous studies have shown that people with schizophrenia who were prone to auditory hallucinations demonstrated attenuated activation of brain areas during the monitoring of inner speech.

AIMS

To investigate whether the same pattern of functional abnormalities would be evident as the rate of inner speech production was varied.

METHOD

Eight people with schizophrenia who had a history of prominent auditory hallucinations and eight control participants were studied using functional magnetic resonance imaging while the rate of inner speech generation was varied experimentally.

RESULTS

When the rate of inner speech generation was increased, the participants with schizophrenia showed a relatively attenuated response in the right temporal, parietal, parahippocampal and cerebellar cortex.

CONCLUSIONS

In people with schizophrenia who are prone to auditory hallucinations, increasing the demands on the processing of inner speech is associated with attenuated engagement of the brain areas implicated in verbal self-monitoring.

Morphology of the anterior cingulate cortex in young men at ultra-high risk of developing a psychotic illness

BACKGROUND

The anterior cingulate cortex (ACC) is consistently implicated in the pathophysiology of schizophrenia, and our own work has identified morphological anomalies in the ACC of people with this disorder.

AIMS

To examine whether ACC morphological anomalies are present in a group at ultra-high risk of psychosis and whether such anomalies can be used to predict the subsequent development of a psychotic illness.

METHOD

Magnetic resonance imaging of 75 healthy volunteers and 63 people at ultra-high risk of developing a psychotic disorder (all right-handed males) was used to examine ACC sulcal and gyral features.

RESULTS

Compared with the controls, significantly fewer people in the ultra-high risk group had a well-developed left paracingulate sulcus and significantly more had an interrupted left cingulate sulcus. There was no difference between those who did (n=21) and did not (n=42) subsequently develop a psychotic illness.

CONCLUSIONS

Although ACC anomalies are present in young people considered to be at ultra-high risk of psychosis, they do not identify individuals who subsequently make the transition to psychosis.

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.

Gender differences in schizophrenia

Sex differences in schizophrenia can be caused by the disease process itself, by genetic and hormonal differences, by differences in the maturation and morphology of the brain and in age- and gender-specific behavioural patterns. These hypotheses will be tested on the major results reported in the literature as well as on different levels (epidemiology, risk factors, animal experiments, a controlled clinical study) on data from the ABC Schizophrenia Study. Symptomatology, lifetime risk and symptom-related course of illness-the latter without consideration of age-show no gender differences. However, until menopause illness onset is delayed and severity of illness is reduced by oestrogen on the level of gene expression and transmitter functioning. Oestrogen has an antagonistic effect on the-familial or exogenous-predisposition to illness. As a result, the age distribution of onset and the severity of first-episode illness in young men and post-menopausal women differ from the normal. First intervention trials with oestrogen substitution of neuroleptic therapy have demonstrated antipsychotic effects. The poorer social course of schizophrenia in men than in premenopausal women is accounted for by men's lower level of social development at illness onset and the subsequent impediment of their further development. Men's socially adverse illness behaviour, too, is a contributing factor. Scarcity of the knowledge of differences in the development, morphology and functioning of the male and female brain does not yet allow any definitive conclusions about gender differences in schizophrenia.

Paracingulate sulcus morphology in men with early-onset schizophrenia

BACKGROUND

Cingulate dysfunction has been reported in schizophrenia. Although the paracingulate sulcus (PCS) is known to be asymmetric in healthy people, little information is available about its morphology in schizophrenia.

AIMS

To search for morphological anomalies of the PCS in men with early-onset schizophrenia.

METHOD

The PCS was examined in magnetic resonance images of the brains of men with schizophrenia and 100 healthy men.

RESULTS

A significant asymmetry was found in the brains of healthy volunteers, whose sulci were more frequent and more marked in the left hemisphere. In contrast, the sulcus was as frequent in the right as in the left hemisphere in the patient group. Moreover, patients displayed significantly more rightward asymmetry, and overall less-asymmetrical patterns than the comparison group.

CONCLUSIONS

Since the PCS has developed at 36 weeks of gestation, these findings suggest an impaired maturation of the cingulate region during the third trimester.

Quantification of lateral ventricular subdivisions in schizophrenia by high-resolution three-dimensional magnetic resonance imaging

In vivo brain imaging and postmortem investigations have demonstrated ventricular enlargement in the brains of schizophrenic patients. However, the extent of changes in the volume of discrete ventricle subdivisions has not been clearly established. We conducted high-resolution three-dimensional magnetic resonance imaging in 40 schizophrenic patients (20 males and 20 females) and 40 healthy volunteers (20 males and 20 females). The lateral ventricle in each hemisphere was divided into the anterior horn, body, posterior horn and temporal horn. The volumes of the hemispheres, four subdivisions of the lateral ventricles and the third ventricle were measured. Compared to the control subjects, the bilateral hemisphere volumes were significantly lower in the patients than in the control subjects. In the lateral ventricular subdivisions of the male patients, the most substantial volume increase was in the left temporal horn, and volume increases were also observed in the bilateral anterior horns and the right body. The male patients also had a significantly increased volume of the third ventricle. The female patients showed similar patterns with less statistical significance. Thus, the schizophrenia patients showed ventricular enlargement, particularly in the left temporal horn, being more severely affected in the male than in the female.

Immediate and delayed hippocampal neuronal loss induced by kainic acid during early postnatal development in the rat

The degree to which the neonatal hippocampus is resistant to the effects of excitotoxins, such as kainic acid (KA) remains uncertain. Previously, we showed delayed loss of hippocampal neurons during pubescence in neonatal rats subjected to intracerebroventricular (i.c.v.) KA administration (10 nmol) at postnatal day 7 (P7). To further characterize the time course as well as the underlying mechanisms of this neuronal loss, we administered i.c.v. KA (10 or 50 nmol) to P7 preweanling rats. Brain sections were then examined at several neurodevelopmental time points (i.e., P8, P14, P25, P40, P60 and P75) using thionin staining and three-dimensional, non-biased cell counting to assess neuronal loss, and immunohistochemistry and electron microscopy to search for evidence of necrosis and apoptosis. Dose-dependent acute neuronal loss was observed at P8-P14 in hippocampal subfields CA3a and CA3c. Transient heat shock protein (HSP-70) immunostaining accompanied this acute neuronal loss. Progressive neuronal loss then continued in CA3 until P75, but without concomitant HSP-70 immunostaining. Progressive neuronal cell loss was also observed in the CA1 subfield of the hippocampus beginning at pubescence (i.e., P40) and continuing until P75. The appearance of TUNEL-positive hippocampal neurons accompanied the delayed neuronal loss in both CA3 and CA1 and electron micrographs confirmed that neurons in these subfields were undergoing apoptosis. KA administration (i.c.v.) to preweanling rats caused both immediate and delayed damage to hippocampal neurons. The effect of KA was dose-dependent, and the delayed neuronal damage occurred through an apoptosis-mediated mechanism. These findings may be relevant to the pathogenesis of some neuropsychiatric disorders, where early CNS injury is not apparent until the onset of clinical symptoms in young adulthood.

Paracingulate morphologic differences in males with established schizophrenia: a magnetic resonance imaging morphometric study

BACKGROUND

Our previous work on sulcal-gyral brain morphology in healthy volunteers revealed that males were characterized by greater cortical folding in the left versus right anterior cingulate cortex. Given the evidence showing an absence or reversal of normal anatomical asymmetries in patients with schizophrenia, the current study examined the anterior cingulate cortex sulcal-gyral patterns in patients with schizophrenia.

METHODS

Using high-resolution magnetic resonance imaging, we examined anterior cingulate cortex surface morphology in a group of 55 patients with established schizophrenia and 75 healthy controls. All subjects were male and right-handed. Depending on the presence of a paracingulate sulcus and its antero-posterior extent, three types of anterior cingulate cortex sulcal patterns were identified: "prominent," "present," and "absent." Measures of overall cerebral hemispheric folding were used as independent variables and as covariates to ascertain the specificity of the findings to the anterior cingulate cortex.

RESULTS

Examination of anterior cingulate cortex morphology showed that, compared with controls, patients with schizophrenia lacked the leftward anterior cingulate cortex sulcal asymmetry, which was explained by reduced folding in the left anterior cingulate cortex. These differences were over and above differences in cortical folding across the entire left hemisphere.

CONCLUSIONS

These findings suggest that, in male patients with schizophrenia, there is a disturbance in the neurodevelopment of the left anterior cingulate cortex, as well as a more general aberration of left hemisphere development.

Motor cortical excitability in schizophrenia

BACKGROUND

Transcranial magnetic stimulation (TMS) provides a method to examine cortico-cortical motor excitability and hemispheric asymmetry in unmedicated and medicated schizophrenia patients.

METHODS

Fourteen right-handed schizophrenia patients (seven on conventional neuroleptics and seven medication-free) were compared with seven right-handed, age- and gender-matched normal control subjects. Motor threshold for induction of motor-evoked potentials (MEPs) and bihemispheric intracortical inhibition and facilitation were measured with single-pulse and paired-pulse TMS.

RESULTS

Medicated patients showed an approximately 5% higher motor thresholds in both hemispheres than unmedicated patients and control subjects. Normal control subjects had a nearly 10% higher threshold for the left than the right hemisphere, whereas the opposite was true for the patient groups (5-10% higher threshold on the right than the left). Medicated patients showed significantly decreased intracortical inhibition relative to unmedicated patients and control subjects. This difference was more pronounced for the right than for the left hemisphere.

CONCLUSIONS

Treatment with conventional neuroleptics is associated with increased motor threshold and decreased intracortical inhibition, whereas unmedicated patients did not differ from normal control subjects on these measures; however, schizophrenia may be characterized by a reversed pattern of interhemispheric corticospinal excitability.

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.

Uncinate fasciculus findings in schizophrenia: a magnetic resonance diffusion tensor imaging study

OBJECTIVE

Disruptions in connectivity between the frontal and temporal lobes may explain some of the symptoms observed in schizophrenia. Conventional magnetic resonance imaging (MRI) studies, however, have not shown compelling evidence for white matter abnormalities, because white matter fiber tracts cannot be visualized by conventional MRI. Diffusion tensor imaging is a relatively new technique that can detect subtle white matter abnormalities in vivo by assessing the degree to which directionally organized fibers have lost their normal integrity. The first three diffusion tensor imaging studies in schizophrenia showed lower anisotropic diffusion, relative to comparison subjects, in whole-brain white matter, prefrontal and temporal white matter, and the corpus callosum, respectively. Here the authors focus on fiber tracts forming temporal-frontal connections.

METHOD

Anisotropic diffusion was assessed in the uncinate fasciculus, the most prominent white matter tract connecting temporal and frontal brain regions, in 15 patients with chronic schizophrenia and 18 normal comparison subjects. A 1.5-T GE Echospeed system was used to acquire 4-mm-thick coronal line-scan diffusion tensor images. Maps of the fractional anisotropy were generated to quantify the water diffusion within the uncinate fasciculus.

RESULTS

Findings revealed a group-by-side interaction for fractional anisotropy and for uncinate fasciculus area, derived from automatic segmentation. The patients with schizophrenia showed a lack of normal left-greater-than-right asymmetry seen in the comparison subjects.

CONCLUSIONS

These findings demonstrate the importance of investigating white matter tracts in vivo in schizophrenia and support the hypothesis of a disruption in the normal pattern of connectivity between temporal and frontal brain regions in schizophrenia.

Evidence for non-progressive changes in adolescent-onset schizophrenia: follow-up magnetic resonance imaging study

BACKGROUND

It is not clear how far brain abnormalities in early-onset schizophrenia result from progressive neurodevelopmental or neurodegenerative processes. Aims To investigate the hypothesis that structural brain abnormalities in adolescent-onset schizophrenia are progressive in the early phase of the illness.

METHOD

A magnetic resonance imaging case-control study of 16 adolescents with schizophrenia (mean age 16.6 years, s.d.=1.9 years) with a mean time of 2.7 years (s.d.=1.7 years) between measurements and 16 matched controls (average age 16.0 years, s.d.=2.0 years) with a mean time of 1.7 years (s.d.=0.5 years) between measurements.

RESULTS

There was no evidence of progressive structural brain changes during late adolescence. Significant ventricular enlargement (greater in males) and left-sided temporal lobe changes were evident from the outset of the illness.

CONCLUSIONS

Neurodevelopmental brain abnormalities are non-progressive during late adolescence.

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.

Schizophrenia and viral infection during neurodevelopment: a focus on mechanisms

The task of defining schizophrenia pathogenesis has fascinated and frustrated researchers for nearly a century. In recent years, unprecedented advances from diverse fields of study have given credence to both viral and developmental theories. This review considers possible mechanisms by which viral and developmental processes may interact to engender schizophrenia. Many of the current controversies in schizophrenia pathogenesis are reviewed in light of the viral hypothesis, including: epidemiological findings and the role of a genetic diathesis, phenotype heterogeneity, abnormalities in excitatory and inhibitory neurotransmitter systems, anomalous cerebral latereralization, and static vs progressive disease. The importance of animal models in elucidating the impact of viral infections on developing neurons is illustrated by recent studies in which neonatal rats are infected with lymphocytic choriomeningitis virus in order to examine alterations in hippocampal circuitry. Finally, consideration is given to a new hypothesis that some cases of schizophrenia could be instigated by a viral infection that disrupts developing inhibitory circuits, consequently unleashing glutamatergic neurotransmission leading to selective excitotoxicity, and a degenerative disease course.

Language lateralization in schizophrenia, an fMRI study

Anatomical studies have shown that cerebral asymmetry is reduced in schizophrenia. Functional asymmetry appears to be reduced also, as was shown with dichotic listening studies. These studies, however, have not revealed whether reduced lateralization is the result of decreased language activity of the left hemisphere or whether it is the consequence of increased language-related activity in the right hemisphere. To elucidate this, we examined hemispheric dominance for language processing by means of functional MRI. Twelve schizophrenic patients and twelve healthy controls were scanned while they were engaged in a verb-generation and a semantic decision task. Activation was measured bilaterally in the frontal, temporal and temporo-parietal language areas, and a laterality index was derived from activity in these regions of interest in the left and the right hemispheres. Clinical symptoms were rated at the time of scanning. The results indicate that language processing is less lateralized in patients than in controls (a mean laterality index of 0.35 versus 0.63, respectively, difference p<0.01). Analysis of variance of the extent of activity, i.e. numbers of active voxels, revealed a significant hemisphere by group interaction (F(1,22)=11.2, p<0.001), which was due to increased activation in the right hemisphere of the patients (post hoc t-test p<0.05). We found no evidence of reduced activity in the left hemisphere. Further analysis of clinical symptoms rated prior to scanning revealed that decreased language lateralization was associated with more severe hallucinations (r=-0.54, p<0.05). We postulate that decreased language lateralization in schizophrenia may result from failure to inhibit the right hemisphere.

An integration of 40 Hz Gamma and phasic arousal: novelty and routinization processing in schizophrenia

OBJECTIVES

Frontal and lateralized schizophrenia disturbances were examined in terms of arousal-modulated changes in 40 Hz Gamma activity.

METHODS

Forty patients with schizophrenia and 40 age- and gender-matched controls were studied in a conventional auditory ERP oddball paradigm. We investigated sub-averaged Gamma activity based upon a simultaneous measure of electrodemal skin conductance response (phasic arousal) to differentiate novelty (large responses) from routinization (small or no responses). Both early Gamma (Gamma 1) and later induced Gamma (Gamma 2) activities were examined.

RESULTS

Patients with schizophrenia (compared with controls) had significantly reduced Gamma 1 amplitude in the right hemisphere for novelty processing and delayed Gamma 2 latency in the left hemisphere for both novelty and routinization. Overall, reduced Gamma 1 amplitude in patients with schizophrenia was also evident.

CONCLUSIONS

These findings indicate that the normal laterality of Gamma activity is specifically disturbed in schizophrenia in response to novel, but not routine (familiar) stimuli. The distinct pattern of findings suggests a dysregulation of activation across left and right hemispheres during initial attention and preparatory phases of information processing, in particular, in patients with schizophrenia.

Glial cell abnormalities in major psychiatric disorders: the evidence and implications

Recent quantitative post-mortem investigations of the cerebral cortex have convincingly demonstrated cortical glial cell loss in subjects with major depression. Evidence is also mounting that glial cell loss may also be a feature of schizophrenia. These findings coincide with a re-evaluation of the importance of glial cells in normal cortical function. In addition to their traditional roles in neuronal migration and inflammatory processes, glia are now accepted to have roles in providing trophic support to neurons, neuronal metabolism, and the formation of synapses and neurotransmission. Consequently, reduced cortical glial cell numbers could be responsible for some of the pathological changes in schizophrenia and depression, including reduced neuronal size, reduced levels of synaptic proteins, and abnormalities of cortical neurotransmission. Additionally, as astrocytes provide the energy requirements of neurons, deficient astrocyte function could account for aspects of the functional magnetic imaging abnormalities found in these disorders. We discuss the possible basis of glial cell loss in these disorders and suggest that elevated levels of glucocorticoids, due to illness-related stress or to hyperactivity of the hypothalamic-pituitary-adrenal may down-regulate glial activity and so predispose to, or exacerbate psychiatric illness through enhanced excitotoxicity. The potential therapeutic impact of agents which up-regulate glial activity or normalise glial cell numbers is also discussed.

Dermatoglyphic fluctuating asymmetry and atypical handedness in schizophrenia

Atypical handedness and dermatoglyphic abnormalities are hypothesized to reflect a neurodevelopmental disturbance in schizophrenia. Developmental instability, indexed by dermatoglyphic fluctuating asymmetry (FA), reflects the degree to which an individual's ontogenetic program is maintained and provides a useful framework in which to consider atypical handedness in schizophrenia. Thirty patients diagnosed with schizophrenia were compared with 37 matched healthy controls on levels of dermatoglyphic FA, a demonstration task determining hand preference and a test of relative hand skill. Multivariate analyses established that patients demonstrated greater FA and more atypical hand skill compared with controls. In patients, but not in controls, there was a strong positive association between a measure of FA and a measure of atypical hand skill, suggesting that these markers of neurodevelopmental disturbance are related in schizophrenia. On a measure of hand preference, patients were more likely than controls to be classified as mixed handed than either right or left handed. Results from the present study support the conjecture of greater developmental instability in schizophrenia affecting neurodevelopmental processes, including those conferring manual dominance.

Right amygdala volume in adolescent and young adult offspring from families at high risk for developing alcoholism

BACKGROUND

Neurobiological factors have been implicated in the increased susceptibility for developing alcohol dependence that offspring from alcoholic families exhibit. The P300 component of the event-related potential shows developmental changes during childhood and adolescence that appear to be related to risk status. The underlying structural changes that accompany these neurophysiological changes are not well understood.

METHODS

Magnetic resonance imaging was used to measure cerebral, amygdala, and hippocampal volumes in 17 high-risk adolescent and young adult offspring from multiplex alcoholism families and 17 age-, gender-, and IQ-matched control subjects without a family history for alcoholism or other substance dependence. Twenty-two of the subjects are part of a longitudinal prospective study and have been followed an average of 7.3 years, making it possible to relate P300 developmental trajectories to structural volumes.

RESULTS

High-risk adolescents and young adults showed reduced right amygdala volume in comparison with control subjects. Right amygdala volume was significantly correlated with visual P300 amplitude.

CONCLUSIONS

Offspring from families having a high density of alcoholism differ in both neurophysiological and neuroanatomical characteristics that could not be explained by personal drinking history or particular childhood and adolescent psychopathology. Because the amygdala tends to increase in volume during childhood and adolescence, smaller volumes in high-risk children may indicate a developmental delay that parallels delays seen in visual P300 amplitude.

Altered hemispheric asymmetry of auditory magnetic fields to tones and syllables in schizophrenia

BACKGROUND

A growing body of literature suggests that schizophrenic patients often do not show the normal brain hemispheric asymmetry. We have found this for simple tones presented to the right ear in a previous study. In this study we extended this investigation to left ear stimulation and verbal stimuli.

METHODS

With a whole-head neuromagnetometer, contra- and ipsilateral auditory-evoked magnetic fields in response to tones (1000 Hz) and to the syllables ("ba") delivered to the left and right ears in separate runs were compared between schizophrenic patients (n = 17) and healthy control subjects (n = 15).

RESULTS

In response to tones, all control subjects showed the expected asymmetry (contralateral predominance) of the auditory-evoked magnetic N100m (dipole moment). In the patient sample asymmetry was reversed following tones presented to the left ear in 47% and following tones to the right ear in 24%. In response to syllables, the asymmetry was similar between groups. In patients compared with control subjects the N100m was located more anterior without asymmetry between hemispheres.

CONCLUSIONS

Results suggest that deviation from the normal functional lateralization in schizophrenia appears in a proportion of patients at a basic stage of auditory processing, but may be compensated for at higher levels such as the processing of syllables.

A review of MRI findings in schizophrenia

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

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

BACKGROUND

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

AIMS

To review quantitatively the literature on decreased lateralisation in schizophrenia.

METHOD

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

RESULTS

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

CONCLUSION

Strong evidence is provided for decreased cerebral lateralisation in schizophrenia.

Schizophrenia and the frontal lobes: post-mortem stereological study of tissue volume

BACKGROUND

It has been suggested that there is frontal lobe involvement in schizophrenia, and that it may be lateralised and gender-specific.

AIMS

To clarify the structure of the frontal lobes in schizophrenia in a post-mortem series.

METHOD

The volume of white matter and cortical components of the frontal lobes was measured in brains of controls and patients with schizophrenia using planimetry and the Cavalieri principle. The components measured were: superior frontal gyrus, middle frontal gyrus, a composite of inferior frontal gyrus and orbito-frontal cortex, as well as total frontal lobe cortex and white matter. In addition, the anterior cingulate gyrus was measured.

RESULTS

No diagnosis, gender, diagnosis x side, diagnosis x gender or diagnosis x gender x side interactions were observed in the volume of any of the components, the grey matter as a whole or the white matter. No evidence for volumetric inter-group differences was found for the anterior cingulate gyrus.

CONCLUSIONS

Such structural abnormalities as are present in the frontal lobes are more subtle than straightforward alterations in tissue volume; they may include changes in shape and the pattern of gyral folding.

Functional neuroanatomy of auditory working memory in schizophrenia: relation to positive and negative symptoms

Functional brain imaging studies of working memory (WM) in schizophrenia have yielded inconsistent results regarding deficits in the dorsolateral prefrontal (DLPFC) and parietal cortices. In spite of its potential importance in schizophrenia, there have been few investigations of WM deficits using auditory stimuli and no functional imaging studies have attempted to relate brain activation during auditory WM to positive and negative symptoms of schizophrenia. We used a two-back auditory WM paradigm in a functional MRI study of men with schizophrenia (N = 11) and controls (N = 13). Region of interest analysis was used to investigate group differences in activation as well as correlations with symptom scores from the Brief Psychiatric Rating Scale. Patients with schizophrenia performed significantly worse and were slower than control subjects in the WM task. Patients also showed decreased lateralization of activation and significant WM related activation deficits in the left and right DLPFC, frontal operculum, inferior parietal, and superior parietal cortex but not in the anterior cingulate or superior temporal gyrus. These results indicate that in addition to the prefrontal cortex, parietal cortex function is also disrupted during WM in schizophrenia. Withdrawal-retardation symptom scores were inversely correlated with frontal operculum activation. Thinking disturbance symptom scores were inversely correlated with right DLPFC activation. Our findings suggest an association between thinking disturbance symptoms, particularly unusual thought content, and disrupted WM processing in schizophrenia.

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.

Ten year progressive ventricular enlargement in schizophrenia: an MRI morphometrical study

Recent studies of the brain using magnetic resonance imaging (MRI) have suggested progressive structural changes in schizophrenics. However, those studies were conducted over periods of less than 5 years and thus lacked sufficient capacity to determine the course and nature of this process. In this study, MRI scans were obtained in 15 schizophrenics and 12 controls at baseline and after 4- and 10-year follow ups. Volumes of the lateral ventricles were measured. Patients were assessed by the Brief Psychiatric Rating Scale (BPRS) at the same two time points: at baseline and at 10-year follow up. After 10 years, a significant lateral ventricular enlargement was found in patients (mean percentage change: +22.9%) but not in controls (5.1%). Although our results are not in disagreement with the neurodevelopmental hypothesis, they do provide strong evidence that in schizophrenia progressive brain reduction occurs even in its chronic stage.

Abnormal peripheral auditory asymmetry in schizophrenia

OBJECTIVE

Auditory processing difficulties have been reported in schizophrenia. This study explores peripheral auditory function in patients with schizophrenia in whom certain early disturbances of auditory message filtering have been found and may be associated with certain abnormalities which are particularly localised in the left temporal lobe.

METHODS

Otoacoustic emissions, including click evoked and spontaneous emissions and measurements of functioning of the medial olivocochlear efferent system were obtained from 12 chronic schizophrenic patients and compared with normative data recorded from 12 normal controls.

RESULTS

Otoacoustic emission amplitudes and medial olivocochlear functioning were similar between the normal controls and schizophrenic patients; the schizophrenic patients did, however, differ from the normal controls in otoacoustic emission intensity and in medial olivocochlear asymmetry. A tendency to a higher number of spontaneous peaks, and a significantly higher click evoked otoacoustic emission response amplitude were found in the right ear compared with the left ear of schizophrenic patients. For the medial olivocochlear system, whereas normal controls showed greater attenuation in the right than in the left ear, schizophrenic patients lacked such an asymmetry.

CONCLUSION

In the absence of any attention task, the findings show disturbed peripheral lateralisation in schizophrenia of mechanisms involved in auditory information filtering. Such a lack of right ear advantage in medial olivocochlear functioning may thus be a peripheral reflection of central lateralisation anomalies.

Regional cerebral blood flow in schizophrenia before and after neuroleptic medication

In order to investigate cerebral perfusion changes induced by neuroleptic drugs, we performed 99Tc(m) hexamethyl propyleneamine oxime (HMPAO) single-photon emission computed tomography (SPET). Fifteen patients (nine drug naive, six non-naive) diagnosed by using the DSM-III-R criteria, and 10 right-handed age and sex matched normal volunteers were included in this study. The SPET study was performed with 740 MBq 99Tc(m)-HMPAO by using a 128 x 128 matrix, 30 s/frame for a total 64 view over 360 degrees before and after 1 month of neuroleptic treatment. A semiquantitative method was used for the analysis. Patients were clinically assessed using the Brief Psychiatric Rating Scale (BPRS). There was no significant regional cerebral blood flow (rCBF) difference between the patient group and control group in whole-brain regions except in the left temporal lobe. Although clinical scores of the patients improved after neuroleptic treatment no statistically significant difference was found in the rCBF between pre- and post-treatment. Moreover, there was no statistically significant correlation between the rCBF and BPRS in any region. These results suggest that there was a discrepancy between the clinical situation and rCBF in schizophrenia and the lateralized temporal lobe blood flow, which may have important implications for the evaluation of patients with schizophrenia.

Brain hemispheric organization, anxiety, and psychoses

Abnormalities of brain hemispheric organization have been found in a variety of psychiatric disorders. Despite the great amount of data collected and the number of theoretical models elaborated, the role of these abnormalities in the pathogenesis of these disorders remains controversial. This article briefly reviews current concepts of hemispheric functioning, discusses the role of abnormalities of brain hemispheric organization in schizophrenia and in two anxiety disorders (panic disorder and obsessive-compulsive disorder), and outlines a developmental perspective that accounts for the observed abnormalities.

Detecting the brain surface in sparse MRI using boundary models

We introduce a framework for the detection of the brain boundary (arachnoid) within sparse MRI. We use the term sparse to describe volumetric images in which the sampling resolution within the imaging plane is far higher than that of the perpendicular direction. Generic boundary detection schemes do not provide good results for such data. In the scheme we propose, the boundary is extracted using a constrained mesh surface which iteratively approximates a 3D point set consisting of detected boundary points. Boundary detection is based on a database of piecewise constant models, which represent the idealised MR intensity profile of the underlying boundary anatomy. A non-linear matching scheme is introduced to estimate the location of the boundary points using only the intensity data within each image plane. Results are shown for a number of images and are discussed in detail.

Evidence for the involvement of the hippocampus in the pathophysiology of schizophrenia

The hippocampus, a medial temporal lobe structure, is often considered to play an important role in the pathophysiology of schizophrenia. Recent developments of neuroimaging and molecular postmortem techniques have significantly increased our ability to study the role of discrete brain regions in the pathophysiology of schizophrenia. This article describes animal models, structural, histological, molecular biology, and neuropsychological evidence for the involvement of the hippocampus in the pathophysiology of schizophrenia. The major findings in schizophrenic patients are decreased volumes, hypometabolism, and cytoarchitectural abnormalities which are more robust on the left hippocampus, as well as verbal memory impairment. It is yet to be determined whether these changes are neurodevelopmental or neurodegenerative in nature. Overall, these findings indicate that there are subtle changes in the hippocampus of schizophrenic patients. More comprehensive and focused hippocampal research in schizophrenia is required to elucidate the contribution of this intriguing brain structure to the pathophysiology of schizophrenia.

Failure to establish linkage on the X chromosome in 301 families with schizophrenia or schizoaffective disorder

The hypothesis that a gene for susceptibility to psychosis (specifically in the X-Y homologous class) is located on the sex chromosomes has been proposed. Such a gene would account for the excess of sex chromosome anomalous males and females in populations of patients with psychosis, a tendency towards concordance by sex within families, and sex differences associated with psychosis and its underlying brain pathology. In earlier studies we observed small positive LOD scores in Xp11, and in a more recent and larger cohort of 178 sibling pairs, a peak multipoint nonparametric LOD score of 1. 55 at the locus DXS8032 in Xq21. The present study with a new set of markers extended the cohort to 301 ill sibling pairs and their parents. Despite the increase in sample size, the LOD score did not increase. A peak NPL of 1.55 was observed at the locus DXS1068 in proximal Xp, a region remote from the previous report. Separating families into those who were more likely to have X chromosome inheritance (maternal with no male to male transmission) did not yield stronger findings. In spite of the evidence that psychosis is related to a sex-dependent dimension of cerebral asymmetry, it is concluded that no consistent linkage of schizophrenia to the X chromosome can be demonstrated. In the context of the general failure of replication of linkage in psychosis, the possibility that the genetic predisposition to psychosis is contributed to by epigenetic modification rather than variations in the nucleotide sequence has to be considered.

Regional cerebral blood flow in male schizophrenic patients performing an auditory discrimination task

Regional cerebral blood flow (rCBF) was measured in 11 schizophrenic patients amid 10 normal controls, both at rest and while performing an auditory discrimination task. Single photon emission computed tomography with technetium-99m hexamethylpropylene amine oxime was used for quantitative evaluation of rCBF. The schizophrenic patients showed greater rCBF in the temporal and parietal regions at rest than the controls, but no abnormalities were found in frontal perfusion. During task performance. on the other hand, the patients showed a reduced frontal rCBF. whereas there was no group difference in rCBF in the temporal and parietal regions. In addition, the left> right hemisphere asymmetries of rCBF observed in the controls during task performance were not present in the patients. although there was no group difference in hemisphere laterality in rCBF at rest. These findings suggest that the employment of a cognitive task for neuroimaging studies is useful for detecting abnormalities of brain activation. such as hypofrontality and altered hemisphere laterality. in patients with schizophrenia.

Changes in limbic dopamine metabolism following quinolinic acid lesions of the left entorhinal cortex in rats

To examine the effects of lesions of the entorhinal cortex on limbic dopamine (DA) metabolism, DA and its metabolites were assayed in five brain regions (the medial prefrontal cortex, anterior cingulate cortex, caudate-putamen, accumbens nucleus, and lateral amygdala), 14 and 28 days after quinolinic acid or sham lesions of the left entorhinal cortex in rats. Concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) on day 14 in the medial prefrontal cortex, accumbens nucleus, and lateral amygdala of the entorhinal cortex lesioned animals were significantly decreased compared with the controls, but they returned to control levels on day 28. The concentration of DA in the lateral amygdala and spontaneous locomotion to a novel environment were significantly increased on day 28 after the lesion. These results suggest that entorhinal cortex lesions alter mesolimbic dopamine metabolism, particularly in the amygdala.

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.

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

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