Reduced left angular gyrus volume in first-episode schizophrenia

Sex-related cortical asymmetry in antipsychotic-naïve first-episode schizophrenia

Schizophrenia has been considered to exhibit sex-related clinical differences that might be associated with distinctly abnormal brain asymmetries between sexes. One hundred and thirty-two antipsychotic-naïve first-episode patients with schizophrenia and 150 healthy participants were recruited in this study to investigate whether cortical asymmetry would exhibit sex-related abnormalities in schizophrenia. After a 1-yr follow-up, patients were rescanned to obtain the effect of antipsychotic treatment on cortical asymmetry. Male patients were found to show increased lateralization index while female patients were found to exhibit decreased lateralization index in widespread regions when compared with healthy participants of the corresponding sex. Specifically, the cortical asymmetry of male and female patients showed contrary trends in the cingulate, orbitofrontal, parietal, temporal, occipital, and insular cortices. This result suggested male patients showed a leftward shift of asymmetry while female patients showed a rightward shift of asymmetry in these above regions that related to language, vision, emotion, and cognition. Notably, abnormal lateralization indices remained stable after antipsychotic treatment. The contrary trends in asymmetry between female and male patients with schizophrenia together with the persistent abnormalities after antipsychotic treatment suggested the altered brain asymmetries in schizophrenia might be sex-related disturbances, intrinsic, and resistant to the effect of antipsychotic therapy.

White and Gray Matter Abnormalities in Young Adult Females with Dependent Personality Disorder: A Diffusion-Tensor Imaging and Voxel-Based Morphometry Study

We applied diffusion-tensor imaging (DTI) including measurements of fractional anisotropy (FA), a parameter of neuronal fiber integrity, mean diffusivity (MD), a parameter of brain tissue integrity, as well as voxel-based morphometry (VBM), a measure of gray and white matter volume, to provide a basis to improve our understanding of the neurobiological basis of dependent personality disorder (DPD). DTI was performed on young girls with DPD (N = 17) and young female healthy controls (N = 17). Tract-based spatial statistics (TBSS) were used to examine microstructural characteristics. Gray matter volume differences between the two groups were investigated using voxel-based morphometry (VBM). The Pearson correlation analysis was utilized to examine the relationship between distinct brain areas of white matter and gray matter and the Dy score on the MMPI. The DPD had significantly higher fractional anisotropy (FA) values than the HC group in the right retrolenticular part of the internal capsule, right external capsule, the corpus callosum, right posterior thalamic radiation (include optic radiation), right cerebral peduncle (p < 0.05), which was strongly positively correlated with the Dy score of MMPI. The volume of gray matter in the right postcentral gyrus and left cuneus in DPD was significantly increased (p < 0.05), which was strongly positively correlated with the Dy score of MMPI (r1,2= 0.467,0.353; p1,2 = 0.005,0.04). Our results provide new insights into the changes in the brain structure in DPD, which suggests that alterations in the brain structure might implicate the pathophysiology of DPD. Possible visual and somatosensory association with motor nerve circuits in DPD.

Analysis of functional connectivity using machine learning and deep learning in different data modalities from individuals with schizophrenia

Objective. Schizophrenia(SCZ) is a severe mental disorder associated with persistent or recurrent psychosis, hallucinations, delusions, and thought disorders that affect approximately 26 million people worldwide, according to the World Health Organization. Several studies encompass machine learning (ML) and deep learning algorithms to automate the diagnosis of this mental disorder. Others study SCZ brain networks to get new insights into the dynamics of information processing in individuals suffering from the condition. In this paper, we offer a rigorous approach with ML and deep learning techniques for evaluating connectivity matrices and measures of complex networks to establish an automated diagnosis and comprehend the topology and dynamics of brain networks in SCZ individuals.Approach.For this purpose, we employed an functional magnetic resonance imaging (fMRI) and electroencephalogram (EEG) dataset. In addition, we combined EEG measures, i.e. Hjorth mobility and complexity, with complex network measurements to be analyzed in our model for the first time in the literature.Main results.When comparing the SCZ group to the control group, we found a high positive correlation between the left superior parietal lobe and the left motor cortex and a positive correlation between the left dorsal posterior cingulate cortex and the left primary motor. Regarding complex network measures, the diameter, which corresponds to the longest shortest path length in a network, may be regarded as a biomarker because it is the most crucial measure in different data modalities. Furthermore, the SCZ brain networks exhibit less segregation and a lower distribution of information. As a result, EEG measures outperformed complex networks in capturing the brain alterations associated with SCZ.Significance. Our model achieved an area under receiver operating characteristic curve (AUC) of 100% and an accuracy of 98.5% for the fMRI, an AUC of 95%, and an accuracy of 95.4% for the EEG data set. These are excellent classification results. Furthermore, we investigated the impact of specific brain connections and network measures on these results, which helped us better describe changes in the diseased brain.

Neuronal signatures of anger and fear in patients with psychosis

The present study investigated the functional neuroanatomy in response to sentence stimuli related to anger-provoking situations and fear of negative evaluation in patients with psychosis. The tasks consisted of four active conditions, Self-Anger (SA), Self-Fear, Other-Anger (OA), and Other-Fear (OF), and two neutral conditions, Neutral-Anger (NA) and Neutral-Fear (NF). Several relevant clinical measures were obtained. Under all contrasts, significantly higher activation in the left inferior parietal gyrus or superior parietal gyrus and the left middle occipital gyrus or superior occipital gyrus was observed in patients compared to healthy controls (HCs). However, we observed significantly lower activation in the left angular gyrus (AG) and left middle temporal gyrus (MTG) under the OA vs. NA contrast, as well as in the left precuneus and left posterior cingulate gyrus (PCG) under the OF vs. NF contrast in patients. The mean beta values for the significant regions under the SA vs. NA and OF vs. NF contrasts were significantly associated with the total PI and PANSS scores, respectively. These findings indicate that patients with psychosis exhibit hypoactivation in the AG, MTG, precuneus, and PCG compared to HCs. The findings suggest that patients with psychosis are less efficient at recruiting neural responses in those regions for semantic processing and social evaluation.

The Static and dynamic functional connectivity characteristics of the left temporoparietal junction region in schizophrenia patients with auditory verbal hallucinations during low-frequency rTMS treatment

BACKGROUND

Auditory verbal hallucinations (AVH) are a core symptom of schizophrenia. Low-frequency (e.g., 1 Hz) repetitive transcranial magnetic stimulation (rTMS) targeting language processing regions (e.g., left TPJ) has been evident as a potential treatment for AVH. However, the underlying neural mechanisms of the rTMS treatment effect remain unclear. The present study aimed to investigate the effects of 1 Hz rTMS on functional connectivity (FC) of the temporoparietal junction area (TPJ) seed with the whole brain in schizophrenia patients with AVH.

METHODS

Using a single-blind placebo-controlled randomized clinical trial, 55 patients with AVH were randomly divided into active treatment group (n = 30) or placebo group (n = 25). The active treatment group receive 15-day 1 Hz rTMS stimulation to the left TPJ, whereas the placebo group received sham rTMS stimulation to the same site. Resting-state fMRI scans and clinical measures were acquired for all patients before and after treatment. The seed-based (left TPJ) static and DFC was used to assess the connectivity characteristics during rTMS treatment in patients with AVH.

RESULTS

Overall, symptom improvement following 1 Hz rTMS treatment was found in the active treatment group, whereas no change occurred in the placebo group. Moreover, decreased static FC (SFC) of the left TPJ with the right temporal lobes, as well as increased SFC with the prefrontal cortex and subcortical structure were observed in active rTMS group. Increased dynamic FC (DFC) of the left TPJ with frontoparietal areas was also found in the active rTMS group. However, seed-based SFC and DFC were reduced to a great extent in the placebo group. In addition, these changed FC (SFC) strengths in the active rTMS group were associated with reduced severity of clinical outcomes (e.g., positive symptoms).

CONCLUSION

The application of 1 Hz rTMS over the left TPJ may affect connectivity characteristics of the targeted region and contribute to clinical improvement, which shed light on the therapeutic effect of rTMS on schizophrenia with AVH.

Spatial and chronic differences in neural activity in medicated and unmedicated schizophrenia patients

•

The medicated schizophrenia group yielded concordant activity among three right lateralized frontal clusters and a left lateralized parietal cluster.

•

The unmedicated schizophrenia group yielded concordant activity among right lateralized frontal-parietal regions.

•

A neural compensatory mechanism in schizophrenia.

A major caveat with investigations on schizophrenic patients is the difficulty to control for medication usage across samples as disease-related neural differences may be confounded by medication usage. Following a thorough literature search (632 records identified), we included 37 studies with a total of 740 medicated schizophrenia patients and 367 unmedicated schizophrenia patients. Here, we perform several meta-analyses to assess the neurofunctional differences between medicated and unmedicated schizophrenic patients across fMRI studies to determine systematic regions associated with medication usage. Several clusters identified by the meta-analysis on the medicated group include three right lateralized frontal clusters and a left lateralized parietal cluster, whereas the unmedicated group yielded concordant activity among right lateralized frontal-parietal regions. We further explored the prevalence of activity within these regions across illness duration and task type. These findings suggest a neural compensatory mechanism across these regions both spatially and chronically, offering new insight into the spatial and temporal dynamic neural differences among medicated and unmedicated schizophrenia patients.

Comparison of resting-state spontaneous brain activity between treatment-naive schizophrenia and obsessive-compulsive disorder

BACKGROUND

Schizophrenia (SZ) and obsessive-compulsive disorder (OCD) share many demographic characteristics and severity of clinical symptoms, genetic risk factors, pathophysiological underpinnings, and brain structure and function. However, the differences in the spontaneous brain activity patterns between the two diseases remain unclear. Here this study aimed to compare the features of intrinsic brain activity in treatment-naive participants with SZ and OCD and to explore the relationship between spontaneous brain activity and the severity of symptoms.

METHODS

In this study, 22 treatment-naive participants with SZ, 27 treatment-naive participants with OCD, and sixty healthy controls (HC) underwent a resting-state functional magnetic resonance imaging (fMRI) scan. The amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo) and degree of centrality (DC) were performed to examine the intrinsic brain activity of participants. Additionally, the relationships among spontaneous brain activity, the severity of symptoms, and the duration of illness were explored in SZ and OCD groups.

RESULTS

Compared with SZ group and HC group, participants with OCD had significantly higher ALFF in the right angular gyrus and the left middle frontal gyrus/precentral gyrus and significantly lower ALFF in the left superior temporal gyrus/insula/rolandic operculum and the left postcentral gyrus, while there was no significant difference in ALFF between SZ group and HC group. Compared with HC group, lower ALFF in the right supramarginal gyrus/inferior parietal lobule and lower DC in the right lingual gyrus/calcarine fissure and surrounding cortex of the two patient groups, higher ReHo in OCD group and lower ReHo in SZ group in the right angular gyrus/middle occipital gyrus brain region were documented in the present study. DC in SZ group was significantly higher than that in HC group in the right inferior parietal lobule/angular gyrus, while there were no significant DC differences between OCD group and HC group. In addition, ALFF in the left postcentral gyrus were positively correlated with positive subscale score (r = 0.588, P = 0.013) and general psychopathology subscale score (r = 0.488, P = 0.047) respectively on the Positive and Negative Syndrome Scale (PANSS) in SZ group. ALFF in the left superior temporal gyrus/insula/rolandic operculum of participants with OCD were positively correlated with compulsion subscale score (r = 0.463, P = 0.030) on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). The longer the illness duration in SZ group, the smaller the ALFF of the left superior temporal gyrus/insula/rolandic operculum (Rho = 0.-492, P = 0.020). The longer the illness duration in OCD group, the higher the ALFF of the right supramarginal gyrus/inferior parietal lobule (Rho = 0.392, P = 0.043) and the left postcentral gyrus (Rho = 0.385, P = 0.048), and the lower the DC of the right inferior parietal lobule/angular gyrus (Rho = - 0.518, P = 0.006).

CONCLUSION

SZ and OCD show some similarities in spontaneous brain activity in parietal and occipital lobes, but exhibit different patterns of spontaneous brain activity in frontal, temporal, parietal, occipital, and insula brain regions, which might imply different underlying neurobiological mechanisms in the two diseases. Compared with OCD, SZ implicates more significant abnormalities in the functional connections among brain regions.

Altered functional connectivity of the dentate nuclei in patients with schizophrenia

Dentate nuclei (DN) are vital structures in the anatomical circuits that link the cerebellum to the cerebrum. However, the characteristics of DN functional connectivity (FC) in schizophrenia remain largely unknown. In this study, we investigated the FC of the DN in patients with schizophrenia and examined their possible clinical correlates using resting-state functional magnetic imaging data. We found that the patient group had greater DN FC with the parietal lobe (e.g., postcentral gyrus and superior parietal lobule) and less DN FC with the prefrontal cortex (e.g., superior frontal gyrus), posterior cingulate cortex, and regional cerebellum (e.g., vermis 4-5 and crus I) than did the control group. Furthermore, some abnormal connectivities of the DN with these regions significantly correlated with psychiatric symptoms. These results suggest that the DN circuits are disturbed and may participate in the pathophysiology of schizophrenia.

Distinct Neuroanatomical Correlates of Neuropsychiatric Symptoms in the Three Main Forms of Genetic Frontotemporal Dementia in the GENFI Cohort

Background:

The overlap between frontotemporal dementia (FTD) and primary psychiatric disorders has been brought to light by reports of prominent neuropsychiatric symptoms (NPS) in FTD-related genetic mutations, particularly among C9orf72 and GRN carriers. It has been recently demonstrated that early neuroanatomical changes in genetic FTD may be different across the major disease-causing mutations.

Objective:

We aimed to identify whether NPS could be driven by distinct structural correlates.

Methods:

One hundred and sixty-seven mutation carriers (75 GRN, 60 C9orf72, and 32 MAPT) were included from the Genetic FTD Initiative (GENFI) study, a large international cohort of genetic FTD. Neuropsychiatric symptoms including delusions, hallucinations (visual, auditory, and tactile), depression, and anxiety were investigated using a structured interview. Voxel-based morphometry was performed to identify neuroanatomical correlates of NPS.

Results:

Psychotic symptoms correlated mainly with grey matter (GM) atrophy in the anterior insula, left thalamus, cerebellum, and cortical regions including frontal, parietal, and occipital lobes in GRN mutations carriers. GM atrophy in posterior structures of the default-mode network was associated with anxiety in the GRN group. Delusions in C9orf72 expansion carriers were mainly associated with left frontal cortical atrophy. Cerebellar atrophy was found to be correlated only with anxiety in C9orf72 carriers. NPS in the MAPT group were mainly associated with volume loss in the temporal lobe.

Conclusion:

Neuroanatomical correlates of NPS appear to be distinct across the main forms of genetic FTD. Overall, our findings support overlapping brain structural changes between FTD and primary psychiatric disorders.

Alteration of Semantic Networks during Swear Words Processing in Schizophrenia

Objective

Positive symptoms, such as delusion and hallucination, commonly include negative emotional content in schizophrenia. We investigated the neural basis implicated during the processing of strong negative emotional words in patients with schizophrenia.

Methods

In our study, 35 patients with schizophrenia and 19 healthy controls were recruited, and the participants were asked to passively view the words that contained swearing and neutral content during functional magnetic resonance imaging.

Results

Patients with schizophrenia, compared to healthy controls, showed hypoactivation to the swear and neutral words stimuli in the left inferior frontal gyrus, left middle frontal gyrus, and left angular/supramarginal gyrus. More specifically, patients with remitted schizophrenia were found to have greater activation to the stimuli in the left middle/inferior frontal gyrus than patients with active schizophrenia. Furthermore, in the analysis of regions of interests, the left inferior and middle frontal gyrus activity was related to the severity of positive symptoms, including delusion and suspiciousness.

Conclusion

Our results suggest that patients with schizophrenia have difficulty in semantic processing and inhibitory control of swear words, and these abnormalities may be connected with the severity of positive symptoms.

Variation in fourteen brain structure volumes in schizophrenia: A comprehensive meta-analysis of 246 studies

Despite hundreds of structural MRI studies documenting smaller brain volumes on average in schizophrenia compared to controls, little attention has been paid to group differences in the variability of brain volumes. Examination of variability may help interpret mean group differences in brain volumes and aid in better understanding the heterogeneity of schizophrenia. Variability in 246 MRI studies was meta-analyzed for 13 structures that have shown medium to large mean effect sizes (Cohen's d≥0.4): intracranial volume, total brain volume, lateral ventricles, third ventricle, total gray matter, frontal gray matter, prefrontal gray matter, temporal gray matter, superior temporal gyrus gray matter, planum temporale, hippocampus, fusiform gyrus, insula; and a control structure, caudate nucleus. No significant differences in variability in cortical/subcortical volumes were detected in schizophrenia relative to controls. In contrast, increased variability was found in schizophrenia compared to controls for intracranial and especially lateral and third ventricle volumes. These findings highlight the need for more attention to ventricles and detailed analyses of brain volume distributions to better elucidate the pathophysiology of schizophrenia.

Diverse definitions of the early course of schizophrenia-a targeted literature review

Schizophrenia is a debilitating psychiatric disorder and patients experience significant comorbidity, especially cognitive and psychosocial deficits, already at the onset of disease. Previous research suggests that treatment during the earlier stages of disease reduces disease burden, and that a longer time of untreated psychosis has a negative impact on treatment outcomes. A targeted literature review was conducted to gain insight into the definitions currently used to describe patients with a recent diagnosis of schizophrenia in the early course of disease ('early' schizophrenia). A total of 483 relevant English-language publications of clinical guidelines and studies were identified for inclusion after searches of MEDLINE, MEDLINE In-Process, relevant clinical trial databases and Google for records published between January 2005 and October 2015. The extracted data revealed a wide variety of terminology and definitions used to describe patients with 'early' or 'recent-onset' schizophrenia, with no apparent consensus. The most commonly used criteria to define patients with early schizophrenia included experience of their first episode of schizophrenia or disease duration of less than 1, 2 or 5 years. These varied definitions likely result in substantial disparities of patient populations between studies and variable population heterogeneity. Better agreement on the definition of early schizophrenia could aid interpretation and comparison of studies in this patient population and consensus on definitions should allow for better identification and management of schizophrenia patients in the early course of their disease.

Classification of multi-site MR images in the presence of heterogeneity using multi-task learning

With the advent of Big Data Imaging Analytics applied to neuroimaging, datasets from multiple sites need to be pooled into larger samples. However, heterogeneity across different scanners, protocols and populations, renders the task of finding underlying disease signatures challenging. The current work investigates the value of multi-task learning in finding disease signatures that generalize across studies and populations. Herein, we present a multi-task learning type of formulation, in which different tasks are from different studies and populations being pooled together. We test this approach in an MRI study of the neuroanatomy of schizophrenia (SCZ) by pooling data from 3 different sites and populations: Philadelphia, Sao Paulo and Tianjin (50 controls and 50 patients from each site), which posed integration challenges due to variability in disease chronicity, treatment exposure, and data collection. Some existing methods are also tested for comparison purposes. Experiments show that classification accuracy of multi-site data outperformed that of single-site data and pooled data using multi-task feature learning, and also outperformed other comparison methods. Several anatomical regions were identified to be common discriminant features across sites. These included prefrontal, superior temporal, insular, anterior cingulate cortex, temporo-limbic and striatal regions consistently implicated in the pathophysiology of schizophrenia, as well as the cerebellum, precuneus, and fusiform, middle temporal, inferior parietal, postcentral, angular, lingual and middle occipital gyri. These results indicate that the proposed multi-task learning method is robust in finding consistent and reliable structural brain abnormalities associated with SCZ across different sites, in the presence of multiple sources of heterogeneity.

Heredity characteristics of schizophrenia shown by dynamic functional connectivity analysis of resting-state functional MRI scans of unaffected siblings

Previous static resting-state functional connectivity (FC) MRI (rs-fcMRI) studies have suggested certain heredity characteristics of schizophrenia. Recently, dynamic rs-fcMRI analysis, which can better characterize the time-varying nature of intrinsic activity and connectivity and may therefore unveil the special connectivity patterns that are always lost in static FC analysis, has shown a potential neuroendophenotype of schizophrenia. In this study, we have extended previous static rs-fcMRI studies to a dynamic study by exploring whether healthy siblings share aberrant dynamic FC patterns with schizophrenic patients, which may imply a potential risk for siblings to develop schizophrenia. We utilized the dynamic rs-fcMRI method using a sliding window approach to evaluate FC discrepancies within transient states across schizophrenic patients, unaffected siblings, and matched healthy controls. Statistical analysis showed five trait-related connections that are related to cingulo-opercular, occipital, and default mode networks, reflecting the shared connectivity alterations between schizophrenic patients and their unaffected siblings. The findings suggested that schizophrenic patients and their unaffected siblings shared common transient functional disconnectivity, implying a potential risk for the healthy siblings of developing schizophrenia.

Phase-Amplitude Coupling of the Electroencephalogram in the Auditory Cortex in Schizophrenia

BACKGROUND

Cross-frequency interactions may coordinate neural circuits operating at different frequencies. While neural oscillations associated with particular circuits in schizophrenia (SZ) are impaired, few studies have examined cross-frequency interactions. Here we examined phase-amplitude coupling (PAC) in the electroencephalograms of individuals with SZ and healthy control subjects (HCs). We computed PAC during the baseline period of 40-Hz auditory steady-state stimulation and rest. We hypothesized that subjects with SZ would show abnormal theta/gamma coupling during stimulation, especially in the left auditory cortex, and coupling with high frequencies would be higher during stimulation than during rest.

METHODS

We reanalyzed data from 18 subjects with SZ and 18 HCs. Auditory cortex electroencephalogram activity was estimated using dipole source localization. PAC was computed using the debiased PAC measure, calculated with the generalized Morse wavelet transform. PAC clusters were identified using cluster-corrected permutation testing and interrogated in analyses of variance with correction for multiple tests.

RESULTS

Overall, coupling of high beta and gamma amplitude was higher during the auditory steady-state response, while alpha/beta PAC was higher during rest. Theta/alpha PAC was higher in subjects with SZ than in HCs. Theta/gamma PAC was lateralized to the left hemisphere in HCs but was not lateralized in subjects with SZ.

CONCLUSIONS

PAC involving high frequencies was state dependent and not abnormal in SZ. Increased theta/alpha PAC in subjects with SZ was consistent with other evidence of increased low-frequency activity. Hemispheric lateralization of theta/gamma PAC was reduced in subjects with SZ, consistent with evidence for left hemisphere auditory cortex abnormalities in subjects with SZ. PAC may reveal new insights into neural circuitry abnormalities in SZ and other neuropsychiatric disorders.

Gyri of the human parietal lobe: Volumes, spatial extents, automatic labelling, and probabilistic atlases

Accurately describing the anatomy of individual brains enables interlaboratory communication of functional and developmental studies and is crucial for possible surgical interventions. The human parietal lobe participates in multimodal sensory integration including language processing and also contains the primary somatosensory area. We describe detailed protocols to subdivide the parietal lobe, analyze morphological and volumetric characteristics, and create probabilistic atlases in MNI152 stereotaxic space. The parietal lobe was manually delineated on 3D T1 MR images of 30 healthy subjects and divided into four regions: supramarginal gyrus (SMG), angular gyrus (AG), superior parietal lobe (supPL) and postcentral gyrus (postCG). There was the expected correlation of male gender with larger brain and intracranial volume. We examined a wide range of anatomical features of the gyri and the sulci separating them. At least a rudimentary primary intermediate sulcus of Jensen (PISJ) separating SMG and AG was identified in nearly all (59/60) hemispheres. Presence of additional gyri in SMG and AG was related to sulcal features and volumetric characteristics. The parietal lobe was slightly (2%) larger on the left, driven by leftward asymmetries of the postCG and SMG. Intersubject variability was highest for SMG and AG, and lowest for postCG. Overall the morphological characteristics tended to be symmetrical, and volumes also tended to covary between hemispheres. This may reflect developmental as well as maturation factors. To assess the accuracy with which the labels can be used to segment newly acquired (unlabelled) T1-weighted brain images, we applied multi-atlas label propagation software (MAPER) in a leave-one-out experiment and compared the resulting automatic labels with the manually prepared ones. The results showed strong agreement (mean Jaccard index 0.69, corresponding to a mean Dice index of 0.82, average mean volume error of 0.6%). Stereotaxic probabilistic atlases of each subregion were obtained. They illustrate the physiological brain torque, with structures in the right hemisphere positioned more anteriorly than in the left, and right/left positional differences of up to 10 mm. They also allow an assessment of sulcal variability, e.g. low variability for parietooccipital fissure and cingulate sulcus. Illustrated protocols, individual label sets, probabilistic atlases, and a maximum-probability atlas which takes into account surrounding structures are available for free download under academic licences.

Forty years of structural imaging in psychosis: promises and truth

OBJECTIVE

Since the first study published in the Lancet in 1976, structural neuroimaging has been used in psychosis with the promise of imminent clinical utility. The actual impact of structural neuroimaging in psychosis is still unclear.

METHOD

We present here a critical review of studies involving structural magnetic resonance imaging techniques in patients with psychosis published between 1976 and 2015 in selected journals of relevance for the field. For each study, we extracted summary descriptive variables. Additionally, we qualitatively described the main structural findings of each article in summary notes and we employed a biomarker rating system based on quality of evidence (scored 1-4) and effect size (scored 1-4).

RESULTS

Eighty studies meeting the inclusion criteria were retrieved. The number of studies increased over time, reflecting an increased structural imaging research in psychosis. However, quality of evidence was generally impaired by small samples and unclear biomarker definitions. In particular, there was little attempt of replication of previous findings. The effect sizes ranged from small to modest. No diagnostic or prognostic biomarker for clinical use was identified.

CONCLUSIONS

Structural neuroimaging in psychosis research has not yet delivered on the clinical applications that were envisioned.

Selective functional connectivity abnormality of the transition zone of the inferior parietal lobule in schizophrenia

Structural and functional alterations in the inferior parietal lobule (IPL) in schizophrenia have been frequently reported; however, the IPL connectivity changes in schizophrenia remain largely unknown. Based on heterogeneity of the IPL in structure, connection and function, we hypothesize that the resting-state functional connectivities (rsFCs) of the IPL subregions are differentially affected in schizophrenia. This study included 95 schizophrenia patients and 104 healthy controls. The IPL subregions were defined according to a previous in vivo connection-based parcellation study. We calculated the rsFC of each IPL subregion and compared them between the two groups while controlling for the effects of age, gender, and grey matter volume. Among the six subregions of the left IPL and the five subregions of the right IPL, only the bilateral PFm (a transition zone of the IPL) subregions exhibited abnormal rsFC in schizophrenia. Specifically, the left PFm showed increased rsFC with the bilateral lingual gyri in schizophrenia patients than in healthy controls. The right PFm exhibited increased rsFC with the right lingual gyrus and inferior occipital gyrus, and bilateral mid-cingulate and sensorimotor cortices in schizophrenia patients. These findings suggest a selective rsFC abnormality in the IPL subregions in schizophrenia, characterized by the increased rsFC between the PFm subregion of the IPL and the visual and sensorimotor areas.

•

Investigation of the subregional-level rsFC changes of the IPL in schizophrenia

•

The PFm is only IPL subregion with significant rsFC changes in schizophrenia.

•

Suggesting a selective rsFC abnormality in the IPL subregions in schizophrenia

A cross-sectional and longitudinal structural magnetic resonance imaging study of the post-central gyrus in first-episode schizophrenia patients

The post-central gyrus (PoCG) has received little attention in brain imaging literature. However, some magnetic resonance imaging (MRI) studies have detected the presence of PoCG abnormalities in patients with schizophrenia. Fifty-six first-episode schizophrenia patients, selected through the program of first-episode psychosis (PAFIP) and carefully assessed for dimensional psychopathology and cognitive functioning, and 56 matched healthy controls were scanned twice over 1-year follow-up. PoCG gray matter volumes were measured at both time-points and compared between the groups. Differences in volume change over time and the relationship between PoCG volume and clinical and cognitive variables were also investigated. The right PoCG volume was significantly smaller in patients than in controls at the 1-year follow-up; furthermore, it was significantly smaller in male patients compared with male controls, with no differences in female. Although there was no significant time by group interaction in the overall sample, a trend-level interaction was found for the right PoCG in males. This is the first study, as per our knowledge, to focus on PoCG in first-episode schizophrenia patients. The presence of PoCG abnormalities in the first year of schizophrenia suggests a possible contribution to the pathophysiology of the illness, probably as part of a more extensive network of abnormalities.

Impairment in semantic retrieval is associated with symptoms in schizophrenia but not bipolar disorder

BACKGROUND

The Semantic Object Retrieval Task (SORT) requires participants to indicate whether word pairs recall a third object. Schizophrenia individuals (SZ) tend to report associations between nonassociated word pairs; this overretrieval is related to formal thought disorder (FTD). Since semantic memory impairments and psychosis are also found in bipolar disorder (BP), we examined whether SORT impairments and their relationship to symptoms are also present in BP.

METHODS

Participants (n = 239; healthy control subjects [HC] = 133; BP = 32; SZ = 74) completed SORT while undergoing functional magnetic resonance imaging (fMRI) scanning.

RESULTS

Retrieval accuracy negatively correlated with negative symptoms and no-retrieval accuracy negatively correlated with FTD severity in SZ but not BP. Retrieval versus no-retrieval trials activated a distributed fronto-parieto-temporal network; bilateral inferior parietal lobule (IPL) activity was larger in HC versus SZ and HC versus BP, with no difference in SZ versus BP. Right IPL activity positively correlated with positive and general psychosis symptoms in SZ but not BP.

CONCLUSIONS

SZ reported more associations between unrelated word pairs than HC; this overretrieval increased with FTD severity. Schizophrenia individuals were also more likely to fail to find associations between related word pairs; this underretrieval increased with negative symptom severity. fMRI symptom correlations in IPL in SZ are consistent with arguments that IPL abnormality relates to loosening of associations in SZ. By comparison, BP showed intermediate impairments on SORT, uncorrelated with symptoms, suggesting that the relationship between SORT performance, fMRI activity, and psychotic symptoms is schizophrenia-specific.

Dissociable morphometric differences of the inferior parietal lobule in schizophrenia

Inferior parietal lobule (IPL) forms an integral part of a critical frontoparietal network, which has been implicated in various clinical symptoms and cognitive deficits seen in schizophrenia. Despite its functional relevance, the relatively few studies that have investigated the structural changes in the IPL report inconsistent findings concerning the nature and localization of these changes. We employed a blinded, automated labelling procedure to measure cortical thickness, surface area and the degree of cortical folding of the two distinct subregions of the IPL (Angular Gyrus and Supramarginal Gyrus) in 57 patients with schizophrenia and 41 controls using high-resolution magnetic resonance imaging. Within the IPL, we observed more pronounced morphological changes in supramarginal gyrus compared to angular gyrus in schizophrenia. While supramarginal gyrus in patients showed reduced gyrification, contracted surface area and thinning, the morphometric changes in angular gyrus were largely confined to a reduction in surface area. Significant hemispheric asymmetry was observed in the gyrification of the supramarginal gyrus. Our findings suggest that in addition to abnormalities in the neurodevelopmental processes that contribute to regional surface area and cortical thickness, a specific defect in cortical folding, especially affecting the left hemisphere, is likely to occur in schizophrenia.

The potential role of the parietal lobe in schizophrenia

Although the anatomy of the parietal lobe has been under-investigated in schizophrenia, some magnetic resonance imaging studies have shown decreased volumes, suggesting its possible implication for the pathophysiology of the disease.

Schneiderian first rank symptoms and inferior parietal lobule cortical thickness in antipsychotic-naïve schizophrenia

Inferior parietal lobule (IPL) is implicated in the pathogenesis of first rank symptoms (FRS) in schizophrenia by functional neuroimaging studies. However, the relationship between IPL cortical thickness and FRS is yet to be explored. In this study, cortical thickness of IPL was analyzed in antipsychotic-naïve schizophrenia patients (total number = 51) with [FRS(+); N = 25] and those without FRS [FRS(-); N = 26] in comparison with group-matched healthy controls (N = 47). FRS(+) patients showed significant cortical thickness deficit in right IPL (specifically angular gyrus) in comparison with both FRS(-) patients (p = 0.005) and healthy controls (p = 0.0002); lack of difference on the left side might possibly be related to larger variance in healthy controls. Deficient cortical thickness involving IPL in FRS(+) schizophrenia patients adds further support to the role of internal monitoring system in the pathogenesis of FRS in schizophrenia.

Parietal lobes in schizophrenia: do they matter?

Objective. Despite observations that abnormal parietal lobe (PL) function is associated with psychotic-like experiences, our knowledge about the nature of PL involvement in schizophrenia is modest. The objective of this paper is to investigate the role of the PL in schizophrenia. Method. Medline databases were searched for English language publications using the following key words: parietal lobe, combined with schizophrenia, lesions, epilepsy, cognition, rare genetic disorders, MRI, fMRI, PET, and SPECT, respectively, followed by cross-checking of references. Results. Imaging studies in childhood onset schizophrenia suggest that grey matter abnormalities start in parietal and occipital lobes and proceed to frontal regions. Although, the findings are inconsistent, several studies with patients at risk to develop schizophrenia indicate early changes in the PL. Conclusions. We want to propose that in a proportion of individuals with emerging schizophrenia structural and functional alterations may start in the PL and progress to frontal regions.

Executive function, neural circuitry, and genetic mechanisms in schizophrenia

After decades of research aimed at elucidating the pathophysiology and etiology of schizophrenia, it has become increasingly apparent that it is an illness knowing few boundaries. Psychopathological manifestations extend across several domains, impacting multiple facets of real-world functioning for the affected individual. Even within one such domain, arguably the most enduring, difficult to treat, and devastating to long-term functioning-executive impairment-there are not only a host of disrupted component processes, but also a complex underlying dysfunctional neural architecture. Further, just as implicated brain structures (eg, dorsolateral prefrontal cortex) through postmortem and neuroimaging techniques continue to show alterations in multiple, interacting signaling pathways, so too does evolving understanding of genetic risk factors suggest multiple molecular entry points to illness liability. With this expansive network of interactions in mind, the present chapter takes a systems-level approach to executive dysfunction in schizophrenia, by identifying key regions both within and outside of the frontal lobes that show changes in schizophrenia and are important in cognitive control neural circuitry, summarizing current knowledge of their relevant functional interactions, and reviewing emerging links between schizophrenia risk genetics and characteristic executive circuit aberrancies observed with neuroimaging methods.

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.

Schizophrenia and the inferior parietal lobule

OBJECTIVE

Studies of the neuroanatomical localization of schizophrenia have not given sufficient attention to the inferior parietal lobule (IPL).

METHODS

A search of the medical literature was carried out for links between schizophrenia and the IPL.

RESULTS

Structural differences in the IPL in schizophrenia were reported by 10 recent neuroimaging studies, although the studies did not all agree with each other. Functional differences in the IPL in schizophrenia have been prominently reported in four areas: sensory integration, body image, concept of self, and executive function.

CONCLUSION

The IPL appears to be an important, but relatively neglected, component of the frontal-limbic-temporal-parietal neural network involved in the schizophrenia disease process. To encourage histopathological research of this area, the Stanley Medical Research Institute is making available a new collection of sucrose-fixed IPL tissue from 25 individuals with schizophrenia and 25 matched controls. Additional imaging and functional studies are needed to better define the network and role of the IPL.

Size abnormalities of the superior parietal cortices are related to dissociation in borderline personality disorder

Recent evidence suggests that borderline personality disorder (BPD) is related to reduced size of the parietal lobe. Dissociative symptoms occur in the majority of individuals with BPD. Structural magnetic resonance imaging (3D-MRI) was used to assess volumes of the superior (precuneus, postcentral gyrus) and inferior parietal cortices in 30 young women with BPD who had been exposed to severe childhood sexual and physical abuse and 25 healthy control subjects. Compared with control subjects, BPD subjects had significantly smaller right-sided precuneus (-9%) volumes. The left postcentral gyrus of BPD subjects with the comorbid diagnosis of dissociative amnesia (DA) or dissociative identity disorder (DID) was significantly increased compared with controls (+13%) and compared with BPD subjects without these disorders (+11%). In BPD subjects, stronger depersonalization was significantly related to larger right precuneus size. Possibly, larger precuneus size in BPD is related to symptoms of depersonalization. Increased postcentral gyrus size in BPD may be related to the development of DA or DID in the presence of severe childhood abuse.

fMRI study of language activation in schizophrenia, schizoaffective disorder and in individuals genetically at high risk

BACKGROUND

Structural and functional abnormalities have been found in language-related brain regions in patients with schizophrenia. We previously reported findings pointing to differences in word processing between people with schizophrenia and individuals who are at high-risk for schizophrenia using a voxel-based (whole brain) fMRI approach. We now extend this finding to specifically examine functional activity in three language related cortical regions using a larger cohort of individuals.

METHOD

A visual lexical discrimination task was performed by 36 controls, 21 subjects at high genetic-risk for schizophrenia, and 20 patients with schizophrenia during blood oxygenation level dependent (BOLD) fMRI scanning. Activation in bilateral inferior frontal gyri (Brodmann's area 44-45), bilateral inferior parietal lobe (Brodmann's area 39-40), and bilateral superior temporal gyri (Brodmann's area 22) was investigated. For all subjects, two-tailed Pearson correlations were calculated between the computed laterality index and a series of cognitive test scores determining language functioning.

RESULTS

Regional activation in Brodmann's area 44-45 was left lateralized in normal controls, while high-risk subjects and patients with schizophrenia or schizoaffective disorder showed more bilateral activation. No significant differences among the three diagnostic groups in the other two regions of interest (Brodmann's area 22 or areas 39-40) were found. Furthermore, the apparent reasons for loss of leftward language lateralization differed between groups. In high-risk subjects, the loss of lateralization was based on reduced left hemisphere activation, while in the patient group, it was due to increased right side activation. Language ability related cognitive scores were positively correlations with the laterality indices obtained from Brodmann's areas 44-45 in the high-risk group, and with the laterality indices from Brodmann's areas 22 and 44-45 in the patient group.

CONCLUSIONS

This study reinforces previous language related imaging studies in high-risk subjects and patients with schizophrenia suggesting that reduced functional lateralization in language related frontal cortex may be a vulnerability marker for schizophrenia. Future studies will determine whether it is predictive of who develops illness.

Cerebral Disconnectivity: An Early Event in Schizophrenia

Neuroimaging and electrophysiological investigations have demonstrated numerous differences in brain morphology and function of chronic schizophrenia patients compared to healthy controls. Studying patients at the beginning of their disease without the confounding effects of chronicity, medication, and institutionalization may provide a better understanding of schizophrenia. Recently, at many institutions around the world, special projects have been launched for specialized treatment and research of this interesting patient group. Using the PubMed search engine in this update, the authors summarize recent investigations between January 2002 and September 2006 that focus on whether signs of disconnectivity already exist early in the disease process. They discuss gray and white matter changes, their impact on symptomatology, electroencephalogram-based studies on connectivity, and possible influences of medication. NEUROSCIENTIST 14(1):19—45, 2008. DOI: 10.1177/1073858406298391

“Dark Nights of the Soul”: Phenomenology and Neurocognition of Spiritual Suffering in Mysticism and Psychosis

Phenomenological, clinical, and neurocognitive levels of analysis are combined to understand the cognitive bases of spirituality and spiritual suffering. In particular, the “dark night of the soul” in classical mysticism, with its painful “metapathological” loss of felt meaning is compared with the anhedonias central to the negative symptoms of schizophrenia and schizotypicality. Paul Schilder's early understanding of instabilities in the body image, as our core sense of self, offers a key to both the disorganized hallucinatory syndromes of psychosis and to the relative enhancements of body image/ecological self in spirituality. Expanded versus deleted felt presence/embodiment, as outwardly indexed in measures of physical balance and spatial abilities, becomes the general dimension underlying integrative versus disintegrative transformations of consciousness. “Dark night” suffering can be seen as a semantic satiation leading to a relative deletion of experienced presence in the context of its previous enhancement, a focalized version of the more general anhedonic despair shared by clinical schizotypy and aspects of a larger secularized culture.

Progressive grey matter atrophy over the first 2-3 years of illness in first-episode schizophrenia: a tensor-based morphometry study

Little is known about the structural brain changes that occur over the first few years of schizophrenia, or how these changes differ from those associated with healthy brain development in adolescence and early adulthood. In this study, we aimed to identify regional differences in grey matter (GM) volume between patients with first-episode schizophrenia (FES) and matched healthy controls, both at the time of the patients' first psychotic episode (baseline condition) and 2-3 years subsequently (follow-up condition). Forty-one patients with FES and 47 matched healthy controls underwent a T1-weighted structural MRI scan. Of these participants, 25 FES patients and 26 controls returned 2-3 years later for a follow-up scan. Voxel-based morphometry in SPM2 was used to identify the regions of GM difference between the groups in the baseline condition, while tensor-based morphometry was used to identify the longitudinal change within subject over the follow-up interval. The FES patients exhibited widespread GM reductions in the frontal, parietal, and temporal cortices and cerebellum in the baseline condition, as well as more circumscribed regions of GM increase, particularly in the occipital lobe. Furthermore, the FES subjects were observed to lose considerably more GM over the follow-up interval than the controls, especially in the parietal and temporal cortices. We argue that the progressive GM atrophy we have found to be associated with the onset of schizophrenia arises from a dysfunction in the dramatic period of healthy brain development typically associated with adolescence.