Decreased anterior cingulate gyrus metabolic rate in schizophrenia

Cortical thickness of the posterior cingulate cortex is associated with the ketamine-induced altered sense of self: An ultra-high field MRI study

Subanesthetic doses of ketamine induce an antidepressant effect within hours in individuals with treatment-resistant depression while it furthermore induces immediate but transient psychotomimetic effects. Among these psychotomimetic effects, an altered sense of self has specifically been associated with the antidepressant response to ketamine as well as psychedelics. However, there is plenty of variation in the extent of the drug-induced altered sense of self experience that might be explained by differences in basal morphological characteristics, such as cortical thickness. Regions that have been previously associated with a psychedelics-induced sense of self and with ketamine's mechanism of action, are the posterior cingulate cortex (PCC) and the pregenual anterior cingulate cortex (pgACC). In this randomized, placebo-controlled, double-blind cross-over magnetic resonance imaging study, thirty-five healthy male participants (mean age ± standard deviation (SD) = 25.1 ± 4.2 years) were scanned at 7 T. We investigated whether the cortical thickness of two DMN regions, the PCC and the pgACC, are associated with disembodiment and experience of unity scores, which were used to index the ketamine-induced altered sense of self. We observed a negative correlation between the PCC cortical thickness and the disembodiment scores (R = -0.54, p < 0.001). In contrast, no significant association was found between the pgACC cortical thickness and the ketamine-induced altered sense of self. In the context of the existing literature, our findings highlight the importance of the PCC as a structure involved in the mechanism of ketamine-induced altered sense of self that seems to be shared with different antidepressant agents with psychotomimetic effects operating on different classes of transmitter systems.

Protein Succinylation and Malonylation as Potential Biomarkers in Schizophrenia

Two protein post-translational modifications, lysine succinylation and malonylation, are implicated in protein regulation, glycolysis, and energy metabolism. The precursors of these modifications, succinyl-CoA and malonyl-CoA, are key players in central metabolic processes. Both modification profiles have been proven to be responsive to metabolic stimuli, such as hypoxia. As mitochondrial dysfunction and metabolic dysregulation are implicated in schizophrenia and other psychiatric illnesses, these modification profiles have the potential to reveal yet another layer of protein regulation and can furthermore represent targets for biomarkers that are indicative of disease as well as its progression and treatment. In this work, data from shotgun mass spectrometry-based quantitative proteomics were compiled and analyzed to probe the succinylome and malonylome of postmortem brain tissue from patients with schizophrenia against controls and the human oligodendrocyte precursor cell line MO3.13 with the dizocilpine chemical model for schizophrenia, three antipsychotics, and co-treatments. Several changes in the succinylome and malonylome were seen in these comparisons, revealing these modifications to be a largely under-studied yet important form of protein regulation with broad potential applications.

Reprint of: F-18Fluorodeoxyglucose positron emission tomography studies of the schizophrenia spectrum: The legacy of Monte S. Buchsbaum, M.D

This is a selective review of the work of Buchsbaum and colleagues. It revisits and pays tribute to four decades of publications employing positron emission tomography (PET) with ^F-18fluorodeoxyglucose (FDG) to examine the neurobiology of schizophrenia-spectrum disorders (including schizotypal personality disorder (SPD) and schizophrenia). Beginning with a landmark FDG-PET study in 1982 reporting hypofrontality in unmedicated schizophrenia patients, Buchsbaum and colleagues published high-impact work on regional glucose metabolic rate (GMR) abnormalities in the spectrum. Several key discoveries were made, including the delineation of schizophrenia-spectrum abnormalities in frontal and temporal lobe, cingulate, thalamus, and striatal regions using three-dimensional mapping with coregistered MRI and PET. These findings indicated that SPD patients have less marked frontal lobe and striatal dysfunction compared with schizophrenia patients, possibly mitigating frank psychosis. Additionally, these investigations were among the first to conduct early seed-based functional connectivity analyses with FDG-PET, showing aberrant cortical-subcortical circuitry and, in particular, revealing a thalamocortical circuitry abnormality in schizophrenia. Finally, pioneering work employing the first double-blind randomized antipsychotic (haloperidol) vs. placebo FDG-PET study design in schizophrenia indicated that GMR in the striatum, more than in any other region, was related to clinical response.

eQTLs Weighted Genetic Correlation Analysis Detected Brain Region Differences in Genetic Correlations for Complex Psychiatric Disorders

BACKGROUND

Psychiatric disorders are usually caused by the dysfunction of various brain regions. Incorporating the genetic information of brain regions into correlation analysis can provide novel clues for pathogenetic and therapeutic studies of psychiatric disorders.

METHODS

The latest genome-wide association study (GWAS) summary data of schizophrenia (SCZ), bipolar disorder (BIP), autism spectrum disorder (AUT), major depression disorder (MDD), and attention-deficit/hyperactivity disorder (ADHD) were obtained from the Psychiatric GWAS Consortium (PGC). The expression quantitative trait loci (eQTLs) datasets of 10 brain regions were driven from the genotype-tissue expression (GTEx) database. The PGC GWAS summaries were first weighted by the GTEx eQTLs summaries for each brain region. Linkage disequilibrium score regression was applied to the weighted GWAS summary data to detect genetic correlation for each pair of 5 disorders.

RESULTS

Without considering brain region difference, significant genetic correlations were observed for BIP vs SCZ (P = 1.68 × 10-63), MDD vs SCZ (P = 5.08 × 10-45), ADHD vs MDD (P = 1.93 × 10-44), BIP vs MDD (P = 6.39 × 10-9), AUT vs SCZ (P = .0002), and ADHD vs SCZ (P = .0002). Utilizing brain region related eQTLs weighted LD score regression, different strengths of genetic correlations were observed within various brain regions for BIP vs SCZ, MDD vs SCZ, ADHD vs MDD, and SCZ vs ADHD. For example, the most significant genetic correlations were observed at anterior cingulate cortex (P = 1.13 × 10-34) for BIP vs SCZ.

CONCLUSIONS

This study provides new clues for elucidating the mechanism of genetic correlations among various psychiatric disorders.

F-18Fluorodeoxyglucose positron emission tomography studies of the schizophrenia spectrum: The legacy of Monte S. Buchsbaum, M.D

This is a selective review of the work of Buchsbaum and colleagues. It revisits and pays tribute to four decades of publications employing positron emission tomography (PET) with ^F-18fluorodeoxyglucose (FDG) to examine the neurobiology of schizophrenia-spectrum disorders (including schizotypal personality disorder (SPD) and schizophrenia). Beginning with a landmark FDG-PET study in 1982 reporting hypofrontality in unmedicated schizophrenia patients, Buchsbaum and colleagues published high-impact work on regional glucose metabolic rate (GMR) abnormalities in the spectrum. Several key discoveries were made, including the delineation of schizophrenia-spectrum abnormalities in frontal and temporal lobe, cingulate, thalamus, and striatal regions using three-dimensional mapping with coregistered MRI and PET. These findings indicated that SPD patients have less marked frontal lobe and striatal dysfunction compared with schizophrenia patients, possibly mitigating frank psychosis. Additionally, these investigations were among the first to conduct early seed-based functional connectivity analyses with FDG-PET, showing aberrant cortical-subcortical circuitry and, in particular, revealing a thalamocortical circuitry abnormality in schizophrenia. Finally, pioneering work employing the first double-blind randomized antipsychotic (haloperidol) vs. placebo FDG-PET study design in schizophrenia indicated that GMR in the striatum, more than in any other region, was related to clinical response.

Correlation Between Levels of Delusional Beliefs and Perfusion of the Hippocampus and an Associated Network in a Non-Help-Seeking Population

BACKGROUND

Delusions are a defining and common symptom of psychotic disorders. Recent evidence suggests that subclinical and clinical delusions may represent distinct stages on a phenomenological and biological continuum. However, few studies have tested whether subclinical psychotic experiences are associated with neural changes that are similar to those observed in clinical psychosis. For example, it is unclear if overactivity of the hippocampus, a replicated finding of neuroimaging studies of schizophrenia, is also present in individuals with subclinical psychotic symptoms.

METHODS

To investigate this question, structural and pulsed arterial spin labeling scans were collected in 77 adult participants with no psychiatric history. An anatomical region of interest approach was used to extract resting perfusion of the hippocampus, and 15 other regions, from each individual. A self-report measure of delusional ideation was collected on the day of scanning.

RESULTS

The level of delusional thinking (number of beliefs [r = .27, p = .02]), as well as the associated level of distress (r = .29, p = .02), was significantly correlated with hippocampal perfusion (averaged over right and left hemispheres). The correlations remained significant after controlling for age, hippocampal volume, symptoms of depression and anxiety, and image signal-to-noise ratio, and they were confirmed in a voxelwise regression analysis. The same association was observed in the thalamus and parahippocampal, lateral temporal, and cingulate cortices.

CONCLUSIONS

Similar to patients with schizophrenia, non-help-seeking individuals show elevated perfusion of a network of limbic regions in association with delusional beliefs.

Neurobiology of early psychosis

Background

Neurobiological studies of the early course of psychoses, such as schizophrenia, allow investigation of pathophysiology without the confounds of illness chronicity and treatment.

Aims

To review the recent literature on the biology of the early course of psychoses.

Method

We carried out a critical appraisal of the recent findings in the neurobiology of early psychoses, using structural, functional and neurochemical imaging techniques.

Results

Brain structural alterations are present early in the illness and may predate symptom onset. Some changes, notably those in frontal and temporal lobes, can progress during the early phases of the illness. Functional and neurochemical brain abnormalities can also be seen in the premorbid and the early phases of the illness. Some, although not all, changes can be trait-like whereas some others might progress during the early years.

Conclusions

A better understanding of such changes, especially during the critical periods of the prodrome, around the transition to the psychotic phase and during the early phases of the illness is crucial for continued research into preventive intervention strategies.

Abnormalities in personal space and parietal-frontal function in schizophrenia

Schizophrenia is associated with subtle abnormalities in day-to-day social behaviors, including a tendency in some patients to “keep their distance” from others in physical space. The neural basis of this abnormality, and related changes in social functioning, is unknown. Here we examined, in schizophrenic patients and healthy control subjects, the functioning of a parietal–frontal network involved in monitoring the space immediately surrounding the body (“personal space”). Using fMRI, we found that one region of this network, the dorsal intraparietal sulcus (DIPS), was hyper-responsive in schizophrenic patients to face stimuli appearing to move towards the subjects, intruding into personal space. This hyper-responsivity was predicted both by the size of personal space (which was abnormally elevated in the schizophrenia group) and the severity of negative symptoms. In contrast, in a second study, the activity of two lower-level visual areas that send information to DIPS (the fusiform face area and middle temporal area) was normal in schizophrenia. Together, these findings suggest that changes in parietal–frontal networks that support the sensory-guided initiation of behavior, including actions occurring in the space surrounding the body, contribute to social dysfunction and negative symptoms in schizophrenia.

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A parietal–frontal network in the primate brain monitors the space near the body.

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“Personal space”, a person's “comfort zone”, is influenced by this network.

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Patients with schizophrenia show an abnormal enlargement of personal space.

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This enlargement correlates with negative symptom levels.

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This enlargement also correlates with parietal responses to personal space intrusions.

Fibrillary astrocytes are decreased in the subgenual cingulate in schizophrenia

Decreases in astrocyte density and in glial fibrillary acid protein (GFAP) mRNA in the anterior cingulate cortex have been reported changed in mood and affective disorders. Our study examines the relative density and frequency of fibrillary and gemistocytic astrocytes in the white matter of the subgenual cingulate cortex in 11 schizophrenia, 16 bipolar disorder, 20 major depression and 20 normal control cases. Serial coronal sections were stained with H&E for anatomical guidance and GFAP immunohistochemistry for astrocyte identification. Astrocyte density was measured using systematic anatomical distinctions and randomised counting methods previously reported. Astrocytes were classified as fibrillary or gemistocytic based on staining and morphometric criteria and were measured in the crown and base of the gyral white matter. Fibrillary astrocytes were decreased in the base of the cingulate white matter in schizophrenia (p = 0.046), with no change in the density of gemistocytic astrocytes. There was no change in density of gemistocytic astrocytes. This suggests that the previously reported decrease in astrocytes in schizophrenia in the subgenual cingulate is accounted for only by a change in fibrillary astrocytes. With recent findings suggesting fibrillary astrocytes regulate synaptic glutamate this morphological change may relate to disregulation of function of the subgenual cingulate cortex.

Abnormal default-mode network homogeneity in first-episode, drug-naive schizophrenia at rest

BACKGROUND

Dysconnectivity hypothesis posits that schizophrenia relates to abnormal resting-state connectivity within the default-mode network (DMN) and this aberrant connectivity is considered as contribution of difficulties in self-referential and introspective processing. However, little is known about the alterations of the network homogeneity (NH) of the DMN in schizophrenia. In the present study, we used an automatic NH method to investigate the NH of the DMN in schizophrenia patients at rest.

METHODS

Forty-nine first-episode, drug-naive schizophrenia patients and 50 age-, gender-, and education-matched healthy controls underwent a resting-state functional magnetic resonance imaging (fMRI). An automated NH approach was used to analyze the data.

RESULTS

Patients exhibited lower NH than controls in the left medial prefrontal cortex (MPFC) and the right middle temporal gyrus (MTG). Significantly higher NH values in the left posterior cingulate cortex (PCC) and the right cerebellum Crus I were found in the patient group than in the control group. No significant correlation was found between abnormal NH values and Positive and Negative Symptom Scale (PANSS) scores, duration of untreated psychosis (DUP), age or years of education in the patient group.

CONCLUSIONS

Our findings suggest that abnormal NH of the DMN exists in first-episode, drug-naive schizophrenia and further highlight the importance of the DMN in the pathophysiology of schizophrenia.

Alteration of cyclic-AMP response element binding protein in the postmortem brain of subjects with bipolar disorder and schizophrenia

BACKGROUND

Abnormalities of cyclic-AMP (cAMP) response element binding protein (CREB) function has been suggested in bipolar (BP) illness and schizophrenia (SZ), based on both indirect and direct evidence. To further elucidate the role of CREB in these disorders, we studied CREB expression and function in two brain areas implicated in these disorders, i.e., dorsolateral prefrontal cortex (DLPFC) and cingulate gyrus (CG).

METHODS

We determined CREB protein expression using Western blot technique, CRE-DNA binding using gel shift assay, and mRNA expression using real-time RT-polymerase chain reaction (qPCR) in DLPFC and CG of the postmortem brain of BP (n=19), SZ (n=20), and normal control (NC, n=20) subjects.

RESULTS

We observed that CREB protein and mRNA expression and CRE-DNA binding activity were significantly decreased in the nuclear fraction of DLPFC and CG obtained from BP subjects compared with NC subjects. However, the protein and mRNA expression and CRE-DNA binding in SZ subjects was significantly decreased in CG, but not in DLPFC, compared with NC.

CONCLUSION

These studies thus indicate region-specific abnormalities of CREB expression and function in both BP and SZ. They suggest that abnormalities of CREB in CG may be associated with both BP and SZ, but its abnormality in DLPFC is specific to BP illness.

Astrocyte decrease in the subgenual cingulate and callosal genu in schizophrenia

Decreases in glial cell density and in GFAP mRNA in the anterior cingulate cortex have been reported in schizophrenia, bipolar disorder and major depressive disorder. Our study examines astrocyte and oligodendrocyte density in the white and grey matter of the subgenual cingulate cortex, and at the midline of the genu of the corpus callosum, in schizophrenia, bipolar disorder, depression and normal control cases. Serial coronal sections were stained with H and E for anatomical guidance, cresyl haematoxylin for oligodendrocyte identification and GFAP immunohistochemistry for astrocyte identification. Oligodendrocyte and astrocyte density was measured using systematic anatomical distinctions and randomised counting methods. A significant decrease in astrocyte density was observed in schizophrenia compared with normal controls in the cingulate grey matter, cingulate white matter and the midline of the corpus callosum (p = 0.025). Bipolar disorder and depression cases showed no significant changes in astrocyte density. Oligodendrocytes did not show any changes between diagnostic groups. In subgenual cingulate cortex, the ratio of oligodendrocytes to astrocytes was decreased between the controls and the three disease groups, suggesting a specific glial cell type specific change in schizophrenia.

Apathy symptoms modulate motivational decision making on the Iowa gambling task

Background

The present study represents an initial attempt to assess the role of apathy in motivated decision making on the Iowa Gambling Task. Clinical descriptions of patients with apathy highlight deficits in the cognitive, emotional and behavioural aspects of goal directed activity, yet standard neurocognitive tests of these measures fail to demonstrate reliable sensitivity to the disorder. Available research suggests the Iowa Gambling Task is a robust test of complex emotional socio-executive processes involved in motivational decision making, which can analogue real-world goal-directed behaviour.

Methods

We ask whether performance on the Iowa Gambling Task can distinguish brain damaged patients with apathy symptoms from 1) brain damaged patients without apathy and 2) neurologically intact controls. Overall, 22 healthy adults and 29 brain damaged patients took part in this study.

Results

Brain damaged patients with apathy were distinctively impaired on the Iowa Gambling Task compared to both non-apathetic brain damaged patients and neurologically intact healthy controls. On the other hand, standard measures for the cognitive control of behaviour failed to show this sensitivity.

Conclusions

Our results demonstrated that the Iowa Gambling Task is sensitive to the presence of apathy symptoms. We discuss these findings in terms of neurocognition deficits in apathy and the related implications for rehabilitation and clinical intervention.

Egocentric spatial learning in schizophrenia investigated with functional magnetic resonance imaging

Psychotic symptoms in schizophrenia are related to disturbed self-recognition and to disturbed experience of agency. Possibly, these impairments contribute to first-person large-scale egocentric learning deficits. Sixteen inpatients with schizophrenia and 16 matched healthy comparison subjects underwent functional magnetic resonance imaging (fMRI) while finding their way in a virtual maze. The virtual maze presented a first-person view, lacked any topographical landmarks and afforded egocentric navigation strategies. The participants with schizophrenia showed impaired performance in the virtual maze when compared with controls, and showed a similar but weaker pattern of activity changes during egocentric learning when compared with controls. Especially the activity of task-relevant brain regions (precuneus and posterior cingulate and retrosplenial cortex) differed from that of controls across all trials of the task. Activity increase within the right-sided precuneus was related to worse virtual maze performance and to stronger positive symptoms in participants with schizophrenia. We suggest that psychotic symptoms in schizophrenia are related to aberrant neural activity within the precuneus. Possibly, first-person large-scale egocentric navigation and learning designs may be a feasible tool for the assessment and treatment of cognitive deficits related to self-recognition in patients with schizophrenia.

Schizophrenic patients and their unaffected siblings share increased resting-state connectivity in the task-negative network but not its anticorrelated task-positive network

BACKGROUND

Abnormal connectivity of the anticorrelated intrinsic networks, the task-negative network (TNN), and the task-positive network (TPN) is implicated in schizophrenia. Comparisons between schizophrenic patients and their unaffected siblings enable further understanding of illness susceptibility and pathophysiology. We examined the resting-state connectivity differences in the intrinsic networks between schizophrenic patients, their unaffected siblings, and healthy controls.

METHODS

Resting-state functional magnetic resonance images were obtained from 25 individuals in each subject group. The posterior cingulate cortex/precuneus and right dorsolateral prefrontal cortex were used as seed regions to identify the TNN and TPN through functional connectivity analysis. Interregional connectivity strengths were analyzed using overlapped intrinsic networks composed of regions common to all subject groups.

RESULTS

Schizophrenic patients and their unaffected siblings showed increased connectivity in the TNN between the bilateral inferior temporal gyri. By contrast, schizophrenic patients alone demonstrated increased connectivity between the posterior cingulate cortex/precuneus and left inferior temporal gyrus and between the ventral medial prefrontal cortex and right lateral parietal cortex in the TNN. Schizophrenic patients exhibited increased connectivity between the left dorsolateral prefrontal cortex and right inferior frontal gyrus in the TPN relative to their unaffected siblings, though this trend only approached statistical significance in comparison to healthy controls.

CONCLUSION

Resting-state hyperconnectivity of the intrinsic networks may disrupt network coordination and thereby contribute to the pathophysiology of schizophrenia. Similar, though milder, hyperconnectivity of the TNN in unaffected siblings of schizophrenic patients may contribute to the identification of schizophrenia endophenotypes and ultimately to the determination of schizophrenia risk genes.

Effect of D-amino acid oxidase activator (DAOA; G72) on brain function during verbal fluency

BACKGROUND

The D-Amino acid oxidase activator (G72 or DAOA) is believed to play a key role in the regulation of central glutamatergic transmission which is seen to be altered in psychosis. It is thought to regulate D-amino acid oxidase (DAO), which metabolizes D-serine, a co-agonist of NMDA-type glutamate receptors and to be involved in dendritic arborization. Linkage, genetic association and expression studies have implicated the G72 gene in both schizophrenia and bipolar disorder.

AIMS

To examine the influence of G72 variation on brain function in the healthy population.

METHOD

Fifty healthy volunteers were assessed using functional magnetic resonance imaging while performing a verbal fluency task. Regional brain activation and task-dependent functional connectivity during word generation was compared between different rs746187 genotypes.

RESULTS

G72 rs746187 genotype had a significant effect on activation in the left postcentral and supramarginal gyri (FWE P < 0.05), and on the task-dependent functional coupling of this region with the retrosplenial cingulate gyrus (FWE P < 0.05).

CONCLUSIONS

Our results may reflect an effect of G72 on glutamatergic transmission, mediated by an influence on D-amino acid oxidase activity, on brain areas particularly relevant to the hypoglutamatergic model of psychosis.

Altered glycogen metabolism in cultured astrocytes from mice with chronic glutathione deficit; relevance for neuroenergetics in schizophrenia

Neurodegenerative and psychiatric disorders including Alzheimer's, Parkinson's or Huntington's diseases and schizophrenia have been associated with a deficit in glutathione (GSH). In particular, a polymorphism in the gene of glutamate cysteine ligase modulatory subunit (GCLM) is associated with schizophrenia. GSH is the most important intracellular antioxidant and is necessary for the removal of reactive by-products generated by the utilization of glucose for energy supply. Furthermore, glucose metabolism through the pentose phosphate pathway is a major source of NADPH, the cofactor necessary for the regeneration of reduced glutathione. This study aims at investigating glucose metabolism in cultured astrocytes from GCLM knockout mice, which show decreased GSH levels. No difference in the basal metabolism of glucose was observed between wild-type and knockout cells. In contrast, glycogen levels were lower and its turnover was higher in knockout astrocytes. These changes were accompanied by a decrease in the expression of the genes involved in its synthesis and degradation, including the protein targeting to glycogen. During an oxidative challenge induced by tert-Butylhydroperoxide, wild-type cells increased their glycogen mobilization and glucose uptake. However, knockout astrocytes were unable to mobilize glycogen following the same stress and they could increase their glucose utilization only following a major oxidative insult. Altogether, these results show that glucose metabolism and glycogen utilization are dysregulated in astrocytes showing a chronic deficit in GSH, suggesting that alterations of a fundamental aspect of brain energy metabolism is caused by GSH deficit and may therefore be relevant to metabolic dysfunctions observed in schizophrenia.

An anterior-to-posterior shift in midline cortical activity in schizophrenia during self-reflection

BACKGROUND

Deficits in social cognition, including impairments in self-awareness, contribute to the overall functional disability associated with schizophrenia. Studies in healthy subjects have shown that social cognitive functions, including self-reflection, rely on the medial prefrontal cortex (mPFC) and posterior cingulate gyrus, and these regions exhibit highly correlated activity during "resting" states. In this study, we tested the hypothesis that patients with schizophrenia show dysfunction of this network during self-reflection and that this abnormal activity is associated with changes in the strength of resting-state correlations between these regions.

METHODS

Activation during self-reflection and control tasks was measured with functional magnetic resonance imaging in 19 patients with schizophrenia and 20 demographically matched control subjects. In addition, the resting-state functional connectivity of midline cortical areas showing abnormal self-reflection-related activation in schizophrenia was measured.

RESULTS

Compared with control subjects, the schizophrenia patients demonstrated lower activation of the right ventral mPFC and greater activation of the mid/posterior cingulate gyri bilaterally during self-reflection, relative to a control task. A similar pattern was seen during overall social reflection. In addition, functional connectivity between the portion of the left mid/posterior cingulate gyrus showing abnormally elevated activity during self-reflection in schizophrenia, and the dorsal anterior cingulate gyrus was lower in the schizophrenia patients compared with control subjects.

CONCLUSIONS

Schizophrenia is associated with an anterior-to-posterior shift in introspection-related activation, as well as changes in functional connectivity, of the midline cortex. These findings provide support for the hypothesis that aberrant midline cortical function contributes to social cognitive impairment in schizophrenia.

Dysfunction of a cortical midline network during emotional appraisals in schizophrenia

A cardinal feature of schizophrenia is the poor comprehension, or misinterpretation, of the emotional meaning of social interactions and events, which can sometimes take the form of a persecutory delusion. It has been shown that the comprehension of the emotional meaning of the social world involves a midline paralimbic cortical network. However, the function of this network during emotional appraisals in patients with schizophrenia is not well understood. In this study, hemodynamic responses were measured in 14 patients with schizophrenia and 18 healthy subjects during the evaluation of descriptions of social situations with negative, positive, and neutral affective valence. The healthy and schizophrenia groups displayed opposite patterns of responses to emotional and neutral social situations within the medial prefrontal and posterior cingulate cortices--healthy participants showed greater activity to the emotional compared to the neutral situations, while patients exhibited greater responses to the neutral compared to the emotional situations. Moreover, the magnitude of the response within bilateral cingulate gyri to the neutral social stimuli predicted delusion severity in the patients with schizophrenia. These findings suggest that impaired functioning of cortical midline structures in schizophrenia may underlie faulty interpretations of social events, contributing to delusion formation.

Resting-state perfusion in nonmedicated schizophrenic patients: a continuous arterial spin-labeling 3.0-T MR study

PURPOSE

To determine whether well-described patterns of altered perfusion in schizophrenia can be identified by using continuous arterial spin labeling (CASL) with a whole-brain imaging sequence.

MATERIALS AND METHODS

This study was approved by the ethics committee of the local institutional review board, and written informed consent was obtained from all subjects. CASL was used to compare cerebral perfusion between 11 nonmedicated patients with schizophrenia and 25 healthy control subjects. Since antipsychotic medication may affect perfusion, only drug-free subjects were examined. Resting-state perfusion, as measured in terms of regional cerebral blood flow, was compared voxel wise by using an analysis of variance design in a statistical parametric mapping program, with patient age and sex as covariates.

RESULTS

Compared with the healthy control subjects, the schizophrenic patients had extensive areas of hypoperfusion in the frontal lobes bilaterally, in the anterior and medial cingulate gyri, and in the parietal lobes bilaterally. Increased perfusion was observed in the cerebellum, brainstem, and thalamus of the schizophrenic patients as compared with the perfusion in these areas in the control subjects.

CONCLUSION

CASL in schizophrenia revealed patterns of hypo- and hyperperfusion similar to the perfusion patterns in previously published positron emission tomographic and single photon emission computed tomographic studies. The advantages of CASL, including independence from injected contrast agents, no irradiation, and fast acquisition time, may facilitate intensive perfusion studies of the early recognition of schizophrenia and other psychiatric disorders, as well as longitudinal disease-monitoring research of these conditions.

Source-based morphometry of gray matter volume in men with first-episode schizophrenia

OBJECTIVES

There is a lot of variability between the results of studies reporting the pattern of gray matter volume changes in schizophrenia. Methodological issues may play an important role in this heterogeneity. The aim of the present study was to replicate the better performance of multivariate "source-based morphometry" (SBM) over the mass-univariate approach.

EXPERIMENTAL DESIGN

Voxel-based morphometry of Jacobian-modulated gray matter volume images, using voxel and cluster level inference, and SBM were performed in a group of first-episode schizophrenia patients (N = 49) and healthy controls (N = 127).

RESULTS

Using SBM we were able to find a significant reduction of gray matter volume in fronto-temporo-cerebellar areas whereas no significant results were obtained using voxel-based morphometry.

CONCLUSION

Multivariate analysis of gray matter volume seems to be a suitable method for characterization of the pattern of changes at the beginning of the illness in schizophrenia subjects.

Diffusion tensor anisotropy in the cingulate gyrus in schizophrenia

It has been proposed that schizophrenia results partly from altered brain connectivity. The anterior cingulate cortex in particular has been demonstrated to be affected in schizophrenia, with studies reporting reduced volume, altered neuronal arrangement, decreased anisotropy in diffusion tensor images, and hypometabolism. We used a 3T Siemens scanner to acquire structural and diffusion tensor imaging in age-and sex-matched groups of 41 adults with chronic schizophrenia, 6 adults with recent-onset schizophrenia, and 38 healthy control subjects. We manually traced the anterior and posterior cingulate gyri on all subjects and then compared the volume and anisotropy across groups for the left and right anterior and posterior cingulate gyri. The anterior cingulate gyrus was divided axially into six equal segments, and the posterior cingulate gyrus into two segments. Volume was calculated for the anterior and posterior gyri, and average anisotropy was then calculated for each individual segment, looking separately at gray and white matter. We found decreased overall relative left and right gray matter volume in the anterior cingulate gyrus in persons with schizophrenia compared with healthy controls. Additionally, in both gray and white matter of the cingulate, we found that recent-onset patients had the highest anisotropy, chronic patients had the lowest, and controls were intermediate. These results provide additional evidence for the presence of both white and gray matter abnormalities in the cingulate gyrus, which has been implicated in schizophrenia.

Spatial distribution and density of oligodendrocytes in the cingulum bundle are unaltered in schizophrenia

It has been proposed that schizophrenia results partly from altered brain connectivity. Gene microarray analyses performed in gray matter have indicated that several myelin-related genes normally expressed in oligodendrocytes have decreased expression levels in schizophrenia. These data suggest that oligodendrocytes may be involved in the deficits of schizophrenia and may be decreased in number in the case of disease. The anterior cingulate cortex in particular has been demonstrated to be affected in schizophrenia, with studies reporting altered neuronal arrangement, decreased anisotropy in diffusion tensor images, and hypometabolism. We used a stereologic nearest-neighbor estimator of spatial distribution to investigate oligodendrocytes in the anterior cingulum bundle using postmortem tissue from 13 chronic schizophrenics and 13 age-matched controls. Using a spatial point pattern analysis, we measured the degree of oligodendrocyte clustering by comparing the probability of finding a nearest-neighbor at a given distance in schizophrenics and controls. At the same time, we also estimated the number and density of oligodendrocytes in the region of interest. In the present study, we found no significant differences in the oligodendrocyte distribution or density in the cingulum bundle between the two groups, in contrast to earlier data from the prefrontal subcortical white matter. These results suggest that a subtler oligodendrocyte or myelin anomaly may underlie the structural deficits observed by brain imaging in the cingulum bundle in schizophrenia.

Meta-analysis of the effects of repetitive transcranial magnetic stimulation (rTMS) on negative and positive symptoms in schizophrenia

BACKGROUND

A growing body of evidence suggests that repetitive transcranial magnetic stimulation (rTMS) can alleviate negative and positive symptoms of refractory schizophrenia. However, trials to date have been small and results are mixed.

METHODS

We performed meta-analyses of all prospective studies of the therapeutic application of rTMS in refractory schizophrenia assessing the effects of high-frequency rTMS to the left dorsolateral prefrontal cortex (DLPFC) to treat negative symptoms, and low-frequency rTMS to the left temporo-parietal cortex (TPC) to treat auditory hallucinations (AH) and overall positive symptoms.

RESULTS

When analyzing controlled (active arms) and uncontrolled studies together, the effect sizes showed significant and moderate effects of rTMS on negative and positive symptoms (based on PANSS-N or SANS, and PANSS-P or SAPS, respectively). However, the analysis for the sham-controlled studies revealed a small non-significant effect size for negative (0.27, p=0.417) and for positive symptoms (0.17, p=0.129). When specifically analyzing AH (based on AHRS, HCS or SAH), the effect size for the sham-controlled studies was large and significant (1.04; p=0.002).

CONCLUSIONS

These meta-analyses support the need for further controlled, larger trials to assess the clinical efficacy of rTMS on negative and positive symptoms of schizophrenia, while suggesting the need for exploration for alternative stimulation protocols.

Posterior cingulate activation during moral dilemma in adolescents

Neuroimaging research examining correlates of adolescent behavioral maturation has focused largely on issues related to higher cognitive development. Currently few studies have explored neural correlates of emotional reactivity in adolescent groups. In this study, we sought to examine the nature of posterior cingulate activation during situations of moral dilemma in normal adolescents. We focused on this region because of emerging evidence that suggests its role in emotionally self-relevant mental processing. Ten healthy teenagers, aged from 14 to 16 years, underwent three fMRI sequences designed to examine (i) brain responses during moral dilemma; (ii) brain responses during passive viewing of the moral dilemma outcome; and (iii); "deactivation" during a simple cognitive task compared with resting-state activity. Our main finding was that during moral dilemma, all subjects showed significant activation of the posterior cingulate cortex, and more variable activation of the medial frontal cortex and angular gyrus. Interestingly, these findings were replicated in each subject using the passive viewing task, suggesting that the previous pattern was not specific to moral reasoning or decision making. Finally, six of the ten subjects showed deactivation of the same posterior cingulate region during the cognitive task, indicating some commonality of function between posterior cingulate activity during moral dilemmas and rest. We propose that these posterior cingulate changes may relate to basic neuronal activities associated with processing self-relevant emotional stimuli. Given the high single-subject reproducibility of posterior cingulate activations, our findings may contribute to further characterize adolescent emotional reactivity in developmental neuroimaging studies.

[Structural and functional brain changes in schizophrenic disorders. Indications of early neuronal developmental disturbances?]

The neurodevelopmental hypothesis of schizophrenia, which was established 30 years ago and discussed controversially for a long time, postulates that pre- and perinatally acting cerebral noxae cause disturbances of corticogenesis in the developing neuronal fibre systems which are essential for later onset of the disease. During recent years the cerebral alterations of schizophrenic patients could be further characterized as area-, layer-, and cell type-specific changes in temporolimbic and frontal regions leading to specific abnormalities of intrinsic and extrinsic connectivity. Animal models allowed for realistic imitations of these structural lesions and for elucidating their functional consequences concerning transmitter systems and behaviour. With modern neuroimaging techniques microstructural changes and alterations in cerebral activation can be exactly demonstrated and related to the specific psychopathologic features of schizophrenia.

Metabolic correlates of antidepressant and antipsychotic response in patients with psychotic depression undergoing electroconvulsive therapy

OBJECTIVES

Although electroconvulsive therapy (ECT) is a very effective treatment of depression and psychosis, the mechanisms by which this occurs are not fully delineated. The objective of this study was to investigate the functional alterations in brain metabolism in response to ECT through the use of positron emission tomography assessment of cerebral glucose metabolism before and after a course of ECT.

METHODS

Ten subjects with psychotic depression were studied with positron emission tomography using [F]fluorodeoxyglucose before and between 2 and 3 weeks after a course of ECT. Statistical parametric mapping and region of interest analyses of the anterior cingulate cortex (ACC) subregions (dorsal, rostral, subcallosal, and subgenual) and hippocampus were used to determine glucose metabolic changes from ECT. The Hamilton Depression Rating Scale and the Scale for Assessing Positive Symptoms were the primary measures used for assessing clinical changes from ECT.

RESULTS

Electroconvulsive therapy led to significant increases in the left subgenual ACC and hippocampal metabolism, which were directly correlated with each other and to a reduction in depression as measured by total Hamilton Depression Rating Scale scores. Better antidepressant responders had increased, whereas poorer responders had a decreased left subgenual ACC and hippocampal metabolism. The decrease in positive symptoms was also correlated with increased left hippocampal metabolism.

CONCLUSIONS

The antidepressant effect of ECT was correlated with increased metabolism in the left subgenual ACC and hippocampus, whereas the antipsychotic effect of ECT was only correlated with increased left hippocampal metabolism. This finding has implications to better understand the mechanism of antidepressant and antipsychotic effects of ECT.

Anterior and posterior cingulum abnormalities and their association with psychopathology in schizophrenia: a diffusion tensor imaging study

Evidence suggests that a disruption in limbic system network integrity and, in particular, the cingulate gyrus may play a role in the pathophysiology of schizophrenia. The cingulum bundles (CBs; posterior and anterior) are the most prominent white matter tracts in the limbic system, furnishing both input and output to the cingulate gyrus . In previous diffusion tensor imaging (DTI) studies, abnormal integrity has been demonstrated in the anterior CB portion, but not the posterior, in schizophrenia. As well, the relationships between the abnormalities of CB integrity and the psychopathology of schizophrenia remain to be elucidated. Using DTI acquired on a 3 T MRI machine, we examined fractional anisotropy (FA) in the anterior and posterior CBs of 42 patients with schizophrenia and 24 group-matched controls. Moreover, we investigated the relationships between CB abnormalities and the psychopathology of schizophrenia. Bilaterally reduced FA was demonstrated in both anterior and posterior CBs in schizophrenia patients. However, the pattern of FA reduction was different between anterior and posterior CBs: the reduction in FA was left-accentuated in anterior CBs, while no such lateralized abnormality was found in posterior ones. Finally, FA in posterior CBs correlated with positive symptom scores in patients with schizophrenia. These findings suggest that CB abnormalities in schizophrenia are not restricted to the anterior CB, but include the posterior as well. Pathology in the posterior CB would be one of the possible neural underpinnings of positive symptoms in schizophrenia.

Improvement of prefrontal brain function in endogenous psychoses under atypical antipsychotic treatment

Typical and atypical antipsychotics are thought to exert their effects on different neurotransmitter pathways with specific action of atypical compounds on the prefrontal cortex, but studies directly investigating the effect of those drugs on neurophysiological measures of prefrontal brain function are sparse. We therefore investigated the influence of different antipsychotics on an electrophysiological marker of prefrontal brain function (NoGo anteriorization, NGA) and neuropsychological test scores. For this purpose, 38 patients with endogenous psychoses were investigated at the beginning of a stationary psychiatric treatment and at a 6-week-follow-up. Patients were treated with typical or atypical antipsychotics, or a combination of both. They underwent psychopathological diagnostic and neuropsychological testing, as well as electrophysiological investigations during a Continuous Performance Test. The results indicate that typical and atypical antipsychotics differentially affected the development of the NGA over the course of the treatment, typical antipsychotics tending to result in decreased values at follow-up, and atypical antipsychotics stabilizing, or increasing this parameter. Performance in tests of frontal lobe function generally declined under typical antipsychotics and improved with atypical compounds, changes in Stroop interference correlated with changes in the NGA. We conclude that typical and atypical antipsychotics differ regarding their effect on prefrontal brain function in schizophrenia, atypical neuroleptics often showing a more favorable impact than conventional antipsychotics on respective parameters.

DNA fragmentation is increased in non-GABAergic neurons in bipolar disorder but not in schizophrenia

Apoptosis is thought to contribute to neuronal loss in bipolar disorder and schizophrenia, although empiric evidence in support of this idea has been lacking. In this study, we investigated whether or not apoptosis is associated with GABAergic interneurons in the anterior cingulate cortex in schizophrenia (n=14) and bipolar disorder (n=14) when compared to normal controls (n=14). A double-labeling technique using the Klenow method of in situ end-labeling (ISEL) of single-stranded DNA breaks was combined with an in situ hybridization localization of mRNA for the 67 kDa isoform of glutamate decarboxylase (GAD67) and applied to the anterior cingulate cortex of 14 normal controls, 14 schizophrenics, and 14 patients with bipolar disorder matched for age and postmortem interval. An increase in Klenow-positive, GAD67-negative nuclei were observed in layer V/VI of patients with bipolar disorder, but not schizophrenics. Klenow-positive cells that were also positive for GAD67 mRNA did not show differences in either patient group.

CONCLUSIONS

This is the first demonstration that there is more DNA fragmentation in cells showing no detectable GAD67 mRNA in patients with bipolar disorder than in schizophrenics or controls. These findings suggest that non-GABAergic cells may be selectively vulnerable to oxidative stress in patients with bipolar disorder.

Medial frontal hyperactivity in reality distortion

BACKGROUND

Schizophrenia/schizoaffective disorder involves reality distortion (RD), which impairs the ability to process socioemotional information. Because this psychological capacity maps to the medial prefrontal cortex (MPFC) and schizophrenia involves abnormal MPFC function, we tested the hypothesis that treated schizophrenic/schizoaffective patients with persistent RD (RD+) would exhibit greater MPFC dysfunction than patients without significant RD (RD-). The amygdala interacts with MPFC, also carries out socioemotional processing, and has been implicated in schizophrenia; thus, we also tested the hypothesis that patients would exhibit aberrant amygdala activity.

METHODS

Eleven RD+ patients, 12 RD- patients, and 15 healthy control subjects (HC) viewed emotionally salient pictures with neutral, aversive, and positive content during the acquisition of blood oxygenation level-dependent (BOLD) sensitive functional magnetic resonance imaging.

RESULTS

All groups had similar behavioral responses to the pictures. The RD+ subjects had greater BOLD responses (compared with the RD- and HC groups) to the aversive pictures in the anterior MPFC. Both patient groups showed reduced activation in MPFC and the left amygdala (compared with HC) for neutral pictures (compared with blank condition), although this effect could be explained by medication.

CONCLUSIONS

Reality distortion is associated with hyperactivity of the MPFC in schizophrenic/schizoaffective patients whose symptoms persist in spite of antipsychotic treatment.

Patterns of anterior cingulate activation in schizophrenia: a selective review

BACKGROUND

Anterior cingulate cortex (ACC) dysfunction is implicated in schizophrenia by numerous strands of scientific investigation. Functional neuroimaging studies of the ACC in schizophrenia have shown task-related hypo-activation, hyper-activation, and normal activation relative to comparison subjects. Interpreting these results and explaining their inconsistencies has been hindered by our ignorance of the healthy ACC's function. This review aims to clarify the site and magnitude of ACC activations in schizophrenia, and sources of their variation.

METHOD

48 studies of mnemonic and executive task-related activations in schizophrenia using both positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) were analyzed.

RESULTS

Abnormal activations in schizophrenia were not restricted to the "cognitive" part of the ACC. Hypoactivations were most common, and were found in all types of tasks. Hyperac-tivations when found, were largely in n-back tasks.

CONCLUSIONS

Hypoactivations cannot be explained by poor performance, more demanding control conditions or chronicity of illness alone. Patients on anti-psychotic medication tended to show both greater ACC activation and better performance, although whether this is directly due to their medication or the resultant reduction in symptoms is unclear. The relationship between ACC rCBF and task performance is not straightforward. Future research should better control confounding factors and incorporate different levels of difficulty.

Proteomic analysis of the anterior cingulate cortex in the major psychiatric disorders: Evidence for disease-associated changes

Abnormalities of the anterior cingulate cortex have previously been described in schizophrenia, major depressive disorder and bipolar disorder. In this study 2-DE was performed followed by mass spectrometric sequencing to identify disease-specific protein changes within the anterior cingulate cortex in these psychiatric disorders. The 2-DE system comprised IPGs 4-7 and 6-9 in the first, IEF dimension and SDS-PAGE in the second dimension. Resultant protein spots were compared between control and disease groups. Statistical analysis indicated that 35 spots were differentially expressed in one or more groups. Proteins comprising 26 of these spots were identified by mass spectroscopy. These represented 19 distinct proteins; aconitate hydratase, malate dehydrogenase, fructose bisphosphate aldolase A, ATP synthase, succinyl CoA ketoacid transferase, carbonic anhydrase, alpha- and beta-tubulin, dihydropyrimidinase-related protein-1 and -2, neuronal protein 25, trypsin precursor, glutamate dehydrogenase, glutamine synthetase, sorcin, vacuolar ATPase, creatine kinase, albumin and guanine nucleotide binding protein beta subunit. All but three of these proteins have previously been associated with the major psychiatric disorders. These findings provide support for the view that cytoskeletal and mitochondrial dysfunction are important components of the neuropathology of the major psychiatric disorders.

Coalescence of psychiatry, neurology, and neuropsychology: from theory to practice

In a climate of renewed interest in the synergy between neurology and psychiatry, practitioners are increasingly recognizing the importance of exchange and collaboration between these two disciplines. However, there are few working models of interdisciplinary teams that freely share expertise in real time, while providing clinical and academic training to future physicians who specialize in the central nervous system. Over the past 11 years, the McLean Hospital Neuropsychiatry and Behavioral Neurology service has provided proof-of-principle for such collaboration, demonstrating that a team comprising psychiatrists, neurologists, and neuropsychologists can function effectively as a unit while maintaining the autonomy of these three disciplines and also synthesizing their combined knowledge. In addition to delivering enhanced patient care and promoting medical research, this clinical service has provided enriched cross-specialty training for fellows, residents, and medical students. The practical functioning of the team is described, and case vignettes are presented to illustrate the team's collaborative synergism in practice.

A proteome analysis of the anterior cingulate cortex gray matter in schizophrenia

The Anterior Cingulate Cortex (ACC, Brodmans Area 24) is implicated in the pathogenesis of schizophrenia due to its normal functions and connectivity together with reports of structural, morphological and neurotransmitter aberrations within this brain area in the disease state. Two-dimensional gel electrophoresis (2DE) was employed to scan and compare the ACC gray matter proteomes between schizophrenia (n = 10) and control (n = 10) post-mortem human tissue. This proteomic approach has detected 42 protein spots with altered levels in the schizophrenia cohort, which to our knowledge is the first proteomic analysis of the ACC in schizophrenia. Thirty nine of these proteins were subsequently identified using mass spectrometry and functionally classified into metabolism and oxidative stress, cytoskeletal, synaptic, signalling, trafficking and glial-specific groups. Some of the identified proteins have previously been implicated in the disease pathogenesis and some offer new insights into schizophrenia. Investigating these proteins, the genes encoding these proteins, their functions and interactions may shed light on the molecular mechanisms underlying the heterogeneous symptoms characteristic of schizophrenia.

Proteomics-driven progress in neurodegeneration research

Proteomics technologies have been widely used in the investigation of neurodegenerative and psychiatric disorders, and in particular in the detection of differences between healthy individuals and patients suffering from such diseases. Thus, brain and cerebrospinal fluid (CSF) samples from patients with Alzheimer's disease, Down syndrome, Pick's disease, Parkinson's disease, schizophrenia, and other disorders as well as brain and CSF from animals serving as models of neurological disorders have been analyzed by proteomics. 2-DE followed by MALDI-TOF-MS has been mainly applied as this proteomics approach provides the possibility of convenient quantification of protein levels and detection of post-translational modifications. About 330 unique proteins with deranged levels and modifications have been detected by proteomics approaches to be related to neurodegeneration and psychiatric disorders. They are mainly involved in metabolism pathways, cytoskeleton formation, signal transduction, guidance, detoxification, transport, and conformational changes. In this article, we provide a summary of the major contributions of proteomics technologies in the study of neurodegenerative and psychiatric diseases, in particular, in the detection of changes in protein levels and modifications related to these disorders.

Effects of atypical and typical neuroleptics on anterior cingulate volume in schizophrenia

We have previously found typical neuroleptic exposure to be correlated with an increase in anterior cingulate volume over time in patients with schizophrenia. However, the effect of atypical neuroleptics on anterior cingulate volume and the clinical significance of these changes are not known. To determine if atypicals differ from typicals in their effect on anterior cingulate volume change over time and to assess the clinical significance of such changes, subjects with schizophrenia were compared to normal controls over time. Anterior cingulate volume was delineated with manual traces on magnetic resonance images of the brain in 31 neuroleptic-naïve subjects and 18 normal controls at admission and 2-3 years later. Neuroleptic exposure for each subject was calculated using a dose-year formula. Increased typical neuroleptics exposure over time was correlated to increased anterior cingulate volume over time (r = 0.92, p < 0.001), while increased atypical neuroleptics exposure was correlated to decreased anterior cingulate volume (r = -0.57, p < 0.006). Increased anterior cingulate volume was correlated to greater psychotic symptom improvement (r = 0.78, p < 0.010). Anterior cingulate volume changes over time are correlated differently with atypical versus typical neuroleptic exposure over time. The increase in anterior cingulate volume with typicals is correlated to improved psychotic symptoms over time.

Cortical glutamate-dopamine interaction and ketamine-induced psychotic symptoms in man

RATIONALE

The noncompetitive glutamate N-methyl-D: -aspartate receptor antagonist ketamine induces transient psychotic symptoms in man. Involvement of dopaminergic mechanisms in these effects has been suggested.

OBJECTIVES

The purpose of this article is to study the effects of ketamine on extrastriatal dopamine receptor availability in healthy subjects and extracellular dopamine levels in rat cortex.

MATERIALS AND METHODS

The effect of computer-driven subanesthetic ketamine infusion on cortical dopamine release was studied in healthy male subjects using a controlled study design. Dopamine D2/D3 receptor availability was quantified using positron emission tomography (PET) and [11C]FLB 457. A conventional region of interest-based analysis and voxel-based analysis was applied to the PET data. The ketamine-induced cortical dopamine release in rats was studied using in vivo microdialysis.

RESULTS

Ketamine infusion reduced significantly the [11C]FLB 457 binding potential (BP) in the posterior cingulate/retrosplenial cortices, suggestive of increased dopamine release. This brain imaging finding was further supported by a microdialysis experiment in rats showing that ketamine increased the extracellular dopamine concentration by up to 200% in the retrosplenial cortex. Ketamine-induced psychotic symptoms were associated with changes in the [11C]FLB 457 BP in the dorsolateral prefrontal and anterior cingulate cortices.

CONCLUSIONS

Our results suggest that cortical dopaminergic mechanisms have a role in the emergence of ketamine-induced psychosis-like symptoms in man. The glutamate-dopamine interaction in the posterior cingulate during ketamine infusion is well in line with the recent functional and structural imaging studies suggesting involvement of this cortical area in the development of schizophrenic psychosis.

Hypermetabolic pattern in frontal cortex and other brain regions in unmedicated schizophrenia patients. Results from a FDG-PET study

We report results of a FDG-PET study in 10 patients with schizophrenia (6 unmedicated, 4 never medicated) and 12 healthy age-matched controls. The patients met ICD-10 and DSM-IV criteria for schizophrenia and all reported psychotic, "positive" symptoms when tested. Schizophrenic patients had higher absolute CMRGlu values in almost all quantified regions compared to normal subjects. Using the occipital cortex as the reference region patients showed a hyperfrontal metabolic pattern. Other significant regional differences were found with respect to thalamus, striatum and temporal cortex. The finding of a hyperfrontality in un- and never medicated psychotic schizophrenic patients must be discussed in the light of the psychopathological symptoms of patients when tested, a possible disruption of cortico-striato-thalamic feedback loops and recent findings of a hyperfrontality in experimentally induced psychosis (ketamine- and psilocybin-model of schizophrenia).

Decreased caudal anterior cingulate gyrus volume and positive symptoms in schizophrenia

The anterior cingulate gyrus is a heterogeneous region that has specialized subdivisions with respect to its cytoarchitecture, function and connectivity. The aim of this study was to examine the morphological changes of the caudal subdivision of the anterior cingulate gyrus in the context of the cortico-striatal-thalamo-cortical circuitry of schizophrenia and their relationship to clinical symptoms. Accordingly, we measured the volumes of the caudal and rostral anterior cingulate gyrus, the orbitofrontal cortex, the caudate and the thalamus by magnetic resonance imaging in age- and sex-matched groups, which consisted of 22 patients with schizophrenia and 22 normal volunteers. The clinical symptoms of schizophrenia patients were obtained using the Positive and Negative Syndrome Scale. Volumetric reduction of the right caudal anterior cingulate gyrus was observed in patients with schizophrenia as compared with the normal controls. Furthermore, a smaller volume of the caudal anterior cingulate gyrus was significantly correlated with more severe positive symptoms of schizophrenia. Thus, these findings suggest that a volumetric abnormality of the caudal anterior cingulate gyrus in schizophrenia may be related to positive symptoms and possibly involved in the pathophysiology of schizophrenia.

Volumetric analysis of sulci/gyri-defined in vivo frontal lobe regions in schizophrenia: Precentral gyrus, cingulate gyrus, and prefrontal region

Methodological limitations in most previous magnetic resonance imaging (MRI)-based volumetric studies might have contributed to the inconsistent results regarding the frontal lobe regions of schizophrenia. Thus, applying the largest sample to date among those that have fully taken account of the intrinsic anatomical landmarks, this study aimed at clarifying the volumetric alterations of the frontal lobe and its subregions in schizophrenia. Participants comprised 59 patients with schizophrenia and 58 healthy controls. Measurements were performed on consecutive 1-mm-thick coronal slices reformatted from three-dimensional 1.5-T MR images. The whole frontal lobe was demarcated and then subdivided into the precentral gyrus (PCG), anterior cingulate, and posterior cingulate, and the remainder temporarily as the prefrontal region. Patients with schizophrenia had significant cortical volume reductions in the bilateral whole frontal lobe, prefrontal region, PCG, posterior cingulate, and right anterior cingulate. This study has confirmed that patients with schizophrenia do have cortical volume reductions in the whole frontal lobe and its subregions. Volume reduction in the PCG suggests that the primary motor cortex might contribute to the mechanisms of schizophrenia, considering its important role in the processing of multiple motor-related cognitive functioning suggested by the recent literature.

A 4.0-T fMRI study of brain connectivity during word fluency in first-episode schizophrenia

OBJECTIVE

To use functional magnetic resonance imaging (fMRI) to investigate functional connectivity, and hence, underlying neural networks, in never-treated, first-episode patients with schizophrenia using a word fluency paradigm known to activate prefrontal, anterior cingulate, and thalamic regions. Abnormal connectivity between the prefrontal cortex (PFC) and other brain regions has been demonstrated in chronic, medicated patients in previous positron emission tomography (PET) studies, but has not to our knowledge, previously been demonstrated using both first-episode, drug-naïve patients and fMRI technology.

METHODS

A 4.0-Tesla (T) fMRI was used to examine activation and functional connectivity [psychophysiological interactions (PPIs)] during a word fluency task compared to silent reading in 10 never-treated, first-episode patients with schizophrenia and 10 healthy volunteers of comparable age, sex, handedness, and parental education.

RESULTS

Compared to healthy volunteers, the schizophrenia patient group exhibited less activation during the word fluency task, mostly in the right anterior cingulate and prefrontal regions. Psychophysiological interactions between right anterior cingulate and other parts of the brain revealed a localized interaction with the left temporal lobe in healthy volunteers during the task and a widespread unfocussed interaction in patients.

CONCLUSION

These findings suggest anterior cingulate involvement in the neuronal circuitry underlying schizophrenia.

Abnormal development of the anterior cingulate in childhood-onset schizophrenia: a preliminary quantitative MRI study

The anterior cingulate is a key component of neural networks subserving attention and emotion regulation, functions often impaired in patients with psychosis. The study aimed to examine anterior cingulate volumes and sulcal morphology in a group of patients with childhood-onset schizophrenia (COS) compared with controls. Brain magnetic resonance imaging (MRI) scans were obtained in 13 COS and 18 matched control children, ages 6-17 years. Volume measures for the anterior cingulate gyrus (ACG) were obtained through manual labeling. A determination of cingulate sulcal pattern (single or double) was made for each hemisphere. The COS group had a reduced leftward skew of the double cingulate sulcal pattern, and absence of the normal left>right ACG volume asymmetry. The right ACG was larger in the COS than in controls. The schizophrenic children showed decreases in all ACG volumes with age, while the controls showed increases or no change. The data suggest that significant cingulate abnormalities may result from deviations in progressive neurodevelopmental processes, beginning before birth and continuing through childhood and adolescence, in persons who develop schizophrenia. These structural differences may relate to the well-described cognitive deficits these children display, and to the cardinal symptoms of schizophrenia.

Interictal SPECT in patients with mesial temporal lobe epilepsy and psychosis: a case-control study

Psychosis is commonly observed in patients with mesial temporal lobe epilepsy related to hippocampal sclerosis (MTLE-HS). Interictal single photon emission computed tomography (SPECT) was performed to compare regional cerebral blood flow (rCBF) pattern of MTLE-HS patients with psychosis of epilepsy (POE) comorbidity and MTLE-HS patients without any psychiatric disorders (Control group). For this, 21 patients with POE and 23 Control patients were matched by educational level, clinical, demographic, electrophysiological, and MRI data. SPECT scans were acquired using (99m)Tc and interpreted with a semiquantitative method. We analyzed brain regions of interest (ROI) of frontal, temporal, and parietal cortex, in addition to subcortical structures. There were no significant statistical differences of ROI between the POE group and the Control group after Bonferroni adjustment. However, we observed a trend for rCBF increase of right posterior cingulate in the POE Group. This increase would be in accordance with recent findings of cingulate abnormalities in schizophrenia, suggesting that abnormal function in this region might be associated with the psychotic phenomena.

Glial fibrillary acidic protein mRNA levels in the cingulate cortex of individuals with depression, bipolar disorder and schizophrenia

Recent studies have shown a decrease in glial number and glial fibrillary acidic protein (GFAP) levels in the frontal and cingulate cortices of individuals with mood disorders and schizophrenia. In an attempt to verify and expand these findings we examined GFAP messenger ribonucleic acid (mRNA) levels in postmortem sections of the anterior cingulate cortex (ACC) from the Stanley Neuropathology Consortium (SNC). The consortium consists of 15 cases in each of four groups (schizophrenia, bipolar disorder, non-psychotic depression and unaffected controls). By in situ hybridization, we found higher levels of GFAP mRNA in white matter and at the pial surface as compared with gray matter levels in all cases. In the white matter of ACC we detected a significant effect of diagnosis (P<0.04) with GFAP mRNA levels decreased in individuals with schizophrenia and bipolar disorder as compared with normal controls. In the gray matter there was a significant effect of layer (P<0.01) with the highest levels of GFAP mRNA in layer VI in all groups. As in the white matter, the mean GFAP mRNA levels were decreased in individuals with schizophrenia and bipolar disorder as compared with the unaffected controls, however the difference failed to reach statistical significance. Thus, astrocytes positive for GFAP may contribute to the decrease in glial density previously described in subjects with major mental illness, however the relative contribution of astrocytes may vary with diagnosis.

NMDA hypofunction in the posterior cingulate as a model for schizophrenia: an exploratory ketamine administration study in fMRI

BACKGROUND

Based on animal data, NMDA receptor hypofunction has been suggested as a model for positive symptoms in schizophrenia. NMDA receptor hypofunction affects several corticolimbic brain regions, of which the posterior cingulate seems to be the most sensitive. However, empirical support for a crucial role of posterior cingulate NMDA hypofunction in the pathophysiology of positive symptoms is still missing in humans. We therefore conducted an fMRI study using the NMDA antagonist ketamine in healthy human subjects during episodic memory retrieval, which is supposed to activate the posterior cingulate.

METHODS

We investigated 16 healthy subjects which were assigned to either placebo (n = 7; saline) or ketamine (n = 9; 0.6 mg/kg/h) group in a double-blind study design. All subjects received their infusion while performing an episodic memory retrieval task in the scanner. Immediately after the fMRI session, psychopathological effects of ketamine were measured using the Altered States of Consciousness Questionnaire.

RESULTS

The placebo group showed BOLD signal increases in the posterior and anterior cingulate during retrieval. Signal increases were significantly lower in the ketamine group. Lower signal increases in the posterior cingulate correlated significantly with positive (i.e. psychosis-like) symptoms induced by ketamine.

CONCLUSION

The present study for the first time demonstrates a relationship between NMDA receptors, posterior cingulate and positive (i.e. psychosis-like) symptoms in humans. Confirming findings from animal studies, it supports the hypothesis of a pathophysiological role of NMDA receptor hypofunction in the posterior cingulate in schizophrenia.

Gray matter abnormalities in paranoid schizophrenia and their clinical correlations

Numerous imaging studies have shown structural brain abnormalities in schizophrenia. Recently, voxel-based morphometry enabled whole brain analysis beyond the regions of interest (ROI). Regional gray matter concentrations of magnetic resonance (MR) images from 35 patients with paranoid schizophrenia were compared with those from 35 age- and sex-matched controls, and their clinical correlations were explored using voxel-based morphometry. Gray matter concentrations in the patients were significantly reduced in the left insular and dorsolateral prefrontal regions, and bilaterally in the medial frontal, anterior cingulate, inferior frontal and superior temporal regions. On the other hand, gray matter concentrations in the bilateral cerebellum and right striatum were significantly increased in the patients compared with controls. A negative correlation between the score for the severity of 'lack of insight and judgment' and gray matter concentrations in the left posterior and right anterior cingulate and bilateral inferior temporal regions including the lateral fusiform gyri was found. These results suggest the important roles of the paralimbic structures in the pathophysiology of schizophrenia and the involvement of the perceptual and monitoring systems in the mechanism of insight.