Anatomy of schizophrenia revisited

[Psychotic disorder revealing epilepsy linked to a dysembryoma of the left hippocampus]

INTRODUCTION

Psychotic symptoms are a rare but well-known complication of epilepsy. The prevalence is estimated between 4 and 9%.

PATIENT

We report a case of a 40-year-old patient, unrecognized epileptic, who presented an acute psychotic syndrome which seemed to be of functional origin, the EEG performed during the episode, and the cerebral CT scan being normal. Nevertheless, the clinical presentation, especially the sudden ending of delusions, led to further investigations. Careful history taking and repeated EEG recordings allowed the diagnosis of partial epilepsy that had begun 17 years earlier and symptomatic of a dysembryoplastic tumour of the left hippocampus revealed by MRI.

DISCUSSION AND CONCLUSION

Search for an epileptic origin of an acute psychotic syndrome must always be undertaken by systematic EEG. The possibility of a symptomatic temporal tumor must not be overlooked.

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

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

Theories of schizophrenia: a genetic-inflammatory-vascular synthesis

BACKGROUND

Schizophrenia, a relatively common psychiatric syndrome, affects virtually all brain functions yet has eluded explanation for more than 100 years. Whether by developmental and/or degenerative processes, abnormalities of neurons and their synaptic connections have been the recent focus of attention. However, our inability to fathom the pathophysiology of schizophrenia forces us to challenge our theoretical models and beliefs. A search for a more satisfying model to explain aspects of schizophrenia uncovers clues pointing to genetically mediated CNS microvascular inflammatory disease.

DISCUSSION

A vascular component to a theory of schizophrenia posits that the physiologic abnormalities leading to illness involve disruption of the exquisitely precise regulation of the delivery of energy and oxygen required for normal brain function. The theory further proposes that abnormalities of CNS metabolism arise because genetically modulated inflammatory reactions damage the microvascular system of the brain in reaction to environmental agents, including infections, hypoxia, and physical trauma. Damage may accumulate with repeated exposure to triggering agents resulting in exacerbation and deterioration, or healing with their removal. There are clear examples of genetic polymorphisms in inflammatory regulators leading to exaggerated inflammatory responses. There is also ample evidence that inflammatory vascular disease of the brain can lead to psychosis, often waxing and waning, and exhibiting a fluctuating course, as seen in schizophrenia. Disturbances of CNS blood flow have repeatedly been observed in people with schizophrenia using old and new technologies. To account for the myriad of behavioral and other curious findings in schizophrenia such as minor physical anomalies, or reported decreased rates of rheumatoid arthritis and highly visible nail fold capillaries, we would have to evoke a process that is systemic such as the vascular and immune/inflammatory systems.

SUMMARY

A vascular-inflammatory theory of schizophrenia brings together environmental and genetic factors in a way that can explain the diversity of symptoms and outcomes observed. If these ideas are confirmed, they would lead in new directions for treatments or preventions by avoiding inducers of inflammation or by way of inflammatory modulating agents, thus preventing exaggerated inflammation and consequent triggering of a psychotic episode in genetically predisposed persons.

Schizophrenias and epilepsies: why? when? how?

Detailed studies of the association between the epilepsies and the schizophrenias extend over 40 years. Recent studies are abundant and make fertile use of new technologies. However, the pathological changes described in schizophrenias are quite varied. Studies fail to recognize that "epilepsies" and "schizophrenias" have varied in definition over time, and have always been weak categories with which to do science. Now that it is possible to measure deficits in brain structure, it would be better to see what behavioral problems are associated with specific cerebral pathology. It would be wise to be very precise in describing the behaviors and the nature and timing of their emergence rather than using terms such as psychoses. Schizophrenias have neurological, neuropsychological, and behavioral antecedents in childhood. Those associated with later epilepsies show biases, persistent in many studies over a number of years, toward relative excess of females, left temporal lobe structural deficits, and non-right-handedness. Schizophrenia should now be a predictable eventuality in certain people with epilepsies, an important factor in medical and surgical treatment.

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.

P300 asymmetry in schizophrenia: a meta-analysis

P300 event-related brain potential (ERP) amplitude is smaller in patients with schizophrenia compared to unaffected controls, but whether left temporal component amplitude is also smaller is debated. The present study employed meta-analytical methods to quantitatively assess previous P300 schizophrenia asymmetry findings. All P300 articles on schizophrenia using an auditory oddball paradigm published before January 2000 were obtained by comprehensive literature searches and cross-referencing for related articles. A total of 19 original articles reporting complete midline electrode data and 11 articles reporting lateral asymmetry electrode data were reviewed, which included different independent conditions that yielded 50 independent data sets. P300 amplitude differences between patients with schizophrenia and control subjects from the midline electrodes yielded effect sizes that differed among recording sites, such that Fz was significantly smaller than Pz, with Cz effect sizes smaller than Pz but larger than Fz. Comparison of P300 amplitude from the lateral data for the T3 and T4 electrodes found no reliable effect size difference when these electrodes were analyzed separately. However, comparison of P300 amplitude effect sizes from the TCP1 was significantly larger than that from the TCP2 when these electrodes were analyzed separately. P300 amplitude is smaller overall in patients with schizophrenia compared to control subjects and differs in its effect size topography across the midline and temporal electrode sites, with the strongest effect sizes obtained for the Pz midline and TCP1 lateral electrodes.

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

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

Three-dimensional mapping of temporo-limbic regions and the lateral ventricles in schizophrenia: gender effects

BACKGROUND

Local alterations in morphological parameters are poorly characterized in several brain regions widely implicated in schizophrenia neuropathology.

METHODS

Surface-based anatomical modeling was applied to magnetic resonance data to obtain three-dimensional (3D) average anatomical maps and measures of location, shape, asymmetry, and volume for the lateral ventricles, hippocampus, amygdala, and superior temporal gyrus in schizophrenic (n = 25; 15 male) and normal subjects (n = 28; 15 male) matched for demographic variables. For all regions, intra-group variability was visualized and group differences assessed statistically to discriminate local alterations in anatomy across sex and diagnosis.

RESULTS

Posterior hippocampal volumes, lengths, and widths were reduced in patients. The right amygdala showed volume increases in schizophrenia patients versus controls. Ventricular enlargements, pronounced in the left hemisphere, occurred in the superior and lateral dimensions in patients, and these effects interacted with gender. Superior horn anterior extremes, inferior horn volumes, and hippocampal asymmetries exhibited gender effects. Significant group differences were absent in superior temporal gyrus parameters. Finally, regional variability profiles differed across groups.

CONCLUSIONS

Clear morphometric differences of the lateral ventricles, hippocampus, and amygdala indicate regional displacements and shape distortions in several functional systems in schizophrenia. Alterations in these structures as mapped in 3D may provide the foundation for establishing brain abnormalities not previously defined at such a local level.

Recovery at Your Own PACE

1. People can recover fully from even the most severe forms of mental illness. 2. The Empowerment Model of Recovery describes the dynamics of recovery and prevention of mental illness. 3. PACE (personal assistance in community existence) is the application of the recovery principles.

Neurodevelopmental risk factors in schizophrenia

The authors review environmental and neurodevelopmental risk factors for schizophrenic disorders, with emphasis on minor physical anomalies, particularly craniofacial anomalies and dermatoglyphic variations. The high prevalence of these anomalies among schizophrenic subjects supports the neurodevelopmental theory of the etiology of schizophrenia, since they suggest either genetically or epigenetically controlled faulty embryonic development of structures of ectodermal origin like brain and skin. This may disturb neurodevelopment that in turn may cause these subjects to be at increased risk for the development of schizophrenia and related disorders. The precise confirmation of this theory, at least in some cases, will provide further understanding of these illnesses, allowing easy and inexpensive identification of subjects at risk and providing guidelines for the development of new pharmacological interventions for early treatment and even for primary prevention of the illness.

Cumulative effect of anatomical risk factors for schizophrenia: an MRI study

BACKGROUND

Although schizophrenic and control subjects differ on a variety of neuroanatomical measures, the specificity and sensitivity of any one measure for differentiating between groups are low. This study investigated the cumulative effect of deviant brain structure on diagnosis.

METHODS

Hemisphere and third ventricle volume and the normalized (Talairach) location of three association cortex sulcal landmarks were measured on high-resolution MRI scans in 37 male patients with schizophrenia and 33 male control subjects matched on age, handedness, and parental socioeconomic status.

RESULTS

While there were few group differences on individual anatomical measures, the 10 variables reliably discriminated between the two groups when used in concert in a discriminant function analysis (F[10.59] = 3.6, p < .0009) with 77% of the subjects correctly classified. Five of the measures (left posterior cingulate, left inferior frontal sulcus, right sylvian fissure, and left and right halves of the third ventricle) correlated significantly with the discriminant function (p < .005).

CONCLUSIONS

This is the first study to demonstrate that schizophrenics can be distinguished from matched controls on the basis of brain anatomy alone. The risk of schizophrenia may depend on the total amount of neural deviance, rather than on anomalies in a single structure or circuit.

Ventromedial temporal lobe pathology in dementia, brain trauma, and schizophrenia

The ventromedial temporal area contains numerous anatomical structures collectively or selectively involved in a wide range of neurological and psychiatric disorders. Collective involvement is exemplified best by Alzheimer's disease where a host of anatomical structures and a host of cognitive and behavioral changes are manifested. Selective disease of the amygdala can yield deficits in the ability to judge and evaluate emotional expressions. While memory functions are nearly synonymous with the concept of ventromedial temporal area, they overshadow other functions associated with the diverse anatomical structures in this part of the brain. For example, it could be argued that in addition to output directed toward the hippocampal formation, the output of the ventromedial temporal area is equally strong to the ventral striatopallidal system of the basal forebrain. Denervation of these structures could be associated with the behavioral changes that occur in tandem with the memory-related changes of ventromedial temporal lobe pathology. Here we explore the anatomical and pathological correlate associated with ventromedial temporal area pathology and consider how these may impact on ventral striatopallidal conceptualizations. We conclude that ventromedial temporal area pathology deprives the basal forebrain of multimodal association information from the endstages of corticocortical sensory processing. This endstage information carries with it an analysis of real-time sensory awareness, historical-time or past sensory experiences, and decisions from hippocampal output structures regarding relevancy and novelty. In this sense, basal forebrain structures are in a unique position to regulate behavioral responses to a wide range of stimuli and to organize appropriate emotional, motor, autonomic, and endocrine responses to them.

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.

CSF N-CAM in neuroleptic-naïve first-episode patients with schizophrenia

An increased concentration of neural cell adhesion molecule (N-CAM) 105-115 kDa has been reported in patients with schizophrenia in both CSF and in post-mortem brain samples. To determine whether increased N-CAM is integral to the disease process or, alternatively, results from early treatment, CSF N-CAM was measured in a blind study of first episode (FE) patients, who were either neuroleptic-naïve (NN) or neuroleptic-treated (NT, < 100 mg Haldol equivalents), multi-episode (ME) patients, and controls. Overall, the FE patients displayed lower N-CAM concentrations as compared to controls (p = 0.043). This decrease in N-CAM in FE patients was seen only in the FE-NT group as compared to both controls (p = 0.0006). The FE-NT group also showed a lower CSF N-CAM compared to that in the FE-NN (p = 0.025) group. No difference in CSF N-CAM between the FE-NN and control group was found. ME patients showed an increased N-CAM as compared with FE patients (p = 0.018), but not as compared to controls (p = 0.93). Neuroleptic-naïve first-episode patients do not display a phenotypic increase in N-CAM. Thus, N-CAM is altered in first-episode patients following acute neuroleptic treatment and withdrawal, as compared to neuroleptic-naïve first-episode patients.