Searching the schizophrenic brain for temporal lobe deficits: a systematic review and meta-analysis

Ketamine Restores Thalamic-Prefrontal Cortex Functional Connectivity in a Mouse Model of Neurodevelopmental Disorder-Associated 2p16.3 Deletion

2p16.3 deletions, involving heterozygous NEUREXIN1 (NRXN1) deletion, dramatically increase the risk of developing neurodevelopmental disorders, including autism and schizophrenia. We have little understanding of how NRXN1 heterozygosity increases the risk of developing these disorders, particularly in terms of the impact on brain and neurotransmitter system function and brain network connectivity. Thus, here we characterize cerebral metabolism and functional brain network connectivity in Nrxn1α heterozygous mice (Nrxn1α+/- mice), and assess the impact of ketamine and dextro-amphetamine on cerebral metabolism in these animals. We show that heterozygous Nrxn1α deletion alters cerebral metabolism in neural systems implicated in autism and schizophrenia including the thalamus, mesolimbic system, and select cortical regions. Nrxn1α heterozygosity also reduces the efficiency of functional brain networks, through lost thalamic "rich club" and prefrontal cortex (PFC) hub connectivity and through reduced thalamic-PFC and thalamic "rich club" regional interconnectivity. Subanesthetic ketamine administration normalizes the thalamic hypermetabolism and partially normalizes thalamic disconnectivity present in Nrxn1α+/- mice, while cerebral metabolic responses to dextro-amphetamine are unaltered. The data provide new insight into the systems-level impact of heterozygous Nrxn1α deletion and how this increases the risk of developing neurodevelopmental disorders. The data also suggest that the thalamic dysfunction induced by heterozygous Nrxn1α deletion may be NMDA receptor-dependent.

Hippocampal subfields and visuospatial associative memory across stages of schizophrenia-spectrum disorder

BACKGROUND

While previous studies have identified relationships between hippocampal volumes and memory performance in schizophrenia, these relationships are not apparent in healthy individuals. Further, few studies have examined the role of hippocampal subfields in illness-related memory deficits, and no study has examined potential differences across varying illness stages. The current study aimed to investigate whether individuals with early and established psychosis exhibited differential relationships between visuospatial associative memory and hippocampal subfield volumes.

METHODS

Measurements of visuospatial associative memory performance and grey matter volume were obtained from 52 individuals with a chronic schizophrenia-spectrum disorder, 28 youth with recent-onset psychosis, 52 older healthy controls, and 28 younger healthy controls.

RESULTS

Both chronic and recent-onset patients had impaired visuospatial associative memory performance, however, only chronic patients showed hippocampal subfield volume loss. Both chronic and recent-onset patients demonstrated relationships between visuospatial associative memory performance and hippocampal subfield volumes in the CA4/dentate gyrus and the stratum that were not observed in older healthy controls. There were no group by volume interactions when chronic and recent-onset patients were compared.

CONCLUSIONS

The current study extends the findings of previous studies by identifying particular hippocampal subfields, including the hippocampal stratum layers and the dentate gyrus, that appear to be related to visuospatial associative memory ability in individuals with both chronic and first-episode psychosis.

Structural neuroimaging across early-stage psychosis: Aberrations in neurobiological trajectories and implications for the staging model

OBJECTIVE

This review critically examines the structural neuroimaging evidence in psychotic illness, with a focus on longitudinal imaging across the first-episode psychosis and ultra-high-risk of psychosis illness stages.

METHODS

A thorough search of the literature involving specifically longitudinal neuroimaging in early illness stages of psychosis was conducted. The evidence supporting abnormalities in brain morphology and altered neurodevelopmental trajectories is discussed in the context of a clinical staging model.

RESULTS

In general, grey matter (and, to a lesser extent, white matter) declines across multiple frontal, temporal (especially superior regions), insular and parietal regions during the first episode of psychosis, which has a steeper trajectory than that of age-matched healthy counterparts. Although the ultra-high-risk of psychosis literature is considerably mixed, evidence indicates that certain volumetric structural aberrations predate psychotic illness onset (e.g. prefrontal cortex thinning), while other abnormalities present in ultra-high-risk of psychosis populations are potentially non-psychosis-specific (e.g. hippocampal volume reductions).

CONCLUSION

We highlight the advantages of longitudinal designs, discuss the implications such studies have on clinical staging and provide directions for future research.

Subcortical brain volume abnormalities in 2028 individuals with schizophrenia and 2540 healthy controls via the ENIGMA consortium

The profile of brain structural abnormalities in schizophrenia is still not fully understood, despite decades of research using brain scans. To validate a prospective meta-analysis approach to analyzing multicenter neuroimaging data, we analyzed brain MRI scans from 2028 schizophrenia patients and 2540 healthy controls, assessed with standardized methods at 15 centers worldwide. We identified subcortical brain volumes that differentiated patients from controls, and ranked them according to their effect sizes. Compared with healthy controls, patients with schizophrenia had smaller hippocampus (Cohen's d=-0.46), amygdala (d=-0.31), thalamus (d=-0.31), accumbens (d=-0.25) and intracranial volumes (d=-0.12), as well as larger pallidum (d=0.21) and lateral ventricle volumes (d=0.37). Putamen and pallidum volume augmentations were positively associated with duration of illness and hippocampal deficits scaled with the proportion of unmedicated patients. Worldwide cooperative analyses of brain imaging data support a profile of subcortical abnormalities in schizophrenia, which is consistent with that based on traditional meta-analytic approaches. This first ENIGMA Schizophrenia Working Group study validates that collaborative data analyses can readily be used across brain phenotypes and disorders and encourages analysis and data sharing efforts to further our understanding of severe mental illness.

Regional cerebral blood flow in late-onset schizophrenia: a SPECT study using 99mTc-ECD

Progressive disability in schizophrenia has been considered to be associated with onset-age. The objective of this study was to evaluate age onset-related degeneration in rCBF in patients with schizophrenia. We evaluated characteristic changes in brain perfusion by age, gender, medication and clinical symptoms in medicated patients with early-onset (EOS: developed at younger than 40 years old: n = 44) and late-onset (LOS: developed at older than 40 years old: n = 19) schizophrenia and control subjects matched for age and gender (n = 37) using statistical parametric mapping (SPM8) applied to 99mTc-ECD SPECT. We performed SPECT with 99mTc-ECD on the brains of subjects. A voxel-by-voxel group analysis was performed using SPM 8 and ANOVA. rCBF in EOS was found to be reduced in the precentral and inferior frontal gyri; on the other hand, rCBF was reduced in the bilateral postcentral gyrus in LOS. This study revealed a significant difference in brain perfusion between EOS and LOS. The present study might suggest that the characteristic changes in rCBF are related to onset-age in schizophrenia.

Diffusion magnetic resonance imaging study of schizophrenia in the context of abnormal neurodevelopment using multiple site data in a Chinese Han population

Schizophrenia has increasingly been considered a neurodevelopmental disorder, and the advancement of neuroimaging techniques and associated computational methods has enabled quantitative re-examination of this important theory on the pathogenesis of the disease. Inspired by previous findings from neonatal brains, we proposed that an increase in diffusion magnetic resonance imaging (dMRI) mean diffusivity (MD) should be observed in the cerebral cortex of schizophrenia patients compared with healthy controls, corresponding to lower tissue complexity and potentially a failure to reach cortical maturation. We tested this hypothesis using dMRI data from a Chinese Han population comprising patients from four different hospital sites. Utilizing data-driven methods based on the state-of-the-art tensor-based registration algorithm, significantly increased MD measurements were consistently observed in the cortex of schizophrenia patients across all four sites, despite differences in psychopathology, exposure to antipsychotic medication and scanners used for image acquisition. Specifically, we found increased MD in the limbic system of the schizophrenic brain, mainly involving the bilateral insular and prefrontal cortices. In light of the existing literature, we speculate that this may represent a neuroanatomical signature of the disorder, reflecting microstructural deficits due to developmental abnormalities. Our findings not only provide strong support to the abnormal neurodevelopment theory of schizophrenia, but also highlight an important neuroimaging endophenotype for monitoring the developmental trajectory of high-risk subjects of the disease, thereby facilitating early detection and prevention.

Systematic meta-analysis of insula volume in schizophrenia

BACKGROUND

Volume reduction in insular cortex may constitute an important neuropathology in schizophrenia. We provide the first meta-analysis of studies that conducted region-of-interest analyses of the magnitude of effect and pattern of insula volume reduction in schizophrenia compared with healthy control subjects.

METHODS

Included studies examined insula volume in schizophrenia relative to healthy control subjects. Studies were located via electronic database searches and hand searching. Study selection, data extraction, and quality assessment were completed by two independent reviewers. Hedge's g effect sizes were calculated using Comprehensive Meta-Analysis (v.2) to quantify volumetric differences between people with and without schizophrenia, accounting for moderating influences of age, sex, illness duration, medication, whole brain volume, and potential differences in hemispheric and anatomical subregions.

RESULTS

Random-effects analysis showed reductions of bilateral insula (n = 945, g = -.446, 95% confidence interval -.639 to -.252, p = .00001), with moderate heterogeneity apparent (I² = 76%). This effect was consistent across left and right insula and not influenced by illness stage or sex. Additional analyses revealed larger reductions of anterior (n = 605, g = -.643, p < 0.001; I² = 52%) than of posterior insula (n = 453, g = -.321, p = .028; I² = 55%). Meta-regression analyses did not identify any significant predictors of reduced insula volume.

CONCLUSIONS

This meta-analysis indicates medium-sized reduction of insula volume in schizophrenia, of greatest magnitude in the anterior subregion. Cellular distinctions across anterior and posterior insula may contribute to understanding the neuropathology and functional significance of the observed volumetric differences.

Structural brain changes in First Episode Schizophrenia compared with Fronto-Temporal Lobar Degeneration: a meta-analysis

BACKGROUND

The authors sought to compare gray matter changes in First Episode Schizophrenia (FES) compared with Fronto-Temporal Lobar Degeneration (FTLD) using meta-analytic methods applied to neuro-imaging studies.

METHODS

A systematic search was conducted for published, structural voxel-based morphometric MRI studies in patients with FES or FTLD. Data were combined using anatomical likelihood estimation (ALE) to determine the extent of gray matter decreases and analysed to ascertain the degree of overlap in the spatial distribution of brain changes in both diseases.

RESULTS

Data were extracted from 18 FES studies (including a total of 555 patients and 621 comparison subjects) and 20 studies of FTLD or related disorders (including a total of 311 patients and 431 comparison subjects). The similarity in spatial overlap of brain changes in the two disorders was significant (p = 0.001). Gray matter deficits common to both disorders included bilateral caudate, left insula and bilateral uncus regions.

CONCLUSIONS

There is a significant overlap in the distribution of structural brain changes in First Episode Schizophrenia and Fronto-Temporal Lobar Degeneration. This may reflect overlapping aetiologies, or a common vulnerability of these regions to the distinct aetio-pathological processes in the two disorders.

Systematic meta-review and quality assessment of the structural brain alterations in schizophrenia

BACKGROUND

The large quantity of systematic reviews of magnetic resonance imaging studies in schizophrenia challenges their meaningful interpretation. This meta-review synthesises the available information from systematic reviews of structural alteration in both chronic and first-episode schizophrenia.

METHODS

Systematic reviews were identified using electronic databases. Review methodological quality was assessed according to the Assessment of Multiple Systematic Reviews checklist. Data were extracted in duplicate and quality assessed for consistency and precision, guided by Grading of Recommendations Assessment, Development and Evaluation recommendations.

RESULTS

Integration of volumetric and voxel-based estimates allowed critical assessment of the magnitude and location of anatomical differences. There is evidence for grey matter reductions of anterior cingulate, frontal (particularly medial and inferior) and temporal lobes, hippocampus/amygdala, thalamus, and insula that may be magnified over time. Other regional alterations appear specific to illness stage or medication status.

CONCLUSIONS

There is limited high quality evidence supporting grey or white matter changes in schizophrenia, which has previously been obscured by a large volume of conflicting lower quality evidence.

Frequency of attention deficit in first-episode schizophrenia compared to ADHD

Attention deficit in schizophrenia may be underestimated due to limited sensitivity of attention tests. Comparing the frequency of attention deficits in schizophrenia to attention deficit hyperactivity disorder (ADHD) may solve this problem, since all subjects with ADHD should demonstrate impaired attention. Twenty-seven subjects with schizophrenia were compared to 74 clinical controls with ADHD on tests of focused/divided/sustained attention and impulsivity.

RESULTS

The frequency of impaired attention was equal among subjects with schizophrenia and ADHD-combined (ADHD-C), while ADHD-inattentive (ADHD-I) subjects were more impaired. Half the subjects with schizophrenia had a mild impairment in dual processing. Twenty-one percent showed normal performance on all tests. Fewer subjects with schizophrenia were impulsive/hyperactive, and fewer were impaired in sustained attention compared with the ADHD-C and ADHD-I groups, respectively.

CONCLUSION

Attention tests are not sufficiently sensitive to attention deficits in everyday functioning. Taking this into account, the possibility still remains that a substantial portion of subjects with schizophrenia are not impaired in attention.

Interdisciplinary Factors of Neuropathology in Schizophrenia

In the etymology of schizophrenia, the genetic component seems to play an essential role. Studies have shown more than 130 genes of susceptibility for schizophrenia: the majority of these studies, however, has yet to be confirmed- they are searching for more definition on the relevant functions of the genetic variation of schizophrenia. Recent studies suggest that a cluster of candidate genes in the interconnected network pathways are implicated in transmission of the glutamate the plasticity of the synapses, in oxidative stress, myelination and the profitability of oligodendrocytes. Previous neuropathological studies on schizophrenia did not identify specific neurodegenerative characteristics of this disease. Scientific evidence suggests that the physiopathology of schizophrenia involves alterations of the intracellular transmission pathway, those which are associated with reduced cerebral volume in some structures of white and gray matter. In particular, in schizophrenia, a reduction of medium cerebral volume has been observed, as has a reduction of the cortical regional volumes with reference to the frontal, temporal, and parietal areas of the brain - this is all in addition to a reduction of the prefrontal cortex, hippocampus, amygdala, thalamus, and the cerebellum. The cytoarchitectonic alterations in schizophrenia may be an expression of the pathology's processing, as are axonal damage and loss, reduction of myelination, and loss of neuropil. These all contribute to the reduction of the volume of the cerebral parenchima, and the corresponding augmentation of the cerebral spinal fluid. The inheritance of schizophrenia may appear high/elevated, but not a certain eventuality. In analysis of subtype specifics. However, this statistics remains significant in all studies. The role of the environmental factors in the development of schizophrenia is highlighted by studies which have been conducted on monozygotic patients affected by schizophrenia. While their genetic code is 100% similar, that is to say, entirely identical, one of the pair can be diagnosed as schizophrenic, while the other of the monozygotic pair has the 50% of the possibility not to contract schizophrenia. It is well known that genetic and environmental factors influence multiple aspects of human behavior, they can increase the susceptibility towards a mental disturbance. The reciprocal effects of these factors are placed in two distinct and diverse categories: gene environment interaction, which expresses the terminal genetic variations of susceptibility to environmental risk, and environmental gene correlations, where the genetic variability can increase or reduce the likelihood of the exposure to environmental determinant risk, includes early stressful events of life.

Detection of Lewy body disease in patients with late-onset depression, anxiety and psychotic disorder with myocardial meta-iodobenzylguanidine scintigraphy

PURPOSE

Lewy body disease (LBD) is comprised of a spectrum of diseases that includes Parkinson's disease (PD), PD dementia (PDD) and dementia with LBD (DLBD), an array of dementia, and motor symptoms. Low uptake of myocardial meta-iodobenzylguanidine (MIBG) validates diagnosis of LBD. Psychiatric symptoms sometimes precede atypical Parkinsonian syndromes in LBD. Of 34 patients with low MIBG uptake, late-onset depressive, anxiety, or psychotic symptoms were analyzed in term of clinical profiles.

METHOD

Thirty-four patients were classed into three groups according to three main symptoms, 11 patients with visual hallucination (VH), 13 with depression-anxiety (DA), and 10 with psychosis with cognitive disturbance (PCD). Cutoff values of heart-to-mediastinum (HM) ratio of MIBG were set at 1.78 in early phase or 1.68 in late phase.

RESULTS

Group VH patients showed a trend toward higher age at onset and occipital lobe hypoperfusion. Group DA patients lacked central and core features of DLBD and five of them showed frontal lobe hypoperfusion. Group PCD patients had the highest frequencies of suggestive symptoms and UPDRS scores and showed temporal lobe hypoperfusion. HM ratio was not associated with clinical profiles of three groups. Cognitive function was more severely disturbed in atypical Parkinsonian syndrome cases at an initial visit.

CONCLUSION

Group VH was considered to DLBD, and Group PCD was regarded as PDD or DLBD with early psychotic presentation. Group DA has a possibility of early depression or anxiety disorder of LBD although it lacked DLBD criteria. Atypical Parkinsonian syndromes are associated with cognitive disturbance irrespective of psychiatric profiles.

Is semantic memory impaired in schizophrenia? A systematic review and meta-analysis of 91 studies

INTRODUCTION

Semantic memory impairments in schizophrenia have been reported across a wide range of neuropsychological tests. Set against a backdrop of fairly widespread cognitive impairments, it is difficult to know whether there is a primary, or secondary, impairment of semantic memory in schizophrenia. Also, whether there is a profile of differential impairment across the range of neuropsychological tests.

METHODS

Employing a systematic search strategy, 91 papers were identified which have assessed participants with schizophrenia on a measure of semantic memory. A series of meta-analyses were then conducted which provided combined weighted means for performance on tasks of naming, word-picture matching, verbal fluency, priming, and categorisation.

RESULTS

An uneven profile of impairment is reported with large effect sizes for tests of naming and verbal fluency, medium effect sizes for word-picture matching and association and small effect sizes for categorisation and priming tests.

CONCLUSIONS

This uneven profile supports the claim that a degradation of semantic knowledge may not be adequate in explaining the semantic memory impairment in schizophrenia. This conclusion is supported by the data which report a relationship between an executive dysfunction and poor priming and fluency performance particularly. The data support a link between Formal Thought Disorder and semantic memory impairments on tests of naming and verbal fluency but on other tests evidence is equivocal.

Schizophrenia, brain disease and meta-analyses: integrating the pieces and testing Fusar-Poli's hypothesis

This paper aims to discuss and test the hypothesis raised by Fusar-Poli [Fusar-Poli P. Can neuroimaging prove that schizophrenia is a brain disease? A radical hypothesis. Medical Hypotheses in press, corrected proof] that "on the basis of the available imaging literature there is no consistent evidence to reject the radical and provocative hypothesis that schizophrenia is not a brain disease". To achieve this goal, all meta-analyses on 'fMRI and schizophrenia' published during the current decade and indexed in Pubmed were summarized, as much as some other useful information, e.g., meta-analyses on genetic risk factors. Our main conclusion is that the literature fully supports the hypothesis that schizophrenia is a syndrome (not a disease) associated with brain abnormalities, despite the fact that there is no singular and reductionist pathway from the nosographic entity (schizophrenia) to its causes. This irreducibility is due to the fact that the syndrome has more than one dimension (e.g., cognitive, psychotic and negative) and each of them is related to abnormalities in specific neuronal networks. A psychiatric diagnosis is a statistical procedure; these dimensions are not identically represented in each diagnosticated case and this explains the existence of more than one pattern of brain abnormalities related to schizophrenia. For example, chronification is associated with negativism while the first psychotic episode is not; in that sense, the same person living with schizophrenia may reveal different symptoms and fMRI patterns along the course of his life, and this is precisely what defines schizophrenia since the time when it was called Dementia Praecox (first by pick then by Kraepelin). It is notable that 100% of the collected meta-analyses on 'fMRI and schizophrenia' reveal positive findings. Moreover, all meta-analyses that found positive associations between schizophrenia and genetic risk factors have to do with genes (SNPs) especially activated in neuronal tissue of the central nervous system (CNS), suggesting that, to the extent these polymorphisms are related to schizophrenia's etiology, they are also related to abnormal brain activity.

Evaluating the consistency and specificity of neuroimaging data using meta-analysis

Making sense of a neuroimaging literature that is growing in scope and complexity will require increasingly sophisticated tools for synthesizing findings across studies. Meta-analysis of neuroimaging studies fills a unique niche in this process: It can be used to evaluate the consistency of findings across different laboratories and task variants, and it can be used to evaluate the specificity of findings in brain regions or networks to particular task types. This review discusses examples, implementation, and considerations when choosing meta-analytic techniques. It focuses on the multilevel kernel density analysis (MKDA) framework, which has been used in recent studies to evaluate consistency and specificity of regional activation, identify distributed functional networks from patterns of co-activation, and test hypotheses about functional cortical-subcortical pathways in healthy individuals and patients with mental disorders. Several tests of consistency and specificity are described.

Semantic memory impairment in schizophrenia--deficit in storage or access of knowledge?

This study evaluates whether patients with schizophrenia have a degraded memory store for semantic knowledge. 20 patients with a chronic history of schizophrenia and evidence of cognitive impairment were selected, since the literature indicates that this subgroup is most likely to manifest a degraded semantic knowledge store. Their profile of semantic memory impairments was compared to that of a group of Alzheimer's Dementia (AD) patients (n=22), who met neuropsychological criteria for degraded semantic store. Both groups were matched for Performance IQ. 15 elderly healthy controls were also included in the study. The AD and schizophrenia groups produced substantially different profiles of semantic memory impairment. This is interpreted as indicating that the semantic impairments in this subgroup of patients with schizophrenia do not result from a degraded store. This is corroborated by an analysis of the data using other neuropsychological criteria for determining degraded store. We conclude that there is little evidence for a classic degradation of semantic knowledge in schizophrenia, and it appears that impairments result from an inability to use semantic knowledge appropriately, particularly when selection of salient semantic relations is required.

Schizophrenia, "Just the Facts": what we know in 2008 part 1: overview

For every disorder, there is a set of established findings and accepted constructs upon which further understanding is built. The concept of schizophrenia as a disease entity has been with us for a little more than a century, although descriptions resembling this condition predate this conceptualization. In 1988, for the inaugural issue of Schizophrenia Research, at the invitation of the founding editors, a senior researcher, since deceased (RJ Wyatt) published a summary of generally accepted ideas about the disorder, which he termed "the facts" of schizophrenia. Ten years later, in conjunction with two of the authors (MSK, RT), he compiled a more extensive set of "facts" for the purpose of evaluating conceptual models or theoretical constructs developed to understand the nature of schizophrenia. On the 20th anniversary of this journal, we update and substantially expand our effort to periodically summarize the current body of information about schizophrenia. We compile a body of seventy-seven representative major findings and group them in terms of their specific relevance to schizophrenia -- etiologies, pathophysiology, clinical manifestations, and treatments. We rate each such "fact" on a 0-3 scale for measures of reproducibility, whether primary to schizophrenia, and durability over time. We also pose one or more critical questions with reference to each "fact", answers to which might help better elucidate the meaning of that finding for our understanding of schizophrenia. We intend to follow this paper with the submission to the journal of a series of topic-specific articles, critically reviewing the evidence.

Deconstructing psychosis with human brain imaging

This review synthesizes our current knowledge on the neurobiology of psychosis from an array of in vivo brain-imaging studies. The evidence base consists of hundreds of studies of patients with schizophrenia and fewer on bipolar disorder but rarely providing direct comparisons between the disorders or integration across methods. Replicated findings in schizophrenia include reduced whole-brain and hippocampal volume as potential vulnerability markers, with further progression at onset; reduced N-acetyl aspartate concentrations in hippocampus and prefrontal cortex; striatal dopamine D(2) receptors upregulation; and alteration in the relation between frontal and temporal activation. These findings are not attributable to medication effects but are of unclear specificity and may apply across the psychosis spectrum. There are consistently replicated associations of psychotic symptoms and cognitive impairment in both structural and functional imaging in schizophrenia but not, as yet, in bipolar disorder. Therefore, it would be premature to dispense with current diagnostic categories because direct comparisons among them are rare, insufficient studies have examined longitudinal changes, and long-term imaging outcome studies in first-episode psychosis have not yet been done. To address these issues and make neuroimaging "clinically relevant," investigators will need to standardize their approaches to data acquisition and analysis, and construct the necessary range of "human brain maps," to implement studies that are sufficiently powered to provide reliable data pertinent to deconstructing psychosis.

Study of childhood onset schizophrenia (COS) using SPECT and neuropsychological assessment

BACKGROUND

In recent years, the development of positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging has enhanced our understanding of the physiological functioning of the intact brain.

AIM

To study cerebral cortical perfusion defects in patients with childhood onset schizophrenia (COS) and to assess their neuropsychological functioning.

METHODS

This cross-sectional study comprised 14 patients with COS with onset at or before 14 years of age, diagnosed as per ICD-10 DCR criteria, attending a tertiary care centre in North India. All the patients were assessed on sociodemographic, clinical profile sheet, Positive and Negative Symptom Scale (PANSS) and Edinburgh Handedness Inventory (EHI). The Wisconsin Card Sorting Test (WCST) was used to assess their neuropsychological functioning. All patients underwent SPECT. A control group of 10 healthy subjects was studied with SPECT for comparison.

RESULTS

Nine patients (64.3%) showed perfusion anomaly on SPECT scan specifically in the left temporal and frontal areas of the brain. On WCST score these 9 patients showed a higher percentage of total errors (64.49%+/-9.42%) as compared to the other 5 patients (48.54%+/-12.70%) who showed no abnormality on SPECT scan. All normal control subjects showed no abnormality on SPECT.

CONCLUSION

The results from WCST show that COS patients have difficulty in executive functioning. Also, patients had perfusion anomaly in the left temporal, frontal and parietal areas. Deficits found in COS are similar to those found in adult onset schizophrenia (AOS). In view of the findings, the nature of COS and its relationship with AOS are discussed.

Regional brain metabolism in schizophrenia: An FDG-PET study

BACKGROUND

Recent technological advances have established beyond any doubt the biological nature of schizophrenia. Functional neuroimaging using FDG-PET forms an important technique in understanding the biological underpinnings of psychopathology of schizophrenia.

METHODS

Eighteen male patients diagnosed as having schizophrenia and having active psychosis as determined by PANSS were subjected to FDG-PET scanning under resting conditions. The glucose uptake in selected regions of interest was studied across the spectrum of schizophrenia.

RESULTS

Chronicity and severity of illness did not influence cerebral glucose metabolism. Participants with negative schizophrenia had significantly decreased metabolism in all regions of the brain as compared to the positive type. The positive syndrome of schizophrenia was associated with significantly increased glucose metabolism in the medial temporal regions, basal ganglia and left thalamic regions. Hypometabolism was also noted in the cerebellum.

CONCLUSION

While a number of brain areas can be identified as potential causative regions and hypotheses regarding putative mechanisms can be formed, the considerable heterogeneity of schizophrenia poses a great challenge in the precise delineation of the disease process.

The effect of working memory performance on functional MRI in schizophrenia

INTRODUCTION

Studies of prefrontal cortical (PFC) function in schizophrenia have been inconsistent, with studies showing both increased and decreased PFC activation compared to healthy controls. Discrepant findings may be due to task performance effects or demographic differences between samples. We report functional magnetic resonance imaging (fMRI) data comparing subjects with schizophrenia and healthy controls performing a 2-back working memory (WM) task, addressing the effects of task performance.

METHODS

Twenty-two controls and 14 patients with DSM-IV schizophrenia, scanned on a Siemens 1.5 T scanner, performed a visual letter 2-back task and control task (CPT-X) during fMRI. Data were analyzed using Statistical Parametric Mapping (SPM)-99.

RESULTS

After statistical adjustment for performance differences, persons with schizophrenia showed significantly greater activation than controls in the right medial frontal gyrus and left inferior parietal lobule/medial temporal gyrus region (BA 39/40), and a trend toward greater activation in the left ventrolateral PFC. This pattern was also observed in demographically matched subgroups of participants.

CONCLUSIONS

Data are consistent with findings reported in recent studies showing increased PFC and parietal activation in schizophrenia when the effects of reduced WM task performance in patients with schizophrenia are addressed. Further studies are needed to clarify the pathophysiological basis of WM load sensitivity in schizophrenia and its relationship to genes.

The Primacy of Cognition in Schizophrenia

Cognitive tasks and concepts are used increasingly in schizophrenia science and treatment. Recent meta-analyses show that across a spectrum of research domains only cognitive measures distinguish a majority of schizophrenia patients from healthy people. Average effect sizes derived from common clinical tests of attention, memory, language, and reasoning are twice as large as those obtained in structural magnetic resonance imaging and positron emission tomography studies. Chronic stress, genes, brain disturbances, task structure, gender, and sociocultural background may all enhance the sensitivity of cognitive performance to schizophrenia. At the same time, disease heterogeneity and the presence of endophenotypes and subtypes within the patient population may place upper limits on the strength of any specific cognitive finding. Schizophrenia is a complex biobehavioral disorder that manifests itself primarily in cognition.

Validation of distinct amnesic and executive type memory deficit in a psychiatric sample based on retrieval performance

Studies of localized brain dysfunctions have revealed connections between patterns of cognitive dysfunction and specific profiles of memory impairment. The amnesic type of memory impairment is defined by deficits in both free recall and recognition memory, whereas the dysexecutive memory impairment is characterized by retrieval deficits, i.e. a disproportional impairment in free recall relative to recognition memory. The present study tests whether classifications of psychiatric patients into recall impaired only (= RO group) and Recall and Recognition impaired (= RR group) correspond to the executive type and amnesic type of memory impairment. The alternative hypothesis is that the two groups merely differ in degree of neuropsychological and psychiatric disturbance. Forty-four subjects impaired on California Verbal Learning Test (CVLT) were selected from a larger database of 103 impaired and non-impaired subjects with schizophrenia or recurrent major depression. Subjects were classified into RO and RR groups and compared on measures of memory strategy (recency effect and interference on CVLT), overall neuropsychological function (Stroop Test and WAIS-R similarity) and psychiatric symptom load (positive and negative symptoms). Repeated measures ANOVA showed no effects of group, i.e. the RR group did not perform consistently below the RO group with regard to memory strategy, neuropsychological function or psychiatric symptom load. Two out of three analyses showed group x test interaction, supporting the dissociation of distinct executive and amnesic profiles among psychiatric patients. The RO group was more susceptible to interference but had better recency score than the RR group. The RO had higher negative symptoms while the RR group had higher positive symptoms.

A case of psychosis with temporal lobe epilepsy: SPECT changes with treatment

An 8-year-old male was referred to the child psychiatry department because of vivid visual and auditory hallucinations, including multiple voices talking to each other, and loss of consciousness. Magnetic resonance imaging scans revealed cortical dysgenesis in the left inferior frontal cortex and adjacent subcortical structures. Single-photon emission computed tomography imaging revealed left temporal hypoperfusion. Risperidone therapy was initiated because there was no remission after carbamazepine and sodium valproate treatment. After risperidone treatment, symptoms remitted. A control single-photon emission computed tomography study indicated that the left temporal hypoperfusion was normalized. After discontinuation of risperidone, symptoms returned, and electroencephalography revealed generalized slow-wave activity particularly prominent in the left temporal region. To our knowledge, this is one of the first reports of cerebral blood flow changes in a pediatric patient with psychosis after treatment.

Meta-analysis and the science of schizophrenia: variant evidence or evidence of variants?

Quantification (meta-analysis) of the neuroscience evidence on schizophrenia shows very modest average differences between patient and control distributions across a great variety of measures and literatures. The strongest findings involve cognitive and psychophysiological measures. Several possible explanations for this situation are reviewed including technical immaturity, methodological variability, dimensional and multiple illness models and the nature of cognitive measurement. An argument is developed that biological subtypes and endophenotypes within the broad diagnostic category of schizophrenia underpin the meta-analytic evidence. Considerations in the use of this evidence to identify illness variants are described and four candidate subtypes are proposed. Schizophrenia is a disease that will resist biological definition until its variants are isolated and extracted from the generic patient population.

Searching for a structural endophenotype in psychosis using computational morphometry

Structural cerebral abnormalities are frequently observed in schizophrenia. These abnormalities may indicate vulnerability for the disorder, as evidenced by reports of familial clustering of measures identified through region-of-interest analyses using manual outlining procedures. We used computational morphometry to detect structural differences within the entire brain to further examine possible structural endophenotypes. Magnetic resonance imaging scans were obtained in 31 psychotic patients, 32 non-psychotic first-degree relatives of psychotic patients and 27 healthy controls. The images were processed using an automated procedure, yielding global grey matter, white matter, CSF and total brain volume. The relative distribution of grey matter was compared between groups on a clustered-voxel basis. Global grey matter and total brain volume did not differ between the groups. White matter volume was significantly higher and CSF volume significantly lower in relatives compared to both cases and controls. The clustered-voxel based group comparison yielded evidence for significant grey matter deficits in fronto-thalamic-cerebellar regions, in psychotic patients, whereas the most prominent deficits in relatives involved the cerebellum. Patients with psychosis and first-degree healthy relatives of patients with psychosis show cerebellar abnormalities, which may constitute a marker of genetic transmission.

Quantification of frontal and temporal lobe brain-imaging findings in schizophrenia: a meta-analysis

Magnetic resonance imaging (MRI) and positron emission tomography (PET) studies of the frontal and temporal lobes in schizophrenia patients and healthy controls have proliferated over the past 2 decades, but there have been relatively few attempts to quantify the evidence. In this meta-analytic review, 155 studies on frontal and temporal lobe neurobiology were synthesized, reflecting results from 4043 schizophrenia patients and 3977 normal controls. Cohen's d was used to quantify case-control differences, and moderator variable analysis indexed the relation of sample and imaging characteristics to the magnitude of these differences. Frontal metabolic and blood flow deficiencies in conjunction with cognitive activation tasks ("hypofrontality") emerged as the strongest body of evidence, demonstrating abnormalities that distinguish approximately half of schizophrenia patients from healthy people. Most case-control comparisons with structural and functional imaging yield small and in many cases unstable findings. Technical scanning parameters like slice thickness and magnet strength did not vary with case-control differences consistently across the meta-analyses. However, patient sample characteristics including sample size, handedness and gender composition emerged frequently as moderators of brain-imaging effect sizes.

Functional brain mapping of psychopathology

In this paper, we consider the impact that the novel functional neuroimaging techniques may have upon psychiatric illness. Functional neuroimaging has rapidly developed as a powerful tool in cognitive neuroscience and, in recent years, has seen widespread application in psychiatry. Although such studies have produced evidence for abnormal patterns of brain response in association with some pathological conditions, the core pathophysiologies remain unresolved. Although imaging techniques provide an unprecedented opportunity for investigation of physiological function of the living human brain, there are fundamental questions and assumptions which remain to be addressed. In this review we examine these conceptual issues under three broad sections: (1) characterising the clinical population of interest, (2) defining appropriate levels of description of normal brain function, and (3) relating these models to pathophysiological conditions. Parallel advances in each of these questions will be required before imaging techniques can impact on clinical decisions in psychiatry.

The Functional Magnetic Resonance Imaging Data Center (fMRIDC): the challenges and rewards of large-scale databasing of neuroimaging studies

The Functional Magnetic Resonance Imaging Data Center (fMRIDC) (http://www.fmridc.org) was established in the Autumn of 1999 with the objective of creating a mechanism by which members of the neuroscientific community may more easily share functional neuroimaging data. Examples in other sciences offer proof of the usefulness and benefit that sharing data provides through encouraging growth and development in those fields. By building a publicly accessible repository of raw data from peer-reviewed studies, the Data Center hopes to create a similarly successful environment for the neurosciences. In this article, we discuss the continuum of data-sharing efforts and provide an overview of the scientific and practical difficulties inherent in managing various fMRI data-sharing approaches. Next, we detail the organization, design and foundation of the fMRIDC, ranging from its current capabilities to the issues involved in the submitting and requesting of data. We discuss how a publicly accessible database enables other fields to develop relevant tools that can aid in the growth of understanding of cognitive processes. Information retrieval and meta-analytic techniques can be used to search, sort and categorize study information with a view towards subjecting study data to secondary 'meta-' and 'mega-analyses'. In addition, we detail the technical and policy challenges that have had to be addressed in the formation of the Data Center. Among others, these include: human subject confidentiality issues; ensuring investigator's rights; heterogeneous data description and organization; development of search tools; and data transfer issues. We conclude with comments concerning the future of the fMRIDC effort, its role in promoting the sharing of neuroscientific data, and how this may alter the manner in which studies are published.

Does a Neurodevelopmental Lesion Involving the Hippocampus Explain Memory Dysfunction in Schizophrenia?

Abstract: Schizophrenia is a mental disorder that has been associated with structural abnormalities of the medial temporal lobes and with impairments of memory function. The evidence for this association is weak. Many analyses have not investigated whether the impairment of memory is over and above the recognized impairments of global cognitive function, attention or working memory, all of which are disturbed in schizophrenia. Another difficulty evident in studies to date is that the construct of memory has rarely informed the selection of neuropsychological tests used. Lastly, an understanding of the normal development of cognitive functions has not guided interpretation of results. In this review we examine the evidence for a hippocampal memory deficit in schizophrenia, and suggest that an appreciation of these three points can explain the impairments described. In particular, we propose that the effect of a neurodevelopmental lesion will have different consequences for functions that normally develop early in life, such as memory, compared with functions developing later, such as executive functions. The latter develop post-pubertally during the period of peak incidence of schizophrenia, and it is these functions that are most impaired in this disorder.