Anomalous lateral sulcus asymmetry and cognitive function in first-episode schizophrenia

Causal relationship between multiparameter brain MRI phenotypes and age: evidence from Mendelian randomization

To explore the causal relationship between age and brain health (cortical atrophy, white matter integrity, white matter hyperintensities and cerebral microbleeds in various brain regions) related multiparameter imaging features using two-sample Mendelian randomization. Age was determined as chronological age of the subject. Cortical volume, white matter micro-integrity, white matter hyperintensity volume and cerebral microbleeds of each brain region were included as phenotypes for brain health. Age and imaging of brain health related genetic data were analysed to determine the causal relationship using inverse-variance weighted model, validated by heterogeneity and horizontal pleiotropy variables. Age is causally related to increased volumes of white matter hyperintensities (β = 0.151). For white matter micro-integrity, fibres of the inferior cerebellar peduncle (axial diffusivity β = -0.128, orientation dispersion index β = 0.173), cerebral peduncle (axial diffusivity β = -0.136), superior fronto-occipital fasciculus (isotropic volume fraction β = 0.163) and fibres within the limbic system were causally deteriorated. We also detected decreased cortical thickness of multiple frontal and temporal regions (P < 0.05). Microbleeds were not related with aging (P > 0.05). Aging is a threat of brain health, leading to cortical atrophy mainly in the frontal lobes, as well as the white matter degeneration especially abnormal hyperintensity and deteriorated white matter integrity around the hippocampus.

Language Network Dysfunction and Formal Thought Disorder in Schizophrenia

BACKGROUND

Pathophysiological inquiries into schizophrenia require a consideration of one of its most defining features: disorganization and impoverishment in verbal behavior. This feature, often captured using the term Formal Thought Disorder (FTD), still remains to be one of the most poorly understood and understudied dimensions of schizophrenia. In particular, the large-scale network level dysfunction that contributes to FTD remains obscure to date.

STUDY DESIGN

In this narrative review, we consider the various challenges that need to be addressed for us to move towards mapping FTD (construct) to a brain network level account (circuit).

STUDY RESULTS

The construct-to-circuit mapping goal is now becoming more plausible than it ever was, given the parallel advent of brain stimulation and the tools providing objective readouts of human speech. Notwithstanding this, several challenges remain to be overcome before we can decisively map the neural basis of FTD. We highlight the need for phenotype refinement, robust experimental designs, informed analytical choices, and present plausible targets in and beyond the Language Network for brain stimulation studies in FTD.

CONCLUSIONS

Developing a therapeutically beneficial pathophysiological model of FTD is a challenging endeavor, but holds the promise of improving interpersonal communication and reducing social disability in schizophrenia. Addressing the issues raised in this review will be a decisive step in this direction.

Towards Deciphering the Fetal Foundation of Normal Cognition and Cognitive Symptoms From Sulcation of the Cortex

Growing evidence supports that prenatal processes play an important role for cognitive ability in normal and clinical conditions. In this context, several neuroimaging studies searched for features in postnatal life that could serve as a proxy for earlier developmental events. A very interesting candidate is the sulcal, or sulco-gyral, patterns, macroscopic features of the cortex anatomy related to the fold topology-e.g., continuous vs. interrupted/broken fold, present vs. absent fold-or their spatial organization. Indeed, as opposed to quantitative features of the cortical sheet (e.g., thickness, surface area or curvature) taking decades to reach the levels measured in adult, the qualitative sulcal patterns are mainly determined before birth and stable across the lifespan. The sulcal patterns therefore offer a window on the fetal constraints on specific brain areas on cognitive abilities and clinical symptoms that manifest later in life. After a global review of the cerebral cortex sulcation, its mechanisms, its ontogenesis along with methodological issues on how to measure the sulcal patterns, we present a selection of studies illustrating that analysis of the sulcal patterns can provide information on prenatal dispositions to cognition (with a focus on cognitive control and academic abilities) and cognitive symptoms (with a focus on schizophrenia and bipolar disorders). Finally, perspectives of sulcal studies are discussed.

Magnetic resonance imaging in schizophrenia: Luxury or necessity? (Review)

Schizophrenia, one of the most common psychiatric disorders, with a worldwide annual incidence rate of approximately 0.3-0.7%, known to affect the population below 25 years of age, is persistent throughout lifetime and includes people from all layers of society. With recent technological progress that allows better imaging techniques, such as the ones provided by computed tomography and particularly magnetic resonance imaging (MRI), research on schizophrenia imaging has grown considerably. The purpose of this review is to establish the importance of using imaging techniques in the early detection of brain abnormalities in patients diagnosed with schizophrenia. We reviewed all articles which reported on MRI imaging in schizophrenia. In order to do this, we used the PubMed database, using as search words ‘MRI’ and ‘schizophrenia’. MRI studies of first episode patients and chronic patients, suggest reduction of the whole brain volume. Enlargement of lateral ventricles was described as positive in 15 studies out of 19 and was similar to findings in chronic patients. Moreover, for the first episode patients, all data collected point to important changes in medial temporal lobe structures, diminished hippocampal volume, the whole frontal lobe, asymmetry in prefrontal cortex, diminished volume in cingulate, corpus callosum, and cavum septum pellucidum reported abnormalities. MRI is recommended as an important tool in the follow-up process of patients with schizophrenia. Yet, it is still under debate whether the abnormalities described in this condition are able to be used as diagnostic biomarkers.

Altered Cortical Functional Networks in Patients With Schizophrenia and Bipolar Disorder: A Resting-State Electroencephalographic Study

BACKGROUND

Pathologies of schizophrenia and bipolar disorder have been poorly understood. Brain network analysis could help understand brain mechanisms of schizophrenia and bipolar disorder. This study investigates the source-level brain cortical networks using resting-state electroencephalography (EEG) in patients with schizophrenia and bipolar disorder.

METHODS

Resting-state EEG was measured in 38 patients with schizophrenia, 34 patients with bipolar disorder type I, and 30 healthy controls. Graph theory based source-level weighted functional networks were evaluated: strength, clustering coefficient (CC), path length (PL), and efficiency in six frequency bands.

RESULTS

At the global level, patients with schizophrenia or bipolar disorder showed higher strength, CC, and efficiency, and lower PL in the theta band, compared to healthy controls. At the nodal level, patients with schizophrenia or bipolar disorder showed higher CCs, mostly in the frontal lobe for the theta band. Particularly, patients with schizophrenia showed higher nodal CCs in the left inferior frontal cortex and the left ascending ramus of the lateral sulcus compared to patients with bipolar disorder. In addition, the nodal-level theta band CC of the superior frontal gyrus and sulcus (cognition-related region) correlated with positive symptoms and social and occupational functioning scale (SOFAS) scores in the schizophrenia group, while that of the middle frontal gyrus (emotion-related region) correlated with SOFAS scores in the bipolar disorder group.

CONCLUSIONS

Altered cortical networks were revealed and these alterations were significantly correlated with core pathological symptoms of schizophrenia and bipolar disorder. These source-level cortical network indices could be promising biomarkers to evaluate patients with schizophrenia and bipolar disorder.

Altered frontal white matter asymmetry and its implications for cognition in schizophrenia: A tractography study

Background

White matter (WM) alterations are well documented in schizophrenia. Abnormalities in interhemispheric fibers appear to account for altered WM asymmetry in the illness. However, the regional specificity (e.g., frontal versus occipital) of these alterations and their potential contribution to cognitive dysfunction in schizophrenia remain unknown.

Methods

Forty one patients with schizophrenia and 21 healthy controls (HC) underwent diffusion-weighted imaging on a 3 Tesla MRI machine. Tract-based spatial statistic (FSL) was used to assess whole brain differences in WM. Probabilistic tractography was performed in order to separately measure frontal and occipital WM tracts. Participants also completed tests of verbal memory and processing speed. Repeated measures analyses of covariance and Pearson correlation analyses were performed.

Results

A significant group x cerebral hemisphere interaction was found for fractional anisotropy (FA) (F_(1,17) = 7.03; p = .017; η_p² = 0.29) and radial diffusivity (RD) (F_(1,17) = 4.84; p = .042; η_p² = 0.22) in the frontal tract of patients versus HC. Healthy controls showed higher mean FA and lower mean RD in the left frontal tract compared to patients, who showed the opposite pattern. In patients with schizophrenia, mean FA and RD in the right frontal tract correlated with verbal memory (r = −0.68, p = .046; r = 0.77, p = .015).

Conclusions

Asymmetric WM alterations were found in a frontal tract of patients with schizophrenia. Higher mean FA in the right frontal tract correlated with worse verbal memory performance, suggesting a possible contribution these brain changes to cognitive impairment in schizophrenia.

•

Asymmetric white matter alterations were found in a frontal tract of patients with schizophrenia.

•

Higher mean fractional anisotropy in the right frontal tract correlated with worse verbal memory performance in patients.

•

Aberrant white matter asymmetry might contribute to a central form of cognitive dysfunction in schizophrenia.

Effects of BMS-902483, an α7 nicotinic acetylcholine receptor partial agonist, on cognition and sensory gating in relation to receptor occupancy in rodents

The α7 nicotinic acetylcholine receptor is thought to play an important role in human cognition. Here we describe the in vivo effects of BMS-902483, a selective potent α7 nicotinic acetylcholine receptor partial agonist, in relationship to α7 nicotinic acetylcholine receptor occupancy. BMS-902483 has low nanomolar affinity for rat and human α7 nicotinic acetylcholine receptors and elicits currents in cells expressing human or rat α7 nicotinic acetylcholine receptors that are about 60% of the maximal acetylcholine response. BMS-902483 improved 24h novel object recognition memory in mice with a minimal effective dose (MED) of 0.1mg/kg and reversed MK-801-induced deficits in a rat attentional set-shifting model of executive function with an MED of 3mg/kg. Enhancement of novel object recognition was blocked by the silent α7 nicotinic acetylcholine receptor agonist, NS6740, demonstrating that activity of BMS-902483 was mediated by α7 nicotinic acetylcholine receptors. BMS-902483 also reversed ketamine-induced deficits in auditory gating in rats, and enhanced ex vivo hippocampal long-term potentiation examined 24h after dosing in mice. Results from an ex vivo brain homogenate binding assay showed that α7 receptor occupancy ranged from 64% (novel object recognition) to ~90% (set shift and gating) at the MED for behavioral and sensory processing effects of BMS-902483.

Effects of ziprasidone, SCH23390 and SB277011 on spatial memory in the Morris water maze test in naive and MK-801 treated mice

Introduction: Patients with schizophrenia have cognitive dysfunctions; positive psychotic symptoms are the primary purposes for schizophrenia treatment. Improvements in cognitive function should be a characteristic of all newly developed drugs for the treatment of schizophreniawith dementia. Thus,we investigated the effects of the second-generation antipsychotic ziprasidone, dopamine D1 antagonist SCH-23390 and dopamine D3 antagonist SB-277011 on spatial learning and memory. Materials and methods: Male inbred mice were used. The effects of ziprasidone, SCH-23390 and SB-277011 were investigated using the Morris water maze test. Results: Ziprasidone (0.5 and 1mg/kg), SCH-23390 (0.05 and 0.1 mg/kg) and SB-277011 (10 and 20 mg/kg) had no effect on the time spent in the target quadrant in naive mice.MK-801 (0.1mg/kg) significantly decreased the time spent in the target quadrant. The time spent in the target quadrant was significantly prolonged by Ziprasidone (0.5 and 1 mg/kg) and SCH-23390 (0.1 mg/kg), but not with SB-277011 (20 mg/kg) in MK-801-treated mice. Ziprasidone (0.5 and 1mg/kg), SCH-23390 (0.05 and 0.1 mg/kg) and SB-277011 (10 and 20 mg/kg) had no effect on themean distance to the platformin naivemice.MK-801 significantly increased themean distance to the platform. Ziprasidone (1 mg/kg) and SCH-23390 (0.1 mg/kg) significantly decreased the mean distance to the platform in MK-801-treated mice, but SB-277011 (20 mg/kg) didn't. MK-801 significantly increased the total distance moved. Ziprasidone (0.5 and 1 mg/kg), SCH-23390 (0.05 and 0.1 mg/kg) and SB-277011 (10 and 20 mg/kg) had no effect on the total distance moved in naive mice. Ziprasidone (1 mg/kg) and SCH-23390 (0.1 mg/kg) significantly decreased the total distance moved in MK-801-treated mice, but SB-277011 (20 mg/kg) didn't. Conclusions: The second-generation antipsychotic drug ziprasidone and D1 antagonist SCH23390, but not the D3 antagonist SB277011, might be clinically useful for the treatment of cognitive impairments in patients with schizophrenia.

Effect of alpha7 nicotinic acetylcholine receptor agonists on attentional set-shifting impairment in rats

RATIONALE

Attentional set shifting, a measure of executive function, is impaired in schizophrenia patients. Current standard of care has little therapeutic benefit for treating cognitive dysfunction in schizophrenia; therefore, novel drugs and animal models for testing novel therapies are needed. The NMDA receptor antagonist, MK-801, produces deficits in a rat maze-based set-shifting paradigm, an effect which parallels deficits observed on tests of executive function in schizophrenia patients. Alpha7 nicotinic acetylcholine receptor (nAChR) agonists, currently under clinical development by several companies, show promise in treating cognitive symptoms in schizophrenia patients and can improve cognition in various animal models.

OBJECTIVES

The objectives of the present study were to determine whether the MK-801 deficit in set shifting could be reproduced in a drug discovery setting and to determine whether cognitive improvement could be detected for the first time in this task with alpha7 nAChR agonists.

RESULTS

The data presented here replicate findings that a systemic injection of the NMDA receptor antagonist MK-801 can induce a deficit in set shifting in rats. Furthermore, the deficit could be reversed by the atypical antipsychotic clozapine as well as by several alpha7 nAch receptor agonists (SSR-180711, PNU-282987, GTS-21) with varying in vitro properties.

CONCLUSIONS

Results indicate that the MK-801 set-shift assay is a useful preclinical tool for measuring prefrontal cortical function in rodents and can be used to identify novel mechanisms for the potential treatment of cognitive deficits in schizophrenia.

Alterations in brain structures underlying language function in young adults at high familial risk for schizophrenia

INTRODUCTION

Neuroanatomical and cognitive alterations typical of schizophrenia (SZ) patients are observed to a lesser extent in their adolescent and adult first-degree relatives, likely reflecting neurodevelopmental abnormalities associated with genetic risk for the illness. The anatomical pathways for language are hypothesized to be abnormal and to underlie the positive symptoms of schizophrenia. Examining non-psychotic relatives at high familial risk (FHR) for schizophrenia may clarify if these deficits represent trait markers associated with genetic vulnerability, rather than specific markers resulting from the pathological process underlying schizophrenia.

METHODS

T1 MRI scans from a 3T Siemens scanner of young adult FHR subjects (N=46) and controls with no family history of illness (i.e. at low genetic risk LRC; N=31) were processed using FreeSurfer 5.0. We explored volumetric and lateralization alterations in regions associated with language processing. An extensive neuropsychological battery of language measures was administered.

RESULTS

No significant differences were observed between groups on any language measures. Controlling intracranial volume, significantly smaller left pars triangularis (PT) (p<0.01) and right pars orbitalis (PO) (p<0.01) volumes and reversal of the L>R pars orbitalis (p<0.001) lateralization were observed in FHR subjects. In addition, the L pars triangularis and R pars orbitalis correlated with performance on tests of linguistic function in the FHR group.

CONCLUSIONS

Reduced volume and reversed structural asymmetry in language-related regions hypothesized to be altered in SZ are also found in first degree relatives at FHR, despite normal language performance. To clarify if these findings are endophenotypes for Sz, future studies would need to be performed of ill and well family members no longer within the age range of risk for illness to show these deficits segregate with schizophrenia within families. Moreover, measures of complex language need to be studied to determine if FHR individuals manifest impairments in some aspects of language function.

Structural changes in the hippocampus and amygdala at first episode of psychosis

Hippocampus and amygdala changes have been implicated in the pathophysiology and symptomatology of both schizophrenia (SCZ) and bipolar disorder (BD). However relationships between illness course, neuropathological changes and variations in symptomatology remain unclear. This investigation examined the associations between hippocampus and amygdala volumes and symptom dimensions in schizophrenia and bipolar disorder patients after their first episode of psychosis. Symptom severity was associated with decreases in hippocampus/amygdala complex volume across groups. In keeping with previous work bilateral hippocampus and amygdala volume reductions were also identified in the SCZ patients while in BD patients only evidence of amygdala inflation reached significance. The study concludes that there appear to be important relationships between volume changes in the hippocampus and amygdala and dimensions and severity of symptomatology in psychosis. Structural alterations are apparent in both SCZ and BD after first episode of psychosis but present differently in each illness and are more severe in SCZ.

Neuropathological similarities and differences between schizophrenia and bipolar disorder: a flow cytometric postmortem brain study

Recent studies suggest that schizophrenia (SCH) and bipolar disorder (BPD) may share a similar etiopathology. However, their precise neuropathological natures have rarely been characterized in a comprehensive and quantitative fashion. We have recently developed a rapid, quantitative cell-counting method for frozen unfixed postmortem brains using a flow cytometer. In the present study, we not only counted stained nuclei, but also measured their sizes in the gray matter of frontopolar cortices (FPCs) and inferior temporal cortices (ITCs) from patients with SCH or BPD, as well as in that from normal controls. In terms of NeuN(+) neuronal nuclei size, particularly in the reduced densities of small NeuN(+) nuclei, we found abnormal distributions present in the ITC gray matter of both patient groups. These same abnormalities were also found in the FPCs of SCH patients, whereas in the FPCs of BPD patients, a reduction in oligodendrocyte lineage (olig2(+)) cells was much more common. Surprisingly, in the SCH FPC, normal left-greater-than-right asymmetry in neural nuclei densities was almost completely reversed. In the BPD FPC, this asymmetry, though not obvious, differed significantly from that in the SCH FPC. These findings indicate that while similar neuropathological abnormalities are shared by patients with SCH or BPD, differences also exist, mainly in the FPC, which may at least partially explain the differences observed in many aspects in these disorders.

Longitudinal studies of cognition in first episode psychosis: a systematic review of the literature

Although cognitive deficits are recognized as a core feature in schizophrenia, their evolution over the course of the illness is still debated. Longitudinal studies of cognition in patients after a first episode of psychosis (FEP) provide extremely useful information, in that they include an adequate and realistic baseline measure of cognitive performance, while at the same time minimizing the effect of confounding variables associated with chronicity. The aim of this systematic review was to summarize findings of studies assessing the longitudinal course of neuropsychological deficits in patients with FEP for durations of at least one year. Overall, the neuropsychological deficits that are present following a first episode of psychosis appeared to remain stable over time for periods of up to ten years, the only possible exception being verbal memory deficits, where there is some evidence of further deterioration over the long term. However, further studies are needed to confirm this conclusion, especially in the (somewhat inconsistently defined) domain of executive function. Improvements in psychopathology appear to positively influence the course of cognitive deficits, although the effects of antipsychotic medication are not as clear.

Hand preference and hand skill in families with schizophrenia

Direction and degree of handedness in humans are variable between individuals and thought to be in part inherited. Several studies have shown an increase in non-right handedness among patients with schizophrenia, and some have included unaffected relatives. The present study was designed to determine whether reduced right handedness is more frequent among individuals with schizophrenia as compared with their well relatives and whether it clusters within families having multiple ill members. A total of 259 families comprising 418 individuals diagnosed with schizophrenia or schizoaffective disorder, 54 individuals with other psychoses, 145 family members with depression and other minor diagnoses, and 288 unaffected individuals were included. Hand preference was assessed by the Annett Scale and right relative to left hand skill measured using the Tapley-Bryden test. For all assessments of hand preference and hand skill, females were significantly more lateralised towards the right than males. Those individuals with schizophrenia or schizoaffective disorder had significantly less right hand preference than their unaffected relatives when measured as a quantitative index of items from the Annett Scale (p = .019), but not categorically (right, left or mixed). In contrast, there was no difference in hand skill between diagnostic groups. Hand preference was significantly correlated among male-male affected sibling pairs (p = .01) and similar results were found for hand skill among the total group of affected pairs (p = .001). Although these results only partially support a relationship between handedness and schizophrenia, they nevertheless draw attention to sex differences in hand preference and the familial aspects of hand preference in this disorder. More direct approaches to the genetics of cerebral dominance and psychosis are required.

Verbal fluency deficits and altered lateralization of language brain areas in individuals genetically predisposed to schizophrenia

Alterations of verbal fluency may correlate with deficits of gray matter volume and hemispheric lateralization of language brain regions like the pars triangularis (PT) in schizophrenia. Examining non-psychotic individuals at high genetic risk (HR) for schizophrenia may clarify if these deficits represent heritable trait markers or state dependent phenomena. We assessed adolescent and young adult HR subjects (N=60) and healthy controls (HC; N=42) using verbal fluency tests and Freesurfer to process T1-MRI scans. We hypothesized volumetric and lateralization alterations of the PT and their correlation with verbal fluency deficits. HR subjects had letter verbal fluency deficits (controlling for IQ), left PT deficits (p=.00), (controlling ICV) and reversal of the L>R PT asymmetry noted in HC. Right Heschl's (p=.00), left supramarginal (p=.00) and right angular gyrii (p=.02) were also reduced in HR subjects. The L>R asymmetry of the Heschl's gyrus seen in HC was exaggerated and asymmetries of L>R of supramarginal and R>L of angular gyri, seen in HC were attenuated in HR subjects. L>R asymmetry of the PT predicted better verbal fluency across the pooled HR and HC groups. Young relatives of schizophrenia patients have verbal fluency deficits, gray matter volume deficits and reversed asymmetry of the pars triangularis. A reversed structural asymmetry of the PT in HR subjects may impair expressive language abilities leading to verbal fluency deficits. Volumetric deficits and altered asymmetry in inferior parietal and Heschl's gyrii may accompany genetic liability to schizophrenia.

Cognitive performance is related to cortical grey matter volumes in early stages of schizophrenia: a population-based study of first-episode psychosis

BACKGROUND

Neuropsychological deficits have been reported in association with first-episode psychosis (FEP). Reductions in grey matter (GM) volumes have been documented in FEP subjects compared to healthy controls. However, the possible inter-relationship between the findings of those two lines of research has been scarcely investigated.

OBJECTIVE

To investigate the relationship between neuropsychological deficits and GM volume abnormalities in a population-based sample of FEP patients compared to healthy controls from the same geographical area.

METHODS

FEP patients (n=88) and control subjects (n=86) were evaluated by neuropsychological assessment (Controlled Oral Word Association Test, forward and backward digit span tests) and magnetic resonance imaging using voxel-based morphometry.

RESULTS

Single-group analyses showed that prefrontal and temporo-parietal GM volumes correlated significantly (p<0.05, corrected) with cognitive performance in FEP patients. A similar pattern of direct correlations between neocortical GM volumes and cognitive impairment was seen in the schizophrenia subgroup (n=48). In the control group, cognitive performance was directly correlated with GM volume in the right dorsal anterior cingulate cortex and inversely correlated with parahippocampal gyral volumes bilaterally. Interaction analyses with "group status" as a predictor variable showed significantly greater positive correlation within the left inferior prefrontal cortex (BA46) in the FEP group relative to controls, and significantly greater negative correlation within the left parahippocampal gyrus in the control group relative to FEP patients.

CONCLUSION

Our results indicate that cognitive deficits are directly related to brain volume abnormalities in frontal and temporo-parietal cortices in FEP subjects, most specifically in inferior portions of the dorsolateral prefrontal cortex.

Neuroanatomical asymmetry patterns in individuals with schizophrenia and their non-psychotic siblings

Neuroanatomical endophenotypes may reveal insights into the processes by which genetic factors increase the risk of developing schizophrenia. To determine whether patterns of neuroanatomical asymmetries may be useful as schizophrenia-related endophenotypes, we compared patterns of structural asymmetries in patients with schizophrenia, healthy controls, and their respective siblings. The surfaces of the left and right amygdala, hippocampus, thalamus, caudate nucleus, putamen, globus pallidus, and nucleus accumbens were assessed in 40 pairs of healthy comparison controls (CON) and their siblings (CON-SIB) and 25 pairs of patients with schizophrenia (SCZ) and their siblings (SCZ-SIB) in magnetic resonance (MR) images using large deformation diffeomorphic metric mapping (LDDMM) and parallel transport techniques. The within-subject asymmetry deformation of each structure was first measured via LDDMM, and then translated to a global template via parallel transport for evaluation of the patterns of asymmetry both within and across siblings. Our results revealed that asymmetries observed in CON subjects occurred in the amygdala and the anterior segment of the hippocampus with more pronounced expansion deformation in the right-sided structures (R>L asymmetry) but not in the basal ganglia and thalamus. Disturbance in this pattern of asymmetries was observed in both SCZ and SCZ-SIB subjects. More specifically, exaggerations and reductions in the normative pattern of asymmetries were observed in the amygdala-hippocampus formation, basal ganglia, and thalamus. These altered patterns of asymmetries are present in subjects with schizophrenia and their siblings, and therefore may represent a schizophrenia-related endophenotype.

Diffusion tractography of the fornix in schizophrenia

BACKGROUND

White matter fiber tracts, especially those interconnecting the frontal and temporal lobes, are likely implicated in pathophysiology of schizophrenia. Very few studies, however, have focused on the fornix, a compact bundle of white matter fibers, projecting from the hippocampus to the septum, anterior nucleus of the thalamus and the mamillary bodies. Diffusion Tensor Imaging (DTI), and a new post-processing method, fiber tractography, provides a unique opportunity to visualize and to quantify entire trajectories of fiber bundles, such as the fornix, in vivo. We applied these techniques to quantify fornix diffusion anisotropy in schizophrenia.

METHODS

DTI images were used to evaluate the left and the right fornix in 36 male patients diagnosed with chronic schizophrenia and 35 male healthy individuals, group matched on age, parental socioeconomic status, and handedness. Regions of interest were drawn manually, blind to group membership, to guide tractography, and fractional anisotropy (FA), a measure of fiber integrity, was calculated and averaged over the entire tract for each subject. The Doors and People test (DPT) was used to evaluate visual and verbal memory, combined recall and combined recognition.

RESULTS

Analysis of variance was performed and findings demonstrated a difference between patients with schizophrenia and controls for fornix FA (p=0.006). Protected post-hoc independent sample t-tests demonstrated a bilateral FA decrease in schizophrenia, compared with control subjects (left side: p=0.048; right side p=0.006). Higher fornix FA was statistically significantly correlated with DPT and measures of combined visual memory (r=0.554, p=0.026), combined verbal memory (r=0.647, p=0.007), combined recall (r=0.516, p=0.041), and combined recognition (r=0.710, p=0.002) for the control group. No such statistically significant correlations were found in the patient group.

CONCLUSIONS

Our findings show the utility of applying DTI and tractography to study white matter fiber tracts in vivo in schizophrenia. Specifically, we observed a bilateral disruption in fornix integrity in schizophrenia, thus broadening our understanding of the pathophysiology of this disease.

Course of cognitive functioning during the stabilization phase of schizophrenia

The present study aimed at examining the longitudinal course of neuropsychological impairments in schizophrenia patients during the stabilization phase of the illness. Cognitive functioning of 151 schizophrenia patients was assessed at baseline, 9-month, and 15-month follow-up with a comprehensive battery of cognitive tests. Cognitive performance of 40 matched controls was also examined at baseline and follow-up in order to control for effects of repeated testing. We found significant improvements in memory, attention, and global cognitive functioning from baseline to 9-month follow-up. Abstraction was stable at a relatively normal level. Global cognitive functioning remained at 9-month follow-up one standard deviation below normative level. Improvements in patients' cognitive performance between the 9-month and the 15-month follow-up were fewer and less pronounced. The present study implies that schizophrenia is a static encephalopathy with trait and state dependent cognitive components particularly in the attention and memory domain. The statistically and clinically significant cognitive improvements should be ground for clinical optimism.

Neuropsychological functioning and brain structure in schizophrenia

Cognitive deficits are core features of schizophrenia that are already evident at early phases of the illness. The study of specific relationships between cognition and brain structure might provide valuable clues about neural basis of schizophrenia and its phenomenology. The aim of this article was to review the most consistent findings of the studies exploring the relationships between cognitive deficits and brain anomalies in schizophrenia. Besides several important methodological shortcomings to bear in mind before drawing any consistent conclusion from the revised literature, we have attempted to systematically summarize these findings. Thus, this review has revealed that whole brain volume tends to positively correlate with a range of cognitive domains in healthy volunteers and female patients. An association between prefrontal morphological characteristics and general inability to control behaviour seems to be present in schizophrenia patients. Parahippocampal volume is related to semantic cognitive functions. Thalamic anomalies have been associated with executive deficits specifically in patients. Available evidence on the relationship between cognitive functions and cerebellar structure is still contradictory. Nonetheless, a larger cerebellum appears to be associated with higher IQ in controls and in female patients. Enlarged ventricles, including lateral and third ventricles, are associated with deficits in attention, executive and premorbid cognitive functioning in patients. Several of these reported findings seem to be counterintuitive according to neural basis of cognitive functioning drawn from animal, lesion, and functional imaging investigations. Therefore, there is still a great need for more methodologically stringent investigations that would help in the advance of our understanding of the cognition/brain structure relationships in schizophrenia.

Executive control functioning and functional ability in older adults

The manner in which executive control functioning exerts its influence on functional tasks was investigated. Sixty older adults were administered neuropsychological tasks tapping into four domains of executive control function, including working memory, planning, fluency, and flexibility. A test of performance-based functional ability also was administered. Correlational analyses demonstrated that working memory was most strongly associated with performance-based functional ability; however, impairment in planning appeared to best predict performance-based functional decrement in simultaneous regression models. Results highlight the role of planning in the maintenance of functional ability, as measured by performance-based functional measures.

Asymmetries of cortical shape: Effects of handedness, sex and schizophrenia

Some evidence suggests that sex, handedness and disease processes associated with schizophrenia affect the magnitude and/or direction of structural brain asymmetries. There are mixed findings, however, on how these factors influence cerebral torque, when torque is assessed with linear or volumetric measurements. We obtained MRI data from 67 healthy (30 males, 10 non-dextrals) and 84 schizophrenia subjects (60 males; 16 non-dextrals) and applied cortical pattern matching to spatially relate and compare differences in the surface morphology of the two cerebral hemispheres at high spatial resolution. Asymmetry indices, computed at thousands of matched hemispheric locations, were used to examine effects of sex, handedness and schizophrenia on hemispheric shape asymmetries while controlling for age and the other factors. Highly significant and discriminative right-frontal and left parietal-occipital surface expansions and protrusions (petalias) were mapped within groups. Although hemispheric shape asymmetries appeared less pronounced within female non-dextrals, asymmetry indices were not shown to differ significantly across sex, hand preference or diagnosis, or to reveal interactions of handedness with sex or diagnosis. Our 3D maps of spatially detailed anterior and posterior hemispheric shape asymmetries reflect subtle geometric distortions in hemispheric surface morphology that cannot be characterized with 2D or volumetric methods. Inter-individual variations in hemispheric torque appear minimally influenced by sex, dextrality or disease status. Biological factors driving language dominance or other lateralized brain functions dissociable from handedness, may more closely relate to hemispheric shape asymmetries, while the lateralization of other discrete brain regions may be more influenced by sexually dimorphic factors or by schizophrenia pathophysiology.

Does self-perceived mood predict more variance in cognitive performance than clinician-rated symptoms in schizophrenia?

Symptoms are known to account for a small variance in some cognitive functions in schizophrenia, but the influence of self-perceived mood remains largely unknown. The authors examined the influence of subjective mood states, psychopathology, and depressive symptoms in cognitive performance in a single investigation in schizophrenia. A group of 40 stable medicated patients with schizophrenia (20 men, 20 women) and 30 healthy comparison subjects (15 men, 15 women) were assessed on neurocognitive measures of verbal abilities, attention, executive functioning, language, memory, motor functioning, and information processing. All subjects provided self-ratings of mood prior to cognitive testing. Patients were also rated on psychopathology and depressive symptoms. Patients performed worse than comparison subjects on most cognitive domains. Within the patient group, subjective feelings of depression-dejection, fatigue-inertia, confusion, and tension-anxiety predicted (controlling for symptoms) poor performance on measures of attention, executive function, and verbal memory. In the same group of patients, clinician-rated symptoms of psychopathology and depression predicted significantly poor performance only on tests of motor function. In comparison subjects, vigor related to better, and fatigue and inertia to worse, spatial motor performance. Self-perceived negative mood state may be a better predictor of cognitive deficits than clinician-rated symptoms in chronic schizophrenia patients.

Cognitive impairment but preservation of sexual dimorphism in cognitive abilities in chronic schizophrenia

Neurocognitive impairment in schizophrenia is well established, though sex differences on cognitive tasks have produced equivocal findings. The present study was designed to examine performance of schizophrenia patients on a sexually dimorphic cognitive battery. The cognitive battery comprising tests of spatial (mental rotation, computerized version of the Benton Judgment of Line Orientation) and verbal abilities (phonological and semantic fluency) was administered to men (n = 22) and women (n = 21) with schizophrenia and healthy controls (n = 21 men and 21 women). A series of multivariate analyses showed that the patient group performed worse than controls on all the cognitive tasks. Cognitive sexual dimorphism on all spatial tasks favoring men and verbal tasks favoring women remained. Within the patient sample, correlational data demonstrated that earlier age at onset of illness related to poorer spatial performance. It is concluded that normal sexual dimorphism is undisturbed on both spatial and verbal tasks by the schizophrenia disease process.

A longitudinal analysis of memory in patients with schizophrenia

Memory deficits are widely reported in patients with schizophrenia, but uncertainties remain about the extent and the longitudinal course of these deficits. Twenty-eight patients with a DSM-IV diagnosis of schizophrenia were tested on multiple aspects of memory at baseline, 9- and 18-month follow-up. Measures included: digit span, the Rivermead Behavioural Memory test (RBMT) battery, the Graded Naming Test (GNT) and several computerized memory tests from the Cambridge Automated Neuropsychological Testing Battery (CANTAB). A group of healthy controls (N=17) was tested on the CANTAB battery at baseline and 9-month follow up. The patients performed significantly poorer than controls on all CANTAB measures; however, there was no difference in change between groups over a 9-month period. Within-group patient comparisons revealed that symptoms reduced significantly over the study period, but had no association with memory. Significant improvements were observed for patients on two verbal memory tasks: the GNT and digit span, but not on any other measure. Interestingly, these were the only two tests on which patients were within normal limits at baseline. This study shows that patients with schizophrenia have deficits in multiple aspects of memory which remain stable over long periods of time. In addition, patients showed a tendency to improve on memory tasks which contained a verbal component.

The brain, language, and schizophrenia

Language is a defining and prominent feature in humans. This faculty is impaired in those with schizophrenia. Individuals with schizophrenia show numerous abnormalities in language function, including symptoms of disorganized speech, auditory hallucinations, thought disorders, and verbal memory impairments. Structural and functional brain imaging with neurocognitive testing shows various aspects of brain structure and function associated with language that also are abnormal in schizophrenia. This article comparatively reviews this research and relates it to understanding the symptoms and pathophysiologic features of schizophrenia. Understanding the neural basis of language and its disruption in schizophrenia provides a guide for diagnosis, subtyping, treatment, and future research.

An in vivo MRI study of prefrontal cortical complexity in first-episode psychosis

OBJECTIVE

The purpose of this study was to investigate abnormalities in the surface complexity of the prefrontal cortex and in the hemispheric asymmetry of cortical complexity in first-episode patients with schizophrenia.

METHOD

An estimate of the surface complexity of the prefrontal cortex was derived from the number of voxels along the boundary between gray matter and CSF. Magnetic resonance imaging scans were acquired from patients with a first episode of schizophrenia (N=17), patients with a first episode of affective psychosis (N=17), and normal comparison subjects (N=17), age-matched within a narrow age range (18-29 years). This study group was the focus of a previous study that showed lower prefrontal cortical volume in patients with schizophrenia.

RESULTS

Prefrontal cortical complexity was not significantly different among the groups. However, the schizophrenia patients differed significantly from the normal comparison subjects in asymmetry, with the schizophrenia patients showing less left-greater-than-right asymmetry in cortical complexity than the comparison subjects.

CONCLUSIONS

An abnormal pattern of asymmetry in the prefrontal cortex of first-episode patients with schizophrenia provides evidence for a neurodevelopmental mechanism in the etiology of schizophrenia.

The relationship of sex hormones and cortisol with cognitive functioning in Schizophrenia

Gonadal as well as stress hormones have recently been implicated in pathophysiology and sex differences in onset, prognosis and treatment of schizophrenia. The present study investigated the effects of serum levels of oestrogen, progesterone, testosterone and cortisol on neuropsychological functioning and psychopathology in a group of 37 patients (17 women, 20 men) with schizophrenia. Neuropsychological measures included tests of attention, verbal abilities, language, memory, executive functioning, motor and speed of information processing. The results showed that oestrogen and age was associated with low positive symptom scores, and within gender, cortisol predicted poor performance on the information processing domain in men. These findings demonstrate that cortisol, in addition to the commonly reported effects of oestrogen, influences neuropsychological functioning in schizophrenia with differential effects on specific domains of cognitive functioning and underscore the need for further investigation of the modulating role of hormones on neuropsychological functioning in schizophrenia.

Premorbid adjustment in first-episode non-affective psychosis: distinct patterns of pre-onset course

BACKGROUND

Knowledge about premorbid development in psychosis can shed light upon theories about aetiology and schizophrenic heterogeneity, and form a basis for early detection initiatives.

AIMS

To identify and validate patterns of premorbid functioning in first-episode psychosis.

METHOD

The Premorbid Adjustment Scale was used to examine 335 patients.

RESULTS

Social and academic function constituted fairly independent dimensions. Cluster analysis identified groups varying both in level and course. Patients with a stable social course compared with a deteriorating one had a shorter duration of untreated psychosis, were older, had more friends and less negative symptoms. Good childhood academic function correlated with more education, more meaningful activities and better working memory. Patients with a stable academic course were older at admission.

CONCLUSIONS

Patterns of premorbid development suggest both neurodevelopmental and neuroregressive pathways to illness.

Sex differences in the corpus callosum of patients with schizophrenia

The corpus callosum (CC) has been of interest in schizophrenia research because of its possible role in reduced lateralization and because of its sexually dimorphic characteristics. The literature has been replete with structural brain studies that have yielded equivocal results because of failure to address sex differences, handedness, and overall reductions in total brain volume (TBV) associated with schizophrenia. We performed midsagittal corpus callosum area MRI measurements on 71 chronically ill patients with schizophrenia (52 males, 19 females) and 67 controls (49 males, 18 females) using a semiautomated analytic technique subdividing the corpus callosum into five segments. Consistent with a meta-analysis [J. Neurol., Neurosurg. Psychiatry 58 (1995) 457], reductions in total CC area (after controlling for TBV and age) were found in schizophrenia patients relative to controls. However, our effect size, though not statistically significant, was -0.33 compared to -0.18 for the meta-analysis, indicating greater reductions in total CC area in our group of patients. Statistical significance was achieved only in male patients versus male controls (effect size=-0.50). The effect size remained the same when only right-handers were included in the analysis; thus, handedness did not account for this result. CC size was not related to psychiatric symptoms nor cognitive functioning in this group of patients.

Cognitive performance in schizophrenia: relationship to regional brain volumes and psychiatric symptoms

In an all-male sample of schizophrenic patients stabilized by medication (n=62) and normal controls (n=27), we obtained neuropsychological test data and high-resolution whole brain magnetic resonance scans, as well as detailed psychiatric rating scales on a subset of the patients (n=47). Schizophrenic patients had significantly worse overall age-adjusted cognitive performance than normal controls (average z-score=-0.90, range=-0.60 to -1.81), which included relatively more severe deficits with different types of memory, psychomotor speed, verbal fluency and verbal abstraction. Schizophrenic patients also had significantly smaller bilateral volumes in gray but not white matter in the prefrontal region, superior temporal gyrus and whole temporal lobe, but no group differences were observed in the hippocampus and parahippocampus. Correlations between the brain regions and cognitive performance revealed different sets of significant relationships for the two groups, particularly in the prefrontal and hippocampal regions. In addition, inverse correlations were observed between certain cognitive abilities (psychomotor speed, cognitive flexibility and verbal fluency) and patients' psychiatric ratings, especially with measures of negative symptoms. The convergence of findings for schizophrenic patients regarding the prefrontal region, negative symptoms, psychomotor speed and cognitive flexibility suggests that schizophrenic negative symptoms may involve disruption of frontal-subcortical connections.

The relationship between cognitive dysfunction and coping abilities in schizophrenia

Cognitive dysfunction is a core feature of schizophrenia [Psychiatr. Clin. North Am., 16 (1993) 295; Psychopharmacology: The fourth generation of progress, Raven Press, New York (1995) 1171; Clinical Neuropsychology, Oxford University Press, New York (1993) 449] and is related to psychosocial functioning in this population [Am. J. Psychiatry, 153 (1996) 321]. It is unclear whether cognitive dysfunction is related to specific areas of functioning in schizophrenia, such as coping abilities. Individuals with schizophrenia have deficient coping skills, which may contribute to their difficulties dealing with stressors [Am. J. Orthopsychiatry, 62 (1992) 117; J. Abnorm. Psychol., 82 (1986) 189]. The current study examined the relationship between coping abilities and cognitive dysfunction in a community sample of individuals with schizophrenia. It was hypothesized that executive dysfunction and mnemonic impairments would be positively related to deficiencies in active coping efforts involving problem solving and self-initiation (e.g. advocating for oneself and others with mental illness and becoming involved in meaningful activities, such as work), independent of the contributions of the general intellectual deficits associated with the disorder and psychiatric symptoms. The results indicated that both executive dysfunction and mnemonic impairments were related to decreased usage of active coping mechanisms after controlling for general intellectual deficits. Further, recognition memory made independent contributions to the prediction of coping involving action and help seeking after controlling for the effects of negative symptoms. These findings suggest that individuals with schizophrenia may be less flexible in their use of coping strategies, which may in turn contribute to their difficulties in coping with mental illness and its consequences.

Increased hippocampal volume in schizophrenics' parents with ancestral history of schizophrenia

OBJECTIVE

Decreased hippocampal volume is one of the hypothesized pathological features of schizophrenia, but it is not known if this abnormality is familially transmitted. The aim of this study was to measure the hippocampal volume of the parents of schizophrenic probands, in relationship to the apparent transmission of genetic risk.

METHOD

Eighteen subjects from families consisting of a schizophrenic proband and two clinically unaffected parents were studied. Probands were compared to six control subjects, matched for age, sex, and educational level. The six families were selected so that only one parent had an ancestral family history of schizophrenia. The volumes of both hippocampi were measured by magnetic resonance imaging and adjusted for age and whole brain volume.

RESULTS

The total hippocampal volumes of the parents with ancestral family history of schizophrenia were significantly larger than those of their schizophrenic offspring.

CONCLUSIONS

This study suggests that decreased hippocampal volume in schizophrenia is not a familially transmitted abnormality. Rather, it appears that clinically unaffected parents who transmit apparent genetic risk for schizophrenia may have increased hippocampal volume, which may be a protective factor against the illness.

Amygdala volume in schizophrenia: post-mortem study and review of magnetic resonance imaging findings

BACKGROUND

Claims that schizophrenia is a disease of the limbic system have been strengthened by meta-analyses of magnetic resonance imaging (MRI) studies finding reduced hippocampus and amygdala volumes. Some post-mortem studies do not find these abnormalities.

AIMS

To assess the volume of the amygdala in a series of brains post-mortem.

METHOD

Amygdala volume was estimated using point-counting in both hemispheres of the brains of 10 male and 8 female patients with schizophrenia, and a comparison group of 9 males and 9 females.

RESULTS

No significant reduction of amygdala volume was found.

CONCLUSIONS

Significant volume reduction of the amygdala is not a consistent feature of schizophrenia; findings from early MRI studies using coarse delineation methods may introduce bias to subsequent meta-analyses.

Deficits in language-mediated mental operations in patients with schizophrenia

We found previously that a subgroup of schizophrenic patients who passed screening tests of attentional competence showed memory deficits on word memory tasks, but were comparable with controls on tone memory tasks. To better understand the nature of language-specific memory deficits in this subgroup of patients, the present experiment was designed to bypass early perceptual processing of verbal material and determine if patients continue to show impaired performance on verbal memory tasks. Patients who passed the screening tests ('discriminator' patients; DSz) received four serial position tasks. In two, familiar sounds or line drawings were presented and subjects were required to remember the word associated with each stimulus item. In the other two, subjects received hard-to-label auditory and visual stimuli (birdsongs or snowflakes).DSz patients showed large memory deficits compared with controls when required to remember words associated with the familiar sounds or drawings, providing clear evidence of deficits in verbal memory processes independent of sensory processing of verbal stimuli. The interaction between diagnosis and labeling was highly significant, confirming that these patients have particular difficulty with verbal as opposed to non-verbal memory. This was particularly striking on the auditory tests where two patients out-performed all controls on the birdsong test, but were below all controls on the easy-to-label sounds test. The verbal memory tests were easier than the non-verbal memory tests for controls, thus deconfounding task difficulty and deficit specificity.

Language lateralization in schizophrenia, an fMRI study

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

A statistical interpretive method for neuropsychological test data

The accurate interpretation of large numbers of neuropsychological tests within a flexible battery approach is a difficult and sometimes controversial process. We present a statistically based method of interpretation (Rohling's Interpretive Method or RIM) and evaluation of neuropsychological data that allows for varying numbers of tests along a varying number of cognitive domains, yet remains psychometrically based. This method requires informed clinical judgment in that the level of confidence for tests, cognitive domains, and global indices are used as the backdrop for interpretive decisions. Specific procedures for use are presented in a systematic, detailed fashion to allow the interested reader to replicate the method. Two case examples are presented: a straightforward case of cerebrovascular insult and a more complicated case of mixed etiology. Examples include a variety of different neuropsychological tests commonly used in a flexible battery approach. A discussion of the practicality, ease of use, and potential limitations of this method are further presented.

Memory and executive function impairments in deficit syndrome schizophrenia

The relationship between deficit syndrome schizophrenia, as determined by the Schedule for the Deficit Syndrome, and impairments in memory and executive function was investigated by administering the Wisconsin Card Sorting Test, the Wechsler Adult Intelligence Test, and the Wechsler Memory Scales to outpatients with deficit (n=33) and non-deficit (n=57) syndrome. A factor analysis of test variables revealed three factors: executive functioning; simple verbal memory; and semantic verbal memory. Results indicated that the deficit group performed significantly worse on the executive functioning factor, but not on either of the verbal memory factors. These findings support the hypothesis that deficit syndrome schizophrenia represents a specific cognitive impairment in executive processing and not necessarily graver global cognitive impairment.

Abnormal neurochemical asymmetry in the temporal lobe of schizophrenia

Neuroanatomical asymmetries are known to be present in the human brain, and loss of reversal of these asymmetries, particularly through changes in the left temporal lobe, have been found in the brains of patients with schizophrenia. In addition to disturbed neuroanatomical asymmetries, disturbed neurochemical asymmetries have also been reported in the brains of patients with schizophrenia. However, in the temporal lobe, the laterality of most of these neurochemical changes has not been specifically evaluated. Few neurochemical studies have addressed left-right differences in the superior temporal gyrus (STG). A deteriorated serotonin2A receptor-G protein qalpha (Gqalpha)-phosphoinositide-specific phospholipase C beta1(PLC beta1) cascade has been found in the left, but not right, STG of patients with schizophrenia. Not only neuroanatomical but also neurochemical evidence supports the loss or reversal of normal asymmetry of the temporal lobe in schizophrenia, which might be due to a disruption of the neurodevelopmental processes involved in hemispheric lateralization.

Are auditory hallucinations the consequence of abnormal cerebral lateralization? A morphometric MRI study of the sylvian fissure and planum temporale

BACKGROUND

Auditory verbal hallucinations (AVHs) are a characteristic feature of schizophrenia. Patients with schizophrenia have been found to have reduced volumes of a variety of brain structures as well as a reduction in right-left asymmetries, using postmortem and magnetic resonance imaging (MRI) measures. There is also evidence that patients with AVHs differ in these structural asymmetries, relative to those patients who do not hallucinate. The aim of this study was to examine whether patients with and without a prominent history of AVHs differ, both from each other and in comparison with normal subjects, in the asymmetry of the sylvian fissure (SF) and planum temporale (PT).

METHODS

We recruited 74 DSM-IV male patients with schizophrenia (on the basis of their AVH history) and 32 matched normal control subjects. Thirty patients had no history of AVHs and 44 had a strong definitive history of AVHs. The SF length and PT area and volume were measured on a three-dimensional MRI spoiled GRASS volume sequence. Absolute measures and laterality coefficients were calculated.

RESULTS

: All groups had the normal leftward asymmetry in both the SF and PT. Planum temporale volume and surface area and SF length were all larger in the left hemisphere. There were no significant differences in any measures between the two patient groups or between schizophrenic patients and control subjects. Greater leftward asymmetry of the SF correlated with hallucinations and thought disorder within the prominent hallucinator group. An association was found between handedness and brain size, but this did not interact with diagnosis.

CONCLUSIONS

The results of this study do not confirm reports, based on smaller samples, of reduced structural asymmetries of either the SF or PT in schizophrenia, nor do they indicate a specific relationship to a propensity to experience AVHs. A modest correlation between leftward asymmetry of the SF and some positive symptomatology was found.

A review of MRI findings in schizophrenia

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

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

BACKGROUND

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

AIMS

To review quantitatively the literature on decreased lateralisation in schizophrenia.

METHOD

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

RESULTS

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

CONCLUSION

Strong evidence is provided for decreased cerebral lateralisation in schizophrenia.

Three-dimensional mapping of gyral shape and cortical surface asymmetries in schizophrenia: gender effects

OBJECTIVE

People with schizophrenia exhibit abnormalities in brain structure, often in the left hemisphere. Disturbed structural lateralization is controversial, however, and effects appear mediated by gender. The authors mapped differences between schizophrenic and normal subjects in gyral asymmetries, complexity, and variability across the entire cortex.

METHOD

Asymmetry and shape profiles for 25 schizophrenic patients (15 men) and 28 demographically similar normal subjects (15 men) were obtained for 38 gyral regions, including the sylvian fissure and temporal and postcentral gyri, by using magnetic resonance data and a novel surface-based mesh-modeling approach. Cortical complexity was examined for sex and diagnosis effects in lobar regions. Intragroup variability was quantified and visualized to assess regional group abnormalities at the cortical surface.

RESULTS

The patients showed greater variability in frontal areas than the comparison subjects. They also had significant deviations in gyral complexity asymmetry in the superior frontal cortex. In temporoparietal regions, significant gyral asymmetries were present in both groups. Sex differences were apparent in superior temporal gyral measures, and cortical complexity in inferior frontal regions was significantly greater in men.

CONCLUSIONS

Cortical variability and complexity show regional abnormalities in the frontal cortex potentially specific to schizophrenia. The results indicate highly significant temporoparietal gyral asymmetries in both diagnostic groups, contrary to reports of less lateralization in schizophrenia. Substantially larger study groups are necessary to isolate smaller deviations in surface asymmetries, if present in schizophrenia, suggesting their diagnostic value is minimal.

Gender differences in premorbid cognitive performance in a national cohort of schizophrenic patients

Despite significant research, there are still inconsistent findings regarding gender differences in cognitive performance in individuals already diagnosed with schizophrenia; studies have found that males suffering from schizophrenia are more, less or equally impaired compared with females. Gender differences in cognitive performance in individuals suffering from schizophrenia may be influenced by gender differences in premorbid cognitive performance; the very few and very small N studies published indicated that males have a poorer pre-morbid cognitive performance than females. This study examined the gender differences in premorbid cognition, utilizing cognitive assessments performed on female and male adolescents before induction into military service. The Israeli Draft Board Registry, which contains cognitive assessments equivalent to IQ scores on 16-18 year old Israeli adolescents, was linked with the Israeli National Psychiatric Hospitalization Case Registry, which records all psychiatric hospitalizations in the country. Scores on premorbid cognitive performance in schizophrenia were examined in 90 female-male case pairs matched for school attended as a proxy for socio-economic status. The mean age of first hospitalization was 20. 1+/-1.8 years of age for males and 19.6+/-1.8 years of age for females. A repeated-measures ANCOVA with age of first hospitalization and years of formal education as covariates, and controlling for gender differences in cognitive performance in healthy adolescents, revealed a significant difference in pre-morbid cognitive performance between males and females on all four cognitive measures [F(1,87)=8.07, P=0.006] with females scoring lower (worse) than males. In this national cohort, pre-morbid cognition was poorer in female, compared with male, adolescents who will suffer from schizophrenia in the future, a result consistent with some, but not all, similar studies. These results may be valid only for patients with first hospitalization around age 20. Hence, gender differences in premorbid cognition should be taken into account when assessing gender differences in cognition in schizophrenia.

Age and neuropsychologic function in schizophrenia: a decline in executive abilities beyond that observed in healthy volunteers

BACKGROUND

Kraepelin originally conceptualized schizophrenia as a degenerative brain disorder. It remains unclear whether the illness is characterized by a static encephalopathy or a deterioration of brain function, or periods of each condition. Assessments of cognitive function, as measured by neuropsychologic assessment, can provide additional insight into this question. Few studies of patients with schizophrenia have investigated the effect of aging on executive functions, in an extensive neuropsychologic battery across a wide age range, compared to healthy volunteers.

METHODS

We examined the interaction of aging and neuropsychologic function in schizophrenia through a cross-sectional study in patients (n = 87) and healthy control subjects (n = 94). Subjects were divided into three age groups (20-35, 36-49, and 50-75), and performance on an extensive neuropsychologic battery was evaluated.

RESULTS

Compared to control subjects, patients with schizophrenia demonstrated similar age-related declines across most neuropsychologic functions, with the exception of abstraction ability, in which significant evidence of a more accelerated decline was observed.

CONCLUSIONS

These results are consistent with previous reports indicating similar age effects on most aspects of cognition in patients with schizophrenia and healthy adults, but they support the hypothesis that a degenerative process may result in a more accelerated decline of some executive functions in older age in schizophrenia.

Longitudinal neuropsychological follow-up study of patients with first-episode schizophrenia

OBJECTIVE

The primary purpose of this article was to determine if cognitive abilities decline, remain unchanged, or modestly improve throughout the course of schizophrenic illness.

METHOD

Forty-two patients with a first hospitalization for schizophrenia or schizophreniform disorder and 16 normal comparison subjects had a battery of neuropsychological tests and a magnetic resonance imaging (MRI) brain scan at approximate yearly intervals for the first 2 to 5 years of illness. Summary rating scales for language, executive, memory, processing speed, and sensory-perceptual functions were constructed.

RESULTS

Patients with schizophrenia scored 1 to 2 standard deviations below normal comparison subjects on neuropsychological test measures during the course of the study. Patients exhibited less improvement than comparison subjects on measures of verbal memory. In general, improvement in positive symptoms over the time interval was associated with improvement in cognition. No changes in regional brain measurements were correlated with cognitive change in the patient group.

CONCLUSIONS

Patients with schizophrenia have considerable cognitive dysfunction in the first 4 to 5 years of illness, which is stable at a level of 1 to 2 standard deviations below that of comparison subjects. There is little evidence for deterioration of cognitive abilities over the first few years of illness, with the exception of verbal memory, which shows significantly less improvement in patients over time relative to that of comparison subjects.

Structural brain imaging in schizophrenia: a selective review

Structural neuroimaging studies have provided some of the most consistent evidence for brain abnormalities in schizophrenia. Since the initial computed tomography study by Johnstone and co-workers, which reported lateral ventricular enlargement in schizophrenia, advances in brain imaging technology have enabled further and more refined characterization of abnormal brain structure in schizophrenia in vivo. This selective review discusses the major issues and findings in structural neuroimaging studies of schizophrenia. Among these are evidence for generalized and regional brain volume abnormalities, the specificity of anatomic findings to schizophrenia and to men versus women with schizophrenia, the contribution of genetic influences, and the timing of neuroanatomic pathology in schizophrenia. The second section reviews new approaches for examining brain structure in schizophrenia and their applications to studies on the pathophysiology of schizophrenia.

Cognitive deficits and cognitive training in schizophrenic patients: a review

OBJECTIVE

The aim of this paper is to review the current status of knowledge of cognitive deficits and remediation in patients with schizophrenia.

METHOD

Relevant reports were identified by a literature survey. In addition, some outstanding researchers in these areas were asked to add to the identified list relevant literature that was not included.

RESULTS

Our review focuses on the cognitive deficits observed in the areas of attention, memory and executive functions. We attempt to classify dysfunctions as vulnerability- or symptom-linked factors, and we discuss the methodological question of a general performance deficit vs. a differential deficit. Furthermore, we briefly delineate how antipsychotics affect cognitive functions. Finally, controlled studies of cognitive training are discussed in more detail.

CONCLUSION

The most outstanding cognitive dysfunctions in patients with schizophrenia can be related to the areas of attention, memory and executive functions. Interest in cognitive remediation has to some extent been rekindled in the 1990s. However, few studies on the effects of cognitive training programs have been conducted.