Positive and negative symptoms and regional cerebral perfusion in antipsychotic-naive schizophrenic patients: a high-resolution SPECT study

60 Years of Achievements by KSNM in Neuroimaging Research

Nuclear medicine neuroimaging is able to show functional and molecular biologic abnormalities in various neuropsychiatric diseases. Therefore, it has played important roles in the clinical diagnosis and in research on the normal and pathological states of the brain. More than 400 outstanding studies have been conducted by Korean researchers over the past 60 years. In the 1990s, when multiheaded single-photon emission computed tomography (SPECT) scanners were first introduced in South Korea, stroke research using brain perfusion SPECT was conducted. With the spread of positron emission tomography (PET) scanners in the 2000s, research on the clinical usefulness of PET and the evaluation of pathophysiology in various diseases such as epilepsy, brain tumors, degenerative brain diseases, and other neuropsychiatric diseases were actively conducted using [¹⁸F]FDG and various neuroreceptor tracers. In the 2010s, with the clinical application of new radiopharmaceuticals for amyloid and tau imaging, research demonstrating the clinical usefulness of PET imaging and the pathophysiology of dementia has increased rapidly. It is expected that the role of nuclear medicine will expand with the development of new radiopharmaceuticals and analysis technologies, along with the application of artificial intelligence for early and differential diagnosis, and the development of therapeutic agents for degenerative brain diseases.

Characteristic brain hypoperfusion by 99mTc-ECD single photon emission computed tomography (SPECT) in patients with the first-episode schizophrenia

Objective

In this study, we evaluated brain perfusion in patients with first-episode medicated schizophrenia using the new analytical method, statistical parametric mapping (SPM) applied to single photon emission computed tomography (SPECT).

Method

We performed SPECT with 99-Tc-ethyl cysteinate dimer (99mTc-ECD) of the brain and magnetic resonance imaging (MRI) in patients with schizophrenia (n = 30) and control subjects matched for age and gender (n = 37). A voxel-by-voxel group analysis was performed using SPM2 (Z > 3.0, P < 0.001, uncorrected for multiple comparisons).

Result

In comparison with control subjects, the volumes of the bilateral frontal areas were found to be decreased on MRI. Blood flow was found to be reduced in the bilateral temporal areas in the patients with schizophrenia on SPECT.

Conclusion

In this study, patients with first-episode schizophrenia appeared to have significant bilateral temporal hypoperfusion, although temporal volumes were not significantly decreased in comparison with control subjects. Abnormality of temporal lobe blood flow in schizophrenia may show that functional changes occur earlier than structural changes, and may assist in the diagnosis of schizophrenia.

Neurobiological background of negative symptoms

Studies investigating neurobiological bases of negative symptoms of schizophrenia failed to provide consistent findings, possibly due to the heterogeneity of this psychopathological construct. We tried to review the findings published to date investigating neurobiological abnormalities after reducing the heterogeneity of the negative symptoms construct. The literature in electronic databases as well as citations and major articles are reviewed with respect to the phenomenology, pathology, genetics and neurobiology of schizophrenia. We searched PubMed with the keywords "negative symptoms," "deficit schizophrenia," "persistent negative symptoms," "neurotransmissions," "neuroimaging" and "genetic." Additional articles were identified by manually checking the reference lists of the relevant publications. Publications in English were considered, and unpublished studies, conference abstracts and poster presentations were not included. Structural and functional imaging studies addressed the issue of neurobiological background of negative symptoms from several perspectives (considering them as a unitary construct, focusing on primary and/or persistent negative symptoms and, more recently, clustering them into factors), but produced discrepant findings. The examined studies provided evidence suggesting that even primary and persistent negative symptoms include different psychopathological constructs, probably reflecting the dysfunction of different neurobiological substrates. Furthermore, they suggest that complex alterations in multiple neurotransmitter systems and genetic variants might influence the expression of negative symptoms in schizophrenia. On the whole, the reviewed findings, representing the distillation of a large body of disparate data, suggest that further deconstruction of negative symptomatology into more elementary components is needed to gain insight into underlying neurobiological mechanisms.

Abnormal hippocampal-thalamic white matter tract development and positive symptom course in individuals at ultra-high risk for psychosis

Background/Objectives:

Abnormal development of the hippocampus has been reported in adolescents at ultra-high risk (UHR) for psychosis and thalamic abnormalities have been found. However, the white matter connections between the hippocampus and the thalamus have not been studied. The connections between these regions are of key importance to our understanding of the pathophysiology of psychosis.

Methods:

Twenty-six UHR and 21 healthy age-matched controls were tested at a baseline assessment and 12 months later. Symptoms were assessed at both the time points and all the participants underwent diffusion tensor imaging scans. We used tractography to trace the white matter connections in each individual between the thalamus and hippocampus and then extracted fractional anisotropy (FA) to assess white matter structural integrity.

Results:

There was a significant group by time interaction indicating that FA decreased in UHR, and increased in controls over 12 months. Across both groups, baseline FA of the thalamic–hippocampal tract was predictive of positive symptoms at 12-month follow-up. Critically, this pattern remained significant in UHR individual group alone. At baseline, those with higher FA, indicative of abnormal white matter development, show higher positive symptoms 1 year later.

Conclusions:

Here, we provide evidence to indicate that there are differences in white matter development in hippocampal–thalamic connections, both of which are important nodes in networks associated with schizophrenia. Furthermore, abnormal developmental patterns in UHR individuals are associated with positive symptom course.

Positive symptoms and water diffusivity of the prefrontal and temporal cortices in schizophrenia patients: a pilot study

The development of diffusion tensor imaging (DTI) has provided information about microstructural changes in the brain. Most DTI studies have focused on white matter (WM). Few DTI studies have examined the gray matter (GM) in schizophrenia and, to date, there has been no attempt to identify the relationship between water diffusivity and symptom severity in schizophrenia. The present study aimed to examine microstructural deficits in the dorsal prefrontal cortex (DPFC) and temporal cortex in schizophrenia patients using fractional anisotropy (FA) and water diffusivity. This study also explored the relationship between DTI measurements and psychotic symptoms. Magnetic resonance imaging (MRI) and DTI were used to study 19 schizophrenia patients and 19 healthy controls. Fractional anisotropy, axial diffusivity, radial diffusivity, and regional volumes were measured in the prefrontal cortex and temporal cortex. On DTI measurements, patients showed increased axial and radial diffusivities in the prefrontal cortex and temporal cortex, but they did not demonstrate any difference in fractional anisotropy and regional volumes. Additionally, axial and radial diffusivities were significantly correlated with positive symptom scores in all regions of interest. These results indicate that water diffusivity measurements, including axial and radial diffusivities, can be used to identify microstructural changes in the gray matter in schizophrenia that may be related to symptom severity.

Magnetic resonance imaging in studying schizophrenia, negative symptoms, and the glutamate system

Schizophrenia is characterized by positive, negative, and cognitive symptoms. While positive symptoms occur periodically during psychotic exacerbations, negative and cognitive symptoms often emerge before the first psychotic episode and persist with low functional outcome and poor prognosis. This review article outlines the importance of modern functional magnetic resonance imaging techniques for developing a stratified therapy of schizophrenic disorders. Functional neuroimaging evidence on the neural correlates of positive and particularly negative symptoms and cognitive deficits in schizophrenic disorders is briefly reviewed. Acute dysregulation of dopaminergic neurotransmission is crucially involved in the occurrence of psychotic symptoms. However, increasing evidence also implicates glutamatergic pathomechanisms, in particular N-methyl-d-aspartate (NMDA) receptor dysfunction in the pathogenesis of schizophrenia and in the appearance of negative symptoms and cognitive dysfunctions. In line with this notion, several gene variants affecting the NMDA receptor's pathway have been reported to increase susceptibility for schizophrenia, and have been investigated using the imaging genetics approach. In recent years, several attempts have been made to develop medications modulating the glutamatergic pathway with modest evidences for efficacy. The most successful approaches were those that aimed at influencing this pathway using compounds that enhance NMDA receptor function. More recently, the selective glycine reuptake inhibitor bitopertin has been shown to improve NMDA receptor hypofunction by increasing glycine concentrations in the synaptic cleft. Further research is required to test whether pharmacological agents with effects on the glutamatergic system can help to improve the treatment of negative symptoms in schizophrenic disorders.

Orbitofrontal cortex abnormality and deficit schizophrenia

Deficit syndrome, which is characterized by primary and enduring negative symptoms, is a homogeneous subtype within schizophrenia. Negative symptoms in schizophrenia are currently considered to be closely linked with frontal lobe impairment. However, the etiology in the frontal lobe of people with deficit syndrome is not fully understood. We measured regional cerebral blood flow (rCBF) with single photon emission computed tomography (SPECT) in 33 patients with deficit syndrome, 40 patients with nondeficit syndrome, and 45 healthy controls, and we compared groups using the voxel-wise method. Schizophrenia combined group, the deficit syndrome and the nondeficit syndrome presented hypoperfusion in mainly the medial and lateral prefrontal cortices. The deficit syndrome group showed a significant decrease in rCBF in the right orbitofrontal cortex (OFC) compared to the nondeficit group. These results demonstrated that at-rest hypofrontality was a common feature within the disease group and suggested that the OFC might play an important role in the development of severe negative symptoms in people with deficit syndrome.

Resting quantitative cerebral blood flow in schizophrenia measured by pulsed arterial spin labeling perfusion MRI

Arterial spin labeling (ASL) perfusion MRI is a relatively novel technique that can allow for quantitative measurement of cerebral blood flow (CBF) by using magnetically labeled arterial blood water as an endogenous tracer. Available data on resting CBF in schizophrenia primarily come from invasive and expensive nuclear medicine techniques that are often limited to small samples and yield mixed results. The noninvasive nature of ASL offers promise for larger-scale studies. The utility of this approach was examined in 24 healthy controls and 30 patients with schizophrenia. Differences between groups in quantitative CBF were assessed, as were relationships between CBF and psychiatric symptoms. Group comparisons demonstrated greater CBF for controls in several regions including bilateral precuneus and middle frontal gyrus. Patients showed increased CBF in left putamen/superior corona radiata and right middle temporal gyrus. For patients, greater severity of negative symptoms was associated with reduced CBF in bilateral superior temporal gyrus, cingulate gyrus, and left middle frontal gyrus. Increased severity of positive symptoms was related to both higher CBF in cingulate gyrus and superior frontal gyrus and decreased CBF in precentral gyrus/middle frontal gyrus. These findings support the feasibility and utility of implementing ASL in schizophrenia research and expand upon previous results.

Proteome analysis of the thalamus and cerebrospinal fluid reveals glycolysis dysfunction and potential biomarkers candidates for schizophrenia

Schizophrenia (SCZ) is the result of DNA alterations and environmental factors, which together lead to differential protein expression and ultimately to the development of the illness. The diagnosis is based on clinical symptoms, and the molecular background of SCZ is not completely understood. The thalamus, whose dysfunction has been associated with SCZ based in diverse lines of evidences, plays for instance a pivotal role in the central nervous system as a relay center by re-distributing auditory and visual stimuli from diverse brain regions to the cerebral cortex. We analyzed the proteome of postmortem mediodorsal thalamus (MDT) samples from 11 SCZ patients and 8 non-SCZ individuals by using quantitative shotgun-mass spectrometry and two-dimensional gel electrophoresis. Our analyses identified 551 proteins, 50 of which showed significant differential expression. The main pathways affected by the differentially expressed proteins include energy metabolism, oligodendrocyte metabolism, and cytoskeleton assembly. The potential protein biomarkers candidates myelin basic protein and myelin oligodendrocyte protein were validated by Western blot in the MDT samples and also in cerebrospinal fluid from a separate set of samples of 17 first-episode SCZ patients and 10 healthy controls. The differential expression of μ-crystallin, protein kinase C-gamma, and glial fibrillary acidic protein were confirmed in MDT. Because we found several glycolysis enzymes to be differentially expressed, we measured the levels of pyruvate and NADPH and found them to be altered in MDT. The protein changes described here corroborate the importance of myelin/oligodendrocyte and energy metabolism in SCZ and highlight new potential biomarkers candidates that may contribute to the understanding of the pathogenesis of this complex disease.

Thalamic nuclear abnormalities as a contributory factor in sudden cardiac deaths among patients with schizophrenia

Patients with schizophrenia have a two- to three-fold increased risk of premature death as compared to patients without this disease. It has been established that patients with schizophrenia are at a high risk of developing cardiovascular disease. Moreover, an important issue that has not yet been explored is a possible existence of a "cerebral" focus that could trigger sudden cardiac death in patients with schizophrenia. Along these lines, several structural and functional alterations in the thalamic complex are evident in patients with schizophrenia and have been correlated with the symptoms manifested by these patients. With regard to abnormalities on the cellular and molecular level, previous studies have shown that schizophrenic patients have fewer neuronal projections from the thalamus to the prefrontal cortex as well as a reduced number of neurons, a reduced volume of either the entire thalamus or its subnuclei, and abnormal glutamate signaling. According to the glutamate hypothesis of schizophrenia, hypofunctional corticostriatal and striatothalamic projections are directly involved in the pathophysiology of the disease. Animal and post-mortem studies have provided a large amount of evidence that links the sudden unexpected death in epilepsy (SUDEP) that occurs in patients with schizophrenia and epilepsy to thalamic changes. Based on the results of these prior studies, it is clear that further research regarding the relationship between the thalamus and sudden cardiac death is of vital importance.

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.

Deletion of the STOP gene, a microtubule stabilizing factor, leads only to discrete cerebral metabolic changes in mice

In mice, deletion of the STOP protein leads to subtle anatomic changes and induces depleted synaptic vesicle pools, impaired synaptic plasticity, hyperdopaminergy, and major behavioral disorders alleviated by neuroleptics, hence leading to a schizophrenic-like phenotype. In this study, we applied the quantitative autoradiographic [(14)C]2-deoxyglucose technique to study to what extent the basal rate of cerebral glucose utilization in STOP-knockout (STOP-KO) mice occurs in regions where metabolic changes have been reported in schizophrenic patients. Studies were performed on wild-type, heterozygous, and homozygous STOP-KO mice (7-8 per group). Mice were implanted with femoral artery and vein catheters, and cerebral glucose utilization was quantified over 45 min. Compared with that in wild-type mice, glucose utilization in STOP-KO mice was significantly increased in the olfactory cortex, ventromedial and anterolateral hypothalamus, ventral tegmental area, and substantia nigra pars compacta. Nonsignificant increases, ranging between 9% and 19%, were recorded in the whole auditory system, CA1 pyramidal cell layer, and dorsal raphe. Glucose utilization was also significantly increased in heterozygous mice compared with that in wild-type mice in olfactory cortex. These data might reflect hyperdopaminergic activity, olfactory deficits, and sleep disturbances in STOP-KO mice that have also been reported in schizophrenic patients.

Clozapine may partially compensate for task-related brain perfusion abnormalities in risperidone-resistant schizophrenia patients

BACKGROUND

Previous reports show different cerebral activity patterns during treatment with clozapine and typical neuroleptics. However, to date no study has directly compared the brain activity patterns while subjects are undergoing treatment with clozapine and other atypical antipsychotics. This comparison is of interest, given the probably different mechanism of action of clozapine in comparison with other atypicals.

OBJECTIVE

To assess the effect of clozapine on perfusion deviations still evident during treatment with risperidone.

METHODS

Here we used hexamethylene-propylenaminoxime single photon emission computed tomography to compare the perfusion patterns observed during the performance of a Stroop test in 10 patients sequentially treated with risperidone and clozapine, owing to a lack of response to the former, and in 10 healthy controls.

RESULTS

Patients on risperidone showed decreased perfusion as compared to controls in the medial prefrontal, middle cingulate and insular regions, as well as increased activities in brain stem and the posterior hippocampus. After receiving clozapine, the same patients showed an even wider prefrontal perfusion deficit and the brain stem was still hyperactive, but the abnormalities in the cingulate cortex, insula and hippocampus had disappeared. Clinical improvement was directly related to an increase in thalamic perfusion.

CONCLUSION

Clozapine may alleviate hyperactivity in the limbic system in schizophrenia and may facilitate activation of the regions involved in cognitive tasks to a greater degree than risperidone, as well as eliciting greater inhibition of the PF region.

Negative symptoms in schizophrenia: a review

Negative symptoms refer to the weakening or lack of normal thoughts, emotions or behaviour in schizophrenia patients. Their prevalence in first-episode psychosis is high, 50-90%, and 20-40% of schizophrenia patients have persisting negative symptoms. Severe negative symptoms during the early stages of treatment predict poor prognosis. The aim of the study was to review the current literature on the negative symptoms of schizophrenia. In June 2007, the following databases were searched: Web of Science, PubMed, PsycINFO, Medline (Ovid) and Scopus. The search included articles written in English and no time limit was determined. The studies were manually screened by one of the authors according to the title and abstract. About one in three schizophrenia patients suffer from significant negative symptoms. In these patients, negative symptoms constitute a key element of overall symptoms, weakening their ability to cope with everyday activities, affecting their quality of life and their ability to manage without significant outside help. About one in three schizophrenia patients suffer from significant negative symptoms. Attention should be focused on negative symptoms during the early phase of treatment, because they cause significant impairment to patients' quality of life. So far, no treatment appears to substantially improve negative symptoms narrowly defined. However, according to clinical experience, when treating negative symptoms, the best effect is achieved by optimizing the dose of medication and by complementing it with psychosocial therapies.

Negative symptoms of schizophrenia: a problem that will not go away

OBJECTIVE

Negative symptoms of schizophrenia are a common, enduring, and debilitating component of the psychopathology of schizophrenia. Although efforts thus far to elucidate a distinct schizophrenia subtype based upon negative symptoms have yielded mixed results, there are nevertheless neurobiological correlates of the negative symptom typology.

METHOD

A review of nosology, typology, and assessment tools for determining core negative symptoms in schizophrenia.

RESULTS

Negative symptoms can be difficult to evaluate objectively. Current rating scales 'capture' key domains of negative symptoms, in spite of considerable overlap between these domains. However, each objective assessment trades off methodological rigor and detail against brevity of assessment and ease of use.

CONCLUSION

The description of new methods for measuring these devastating symptoms, coupled with the ongoing development of novel antipsychotics and agents that augment antipsychotics have fuelled renewed interest in the evaluation of negative symptoms and optimism that better treatments for negative symptoms can be found.

Dopamine D2 receptor binding in drug-naïve patients with schizophrenia examined with raclopride-C11 and positron emission tomography

The aim was to test the dopamine hypothesis of schizophrenia in a further analysis of D(2)-like dopamine binding using the radioligand [(11)C]raclopride and high resolution 3-dimensional (3D) PET. Eighteen drug-naive patients with schizophrenia and seventeen control subjects were examined. The D(2) binding potential (BP) in the putamen, the caudate and the thalamus was calculated using the simplified reference tissue model. The volume of regions of interest was controlled for by MRI. Symptoms were rated with the Positive and Negative Syndrome Scale for Schizophrenia (PANSS). No significant group differences were found for D(2) BP in the putamen or in the caudate and there was no significant hemispheric difference for any region. In the right thalamus the D(2) BP was significantly lower in patients as compared to control subjects, whereas a numerical difference did not reach statistical significance for the left thalamus. There was no significant correlation between D(2) BP and total PANSS score in any region. There was a highly significant age effect in the caudate and in the putamen, but not in the thalamus. In this relatively large PET study of exclusively drug-naive schizophrenic patients, a lower D(2) BP in the right thalamus was found in the patient group. This finding is in agreement with two previous studies in Sweden and in Japan using the high-affinity radioligand [(11)C]FLB 457 and provide further support for a role of dopamine in the thalamus related to the pathophysiology of schizophrenia.

Left temporal perfusion associated with suspiciousness score on the Brief Psychiatric Rating Scale in schizophrenia

We evaluated the relationship between regional cerebral blood flow (rCBF) and clinical symptoms in patients with schizophrenia. Single photon emission computed tomography with N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) was used to study 29 patients with schizophrenia. Clinical symptoms were assessed using the Brief Psychiatric Rating Scale (BPRS). We examined the correlation between rCBF and each BPRS item score using Statistical Parametric Mapping software. Corrected P-values < 0.05 were considered as statistically significant. The suspiciousness score on the BPRS was positively correlated with rCBF in the left inferior temporal gyrus. There was no significant correlation between rCBF and any other items of the BPRS. There was no significant correlation between rCBF and chlorpromazine-equivalent dosage. This analysis permits the quantitative assessment of the severity of persecutory delusions in relation to left temporal perfusion in patients with schizophrenia.

Reduced anterior internal capsule and thalamic volumes in first-episode psychosis

BACKGROUND

The thalamus is the gateway for sensory and motor information en route to the cortex. Information is processed via thalamocortical and corticothalamic pathways coursing through the internal capsules. In this study, we investigated the relationship between the anterior limb of the internal capsule, posterior limb of the internal capsule, and thalamus in first-episode psychosis (FEP).

METHODS

Twenty-nine FEP subjects (26 DSM-IV schizophrenia, 2 schizoaffective disorder, 1 psychosis not otherwise specified) and 22 healthy volunteers participated in this study. Anterior limb of the internal capsule (AIC), posterior limb of the internal capsule (PIC), and the thalamus volumes were manually determined from MRI scans.

RESULTS

FEP subjects had reduced AIC volumes (F(1,45)=6.18, p=0.017) and thalamic volumes (F(1,45)=8.00, p=0.007) compared to healthy volunteers. PIC volumes did not differ. Significant correlations between AIC volumes and thalamic volumes were observed in subjects with FEP, but not in healthy volunteers. Negative relationships between thalamic volumes and symptom severity were also observed.

CONCLUSIONS

The AIC and thalamic volumes were reduced in subjects with FEP compared to healthy volunteers. Abnormalities in thalamocortical and orticothalamic pathways may contribute to functional disruption of neural circuits in 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.

Correlations between rCBF and symptoms in two independent cohorts of drug-free patients with schizophrenia

We report on the correlations between whole brain rCBF and the positive and negative symptoms of schizophrenia in two cohorts of patients who were scanned while free of antipsychotic medication. We hypothesized that positive symptoms would correlate with rCBF in limbic and paralimbic regions, and that negative symptoms would correlate with rCBF in frontal and parietal regions. Both cohorts of patients with schizophrenia (Cohort 1: n=32; Cohort 2: n=23) were scanned using PET with H(2)(15)O while free of antipsychotic medication for an average of 21 and 15 days, respectively. Both groups were scanned during a resting state. Using SPM99, we conducted pixel by pixel linear regression analyses between BPRS scores and whole brain rCBF. As hypothesized, positive symptoms correlated with rCBF in the anterior cingulate cortex (ACC) in a positive direction and with the hippocampus/parahippocampus in a negative direction in both patient groups. When the positive symptoms were further divided into disorganization and hallucination/delusion scores, similar positive correlations with ACC and negative correlations with hippocampus rCBF were found. In both cohorts, the disorganization scores correlated positively with rCBF in Broca's area. As expected, negative symptoms correlated inversely with rCBF in frontal and parietal regions. This study provides evidence that limbic dysfunction may underlie the production of positive symptoms. It suggests that abnormal function of Broca's area may add a specific language-related dimension to positive symptoms. This study also provides further support for an independent neurobiological substrate of negative symptoms distinct from positive symptoms. The involvement of both frontal and parietal regions is implicated in the pathophysiology of negative symptoms.

SPECT study of Chinese schizophrenic patients suggests that cerebral hypoperfusion and laterality exist in different ethnic groups

Hypofrontality is a common finding in schizophrenia in many countries. To date, there have been few studies on Chinese patients with schizophrenia. We thus wondered whether hypofrontality exists in Chinese patients with schizophrenia. We investigated 45 patients with schizophrenia and 21 healthy controls using brain perfusion single photon emission computed tomography (SPECT). Subjects were also administered the Brief Psychiatric Rating Scale (BPRS), Scale for the Assessment of Positive Symptoms (SAPS), Scale for the Assessment of Negative Symptoms (SANS), Halstead-Reitan Neuropsychological Battery (HRNB) and the Wechsler Memory Scale-Revised (WMS-R). Images were analyzed using a semi-quantitative reading and a quantified region of interest analysis. We found that schizophrenic patients showed hypoperfusion in the frontal and temporal lobes and hyperperfusion in the basal ganglia. Schizophrenic patients with both negative and positive symptoms showed asymmetric perfusion in the temporal lobe. Schizophrenic patients with prominent negative symptoms also showed asymmetric perfusion in the prefrontal lobes. Negative symptoms showed a significantly negative correlation with regional cerebral blood flow (rCBF) in the left frontal lobe. Improved memory quotient (MQ) was significantly correlated with increased rCBF in the left temporal lobe. These findings from Chinese patients confirm a similar regional neuroanatomic dysfunction as in Western patients with the disease.

Delusions in individuals with schizophrenia: factor structure, clinical correlates, and putative neurobiology

BACKGROUND

Delusions are a central feature of schizophrenia, yet our understanding of their neurobiology is limited. Attempt to link dimensions of psychopathology to putative neurobiological mechanisms depends on careful delineation of symptoms. Previous factor analytic studies of delusions in schizophrenia were limited by several methodological problems, including the use of patients medicated with antipsychotics, inclusion of nondelusion symptoms in the analyses, and/or inclusion of patients with psychotic disorders other than schizophrenia. These problems may have possibly biased the resulting factor structure and contributed to the inconclusive findings regarding the neurobiology of positive symptoms. Our goal is to examine the factor structure of delusions in antipsychotic-free individuals with diagnoses of schizophrenia/schizoaffective disorder.

SAMPLING AND METHODS

We assessed 83 antipsychotic-free individuals with DSM-IV diagnoses of schizophrenia/schizoaffective disorder. A principal component analysis was conducted on the delusions symptoms of the SAPS.

RESULTS

The principal component analysis resulted in three distinct and interpretable factors explaining 58.3% of the variance. The Delusions of Influence factor was comprised by delusions of being controlled, thought withdrawal, thought broadcasting, thought insertion, and mind reading. The Self-Significance Delusions factor was comprised by delusions of grandeur, reference, religious, and delusions of guilt/sin. The Delusions of Persecution factor was comprised solely by persecutory delusions. The three factors displayed distinct associations with hallucinations, bizarre behavior, attention, positive formal thought disorder, and avolition/apathy.

CONCLUSIONS

The results indicate that delusions are best described by three distinct subtypes. The authors propose a novel model linking the three delusion subtypes, attributions to self/other, and putative neurobiological mechanisms. Implications for future research are discussed, as well as links to cognitive-behavioral conceptualizations of delusions.

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.

Reduced P3 amplitudes by negative facial emotional photographs in schizophrenia

Event-related potentials (ERPs), mostly P3, were measured in 20 schizophrenia and 20 healthy control subjects, in order to determine whether patients with schizophrenia have greater impairment in the processing of negative emotions. Study subjects were instructed to feel and respond to rare targets of facial photographs placed between frequent nontarget checkerboards. We found that P3 amplitudes associated with negative emotional photographs, in normal controls, were significantly larger than those of positive stimuli. Unlike the controls, in patients with schizophrenia, P3 amplitudes generated by negative emotional targets were significantly smaller than those of positive stimuli. We conclude that schizophrenia patients might be neurophysiologically different from healthy controls in terms of the manner in which they process facial emotion. Our findings are in line with previous neurobehavioral studies, in which patients with schizophrenia showed greater impairment in the recognition of negative emotions.

Similarities in the pattern of regional brain dysfunction in negative schizophrenia and unipolar depression: a single photon emission-computed tomography and auditory evoked potentials study

1. Negative schizophrenic and unipolar depressive patients were clinically assessed. In addition to this SANS and HRSD tests were administered. 2. SPECT and AEP measurements were provided. SPECT resulted in quantified brain blood perfusion, by means of average "count/pixel" values in the brain regions of interest. AEPs resulted in stored multichannel signal waveforms. 3. Statistical analyses of blood perfusion measurement data revealed an overall similarity between these two disorders in the majority of brain regions. An exception to this are the regions: inferior temporalis, inferior occipitalis, hippocampus and the anterior basal ganglia. Both diagnostic groups manifested hypofrontality. In general, hypoperfusion of the left hemisphere was found, albeit displaying different patterns in the two groups investigated. 4. AEP latencies were prolonged and found to be similar in both diagnostic groups, whilst AEP amplitudes were smaller in schizophrenics compared to depressives.