Reconciling neuroimaging and neuropathological findings in schizophrenia and bipolar disorder

Estrogen and psychosis - a review and future directions

The link between sex hormones and schizophrenia has been suspected for over a century; however, scientific evidence supporting the pharmacotherapeutic effects of exogenous estrogen has only started to emerge during the past three decades. Accumulating evidence from epidemiological and basic research suggests that estrogen has a protective effect in women vulnerable to schizophrenia. Such evidence has led multiple researchers to investigate the role of estrogen in schizophrenia and its use in treatment. This narrative review provides an overview of the effects of estrogen as well as summarizes the recent work regarding estrogen as a treatment for schizophrenia, particularly the use of new-generation selective estrogen receptor modulators.

Discriminative analysis of schizophrenia patients using an integrated model combining 3D CNN with 2D CNN: A multimodal MR image and connectomics analysis

OBJECTIVE

Few studies have applied deep learning to the discriminative analysis of schizophrenia (SZ) patients using the fusional features of multimodal MRI data. Here, we proposed an integrated model combining a 3D convolutional neural network (CNN) with a 2D CNN to classify SZ patients.

METHOD

Structural MRI (sMRI) and resting-state functional MRI (rs-fMRI) data were acquired for 140 SZ patients and 205 normal controls. We computed structural connectivity (SC) from the sMRI data as well as functional connectivity (FC), amplitude of low-frequency fluctuation (ALFF), and regional homogeneity (ReHo) from the rs-fMRI data. The 3D images of T1, ReHo, and ALFF were used as the inputs for the 3D CNN model, while the SC and FC matrices were used as the inputs for the 2D CNN model. Moreover, we added squeeze and excitation blocks (SE-blocks) to each layer of the integrated model and used a support vector machine (SVM) to replace the softmax classifier.

RESULTS

The integrated model proposed in this study, using the fusional features of the T1 images, and the matrices of FC, showed the best performance. The use of the SE-blocks and SVM classifiers significantly improved the performance of the integrated model, in which the accuracy, sensitivity, specificity, area under the curve, and F1-score were 89.86%, 86.21%, 92.50%, 89.35%, and 87.72%, respectively.

CONCLUSIONS

Our findings indicated that an integrated model combining 3D CNN with 2D CNN is a promising method to improve the classification performance of SZ patients and has potential for the clinical diagnosis of psychiatric diseases.

Higher Body-Mass Index and Lower Gray Matter Volumes in First Episode of Psychosis

BACKGROUND

Neurostructural alterations are often reported in first episode of psychosis (FEP), but there is heterogeneity in the direction and location of findings between individual studies. The reasons for this heterogeneity remain unknown. Obesity is disproportionately frequent already early in the course of psychosis and is associated with smaller brain volumes. Thus, we hypothesized that obesity may contribute to brain changes in FEP.

METHOD

We analyzed MRI scans from 120 participants with FEP and 114 healthy participants. In primary analyses, we performed voxel-based morphometry (VBM) with small volume corrections to regions associated with FEP or obesity in previous meta-analyses. In secondary analyses, we performed whole-brain VBM analyses.

RESULTS

In primary analyses, we found that when controlling for BMI, FEP had lower GM volume than healthy participants in a) left fronto-temporal region (pTFCE = 0.008) and b) left postcentral gyrus (pTFCE = 0.043). When controlling for FEP, BMI was associated with lower GM volume in left cerebellum (pTFCE < 0.001). In secondary analyses, we found that when controlling for BMI, FEP had lower GM volume than healthy participants in the a) cerebellum (pTFCE = 0.004), b) left frontal (pTFCE = 0.024), and c) right temporal cortex (pTFCE = 0.031). When controlling for FEP, BMI was associated with lower GM volume in cerebellum (pTFCE = 0.004). Levels of C-reactive protein, HDL and LDL-cholesterol correlated with obesity related neurostructural alterations.

CONCLUSIONS

This study suggests that higher BMI, which is frequent in FEP, may contribute to cerebellar alterations in schizophrenia. As previous studies showed that obesity-related brain alterations may be reversible, our findings raise the possibility that improving the screening for and treatment of obesity and associated metabolic changes could preserve brain structure in FEP.

A developmental redox dysregulation leads to spatio-temporal deficit of parvalbumin neuron circuitry in a schizophrenia mouse model

The fast-spiking parvalbumin (PV) interneurons play a critical role in neural circuit activity and dysfunction of these cells has been implicated in the cognitive deficits typically observed in schizophrenia patients. Due to the high metabolic demands of PV neurons, they are particularly susceptible to oxidative stress. Given the extant literature exploring the pathological effects of oxidative stress on PV cells in cortical regions linked to schizophrenia, we decided to investigate whether PV neurons in other select brain regions, including sub-cortical structures, may be differentially affected by redox dysregulation induced oxidative stress during neurodevelopment in mice with a genetically compromised glutathione synthesis (Gclm KO mice). Our analyses revealed a spatio-temporal sequence of PV cell deficit in Gclm KO mice, beginning with the thalamic reticular nucleus at postnatal day (P) 20 followed by a PV neuronal deficit in the amygdala at P40, then in the lateral globus pallidus and the ventral hippocampus Cornu Ammonis 3 region at P90 and finally the anterior cingulate cortex at P180. We suggest that PV neurons in different brain regions are developmentally susceptible to oxidative stress and that anomalies in the neurodevelopmental calendar of metabolic regulation can interfere with neural circuit maturation and functional connectivity contributing to the emergence of developmental psychopathology.

Brain morphologic changes in early stages of psychosis: Implications for clinical application and early intervention

To date, a large number of magnetic resonance imaging (MRI) studies have been conducted in schizophrenia, which generally demonstrate gray matter reduction, predominantly in the frontal and temporo-limbic regions, as well as gross brain abnormalities (e.g., a deviated sulcogyral pattern). Although the causes as well as timing and course of these findings remain elusive, these morphologic changes (especially gross brain abnormalities and medial temporal lobe atrophy) are likely present at illness onset, possibly reflecting early neurodevelopmental abnormalities. In addition, longitudinal MRI studies suggest that patients with schizophrenia and related psychoses also have progressive gray matter reduction during the transition period from prodrome to overt psychosis, as well as initial periods after psychosis onset, while such changes may become almost stable in the chronic stage. These active brain changes during the early phases seem to be relevant to the development of clinical symptoms in a region-specific manner (e.g., superior temporal gyrus atrophy and positive psychotic symptoms), but may be at least partly ameliorated by antipsychotic medication. Recently, increasing evidence from MRI findings in individuals at risk for developing psychosis has suggested that those who subsequently develop psychosis have baseline brain changes, which could be at least partly predictive of later transition into psychosis. In this article, we selectively review previous MRI findings during the course of psychosis and also refer to the possible clinical applicability of these neuroimaging research findings, especially in the diagnosis of schizophrenia and early intervention for psychosis.

Obesity, dyslipidemia and brain age in first-episode psychosis

INTRODUCTION

Obesity and dyslipidemia may negatively affect brain health and are frequent medical comorbidities of schizophrenia and related disorders. Despite the high burden of metabolic disorders, little is known about their effects on brain structure in psychosis. We investigated, whether obesity or dyslipidemia contributed to brain alterations in first-episode psychosis (FEP).

METHODS

120 participants with FEP, who were undergoing their first psychiatric hospitalization, had <24 months of untreated psychosis and were 18-35 years old and 114 controls within the same age range participated in the study. We acquired 3T brain structural MRI, fasting lipids and body mass index. We used machine learning trained on an independent sample of 504 controls to estimate the individual brain age of study participants and calculated the BrainAGE score by subtracting the chronological from the estimated brain age.

RESULTS

In a multiple regression model, the diagnosis of FEP (B = 1.15, SE B = 0.31, p < 0.001) and obesity/overweight (B = 0.92, SE B = 0.35, p = 0.008) were each additively associated with BrainAGE scores (R² = 0.22, F(3, 230) = 21.92, p < 0.001). BrainAGE scores were highest in participants with FEP and obesity/overweight (3.83 years, 95%CI = 2.35-5.31) and lowest in normal weight controls (-0.27 years, 95%CI = -1.22-0.69). LDL-cholesterol, HDL-cholesterol or triglycerides were not associated with BrainAGE scores.

CONCLUSIONS

Overweight/obesity may be an independent risk factor for diffuse brain alterations manifesting as advanced brain age already early in the course of psychosis. These findings raise the possibility that targeting metabolic health and intervening already at the level of overweight/obesity could slow brain ageing in FEP.

Disrupted modular organization of primary sensory brain areas in schizophrenia

Abnormal brain resting-state functional connectivity has been consistently observed in patients affected by schizophrenia (SCZ) using functional MRI and other neuroimaging techniques. Graph theoretical methods provide a framework to investigate these defective functional interactions and their effects on the organization of brain connectivity networks. A few studies have shown altered distribution of connectivity within and between functional modules in SCZ patients, an indication of imbalanced functional segregation ad integration. However, no major alterations of modular organization have been reported in patients, and unambiguous identification of the neural substrates affected remains elusive. Recently, it has been demonstrated that current modularity analysis methods suffer from a fundamental and severe resolution limit, as they fail to detect features that are smaller than a scale determined by the size of the entire connectivity network. This resolution limit is likely to have hampered the ability to resolve differences between patients and controls in previous studies. Here, we apply Surprise, a novel resolution limit-free approach, to study the modular organization of resting state functional connectivity networks in a large cohort of SCZ patients and in matched healthy controls. Leveraging these important methodological advances we find new evidence of substantial fragmentation and reorganization involving primary sensory, auditory and visual areas in SCZ patients. Conversely, frontal and prefrontal areas, typically associated with higher cognitive functions, appear to be largely unaffected, with changes selectively involving language and speech processing areas. Our findings support the hypothesis that cognitive dysfunction in SCZ may involve deficits occurring already at early stages of sensory processing.

Cortical magnetization transfer abnormalities and connectome dysconnectivity in schizophrenia

Macroscale dysconnectivity in schizophrenia is associated with neuropathological abnormalities. The extent to which alterations in cortical myelination as revealed in vivo by magnetization transfer ratio (MTR) are related to macroscale dysconnectivity remains unknown. We acquired magnetization transfer imaging (MTI) data and diffusion weighted imaging (DWI) data from 78 schizophrenia patients and 93 healthy controls for MTR extraction and connectome reconstruction to examine the possible link between cortical myelination and macroscale dysconnectivity. Our findings showed significant cortical MTR disruptions in several prefrontal areas in schizophrenia patients, including bilateral rostral middle frontal areas, right pars orbitalis, and right frontal pole. Furthermore, cortical MTR alterations between patients and controls were significantly correlated with the level of regional disconnectivity. Together, our findings provide evidence that microstructural neuropathological abnormalities in schizophrenia are predominately present in prefrontal areas of the cortex and are associated with alterations in structural connectome architecture at the whole brain network level.

Automated immunohistochemical method to analyze large areas of the human cortex

BACKGROUND

There have been inconsistencies in the histological abnormalities found in the cerebral cortex from patients with schizophrenia, bipolar disorder and major depression. Discrepancies in previously published reports may arise from small sample sizes, inconsistent methodology and biased cell counting.

METHODS

We applied automated quantification of neuron density, neuron size and cortical layer thickness in large regions of the cerebral cortex in psychiatric patients. This method accurately segments DAPI positive cells that are also stained with CUX2 and FEZF2. Cortical layer thickness, neuron density and neuron size were automatically computed for each cortical layer in numerous Brodmann areas.

RESULTS

We did not find pronounced cytoarchitectural abnormalities in the anterior cingulate cortex or orbitofrontal cortex in patients with schizophrenia, bipolar disorder or major depressive disorder. There were no significant differences in layer thickness measured in immunohistochemically stained slides compared with traditional Nissl stained slides. Automated cell counts were correlated, reliable and consistent with manual counts, while being much less time-consuming.

CONCLUSION

We demonstrate the validity of using a novel automated analysis approach to post-mortem brain tissue. We were able to analyze large cortical areas and quantify specific cell populations using immunohistochemical markers. Future analyses could benefit from efficient automated analysis.

Brain change trajectories that differentiate the major psychoses

BACKGROUND

Bipolar disorder and schizophrenia are highly heritable, often chronic and debilitating psychotic disorders that can be difficult to differentiate clinically. Their brain phenotypes appear to overlap in both cross-sectional and longitudinal structural neuroimaging studies, with some evidence to suggest areas of differentiation with differing trajectories. The aim of this review was to investigate the notion that longitudinal trajectories of alterations in brain structure could differentiate the two disorders.

DESIGN

Narrative review. We searched MEDLINE and Web of Science databases in May 2016 for studies that used structural magnetic resonance imaging to investigate longitudinal between-group differences in bipolar disorder and schizophrenia. Ten studies met inclusion criteria, namely longitudinal structural magnetic resonance studies comparing bipolar disorder (or affective psychosis) and schizophrenia within the same study.

RESULTS

Our review of these studies implicates illness-specific trajectories of morphological change in total grey matter volume, and in regions of the frontal, temporal and cingulate cortices. The findings in schizophrenia suggest a trajectory involving progressive grey matter loss confined to fronto-temporal cortical regions. Preliminary findings identify a similar but less severely impacted trajectory in a number of regions in bipolar disorder, however, bipolar disorder is also characterized by differential involvement across cingulate subregions.

CONCLUSION

The small number of available studies must be interpreted with caution but provide initial evidence supporting the notion that bipolar disorder and schizophrenia have differential longitudinal trajectories that are influenced by brain maturation.

ERBB4 polymorphism and family history of psychiatric disorders on age-related cortical changes in healthy children

Genetic variations in ERBB4 were associated with increased susceptibility for schizophrenia (SCZ) and bipolar disorders (BPD). Structural imaging studies showed cortical abnormalities in adolescents and adults with SCZ or BPD. However, less is known about subclinical cortical changes or the influence of ERBB4 on cortical development. 971 healthy children (ages 3-20 years old; 462 girls and 509 boys) were genotyped for the ERBB4-rs7598440 variants, had structural MRI, and cognitive evaluation (NIH Toolbox ®). We investigated the effects of ERBB4 variants and family history of SCZ and/or BPD (FH) on cortical measures and cognitive performances across ages 3-20 years using a general additive model. Variations in ERBB4 and FH impact differentially the age-related cortical changes in regions often affected by SCZ and BPD. The ERBB4-TT-risk genotype children with no FH had subtle cortical changes across the age span, primarily located in the left temporal lobe and superior parietal cortex. In contrast, the TT-risk genotype children with FH had more pronounced age-related changes, mainly in the frontal lobes compared to the non-risk genotype children. Interactive effects of age, FH and ERBB4 variations were also found on episodic memory and working memory, which are often impaired in SCZ and BPD. Healthy children carrying the risk-genotype in ERBB4 and/or with FH had cortical measures resembling those reported in SCZ or BPD. These subclinical cortical variations may provide early indicators for increased risk of psychiatric disorders and improve our understanding of the effect of the NRG1-ERBB4 pathway on brain development.

Neuroimaging distinction between neurological and psychiatric disorders

BACKGROUND

It is unclear to what extent the traditional distinction between neurological and psychiatric disorders reflects biological differences.

AIMS

To examine neuroimaging evidence for the distinction between neurological and psychiatric disorders.

METHOD

We performed an activation likelihood estimation meta-analysis on voxel-based morphometry studies reporting decreased grey matter in 14 neurological and 10 psychiatric disorders, and compared the regional and network-level alterations for these two classes of disease. In addition, we estimated neuroanatomical heterogeneity within and between the two classes.

RESULTS

Basal ganglia, insula, sensorimotor and temporal cortex showed greater impairment in neurological disorders; whereas cingulate, medial frontal, superior frontal and occipital cortex showed greater impairment in psychiatric disorders. The two classes of disorders affected distinct functional networks. Similarity within classes was higher than between classes; furthermore, similarity within class was higher for neurological than psychiatric disorders.

CONCLUSIONS

From a neuroimaging perspective, neurological and psychiatric disorders represent two distinct classes of disorders.

Proteomic pathway analysis of the hippocampus in schizophrenia and bipolar affective disorder implicates 14-3-3 signaling, aryl hydrocarbon receptor signaling, and glucose metabolism: potential roles in GABAergic interneuron pathology

Neuropathological changes of the hippocampus have been associated with psychotic disorders such as schizophrenia and bipolar disorder. Recent work has particularly implicated hippocampal GABAergic interneurons in the pathophysiology of these diseases. However, the molecular mechanisms underlying structural and cellular hippocampal pathology remain poorly understood. We used data from comprehensive difference-in-gel electrophoresis (2-D DIGE) investigations of postmortem human hippocampus of people with schizophrenia and bipolar disorder, covering the acidic (isoelectric point (pI) between pH4 and 7) and, separately, the basic (pI between pH6 and 11) sub-proteome, for Ingenuity Pathway Analysis (IPA) of implicated protein networks and pathways. Comparing disease and control cases, we identified 58 unique differentially expressed proteins in schizophrenia, and 70 differentially expressed proteins in bipolar disorder, using mass spectrometry. IPA implicated, most prominently, 14-3-3 and aryl hydrocarbon receptor signaling in schizophrenia, and gluconeogenesis/glycolysis in bipolar disorder. Both disorders were characterized by alterations of proteins involved in the oxidative stress response, mitochondrial function, and protein-endocytosis, -trafficking, -degradation, and -ubiquitination. These findings are interpreted with a focus on GABAergic interneuron pathology in the hippocampus.

Joint Coupling of Awake EEG Frequency Activity and MRI Gray Matter Volumes in the Psychosis Dimension: A BSNIP Study

BACKGROUND

Many studies have examined either electroencephalogram (EEG) frequency activity or gray matter volumes (GMV) in various psychoses [including schizophrenia (SZ), schizoaffective (SZA), and psychotic bipolar disorder (PBP)]. Prior work demonstrated similar EEG and gray matter abnormalities in both SZ and PBP. Integrating EEG and GMV and jointly analyzing the combined data fully elucidates the linkage between the two and may provide better biomarker- or endophenotype-specificity for a particular illness. Joint exploratory investigations of EEG and GMV are scarce in the literature and the relationship between the two in psychosis is even less explored. We investigated a joint multivariate model to test whether the linear relationship or linkage between awake EEG (AEEG) frequency activity and GMV is abnormal across the psychosis dimension and if such effects are also present in first-degree relatives.

METHODS

We assessed 607 subjects comprising 264 probands [105 SZ, 72 SZA, and 87 PBP], 233 of their first degree relatives [82 SZ relatives (SZR), 71 SZA relatives (SZAR), and 80 PBP relatives (PBPR)], and 110 healthy comparison subjects (HC). All subjects underwent structural MRI (sMRI) and EEG scans. Frequency activity and voxel-based morphometric GMV were derived from EEG and sMRI data, respectively. Seven AEEG frequency and gray matter components were extracted using Joint independent component analysis (jICA). The loading coefficients (LC) were examined for group differences using analysis of covariance. Further, the LCs were correlated with psychopathology scores to identify relationship with clinical symptoms.

RESULTS

Joint ICA revealed a single component differentiating SZ from HC (p < 0.006), comprising increased posterior alpha activity associated with decreased volume in inferior parietal lobe, supramarginal, parahippocampal gyrus, middle frontal, inferior temporal gyri, and increased volume of uncus and culmen. No components were aberrant in either PBP or SZA or any relative group. No significant association was identified with clinical symptom measures.

CONCLUSION

Our data suggest that a joint EEG and GMV model yielded a biomarker specific to SZ, not abnormal in PBP or SZA. Alpha activity was related to both increased and decreased volume in different cortical structures. Additionally, the joint model failed to identify endophenotypes across psychotic disorders.

Common biological mechanisms between bipolar disorder and type 2 diabetes: Focus on inflammation

INTRODUCTION

Bipolar disorder (BD) patients present a 3-5 fold greater risk of developing type 2 diabetes (T2D) compared to general population. The underlying mechanisms for the increased prevalence of T2D in BD population are poorly understood.

OBJECTIVES

The purpose of this review is to critically review evidence suggesting that inflammation may have an important role in the development of both BD and T2D.

RESULTS

The literature covered in this review suggests that inflammatory dysregulation take place among many BD patients. Such dysregulated and low grade chronic inflammatory process may also increase the prevalence of T2D in BD population. Current evidence supports the hypothesis of dysregulated inflammatory processes as a critical upstream event in BD as well as in T2D.

CONCLUSIONS

Inflammation may be a factor for the development of T2D in BD population. The identification of inflammatory markers common to these two medical conditions will enable researchers and clinicians to better understand the etiology of BD and develop treatments that simultaneously target all aspects of this multi-system condition.

Olfactory neuroepithelium as a cellular model for the diagnosis of neuropsychiatric diseases

The neuroepithelium has been used as an experimental model to find biological markers for neuropsychiatric disease diagnosis. Patent information permits understanding of the state of the art of neuroepithelium in neuropsychiatric disease diagnosis, as well as the identification of trends in research and development on this theme. In this article, we discuss diverse methods for obtaining primary cultures of olfactory neurons obtained by animal dissection or by postmortem biopsy of human cadavers. The principal owners of patents related to olfactory neuroepithelia are universities such as John Hopkins and Bristol-Myers Squibb. The USA has the most research lines and approved patents in the world, while Rutgers, the State University of New Jersey, provides composition and methods related to the diagnoses and treatment of neuropsychiatric disorders.

Occipital bending in depression

There are reports of differences in occipital lobe asymmetry within psychiatric populations when compared with healthy control subjects. Anecdotal evidence and enlarged lateral ventricles suggests that there may also be a different pattern of curvature whereby one occipital lobe wraps around the other, termed 'occipital bending'. We investigated the prevalence of occipital bending in 51 patients with major depressive disorder (males mean age = 41.96 ± 14.00 years, females mean age = 40.71 ± 12.41 years) and 48 age- and sex-matched healthy control subjects (males mean age = 40.29 ± 10.23 years, females mean age = 42.47 ± 14.25 years) and found the prevalence to be three times higher among patients with major depressive disorder (18/51, 35.3%) when compared with control subjects (6/48, 12.5%). The results suggest that occipital bending is more common among patients with major depressive disorder than healthy subjects, and that occipital asymmetry and occipital bending are separate phenomena. Incomplete neural pruning may lead to the cranial space available for brain growth being restricted, or ventricular enlargement may exacerbate the natural occipital curvature patterns, subsequently causing the brain to become squashed and forced to 'wrap' around the other occipital lobe. Although the clinical implications of these results are unclear, they provide an impetus for further research into the relevance of occipital bending in major depression disorder.

Brain networks in schizophrenia

Schizophrenia--a severe psychiatric condition characterized by hallucinations, delusions, loss of initiative and cognitive function--is hypothesized to result from abnormal anatomical neural connectivity and a consequent decoupling of the brain's integrative thought processes. The rise of in vivo neuroimaging techniques has refueled the formulation of dysconnectivity hypotheses, linking schizophrenia to abnormal structural and functional connectivity in the brain at both microscopic and macroscopic levels. Over the past few years, advances in high-field structural and functional neuroimaging techniques have made it increasingly feasible to reconstruct comprehensive maps of the macroscopic neural wiring system of the human brain, know as the connectome. In parallel, advances in network science and graph theory have improved our ability to study the spatial and topological organizational layout of such neural connectivity maps in detail. Combined, the field of neural connectomics has created a novel platform that provides a deeper understanding of the overall organization of brain wiring, its relation to healthy brain function and human cognition, and conversely, how brain disorders such as schizophrenia arise from abnormal brain network wiring and dynamics. In this review we discuss recent findings of connectomic studies in schizophrenia that examine how the disorder relates to disruptions of brain connectivity.

The relationship between schizophrenia and frontotemporal dementia

Schizophrenia is a relatively common disorder diagnosed by the presentation of psychotic symptoms in the absence of identifiable neurologic or other organic cause. Frontotemporal dementia (FTD) is a relatively rare progressive neurodegenerative disorder that can present with a multitude of cognitive and behavioral symptoms including psychosis. At times, this phenotypic overlap can mean that schizophrenia and FTD are 2 possibilities in the differential diagnosis of a psychotic presentation. In this article, we systematically review the literature on the relationship between schizophrenia and FTD including case reports that highlight the potential for diagnostic confusion, clinical studies examining the relationship between the disorders, and the molecular evidence of shared pathophysiologic mechanisms. Although a relationship between the disorders is not definitively supported by the current literature, we identify the characteristics of a psychotic presentation that should alert the clinician to the possibility of FTD and describe the areas where further research is needed to clarify the pathophysiologic relationship.

A magnetic resonance imaging study of hippocampal, amygdala and subgenual prefrontal cortex volumes in major depression subtypes: melancholic versus psychotic depression

BACKGROUND

Volumetric studies examining brain structure in depression subtypes are limited and inconclusive. The aim of the current study was to compare the volumes of brain regions previously implicated in depression among patients with melancholic major depressive disorder (MDD), patients with psychotic MDD and normal controls.

METHODS

Twenty two patients with melancholic MDD, 17 with psychotic MDD and 18 normal controls were included in the study. Hippocampal (HV), amygdala (AV), anterior (ASCV) and posterior (PSCV) subgenual cortex volumes were measured on magnetic resonance volumetric images.

RESULTS

There were no volumetric differences between patients with melancholic and psychotic subgroups. We identified larger AVs and smaller left ASCVs in both patient groups compared to controls with medium to large effect sizes. Regression analysis revealed that AVs were predicted by the presence of depression, late depression-onset, insomnia and left hippocampal tail volume in patients, but not in controls. There were no differences in HVs, right ASCVs and PSCVs across the 3 groups.

LIMITATIONS

Small sample size, a possible inclusion of paracingulate gyrus in ASCV and PSCV tracings, significant differences in education level and medication status are discussed as limitations.

CONCLUSIONS

Diagnostically delineated melancholic and psychotic MDD patients do not differ in medial temporal and cingulate volumes. However, significant volumetric differences were detected between both patient-groups and controls.

Lasp1 is down-regulated in NMDA receptor antagonist-treated mice and implicated in human schizophrenia susceptibility

Mice treated with MK-801, a non-competitive antagonist of the N-methyl-d-aspartic (NMDA) acid receptor, are important animal models for schizophrenia studies. In the present study, we compared protein expression levels in the hippocampus of mice treated with MK-801 (0.6 mg/kg) or saline once daily for 7 days. Changes in the proteome were detected by two-dimensional electrophoresis, and the six proteins exhibiting differential expression were identified by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. Down-regulation of one of these proteins, Lasp1 (LIM and SH3 protein 1), in MK-801-treated mice was confirmed by western blotting and immunohistochemical analyses. Lasp1 is a multidomain protein that may recruit signaling molecules to the actin-based cytoskeleton and is known to concentrate in synaptic sites of hippocampal neurons. We next investigated whether polymorphisms in the human LASP1 gene were associated with schizophrenia in the Korean population. A single-nucleotide polymorphism in the LASP1 gene promoter region was associated with schizophrenia susceptibility. Our results suggest that LASP1 might be associated with NMDA receptor antagonism and schizophrenia susceptibility and, thus, might be involved in the pathophysiology of schizophrenia.

Disease and genetic contributions toward local tissue volume disturbances in schizophrenia: a tensor-based morphometry study

Structural brain deficits, especially frontotemporal volume reduction and ventricular enlargement, have been repeatedly reported in patients with schizophrenia. However, it remains unclear whether brain structural deformations may be attributable to disease-related or genetic factors. In this study, the structural magnetic resonance imaging data of 48 adult-onset schizophrenia patients, 65 first-degree nonpsychotic relatives of schizophrenia patients, 27 community comparison (CC) probands, and 73 CC relatives were examined using tensor-based morphometry (TBM) to isolate global and localized differences in tissue volume across the entire brain between groups. We found brain tissue contractions most prominently in frontal and temporal regions and expansions in the putamen/pallidum, and lateral and third ventricles in schizophrenia patients when compared with unrelated CC probands. Results were similar, though less prominent when patients were compared with their nonpsychotic relatives. Structural deformations observed in unaffected patient relatives compared to age-similar CC relatives were suggestive of schizophrenia-related genetic liability and were pronounced in the putamen/pallidum and medial temporal regions. Schizophrenia and genetic liability effects for the putamen/pallidum were confirmed by regions-of-interest analysis. In conclusion, TBM findings complement reports of frontal, temporal, and ventricular dysmorphology in schizophrenia and further indicate that putamen/pallidum enlargements, originally linked mainly with medication exposure in early studies, also reflect a genetic predisposition for schizophrenia. Thus, brain deformation profiles revealed in this study may help to clarify the role of specific genetic or environmental risk factors toward altered brain morphology in schizophrenia.

Special biological issues in the management of women with schizophrenia

Schizophrenia is a debilitating and pervasive mental illness with devastating effects on psychological, cognitive and social wellbeing, and for which current treatment options are far from ideal. Gender differences and the influence of the female reproductive life cycle on the onset, course and symptoms of schizophrenia and the discovery of estrogen's remarkable psychoprotective properties in animal models led to the proposal of the 'estrogen protection hypothesis' of schizophrenia. This has fueled the recent successful investigation of estradiol as a potential adjuvant therapeutic agent in the management of schizophrenia in women. This review explains the scientific rationale behind the estrogen hypothesis and how it can be clinically utilized to address concerns unique to the care of women with schizophrenia.

Role of estrogen treatment in the management of schizophrenia

Increasing evidence from epidemiological, preclinical and clinical studies suggests that estrogens may exert psychoprotective effects in schizophrenia. Observations of gender differences in the onset and course of schizophrenia have prompted exploration of the effects of estrogen on the CNS. The aim of this paper is to provide an overview of different applications of adjunctive estrogen as a possible treatment for symptoms of schizophrenia in both men and women. Recent trials have suggested that estrogen augmentation therapy may be able to enhance the management of schizophrenia; however, the clinical application of estrogen as a treatment has been limited by potential side effects, the most worrying being breast and uterine cancer in women, and feminization in men. Selective estrogen receptor modulators (SERMs), however, may offer therapeutic benefits for both men and women with schizophrenia without posing threat to breast and uterine tissue and without feminizing effects. The use of estrogen opens up new possibilities for both men and women in the treatment of severe mental illnesses such as schizophrenia. With further preclinical and clinical research, it is hoped that this promising field of hormone modulation can continue to evolve and eventually be translated into real therapeutic potential.

Hormones and schizophrenia

PURPOSE OF REVIEW

It is a well established fact that many serious mental illnesses, in particular psychoses such as schizophrenia, may have a significant hormonal aetiological component. This study aims to discuss the oestrogen protection hypothesis of schizophrenia in particular, with an emphasis on findings from the recent literature in support of this theory.

RECENT FINDINGS

Epidemiological and life-cycle data point to significant differences in the incidence and course of schizophrenia between men and women, suggesting a protective role of oestrogen. In-vitro and in-vivo preclinical research has confirmed oestradiol's interactions with central neurotransmitter systems implicated in the pathogenesis of schizophrenia, whereas results from randomized controlled trials investigating the antipsychotic potential of oestrogen have been promising. Research into other neuroactive hormones with possible effects on mental state is a field still in its infancy but is evolving rapidly.

SUMMARY

Schizophrenia and related psychoses are pervasive and debilitating conditions, for which currently available treatments are often only partially effective and entail a high risk of serious side effects. Thus, new therapeutic strategies are needed, and the literature reviewed here suggests that hormones such as oestrogen could be a viable option. It is hoped that, with further research and larger trials, the oestrogen hypothesis can be translated into effective clinical practice.

A selective review of multimodal fusion methods in schizophrenia

Schizophrenia (SZ) is one of the most cryptic and costly mental disorders in terms of human suffering and societal expenditure (van Os and Kapur, 2009). Though strong evidence for functional, structural, and genetic abnormalities associated with this disease exists, there is yet no replicable finding which has proven accurate enough to be useful in clinical decision making (Fornito et al., 2009), and its diagnosis relies primarily upon symptom assessment (Williams et al., 2010a). It is likely in part that the lack of consistent neuroimaging findings is because most models favor only one data type or do not combine data from different imaging modalities effectively, thus missing potentially important differences which are only partially detected by each modality (Calhoun et al., 2006a). It is becoming increasingly clear that multimodal fusion, a technique which takes advantage of the fact that each modality provides a limited view of the brain/gene and may uncover hidden relationships, is an important tool to help unravel the black box of schizophrenia. In this review paper, we survey a number of multimodal fusion applications which enable us to study the schizophrenia macro-connectome, including brain functional, structural, and genetic aspects and may help us understand the disorder in a more comprehensive and integrated manner. We also provide a table that characterizes these applications by the methods used and compare these methods in detail, especially for multivariate models, which may serve as a valuable reference that helps readers select an appropriate method based on a given research question.

Neonatal exposure to phenobarbital potentiates schizophrenia-like behavioral outcomes in the rat

Previous work has indicated an association between seizures early in life and increased risk of psychiatric disorders, including schizophrenia. However, because early-life seizures are commonly treated with antiepileptic drugs (AEDs) such as phenobarbital, the possibility that drug treatment may affect later-life psychiatric outcomes needs to be evaluated. We therefore tested the hypothesis that phenobarbital exposure in the neonatal rat increases the risk of schizophrenia-like behavioral abnormalities in adulthood. Thus, in this study, we examined the effects of a single acute neonatal exposure to phenobarbital on adult behavioral outcomes in the rat neonatal ventral hippocampal (nVH) lesion model of schizophrenia. We compared these outcomes to those in rats a) without nVH lesions and b) with nVH lesions, without phenobarbital. The tasks used for behavioral evaluation were: amphetamine-induced locomotion, prepulse inhibition, elevated plus-maze, and novel object recognition task. We found that neonatal phenobarbital treatment (in the absence of nVH lesions) was sufficient to disrupt sensorimotor gating (as tested by prepulse inhibition) in adulthood to an extent equivalent to nVH lesions. Additionally, neonatal phenobarbital exposure enhanced the locomotor response to amphetamine in adult animals with and without nVH lesions. Our findings suggest that neonatal exposure to phenobarbital can predispose to schizophrenia-like behavioral abnormalities. Our findings underscore the importance of examining AED exposure early in life as a potential risk factor for later-life neuropsychiatric abnormalities in clinical populations.

Disrupted white matter connectivity is associated with reduced cortical thickness in the cingulate cortex in schizophrenia

INTRODUCTION

Both impaired white matter connectivity and alterations in gray matter morphometry have repeatedly been reported in schizophrenia. Neurodevelopmental models propose a close linkage between gray matter alterations and white matter deficits. However, there are no studies investigating alterations in cortical thickness in relation to white matter connectivity changes.

METHODS

This combined diffusion tensor imaging (DTI) - surface based morphometry study examined a potential linkage between disruption in white matter connectivity and alterations in cortical thickness. Cortical thickness was analyzed using the FreeSurfer software package (version 4.0.5, http://surfer.nmr.harvard.edu) in a sample of 19 patients with schizophrenia and 20 healthy controls.

RESULTS

Whole brain node-by-node correlational analysis revealed a highly significant association ( r= -.8, p < .0001) between disturbed white matter connectivity in the superior temporal cortex and diminished cortical thickness in the posterior part of the cingulate cortex (Brodmann area 23/31).

CONCLUSIONS

This result indicates a significant linkage between disturbed white matter connectivity and reduced cortical thickness in a relevant node of the default mode network that is held to be of high pathophysiological relevance in schizophrenia. The result moreover provides support for the assumption of a neurodevelopmental pathogenesis of the disorder.

The role of oestrogen and other hormones in the pathophysiology and treatment of schizophrenia

The theory that many serious mental illnesses, in particular psychoses such as schizophrenia, may have a significant hormonal aetiological component is fast gaining popularity and the support of scientific evidence. Oestrogen in particular has been substantially investigated as a potential mediator of brain function in schizophrenia. Epidemiological and life-cycle data point to significant differences in the incidence and course of schizophrenia between men and women suggests a protective role of oestrogen. In vitro and in vivo preclinical research confirms oestradiol's interactions with central neurotransmitter systems implicated in the pathogenesis of schizophrenia, while results from randomised controlled trials investigating the antipsychotic potential of oestrogen have been positive. Research into other neuroactive hormones with possible effects on mental state is a rapidly evolving field that may hold new promise. Given that schizophrenia and related psychoses are pervasive and debilitating conditions for which currently available treatments are often only partially effective and entail a high risk of serious side-effects, novel therapeutic strategies are needed. The literature reviewed in this paper suggests that hormones such as oestrogen could be a viable option, and it is hoped that with further research and larger trials, the oestrogen hypothesis can be translated into effective clinical practice.

Brain cortical thickness and surface area correlates of neurocognitive performance in patients with schizophrenia, bipolar disorder, and healthy adults

Relationships between cortical brain structure and neurocognitive functioning have been reported in schizophrenia, but findings are inconclusive, and only a few studies in bipolar disorder have addressed this issue. This is the first study to directly compare relationships between cortical thickness and surface area with neurocognitive functioning in patients with schizophrenia (n = 117) and bipolar disorder (n = 121) and healthy controls (n = 192). MRI scans were obtained, and regional cortical thickness and surface area measurements were analyzed for relationships with test scores from 6 neurocognitive domains. In the combined sample, cortical thickness in the right rostral anterior cingulate was inversely related to working memory, and cortical surface area in four frontal and temporal regions were positively related to neurocognitive functioning. A positive relationship between left transverse temporal thickness and processing speed was specific to schizophrenia. A negative relationship between right temporal pole thickness and working memory was specific to bipolar disorder. In conclusion, significant cortical structure/function relationships were found in a large sample of healthy controls and patients with schizophrenia or bipolar disorder. The differences that were found between schizophrenia and bipolar may indicate differential relationship patterns in the two disorders, which may be of relevance for understanding the underlying pathophysiology.

Mapping corticocortical structural integrity in schizophrenia and effects of genetic liability

BACKGROUND

Structural and diffusion tensor imaging studies implicate gray and white matter (WM) abnormalities and disruptions of neural circuitry in schizophrenia. However, the structural integrity of the superficial WM, comprising short-range association (U-fibers) and intracortical axons, has not been investigated in schizophrenia.

METHODS

High-resolution structural and diffusion tensor images and sophisticated cortical pattern matching methods were used to measure and compare global and local variations in superficial WM fractional anisotropy between schizophrenia patients and their relatives and community comparison subjects and their relatives (n = 150).

RESULTS

Compared with control subjects, patients showed reduced superficial WM fractional anisotropy distributed across each hemisphere, particularly in left temporal and bilateral occipital regions (all p < .05, corrected). Furthermore, by modeling biological risk for schizophrenia in patients, patient relatives, and control subjects, fractional anisotropy was shown to vary in accordance with relatedness to a patient in both hemispheres and in the temporal and occipital lobes (p < .05, corrected). However, effects did not survive correction procedures for two-group comparisons between patient relatives and control subjects.

CONCLUSIONS

Results extend previous findings restricted to deep WM pathways to demonstrate that disturbances in corticocortical connectivity are associated with schizophrenia and might indicate a genetic predisposition for the disorder. Because the structural integrity of WM plays a crucial role in the functionality of networks linking gray matter regions, disturbances in the coherence and organization of fibers at the juncture of the neuropil might relate to features of schizophrenia at least partially attributable to disease-related genetic factors.

Pharmacogenetics of lithium response in bipolar disorder

Bipolar disorder (BD) is a serious mental illness with well-established, but poorly characterized genetic risk. Lithium is among the best proven mood stabilizer therapies for BD, but treatment responses vary considerably. Based upon these and other findings, it has been suggested that lithium-responsive BD may be a genetically distinct phenotype within the mood disorder spectrum. This assertion has practical implications both for the treatment of BD and for understanding the neurobiological basis of the illness: genetic variation within lithium-sensitive signaling pathways may confer preferential treatment response, and the involved genes may underlie BD in some individuals. Presently, the mechanism of lithium is reviewed with an emphasis on gene-expression changes in response to lithium. Within this context, findings from genetic-association studies designed to identify lithium response genes in BD patients are evaluated. Finally, a framework is proposed by which future pharmacogenetic studies can incorporate advances in genetics, molecular biology and bioinformatics in a pathway-based approach to predicting lithium treatment response.

A non-invasive method to isolate the neuronal linage from the nasal epithelium from schizophrenic and bipolar diseases

Brain imaging and histopathological studies suggest that neurodevelopmental anomalies play a key role in the etiology of schizophrenia (SZ) and bipolar disorder (BD). New neuron formation and maturation occur in human olfactory epithelium throughout life. Therefore, the olfactory epithelium has been proposed as a model to study alterations in neurodevelopment, particularly in some psychiatric diseases. However, former studies were done with olfactory epithelium biopsies taken post mortem or under anesthesia from patients with SZ and BD. In this work we have developed a new method to obtain viable neural precursors by exfoliation of the anterior region of the medial lateral turbinate of the nasal cavity from healthy controls, and ambulatory patients. Cells were propagated to establish neural precursor banks. Thawed cells showed cytoskeletal phenotypes typical of developing neurons. They also conserved the ability to differentiate in presence of 2mM dibutyril-cyclic adenosine monophosphate, and maintained voltage-operated Ca(2+) currents in culture. Moreover, proportions of neuronal maturation stages were maintained in cultured exfoliates obtained from SZ and BD patients. Data support that neural precursors obtained from a nasal exfoliate are an excellent experimental model to later approach studies on biomarkers, neural development and cellular alterations in the pathophysiology of SZ and BD.

Possible role of glia in cognitive impairment in schizophrenia

Cognitive impairment is a core disorder of the schizophrenia syndrome. Based on glial-neuronal interactions, a pathophysiological model is proposed that could be explanatory for cognitive impairment in schizophrenia. The model consists of three main hypotheses concerning the pathophysiology in tripartite synapses, oligodendrocyte-axonic interactions, and in the glial networks (astrocytic syncytium). In tripartite synapses nonfunctional astrocytic receptors may cause an unconstrained synaptic information flux, since they cannot be occupied by neurotransmitters (NTs). Therefore, a generalization of information processing may occur in the brain causing hallucinations, delusions, and thought disorder. If the oligodendrocyte-axonic system decomposes, the brain is unable to process information in qualitative domains or categories. This may lead to severe incoherence phenomena such as thought disorder. Supposing that in the astrocytic syncytium gap junctions (g.js) normally form plaques functioning as memory devices, loss of function of g.j. may also cause cognitive impairment, since the syncytium decomposes and g.j. plaques cannot be generated. These hypotheses are experimentally testable. Finally, the problem of treatment of patients with schizophrenia is discussed, in case the presented model of schizophrenia might be verified.

Discriminating schizophrenia and bipolar disorder by fusing fMRI and DTI in a multimodal CCA+ joint ICA model

Diverse structural and functional brain alterations have been identified in both schizophrenia and bipolar disorder, but with variable replicability, significant overlap and often in limited number of subjects. In this paper, we aimed to clarify differences between bipolar disorder and schizophrenia by combining fMRI (collected during an auditory oddball task) and diffusion tensor imaging (DTI) data. We proposed a fusion method, "multimodal CCA+ joint ICA", which increases flexibility in statistical assumptions beyond existing approaches and can achieve higher estimation accuracy. The data collected from 164 participants (62 healthy controls, 54 schizophrenia and 48 bipolar) were extracted into "features" (contrast maps for fMRI and fractional anisotropy (FA) for DTI) and analyzed in multiple facets to investigate the group differences for each pair-wised groups and each modality. Specifically, both patient groups shared significant dysfunction in dorsolateral prefrontal cortex and thalamus, as well as reduced white matter (WM) integrity in anterior thalamic radiation and uncinate fasciculus. Schizophrenia and bipolar subjects were separated by functional differences in medial frontal and visual cortex, as well as WM tracts associated with occipital and frontal lobes. Both patients and controls showed similar spatial distributions in motor and parietal regions, but exhibited significant variations in temporal lobe. Furthermore, there were different group trends for age effects on loading parameters in motor cortex and multiple WM regions, suggesting that brain dysfunction and WM disruptions occurred in identified regions for both disorders. Most importantly, we can visualize an underlying function-structure network by evaluating the joint components with strong links between DTI and fMRI. Our findings suggest that although the two patient groups showed several distinct brain patterns from each other and healthy controls, they also shared common abnormalities in prefrontal thalamic WM integrity and in frontal brain mechanisms.

Frontonasal dysmorphology in bipolar disorder by 3D laser surface imaging and geometric morphometrics: comparisons with schizophrenia

Any developmental relationship between bipolar disorder and schizophrenia engenders continuing debate. As the brain and face emerge in embryological intimacy, brain dysmorphogenesis is accompanied by facial dysmorphogenesis. 3D laser surface imaging was used to capture the facial surface of 13 male and 14 female patients with bipolar disorder in comparison with 61 male and 75 female control subjects and with 37 male and 32 female patients with schizophrenia. Surface images were analysed using geometric morphometrics and 3D visualisations to identify domains of facial shape that distinguish bipolar patients from controls and bipolar patients from those with schizophrenia. Both male and female bipolar patients evidenced significant facial dysmorphology: common to male and female patients was overall facial widening, increased width of nose, narrowing of mouth and upward displacement of the chin; dysmorphology differed between male and female patients for nose length, lip thickness and tragion height. There were few morphological differences in comparison with schizophrenia patients. That dysmorphology of the frontonasal prominences and related facial regions in bipolar disorder is more similar to than different from that found in schizophrenia indicates some common dysmorphogenesis. Bipolar disorder and schizophrenia might reflect similar insult(s) acting over slightly differing time-frames or slightly differing insult(s) acting over a similar time-frame.

Cortical thickness and subcortical volumes in schizophrenia and bipolar disorder

BACKGROUND

Schizophrenia and bipolar disorder are severe psychiatric diseases with overlapping symptomatology. Widespread brain morphologic abnormalities, including cortical thinning and subcortical volume reductions, have been demonstrated in schizophrenia but it is unclear whether similar abnormalities are present in bipolar disorder. The purpose of this study was to compare cortical thickness and subcortical volumes in schizophrenia and bipolar disorder, to assess differences and similarities in cortical and subcortical brain structure.

METHODS

We analyzed magnetic resonance images from a sample of 173 patients with schizophrenia spectrum disorder, 139 patients with bipolar disorder, and 207 healthy control subjects. Cortical thickness was compared between the groups in multiple locations across the continuous cortical surface. Subcortical volumes were compared on a structure-by-structure basis.

RESULTS

There was widespread cortical thinning in schizophrenia compared with control subjects, in frontal, temporal, occipital, and smaller parietal regions. There was no cortical thinning in bipolar disorder compared with control subjects or in schizophrenia compared with bipolar disorder. However, the subgroup of patients with bipolar disorder Type 1 showed cortical thinning, primarily in the frontal lobes and superior temporal and temporoparietal regions. Both patient groups showed substantial subcortical volume reductions bilaterally in the hippocampus, the left thalamus, the right nucleus accumbens, the left cerebellar cortex, and the brainstem, along with substantial ventricular enlargements.

CONCLUSIONS

We found substantial overlap in the underlying brain morphologic abnormalities in schizophrenia and bipolar disorder in subcortical structures, and between schizophrenia and bipolar disorder Type 1 in the cerebral cortex.

Gray matter reduction of the superior temporal gyrus in patients with established bipolar I disorder

BACKGROUND

Functional abnormalities of the superior temporal gyrus (STG) have been implicated in the pathophysiology of bipolar disorder, but magnetic resonance imaging (MRI) studies of this region have yielded inconsistent findings.

METHOD

We used MRI to examine the volumes of the STG and its gray matter subregions [planum polare (PP), Heschl gyrus (HG), planum temporale (PT), and lateral STG (rostral and caudal regions)] in 26 patients with established bipolar I disorder (8 males and 18 females, mean age=38.4 years) and 24 age and gender-matched healthy controls (7 males and 17 females, mean age=38.7 years).

RESULTS

Bipolar patients had significantly smaller volumes of the PT and caudal STG compared with controls in the left hemisphere. The STG white matter volume did not differ between the groups. There was no association between the STG volume and number of manic/depressive episodes, family history, or clinical subtype (i.e., psychotic and nonpsychotic), but daily dosage of lithium treatment at the time of scanning was positively correlated with right PP and right rostral STG volumes.

LIMITATIONS

Entire clinical data (e.g., lifetime medication, symptomatology) were not available.

CONCLUSIONS

These findings implicate a role for the STG gray matter, especially its left posterior regions, in the neurobiology of bipolar disorder. Our findings may also support the notion of lithium-induced gray matter expansion.

Midline brain abnormalities in established bipolar affective disorder

BACKGROUND

Morphologic changes of cortico-limbic regions have been reported in bipolar disorder, but it remains unclear whether midline brain abnormalities relevant to cortico-limbic connectivity are also present.

METHODS

We used magnetic resonance imaging to investigate the size of the adhesio interthalamica (AI) and cavum septi pellucidi (CSP), as well as third ventricular volume, in 26 patients with bipolar I disorder and 24 matched controls.

RESULTS

CSP length and prevalence of a large CSP did not differ between the groups, but bipolar patients had significantly shorter AI and larger third ventricles compared to controls.

LIMITATIONS

A comprehensive investigation of medication effects was not possible due to incomplete medication data.

CONCLUSIONS

These findings implicate a role for the AI and connected brain regions in the neurobiology of bipolar disorder.