Prefrontal-thalamic-cerebellar gray matter networks and executive functioning in schizophrenia

Deciphering the interplay between psychopathological symptoms, sensorimotor, cognitive and global functioning: a transdiagnostic network analysis

BACKGROUND

Understanding the relationship between psychopathology and major domains of human neurobehavioral functioning may identify new transdiagnostic treatment targets. However, studies examining the interrelationship between psychopathological symptoms, sensorimotor, cognitive, and global functioning in a transdiagnostic sample are lacking. We hypothesized a close relationship between sensorimotor and cognitive functioning in a transdiagnostic patient sample.

METHODS

We applied network analysis and community detection methods to examine the interplay and centrality [expected influence (EI) and strength] between psychopathological symptoms, sensorimotor, cognitive, and global functioning in a transdiagnostic sample consisting of 174 schizophrenia spectrum (SSD) and 38 mood disorder (MOD) patients. All patients (n = 212) were examined with the Positive and Negative Syndrome Scale (PANSS), the Heidelberg Neurological Soft Signs Scale (NSS), the Global Assessment of Functioning (GAF), and the Brief Cognitive Assessment Tool for Schizophrenia consisted of trail making test B (TMT-B), category fluency (CF) and digit symbol substitution test (DSST).

RESULTS

NSS showed closer connections with TMT-B, CF, and DSST than with GAF and PANSS. DSST, PANSS general, and NSS motor coordination scores showed the highest EI. Sensory integration, DSST, and CF showed the highest strength.

CONCLUSIONS

The close connection between sensorimotor and cognitive impairment as well as the high centrality of sensorimotor symptoms suggests that both domains share aspects of SSD and MOD pathophysiology. But, because the majority of the study population was diagnosed with SSD, the question as to whether sensorimotor symptoms are really a transdiagnostic therapeutic target needs to be examined in future studies including more balanced diagnostic groups.

The relationship between gray/white matter contrast and cognitive performance in first-episode schizophrenia

Previous postmortem brain studies have revealed disturbed myelination in the intracortical regions in patients with schizophrenia, possibly reflecting anomalous brain maturational processes. However, it currently remains unclear whether this anomalous myelination is already present in early illness stages and/or progresses during the course of the illness. In this magnetic resonance imaging study, we examined gray/white matter contrast (GWC) as a potential marker of intracortical myelination in 63 first-episode schizophrenia (FESz) patients and 77 healthy controls (HC). Furthermore, we investigated the relationships between GWC findings and clinical/cognitive variables in FESz patients. GWC in the bilateral temporal, parietal, occipital, and insular regions was significantly higher in FESz patients than in HC, which was partly associated with the durations of illness and medication, the onset age, and lower executive and verbal learning performances. Because higher GWC implicates lower myelin in the deeper layers of the cortex, these results suggest that schizophrenia patients have less intracortical myelin at the time of their first psychotic episode, which underlies lower cognitive performance in early illness stages.

Methylphenidate Ameliorates Behavioural and Neurobiological Deficits in Executive Function for Patients with Chronic Traumatic Brain Injury

(1) Background: Traumatic brain injury (TBI) often results in cognitive impairments, including in visuospatial planning and executive function. Methylphenidate (MPh) demonstrates potential improvements in several cognitive domains in patients with TBI. The Tower of London (TOL) is a visuospatial planning task used to assess executive function. (2) Methods: Volunteers with a history of TBI (n = 16) participated in a randomised, double-blinded, placebo-controlled, fMRI study to investigate the neurobiological correlates of visuospatial planning and executive function, on and off MPh. (3) Results: Healthy controls (HCs) (n = 18) and patients on placebo (TBI-placebo) differed significantly in reaction time (p < 0.0005) and accuracy (p < 0.0001) when considering all task loads, but especially for high cognitive loads for reaction time (p < 0.001) and accuracy (p < 0.005). Across all task loads, TBI-MPh were more accurate than TBI-placebo (p < 0.05) but remained less accurate than HCs (p < 0.005). TBI-placebo substantially improved in accuracy with MPh administration (TBI-MPh) to a level statistically comparable to HCs at low (p = 0.443) and high (p = 0.175) cognitive loads. Further, individual patients that performed slower on placebo at low cognitive loads were faster with MPh (p < 0.05), while individual patients that performed less accurately on placebo were more accurate with MPh at both high and low cognitive loads (p < 0.005). TBI-placebo showed reduced activity in the bilateral inferior frontal gyri (IFG) and insulae versus HCs. MPh normalised these regional differences. MPh enhanced within-network connectivity (between parietal, striatal, insula, and cerebellar regions) and enhanced beyond-network connectivity (between parietal, thalamic, and cerebellar regions). Finally, individual changes in cerebellar-thalamic (p < 0.005) and cerebellar-parietal (p < 0.05) connectivity with MPh related to individual changes in accuracy with MPh. (4) Conclusions: This work highlights behavioural and neurofunctional differences between HCs and patients with chronic TBI, and that adverse differences may benefit from MPh treatment.

Brain Morphological Characteristics of Cognitive Subgroups of Schizophrenia-Spectrum Disorders and Bipolar Disorder: A Systematic Review with Narrative Synthesis

Despite a growing body of research, there is yet to be a cohesive synthesis of studies examining differences in brain morphology according to patterns of cognitive function among both schizophrenia-spectrum disorder (SSD) and bipolar disorder (BD) individuals. We aimed to provide a systematic overview of the morphological differences-inclusive of grey and white matter volume, cortical thickness, and cortical surface area-between cognitive subgroups of these disorders and healthy controls, and between cognitive subgroups themselves. An initial search of PubMed and Scopus databases resulted in 1486 articles of which 20 met inclusion criteria and were reviewed in detail. The findings of this review do not provide strong evidence that cognitive subgroups of SSD or BD map to unique patterns of brain morphology. There is preliminary evidence to suggest that reductions in cortical thickness may be more strongly associated with cognitive impairment, whilst volumetric deficits may be largely tied to the presence of disease.

Relationships between cognitive performance, clinical insight and regional brain volumes in schizophrenia

Impairments in cognitive performance are common in schizophrenia, and these contribute to poor awareness of symptoms and treatment (‘clinical insight’), which is an important predictor of functional outcome. Although relationships between cognitive impairment and reductions in regional brain volumes in patients are relatively well characterised, less is known about the brain structural correlates of clinical insight. To address this gap, we aimed to explore brain structural correlates of cognitive performance and clinical insight in the same sample. 108 patients with schizophrenia (SZH) and 94 age and gender-matched controls (CON) (from the Northwestern University Schizophrenia Data and Software Tool (NUSDAST) database) were included. SZH had smaller grey matter volume across most fronto-temporal regions and significantly poorer performance on all cognitive domains. Multiple regression showed that higher positive symptoms and poorer attention were significant predictors of insight in SZH; however, no significant correlations were seen between clinical insight and regional brain volumes. In contrast, symptomology did not contribute to cognitive performance, but robust positive relationships were found between regional grey matter volumes in fronto-temporal regions and cognitive performance (particularly executive function). Many of these appeared to be unique to SZH as they were not observed in CON. Findings suggest that while there exists a tight link between cognitive functioning and neuropathological processes affecting gross brain anatomy in SZH, this is not the case for clinical insight. Instead, clinical insight levels seem to be influenced by symptomology, attentional performance and other subject-specific variables.

Altered asymmetries of resting‐state MRI in the left thalamus of first‐episode schizophrenia

Background

Schizophrenia (SCZ) is a complex psychiatric disorder associated with widespread alterations in the subcortical brain structure. Hemispheric asymmetries are a fundamental organizational principle of the human brain and relate to human psychological and behavioral characteristics. We aimed to explore the state of thalamic lateralization of SCZ.

Methods

We used voxel‐based morphometry (VBM) analysis, whole‐brain analysis of low‐frequency fluctuations (ALFF), fractional amplitude of low‐frequency fluctuations (fALFF), and resting‐state seed‐based functional connectivity (FC) analysis to investigate brain structural and functional deficits in SCZ. Also, we applied Pearson's correlation analysis to validate the correlation between Positive and Negative Symptom Scale (PANSS) scores and them.

Results

Compared with healthy controls, SCZ showed increased gray matter volume (GMV) of the left thalamus (t = 2.214, p = 0.029), which positively correlated with general psychosis (r = 0.423, p = 0.010). SCZ also showed increased ALFF in the putamen, the caudate nucleus, the thalamus, fALFF in the nucleus accumbens (NAc), and the caudate nucleus, and decreased fALFF in the precuneus. The left thalamus showed significantly weaker resting‐state FC with the amygdala and insula in SCZ. PANSS negative symptom scores were negatively correlated with the resting‐state FC between the thalamus and the insula (r = −0.414, p = 0.025).

Conclusions

Collectively, these results suggest the possibility of aberrant laterality in the left thalamus and its FC with other related brain regions involved in the limbic system.

1.

Experiments to explore the lateralization state of the left thalamus in schizophrenia.

2.

The thalamus is structurally and functionally impaired in schizophrenia.

3.

The limbic system may be linked to altered brain asymmetry.

Facial emotion perception abilities are related to grey matter volume in the culmen of cerebellum anterior lobe in drug-naïve patients with first-episode schizophrenia

Impaired capability for understanding and interpreting the expressions on other people's faces manifests itself as a core feature of schizophrenia, contributing to social dysfunction. With the purpose of better understanding of the neurobiological basis of facial emotion perception deficits in schizophrenia, we investigated facial emotion perception abilities and regional structural brain abnormalities in drug-naïve patients with first-episode schizophrenia, and then examined the correlation between them. Fifty-two drug-naive patients with first-episode schizophrenia and 29 group-matched healthy controls were examined for facial emotion perception abilities assessed with the Facial Emotion Categorization and performed magnetic resonance imaging. The Facial Emotion Categorization data were inserted into a logistic function model so as to calculate shift point and slope as outcome measurements. Voxel-based morphometry was applied to investigate regional grey matter volume (GMV) alterations. The relationship between facial emotion perception and GMV was explored in patients using voxel-wise correlation analysis within brain regions that showed a significant GMV alterations in patients compared with controls. The schizophrenic patients performed differently on Facial Emotion Categorization tasks from the controls and presented a higher shift point and a steeper slope. Relative to the controls, patients showed GMV reductions in the superior temporal gyrus, middle occipital gyrus, parahippocampa gyrus, posterior cingulate, the culmen of cerebellum anterior lobe, cerebellar tonsil, and the declive of cerebellum posterior lobe. Importantly, abnormal performance on Facial Emotion Categorization was found correlated with GMV alterations in the culmen of cerebellum anterior lobe in schizophrenia. This study suggests that reduced GMV in the culmen of cerebellum anterior lobe occurs in first-episode schizophrenia, constituting a potential neuropathological basis for the impaired facial emotion perception in schizophrenia.

The neurobiological characterization of distinct cognitive subtypes in early-phase schizophrenia-spectrum disorders

INTRODUCTION

Cognitive deficits are present in some, but not all patients with schizophrenia-spectrum disorders (SSD). We and others have demonstrated three cognitive clusters: cognitively intact patients, patients with deficits in a few domains and those with global cognitive deficits. This study aimed to identify cognitive subtypes of early-phase SSD with matched controls as a reference group, and evaluated cognitive subgroups regarding clinical and brain volumetric measures.

METHODS

Eighty-six early-phase SSD patients were included. Hierarchical cluster analysis was conducted using global performance on the Brief Assessment of Cognition in Schizophrenia (BACS). Cognitive subgroups were subsequently related to clinical and brain volumetric measures (cortical, subcortical and cortical thickness) using ANCOVA.

RESULTS

Three distinct cognitive clusters emerged: relative to controls we found one cluster of patients with preserved cognition (n = 25), one moderately impaired cluster (n = 38) and one severely impaired cluster (n = 23). Cognitive subgroups were characterized by differences in volume of the left postcentral gyrus, left middle caudal frontal gyrus and left insula, while differences in cortical thickness were predominantly found in fronto-parietal regions. No differences were demonstrated in subcortical brain volume.

DISCUSSION

Current results replicate the existence of three distinct cognitive subgroups including one relatively large group with preserved cognitive function. Cognitive subgroups were characterized by differences in cortical regional brain volume and cortical thickness, suggesting associations with cortical, but not subcortical development and cognitive functioning such as attention, executive functions and speed of processing.

Intermittent theta burst stimulation of cerebellar vermis enhances fronto-cerebellar resting state functional connectivity in schizophrenia with predominant negative symptoms: A randomized controlled trial

OBJECTIVE

Negative symptoms of schizophrenia are substantially disabling and treatment resistant. Novel treatments like repetitive transcranial magnetic stimulation (TMS) need to be examined for the same using the experimental medicine approach that incorporates tests of mechanism of action in addition to clinical efficacy in trials.

METHODS

Study was a double-blind, parallel, randomized, sham-controlled trial recruiting schizophrenia with at least a moderate severity of negative symptoms. Participants were randomized to real or sham intermittent theta burst stimulation (iTBS) under MRI-guided neuro-navigation, targeting the cerebellar vermis area VII-B, at a stimulus intensity of 100% active motor threshold, two sessions/day for five days (total = 6000 pulses). Assessments were conducted at baseline (T0), day-6 (T1) and week-6 (T2) after initiation of intervention. Main outcomes were, a) Scale for the Assessment of Negative Symptoms (SANS) score (T0, T1, T2), b) fronto-cerebellar resting state functional connectivity (RSFC) (T0, T1).

RESULTS

Thirty participants were recruited in each arm. Negative symptoms improved in both arms (p < 0.001) but was not significantly different between the two arms (p = 0.602). RSFC significantly increased between the cerebellar vermis and the right inferior frontal gyrus (p_cluster-FWER = 0.033), right pallidum (p_cluster-FWER = 0.042) and right frontal pole (p_cluster-FWER = 0.047) in the real arm with no change in the sham arm.

CONCLUSION

Cerebellar vermal iTBS engaged a target belonging to the class of cerebello-subcortical-cortical networks, implicated in negative symptoms of schizophrenia. However, this did not translate to a superior clinical efficacy. Future trials should employ enhanced midline cerebellar TMS stimulation parameters for longer durations that can potentiate and translate biological changes into clinical effects.

The central executive network and executive function in healthy and persons with schizophrenia groups: a meta-analysis of structural and functional MRI

This meta-analysis evaluated the extent to which executive function can be understood with structural and functional magnetic resonance imaging. Studies included structural in schizophrenia (k = 8; n = 241) and healthy controls (k = 12; n = 1660), and functional in schizophrenia (k = 4; n = 104) and healthy controls (k = 12; n = 712). Results revealed a positive association in the brain behavior relationship when pooled across schizophrenia and control samples for structural (pr = 0.27) and functional (pr = 0.29) modalities. Subgroup analyses revealed no significant difference for functional neuroimaging (pr = .43, 95%CI = -.08-.77, p = .088) but with structural neuroimaging (pr = .37, 95%CI = -.08-.69, p = .015) the association to executive functions is lower in the control group. Subgroup analyses also revealed no significant differences in the strength of the brain-behavior relationship in the schizophrenia group (pr = .59, 95%CI = .58-.61, p = .881) or the control group (pr = 0.19, 95%CI = 0.18-0.19, p = 0.920), suggesting concordance.

Characterising Demographic, Clinical and Functional Features of Cognitive Subgroups in Schizophrenia Spectrum Disorders: A Systematic Review

Considerable cognitive heterogeneity is present within the schizophrenia spectrum disorder (SSD) population. Several subgroups characterised by more homogenous cognitive profiles have been identified. It is not yet clear however, whether these subgroups represent different points along a continuum of cognitive symptom severity, or whether they reflect unique profiles of the disorder. One way to determine this is by comparing subgroups on their non-cognitive characteristics. The aim of the present review was to systematically summarise our current understanding of the non-cognitive features of the cognitive subgroups of schizophrenia spectrum disorder (SSD). Thirty-five relevant studies were identified from January 1980 to March 2020. Cognitive subgroups were consistently compared on age, sex, education, age of illness onset, illness duration, positive, negative and disorganised symptoms, depression and psychosocial functioning. It was revealed that subgroups were consistently distinguished by education, negative symptom severity and degree of functional impairment; with subgroups characterised by worse cognitive functioning performing/rated worse on these characteristics. The lack of consistent subgroup differences for the majority of the non-cognitive characteristics provides partial support for the notion that cognitive subgrouping in SSD is not simply reflecting a rehash of previously identified clinical subtypes. However, as subgroups were consistently distinguished by three characteristics known to be associated with cognition, our understanding of the extent to which the cognitive subgrouping approach is representing separate subtypes versus subdivisions along a continuum of symptom severity is still not definitive.

Structural and functional brain changes in X-linked Charcot-Marie-Tooth disease: insights from a multimodal neuroimaging study

PURPOSE

Brain involvement in X-linked Charcot-Marie-Tooth disease (CMTX) has been previously reported. We studied the brain structural and functional integrity using a multimodal neuroimaging approach in patients with no current central nervous system (CNS) symptoms, in order to further delineate the disease's phenotype.

METHODS

Seventeen CMTX patients with no current CNS symptoms and 24 matched healthy controls underwent brain magnetic resonance imaging (MRI). Structural integrity was evaluated performing Gray matter analysis with voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) of diffusion tensor imaging (DTI). Functional integrity was evaluated with resting-state functional MRI (rs-fMRI).

RESULTS

Decreased gray matter density was detected in CMTX patients compared to healthy controls in bilateral hippocampus, left thalamus, left postcentral gyrus, left superior parietal lobule, left cerebellum crus I and II, and vermis VI. DTI analysis showed increased fractional anisotropy and radial diffusivity in the right anterior insula and increased axial diffusivity in right cerebellum crus I in CMTX patients. rs-fMRI revealed decreased spontaneous neural activity on left precentral gyrus in patients compared to healthy controls.

CONCLUSION

Advanced magnetic resonance (MR) neuroimaging techniques in CMTX patients revealed structural and functional involvement of multiple motor and extra-motor brain areas. MR neuroimaging techniques have the potential to delineate the CNS phenotype of a peripheral neuropathy like CMTX.

Fronto-Parietal Gray Matter Volume Loss Is Associated with Decreased Working Memory Performance in Adolescents with a First Episode of Psychosis

Cognitive maturation during adolescence is modulated by brain maturation. However, it is unknown how these processes intertwine in early onset psychosis (EOP). Studies examining longitudinal brain changes and cognitive performance in psychosis lend support for an altered development of high-order cognitive functions, which parallels progressive gray matter (GM) loss over time, particularly in fronto-parietal brain regions. We aimed to assess this relationship in a subsample of 33 adolescents with first-episode EOP and 47 matched controls over 2 years. Backwards stepwise regression analyses were conducted to determine the association and predictive value of longitudinal brain changes over cognitive performance within each group. Fronto-parietal GM volume loss was positively associated with decreased working memory in adolescents with psychosis (frontal left (B = 0.096, p = 0.008); right (B = 0.089, p = 0.015); parietal left (B = 0.119, p = 0.007), right (B = 0.125, p = 0.015)) as a function of age. A particular decrease in frontal left GM volume best predicted a significant amount (22.28%) of the variance of decreased working memory performance over time, accounting for variance in age (14.9%). No such association was found in controls. Our results suggest that during adolescence, EOP individuals seem to follow an abnormal neurodevelopmental trajectory, in which fronto-parietal GM volume reduction is associated with the differential age-related working memory dysfunction in this group.

Reduced Microstructural Lateralization in Males with Chronic Schizophrenia: A Diffusional Kurtosis Imaging Study

Decreased brain lateralization is considered a trait marker of schizophrenia. Whereas reductions in both functional and macrostructural gray matter laterality in schizophrenia are well established, the investigation of gray matter microstructural lateralization has so far been limited to a small number of ex vivo studies, which limits the understanding of neurobiological substrates involved and development of adequate treatments. The aim of the current study was to assess in vivo gray matter microstructure lateralization patterns in schizophrenia by employing the diffusion kurtosis imaging (DKI)-derived mean kurtosis (MK) metric. MK was calculated for 18 right-handed males with chronic schizophrenia and 19 age-matched healthy control participants in 46 bilateral gray matter regions of interest (ROI). Microstructural laterality indexes (μLIs) were calculated for each subject and ROI, and group comparisons were conducted across regions. The relationship between μLI values and performance on the Wisconsin Card Sorting Test (WCST) was also evaluated. We found that compared with healthy controls, males with chronic schizophrenia had significantly decreased μLI across cortical and subcortical gray matter regions, which was correlated with poorer performance on the WCST. Our results suggest the ability of DKI-derived MK to capture gray matter microstructural lateralization pathology in vivo.

Executive Dysfunctions in Schizophrenia: A Critical Review of Traditional, Ecological, and Virtual Reality Assessments

In recent years, interest has grown in measuring executive function in schizophrenia with ecological and virtual reality (VR) tools. However, there is a lack of critical analysis comparing those tools with traditional ones. This paper aims to characterize executive dysfunction in schizophrenia by comparing ecological and virtual reality assessments with traditional tools, and to describe the neurobiological and psychopathological correlates. The analysis revealed that ecological and VR tests have higher levels of verisimilitude and similar levels of veridicality compared to traditional tools. Both negative symptoms and disorganization correlate significantly with executive dysfunction as measured by traditional tools, but their relationships with measures based on ecological and VR methods are still unclear. Although there is much research on brain correlates of executive impairments in schizophrenia with traditional tools, it is uncertain if these results will be confirmed with the use of ecological and VR tools. In the diagnosis of executive dysfunction, it is important to use a variety of neuropsychological methods—especially those with confirmed ecological validity—to properly recognize the underlying characteristics of the observed deficits and to implement effective forms of therapy.

Brain morphology does not clearly map to cognition in individuals on the bipolar-schizophrenia-spectrum: a cross-diagnostic study of cognitive subgroups

BACKGROUND

Characterisation of brain morphological features common to cognitively similar individuals with bipolar disorder (BD) and schizophrenia spectrum disorders (SSD) may be key to understanding their shared neurobiological deficits. In the current study we examined whether three previously characterised cross-diagnostic cognitive subgroups differed among themselves and in comparison to healthy controls across measures of brain morphology.

METHOD

T1-weighted structural magnetic resonance imaging scans were obtained for 143 individuals; 65 healthy controls and 78 patients (SSD, n = 40; BD I, n = 38) classified into three cross-diagnostic cognitive subgroups: Globally Impaired (n = 24), Selectively Impaired (n = 32), and Superior/Near-Normal (n = 22). Cognitive subgroups were compared to each other and healthy controls on three separate analyses investigating (1) global, (2) regional, and (3) vertex-wise comparisons of brain volume, thickness, and surface area.

RESULTS

No significant subgroup differences were evident in global measures of brain morphology. In region of interest analyses, the Selectively Impaired subgroup had greater right accumbens volume than those Superior/Near-Normal subgroup and healthy controls, and the Superior/Near-Normal subgroup had reduced volume of the left entorhinal region compared to all other groups. In vertex-wise comparisons, the Globally Impaired subgroup had greater right precentral volume than the Selectively Impaired subgroup, and thicker cortex in the postcentral region relative to the Superior/Near-Normal subgroup.

LIMITATIONS

Exploration of medication effects was limited in our data.

CONCLUSIONS

Although some differences were evident in this sample, generally cross-diagnostic cognitive subgroups of individuals with SSD and BD did not appear to be clearly distinguished by patterns in brain morphology.

SS-Detect: Development and Validation of a New Strategy for Source-Based Morphometry in Multiscanner Studies

BACKGROUND AND PURPOSE

Source-based morphometry(SBM) has been used in multicenter studies pooling magnetic resonance imaging data across different scanners to advance the reproducibility of neuroscience research. In the present study, we developed an analysis strategy for Scanner-Specific Detection (SS-Detect) of SBPs in multiscanner studies, and evaluated its performance relative to a conventional strategy.

METHODS

In the first experiment, the SimTB toolbox was used to generate simulated datasets mimicking 20 different scanners with common and scanner-specific SBPs. In the second experiment, we generated one simulated SBP from empirical gray matter volume (GMV) datasets from two different scanners. Moreover, we applied two strategies to compare SBPs between schizophrenia patients' and healthy controls' GMV from two scanners.

RESULTS

The outputs of the conventional strategy were limited to whole-sample-level results across all scanners; the outputs of SS-Detect included whole-sample-level and scanner-specific results. In the first simulation experiment, SS-Detect successfully estimated all simulated SBPs, including the common and scanner-specific SBPs, whereas the conventional strategy detected only some of the whole-sample SBPs. The second simulation experiment showed that both strategies could detect the simulated SBP. Quantitative evaluations of both experiments demonstrated greater accuracy of the SS-Detect in estimating spatial SBPs and subject-specific loading parameters. In the third experiment, SS-Detect detected more significant between-group SBPs, and these SBPs corresponded with the results from voxel-based morphometry analysis, suggesting that SS-Detect has higher sensitivity in detecting between-group differences.

CONCLUSIONS

SS-Detect outperformed the conventional strategy and can be considered advantageous when SBM is applied to a multiscanner study.

[Executive control of language production in schizophrenia: a pilot neuropsychological study]

OBJECTIVE

To test the general hypothesis about executive deficits in language production in schizophrenia as well as more specific hypothesis that this deficit would be more pronounced in the case of higher demand on executive functions.

MATERIAL AND METHODS

Twenty-five patients with schizophrenia and twenty-seven healthy controls were asked to tell a story based on a series of pictures and then to give an oral composition on the given topic.

RESULTS AND CONCLUSION

Schizophrenia patients, compared to controls, demonstrated poorer programming as well as shorter text and phrase length in both tasks. Oral composition on the given topic in patients was characterized by the presence of agrammatism, need for leading questions due to the difficulties of story plot generation as well as higher variance in syntactic complexity and text length. Therefore, the authors revealed executive deficit in language production, more pronounced in the task with less numerous external cues for planning and sequential text explication, in schizophrenia patients.

Differences in the amplitude of low-frequency fluctuation between methamphetamine and heroin use disorder individuals: A resting-state fMRI study

INTRODUCTION

Methamphetamine has surpassed heroin as the most popular abused drug in China. Although the use of both heroin and methamphetamine leads to use disorders through dysfunction of the dopamine pathway, the incidence of psychiatric disorder caused by methamphetamine abuse is higher than the incidence of psychiatric disorder caused by heroin abuse. The difference in resting-state function between heroin use disorder (HUD) and methamphetamine use disorder (MAUD) and the relationship between resting-state function and psychiatric disorder related to MAUD are unknown.

METHODS

In the present study, 21 male individuals with MAUD, 21 demographically matched individuals with HUD, and 21 normal controls (NC) were recruited. The amplitude of low-frequency fluctuation (ALFF) during resting-state brain function was measured by magnetic resonance imaging. Psychiatric status was evaluated by the Symptom Checklist-90 (SCL90).

RESULTS

Individuals with MAUD had increased SCL90 scores compared to those of the NC for anxiety, paranoia, and additional items, and the hostility score was significantly increased compared to that of individuals with HUD. There is no significant difference between HUD and NC individuals. Individuals with MAUD had increased ALFF compared to those of the NC for thalamus, right postcentral, and right inferior temporal gyri, but a decreased ALFF in the cerebellum. Individuals with HUD had significantly increased ALFF compared to those of the NC for left middle frontal gyrus but a decreased ALFF in the left postcentral gyrus. Individuals with MAUD had significantly increased ALFF compared to those of the HUD for thalamus, the right inferior temporal, and bilateral postcentral gyri, and the ALFF of cerebellum and left middle frontal was significantly increased.

CONCLUSIONS

Methamphetamine can induce more serious psychiatric disorders than heroin. The resting-state function involved in mood adjustment, the auditory, and memory-related brain regions may affect psychotic symptoms related to MAUD.

Differences in executive function among patients with schizophrenia, their unaffected first-degree relatives and healthy participants

BACKGROUND

Patients with schizophrenia (SCZ) display impaired executive functions compared with healthy controls (HCs). Furthermore, unaffected first-degree relatives (FRs) of patients with SCZ independently perform worse executive functions than do HCs. However, few studies have investigated the differences in executive functions assessed among patients with SCZ, FRs, and HCs, and the findings are inconsistent.

METHODS

We investigated diagnostic differences in executive functions, namely, (i) numbers of categories achieved (CA), (ii) total errors (TE) and (iii) %perseverative errors of Nelson types (%PEN), using the Wisconsin card sorting test (WCST) among patients with SCZ (n=116), unaffected FRs (n=62) and HCs (n=146) at a single institute. Correlations between these executive functions and clinical variables were investigated.

RESULTS

Significant differences existed in all executive functions among diagnostic groups (CA, F2,319=15.5, p=3.71×10-7; TE, F2,319=16.2, p=2.06×10-7; and %PEN, F2,319=21.3, p=2.15×10-9). Patients with SCZ had fewer CA and more TE and %PEN than those of HCs (CA, Cohen's d=-0.70, p=5.49×10-8; TE, d=0.70, p=5.62×10-8; and %PEN, d=0.82, p=2.85×10-10) and FRs (TE, d=0.46, p=3.73×10-3 and %PEN, d=0.38, p=0.017). Of the three executive functions, CA and %PEN of FRs were intermediately impaired between patients with SCZ and HCs (CA, d=-0.41, p=0.011 and %PEN, d=0.41, p=0.012). In contrast, no significant difference in TE existed between FRs and HCs (d=0.22, p=0.18). Although CA and TE were affected by the duration of illness (p<0.017), %PEN was not affected by any clinical variable in patients with SCZ (p>0.017).

CONCLUSIONS

Executive function, particularly %PEN, could be a useful intermediate phenotype for understanding the genetic mechanisms implicated in SCZ pathophysiology.

Perinatal complications and executive dysfunction in early-onset schizophrenia

BACKGROUND

The present study examined the association between perinatal obstetric complications and executive dysfunction in early-onset schizophrenia (EOS), compared to healthy controls. Higher incidences of obstetric complications and more severe executive dysfunctions characterize EOS. Research shows extensive brain maturation in newborns, suggesting them to be particularly vulnerable for perinatal insults. Executive function is mainly mediated by the prefrontal cortex, an area that matures last during pregnancy. Thus, exposure to perinatal complications may influence executive dysfunction in EOS.

METHODS

The participants were 19 EOS patients and 54 healthy controls. Executive function was assessed with the D-KEFS Color Word Interference Test and the Wisconsin Card Sorting Test. Information on perinatal obstetric complications and Apgar 5-min scores were obtained from the Norwegian Medical Birth Registry. Associations between perinatal conditions and executive function were studied using stepwise regression analyses.

RESULTS

Perinatal complications, and especially shorter gestational lengths, were significantly associated with significant executive dysfunctions in EOS. Perinatal complications did not affect executive function among healthy controls. A significant relationship between lower Apgar 5-min scores and executive dysfunction was found among both EOS patients and healthy controls.

CONCLUSIONS

Exposure to perinatal complications, and particularly a shorter gestational length, was associated with increased executive dysfunction in EOS. Exposed healthy controls did not exhibit similar executive difficulties, suggesting that the EOS patients seemed especially vulnerable for executive deficits due to perinatal insults. The findings indicate that EOS youths learn more slowly and experience more difficulty with problem-solving, which carry important implications for clinical practice. Lower Apgar 5-min scores were associated with executive dysfunction in both groups. Low Apgar score at 5 min may therefore be an important early indicator of executive difficulties among adolescents, independent of diagnosis.

The Impact of Childhood Adversity on Cognitive Development in Schizophrenia

Childhood adversity, such as physical, sexual, and verbal abuse, as well as neglect and family conflict, is a risk factor for schizophrenia. Such adversity can lead to disruptions of cognitive function during development, undermining intellectual capabilities and academic achievement. Schizophrenia is a neurodevelopmental disorder that is associated with cognitive impairments that may become evident during childhood. The Australian Schizophrenia Research Bank database comprises a large community cohort (N = 1169) in which we previously identified 3 distinct cognitive groups among people with schizophrenia: (1) Compromised, current, and estimated premorbid cognitive impairment; (2) Deteriorated, substantial decline from estimated premorbid function; and (3) Preserved, performing in the normal cognitive range without decline. The compromised group displayed the worst functional and symptom outcomes. Here, we extend our previous work by assessing the relationship among these categories of cognitive abilities and reported childhood adversity in 836 patients and healthy controls. Exploratory factor analysis of the Childhood Adversity Questionnaire revealed 3 factors (lack of parental involvement; overt abuse; family breakdown and hardship). People with schizophrenia reported significantly more childhood adversity than healthy controls on all items and factors. People with schizophrenia in the compromised group reported significantly more lack of parental involvement and family breakdown and hardship and lower socioeconomic status than those in the deteriorated group. The cognitive groups were not related to family history of psychosis. These findings identify specific social and family factors that impact cognition, highlighting the important role of these factors in the development of cognitive and functional abilities in schizophrenia.

Schizophrenia Exhibits Bi-directional Brain-Wide Alterations in Cortico-Striato-Cerebellar Circuits

Distributed neural dysconnectivity is considered a hallmark feature of schizophrenia (SCZ), yet a tension exists between studies pinpointing focal disruptions versus those implicating brain-wide disturbances. The cerebellum and the striatum communicate reciprocally with the thalamus and cortex through monosynaptic and polysynaptic connections, forming cortico-striatal-thalamic-cerebellar (CSTC) functional pathways that may be sensitive to brain-wide dysconnectivity in SCZ. It remains unknown if the same pattern of alterations persists across CSTC systems, or if specific alterations exist along key functional elements of these networks. We characterized connectivity along major functional CSTC subdivisions using resting-state functional magnetic resonance imaging in 159 chronic patients and 162 matched controls. Associative CSTC subdivisions revealed consistent brain-wide bi-directional alterations in patients, marked by hyper-connectivity with sensory-motor cortices and hypo-connectivity with association cortex. Focusing on the cerebellar and striatal components, we validate the effects using data-driven k-means clustering of voxel-wise dysconnectivity and support vector machine classifiers. We replicate these results in an independent sample of 202 controls and 145 patients, additionally demonstrating that these neural effects relate to cognitive performance across subjects. Taken together, these results from complementary approaches implicate a consistent motif of brain-wide alterations in CSTC systems in SCZ, calling into question accounts of exclusively focal functional disturbances.

Cerebellar Theta Frequency Transcranial Pulsed Stimulation Increases Frontal Theta Oscillations in Patients with Schizophrenia

Cognitive dysfunction is a pervasive and disabling aspect of schizophrenia without adequate treatments. A recognized correlate to cognitive dysfunction in schizophrenia is attenuated frontal theta oscillations. Neuromodulation to normalize these frontal rhythms represents a potential novel therapeutic strategy. Here, we evaluate whether noninvasive neuromodulation of the cerebellum in patients with schizophrenia can enhance frontal theta oscillations, with the future goal of targeting the cerebellum as a possible therapy for cognitive dysfunction in schizophrenia. We stimulated the midline cerebellum using transcranial pulsed current stimulation (tPCS), a noninvasive transcranial direct current that can be delivered in a frequency-specific manner. A single 20-min session of theta frequency stimulation was delivered in nine patients with schizophrenia (cathode on right shoulder). Delta frequency tPCS was also delivered as a control to evaluate for frequency-specific effects. EEG signals from midfrontal electrode Cz were analyzed before and after cerebellar tPCS while patients estimated the passage of 3- and 12-s intervals. Theta oscillations were significantly larger following theta frequency cerebellar tPCS in the midfrontal region, which was not seen with delta frequency stimulation. As previously reported, patients with schizophrenia showed a baseline reduction in accuracy estimating 3- and 12-s intervals relative to control subjects, which did not significantly improve following a single-session theta or delta frequency cerebellar tPCS. These preliminary results suggest that single-session theta frequency cerebellar tPCS may modulate task-related oscillatory activity in the frontal cortex in a frequency-specific manner. These preliminary findings warrant further investigation to evaluate whether multiple sessions delivered daily may have an impact on cognitive performance and have therapeutic implications for schizophrenia.

Characterising the structure of cognitive heterogeneity in schizophrenia spectrum disorders. A systematic review and narrative synthesis

The aim of the present review was to systematically summarise our current understanding of the structure of the cognitive heterogeneity that exists within schizophrenia spectrum disorder (SSD). Fifty-two relevant studies were identified from January 1980 to March 2019 that investigated cognitive subgroups within SSD. Twenty-five studies employed classification criteria based on current neuropsychological function, 14 studies employed various data-driven subgrouping methodologies and 13 studies investigated putative cognitive symptom trajectories. Despite considerable methodological variability, three distinct cognitive subgroups reliability emerged; a relatively intact cognitive subgroup characterised by high cognitive performance, an intermediate cognitive subgroup defined by mixed or moderate levels of cognitive function/dysfunction and a globally impaired subgroup characterised by severe cognitive deficits. Whilst preliminary evidence suggests that these subgroups may have further investigative relevance in and of themselves, additional research is required and discussed. A set of reporting guidelines are also presented to overcome the methodological inconsistencies identified in the reviewed literature.

Diffusion kurtosis imaging of gray matter in schizophrenia

Prior postmortem studies have shown gray matter (GM) microstructural abnormalities in schizophrenia. However, few studies to date have examined GM microstructural integrity in schizophrenia in vivo. Here, we employed diffusion kurtosis imaging (DKI) to test for differences in GM microstructure in eighteen schizophrenia (SZ) patients versus nineteen healthy controls (HC). GM microstructure was characterized in each participant using DKI-derived metrics of mean kurtosis (MK) and mean diffusivity (MD). Individual T1-weighted images were used to create subject-specific cortically-labelled regions of interest (ROIs) of the four cortical lobes and sixty-eight cortical GM regions delineated by the Desikan-Killiany atlas, and to derive the associated cortical thickness and area measures. The derived ROIs were also registered to the diffusion space of each subject and used to generate region-specific mean MK and MD values. We additionally administered the Wisconsin Card Sorting Test (WCST), Stroop test, and Trail Making Test part B (Trails-B) to test the relationship between GM metrics and executive function in SZ. We found significantly increased MK and MD in SZ compared to HC participants in the temporal lobe, sub-lobar temporal cortical regions (fusiform, inferior temporal, middle temporal and temporal pole), and posterior cingulate cortex after correcting for multiple comparisons. Correlational analyses revealed significant associations of MK and MD with executive function scores derived from the WCST, Stroop, and Trails-B tests, along with an inverse relationship between MK and MD and cortical thickness and area. A hierarchical multiple linear regression analysis showed that up to 85% of the inter-subject variability in cognitive function in schizophrenia measured by the WCST could be explained by MK in combination with either GM thickness or area. MK and MD appear to be sensitive to GM microstructural pathology in schizophrenia and may provide useful biomarkers of abnormal cortical microstructure in this disorder.

Intra-individual variability in neurocognitive function in schizophrenia: relationships with the corpus callosum

Patients with schizophrenia not only have impairments in neurological function, but also have instability and variability in neurocognitive function. However, previous researchers have not fully studied the relationships between dispersion across multiple neurocognitive domains and white matter (WM) structures of the brain. This study focuses on intra-individual variability (IIV) in patients with schizophrenia and its relationship with WM integrity of the corpus callosum (CC). Thirty-eight patients with schizophrenia were enrolled in the study. All subjects underwent assessments of neurocognitive function using the Korean-Wechsler Adult Intelligence Scale-Revised (K-WAIS-R) and the severity of clinical symptoms using the Positive and Negative Syndrome Scale (PANSS). IIV across subtests of the K-WAIS-R was calculated using the Holtzer's equation. Tract-based spatial statistics were used to analyze diffusion tensor images. In subjects with schizophrenia, a negative correlation was found between IIV in performance intelligence quotient (PIQ) and fractional anisotropy (FA) values in the genu of the CC. In addition, FA values of the same region were negatively correlated with the total and subscale scores of positive symptoms and general psychopathology from the PANSS. Our findings suggest that the genu of the CC may play an important role in IIV in PIQ and symptomatology in patients with schizophrenia.

Callosal and subcortical white matter alterations in schizophrenia: A diffusion tensor imaging study at multiple levels

Diffusion tensor imaging and its distinct capability to detect micro-structural changes in vivo allows the exploration of white matter (WM) abnormalities in patients who have been diagnosed with schizophrenia; however, the results regarding the anatomical positions and degree of abnormalities are inconsistent. In order to obtain more robust and stable findings, we conducted a multi-level analysis to investigate WM disruption in a relatively large sample size (142 schizophrenia patients and 163 healthy subjects). Specifically, we evaluated the univariate fractional anisotropy (FA) in voxel level; the bivariate pairwise structural connectivity between regions using deterministic tractography as the network node defined by the Human Brainnetome Atlas; and the multivariate network topological properties, including the network hub, efficiency, small-worldness, and strength. Our data demonstrated callosal and subcortical WM alterations in patients with schizophrenia. These disruptions were evident in both voxel and connectivity levels and further supported by associations between FA values and illness duration. Based on the findings regarding topological properties, the structural network showed weaker global integration in patients with schizophrenia than in healthy subjects, while brain network hubs showed decreased functionality. We replicated these findings using an automated anatomical labeling atlas to define the network node. Our study indicates that callosal and subcortical WM disruptions are biomarkers for chronic schizophrenia.

Neuroanatomical Correlates of the Unity and Diversity Model of Executive Function in Young Adults

Understanding the neuroanatomical correlates of individual differences in executive function (EF) is integral to a complete characterization of the neural systems supporting cognition. While studies have investigated EF-neuroanatomy relationships in adults, these studies often include samples with wide variation in age, which may mask relationships between neuroanatomy and EF specific to certain neurodevelopmental time points, and such studies often use unreliable single task measures of EF. Here we address both issues. First, we focused on a specific age at which the majority of neurodevelopmental changes are complete but at which age-related atrophy is not likely (N = 251; mean age of 28.71 years, SD = 0.57). Second, we assessed EF through multiple tasks, deriving three factors scores guided by the unity/diversity model of EF, which posits a common EF factor that influences all EF tasks, as well as an updating-specific and shifting-specific factor. We found that better common EF was associated with greater volume and surface area of regions in right middle frontal gyrus/frontal pole, right inferior temporal gyrus, as well as fractional anisotropy in portions of the right superior longitudinal fasciculus (rSLF) and the left anterior thalamic radiation. Better updating-specific ability was associated with greater cortical thickness of a cluster in left cuneus/precuneus, and reduced cortical thickness in regions of right superior frontal gyrus and right middle/superior temporal gyrus, but no aspects of white matter diffusion. In contrast, better shifting-specific ability was not associated with gray matter characteristics, but rather was associated with increased mean diffusivity and reduced radial diffusivity throughout much of the brain and reduced axial diffusivity in distinct clusters of the left superior longitudinal fasciculus, the corpus callosum, and the right optic radiation. These results demonstrate that associations between individual differences in EF ability and regional neuroanatomical properties occur not only within classic brain networks thought to support EF, but also in a variety of other regions and white matter tracts. These relationships appear to differ from observations made in emerging adults (Smolker et al., 2015), which might indicate that the brain systems associated with EF continue to experience behaviorally relevant maturational process beyond the early 20s.

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.

Brain stimulation-induced neuroplasticity underlying therapeutic response in phantom sounds

Noninvasive brain stimulation can modify phantom sounds for longer periods by modulating neural activity and putatively inducing regional neuroplastic changes. However, treatment response is limited and there are no good demographic or clinical predictors for treatment outcome. We used state-of-the-art voxel-based morphometry (VBM) to investigate whether transcranial magnetic stimulation-induced neuroplasticity determines therapeutic outcome. Sixty subjects chronically experiencing phantom sounds (i.e., tinnitus) received repetitive transcranial magnetic stimulation (rTMS) of left dorsolateral prefrontal and temporal cortex according to a protocol that has been shown to yield a significantly higher number of treatment responders than sham stimulation and previous stimulation protocols. Structural magnetic resonance imaging was performed before and after rTMS. In VBM whole-brain analyses (P < 0.05, FWE corrected), we assessed longitudinal gray matter changes as well as structural connectivity between the ensuing regions. We observed longitudinal mesoscopic gray matter changes of left dorsolateral prefontal (DLPFC), left operculo-insular, and right inferior temporal cortex (ITC) in responders (N = 22) but not nonresponders (N = 38), as indicated by a group × time interaction and post-hoc tests. These results were neither influenced by age, sex, hearing loss nor by tinnitus laterality, duration, and severity at baseline. Furthermore, we found robust DLPFC-insula and insula-ITC connectivity in responders, while only relatively weak DLPFC-insula connectivity and no insula-ITC connectivity could be demonstrated in nonresponders. Our results reinforce the implication of nonauditory brain regions in phantom sounds and suggest the dependence of therapeutic response on their neuroplastic capabilities. The latter in turn may depend on (differences in) their individual structural connectivity. Hum Brain Mapp 39:554-562, 2018. © 2017 Wiley Periodicals, Inc.

Cognitive performance is associated with gray matter decline in first-episode psychosis

Progressive loss of gray matter has been demonstrated over the early course of schizophrenia. Identification of an association between cognition and gray matter may lead to development of early interventions directed at preserving gray matter volume and cognitive ability. The present study evaluated the association between gray matter using voxel-based morphometry (VBM) and cognitive testing in a sample of 16 patients with first-episode psychosis. A simple regression was applied to investigate the association between gray matter at baseline and 80 months and cognitive tests at baseline. Performance on the Wisconsin Card Sorting Task (WCST) at baseline was positively associated with gray matter volume in several brain regions. There was an association between decreased gray matter at baseline in the nucleus accumbens and Trails B errors. Performing worse on Trails B and making more WCST perseverative errors at baseline was associated with gray matter decline over 80 months in the right globus pallidus, left inferior parietal lobe, Brodmann's area (BA) 40, and left superior parietal lobule and BA 7 respectively. All significant findings were cluster corrected. The results support a relationship between aspects of cognitive impairment and gray matter abnormalities in first-episode psychosis.

Combination of behaviorally sub-effective doses of glutamate NMDA and dopamine D1 receptor antagonists impairs executive function

Impairment of executive function is a core feature of schizophrenia. Preclinical studies indicate that injections of either N-methyl d-aspartate (NMDA) or dopamine D₁ receptor blockers impair executive function. Despite the prevailing notion based on postmortem findings in schizophrenia that cortical areas have marked suppression of glutamate and dopamine, recent in vivo imaging studies suggest that abnormalities of these neurotransmitters in living patients may be quite subtle. Thus, we hypothesized that modest impairments in both glutamate and dopamine function can act synergistically to cause executive dysfunction. In the present study, we investigated the effect of combined administration of "behaviorally sub-effective" doses of NMDA and dopamine D₁ receptor antagonists on executive function. An operant conditioning-based set-shifting task was used to assess behavioral flexibility in rats that were systemically injected with NMDA and dopamine D₁ receptor antagonists individually or in combination prior to task performance. Separate injections of the NMDA receptor antagonist, MK-801, and the dopamine D₁ receptor antagonist, SCH 23390, at low doses did not impair set-shifting; however, the combined administration of these same behaviorally sub-effective doses of the antagonists significantly impaired the performance during set-shifting without affecting learning, retrieval of the memory of the initial rule, latency of responses or the number of omissions. The combined treatment also produced an increased number of perseverative errors. Our results indicate that NMDA and D₁ receptor blockade act synergistically to cause behavioral inflexibility, and as such, subtle abnormalities in glutamatergic and dopaminergic systems may act cooperatively to cause deficits in executive function.

Decreased Left Putamen and Thalamus Volume Correlates with Delusions in First-Episode Schizophrenia Patients

BACKGROUND

Delusional thinking is one of the hallmark symptoms of schizophrenia. However, the underlying neural substrate for delusions in schizophrenia remains unknown. In an attempt to further our understanding of the neural basis of delusions, we explored gray matter deficits and their clinical associations in first-episode schizophrenia patients with and without delusions.

METHODS

Twenty-four first-episode schizophrenia patients with delusions and 18 without delusions as well as 26 healthy controls (HC) underwent clinical assessment and whole-brain structural imaging which were acquired a 3.0 T scanner. Voxel-based morphometry was used to explore inter-group differences in gray matter volume using analysis of covariance, and Spearman correlation coefficients (rho) between the Scale for the Assessment of Positive Symptoms (SAPS)-delusion scores and mean regional brain volumes was obtained.

RESULTS

Patients with delusions showed decreased brain gray matter volumes in the left putamen, thalamus, and caudate regions compared with HC. Patients with delusions also showed decreased regional volume in the left putamen and thalamus compared with patients without delusions. SAPS-delusion scores were negatively correlated with the gray matter volumes of the left putamen and thalamus.

DISCUSSION

Left putamen and thalamus volume loss may be biological correlates of delusions in schizophrenia.

Gestational length affects neurocognition in early-onset schizophrenia

Obstetric complications (OC) have been linked to an increased risk for schizophrenia in offspring, especially in early-onset schizophrenia (EOS). Extensive cognitive deficits occur in EOS, although no study has yet to investigate the relationship between OC and cognition in EOS. This study aims to examine the frequency of OC in EOS compared to controls, and also investigates the relationship between OC and neurocognitive dysfunction in the two groups. Nineteen EOS patients and 53 healthy controls were tested with the MATRICS Consensus Cognitive Battery (MCCB), and the cognitive measures were combined with OC data from the Norwegian Birth Registry. The results indicated no group differences in OC in EOS and healthy controls, but a shorter gestational length in the EOS group led to significant decreases in the overall neurocognitive composite score, and in processing speed. This suggests that the poorer neuropsychological performances commonly found in EOS may be partly attributable to the length of gestation. The worsened neurocognitive functioning did not appear among controls, so gestational length had a different impact on the two groups. Our findings indicated that a shorter gestational length did not increase the risk for developing EOS, but did significantly affect the cognitive difficulties in this group.

Alterations in gray matter volume due to unilateral hearing loss

Although extensive research on neural plasticity resulting from hearing deprivation has been conducted, the direct influence of compromised audition on the auditory cortex and the potential impact of long durations of incomplete sensory stimulation on the adult cortex are still not fully understood. In this study, using voxel-based morphometry, we evaluated gray matter (GM) volume changes that may be associated with reduced hearing ability and the duration of hearing impairment in 42 unilateral hearing loss (UHL) patients with acoustic neuromas compared to 24 normal controls. We found significant GM volume increases in the somatosensory and motor systems and GM volume decreases in the auditory (i.e., Heschl’s gyrus) and visual systems (i.e., the calcarine cortex) in UHL patients. The GM volume decreases in the primary auditory cortex (i.e., superior temporal gyrus and Heschl’s gyrus) correlated with reduced hearing ability. Meanwhile, the GM volume decreases in structures involving high-level cognitive control functions (i.e., dorsolateral prefrontal cortex and anterior cingulate cortex) correlated positively with hearing loss duration. Our findings demonstrated that the severity and duration of UHL may contribute to the dissociated morphology of auditory and high-level neural structures, providing insight into the brain’s plasticity related to chronic, persistent partial sensory loss.

Cerebellar microstructural abnormalities in bipolar depression and unipolar depression: A diffusion kurtosis and perfusion imaging study

BACKGROUND

Depression in the context of bipolar disorder (BD) is often misdiagnosed as unipolar depression (UD), leading to mistreatment and poor clinical outcomes. However, little is known about the similarities and differences in cerebellum between BD and UD.

METHODS

Patients with BD (n=35) and UD (n=30) during a depressive episode as well as 40 healthy controls underwent diffusional kurtosis imaging (DKI) and three dimensional arterial spin labeling (3D ASL). The DKI parameters including mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr),fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da) and radial diffusivity (Dr) and 3D ASL parameters (i.e. cerebral blood flow) was measured by using regions-of-interest (ROIs) analysis in the superior cerebellar peduncles (SCP), middle cerebellar peduncles (MCP) and dentate nuclei (DN) of cerebellum.

RESULTS

Patients with UD exhibited significant differences from controls for DKI measures in bilateral SCP and MCP and cerebral blood flow (CBF) in bilateral SCP and left DN. Patients with BD exhibited significant differences from controls for DKI measures in the right MCP and left DN and CBF in the left DN. Patients with UD showed significantly lower MD values compared with patients with BD in the right SCP. Correlation analysis showed there were negative correlations between illness duration and MD and Dr values in the right SCP in UD.

LIMITATIONS

This study was cross-sectional and the sample size was not large. Parts of the patients included were under medication prior to MRI scanning.

CONCLUSIONS

Our findings provide new evidence of microstructural changes in cerebellum in BD and UD. The two disorders may have overlaps in microstructural abnormality in MCP and DN during the depressive period. Microstructural abnormality in SCP may be a key neurobiological feature of UD.

Impaired Activation in Cognitive Control Regions Predicts Reversal Learning in Schizophrenia

Reinforcement learning deficits have been associated with schizophrenia (SZ). However, the pathophysiology that gives rise to these abnormalities remains unclear. To address this question, SZ patients (N = 58) and controls (CN; N = 36) completed a probabilistic reversal-learning paradigm during functional magnetic resonance imaging scanning. During the task, participants choose between 2 stimuli. Initially, 1 stimulus was frequently rewarded (80%); the other was infrequently rewarded (20%). The reward contingencies reversed periodically because the participant learned the more rewarded stimulus. The results indicated that SZ patients achieved fewer reversals than CN, and demonstrated decreased winstay-loseshift decision-making behavior. On loseshift compared to winstay trials, SZ patients showed reduced Blood Oxygen Level Dependent activation compared to CN in a network of brain regions widely associated with cognitive control, and striatal regions. Importantly, relationships between group membership and behavior were mediated by alterations in the activity of cognitive control regions, but not striatum. These findings indicate an important role for the cognitive control network in mediating the use and updating of value representations in SZ. Such results provide biological targets for further inquiry because researchers attempt to better characterize decision-making neural circuitry in SZ as a means to discover new pathways for interventions.

Increased Causal Connectivity Related to Anatomical Alterations as Potential Endophenotypes for Schizophrenia

Anatomical and functional abnormalities in the cortico-cerebellar-thalamo-cortical circuit have been observed in schizophrenia patients and their unaffected siblings. However, it remains unclear to the relationship between anatomical and functional abnormalities within this circuit in schizophrenia patients and their unaffected siblings, which may serve as potential endophenotypes for schizophrenia.Anatomical and resting-state functional magnetic resonance imaging data were acquired from 49 first-episode, drug-naive schizophrenia patients, 46 unaffected siblings, and 46 healthy controls. Data were analyzed by using voxel-based morphometry and Granger causality analysis.The patients and the siblings shared anatomical deficits in the left middle temporal gyrus (MTG) and increased left MTG-left angular gyrus (AG) connectivity. Moreover, the left MTG-left AG connectivity negatively correlates to the duration of untreated psychosis in the patients.The findings indicate that anatomical deficits in the left MTG and its increased causal connectivity with the left AG may serve as potential endophenotypes for schizophrenia with clinical implications.

The neuroanatomical basis of panic disorder and social phobia in schizophrenia: a voxel based morphometric study

Objective

It is known that there is a high prevalence of certain anxiety disorders among schizophrenic patients, especially panic disorder and social phobia. However, the neural underpinnings of the comorbidity of such anxiety disorders and schizophrenia remain unclear. Our study aims to determine the neuroanatomical basis of the co-occurrence of schizophrenia with panic disorder and social phobia.

Methods

Voxel-based morphometry was used in order to examine brain structure and to measure between-group differences, comparing magnetic resonance images of 20 anxious patients, 20 schizophrenic patients, 20 schizophrenic patients with comorbid anxiety, and 20 healthy control subjects.

Results

Compared to the schizophrenic patients, we observed smaller grey-matter volume (GMV) decreases in the dorsolateral prefrontal cortex and precentral gyrus in the schizophrenic-anxiety group. Additionally, the schizophrenic group showed significantly reduced GMV in the dorsolateral prefrontal cortex, precentral gyrus, orbitofrontal cortex, temporal gyrus and angular/inferior parietal gyrus when compared to the control group.

Conclusions

Our findings suggest that the comorbidity of schizophrenia with panic disorder and social phobia might be characterized by specific neuroanatomical and clinical alterations that may be related to maladaptive emotion regulation related to anxiety. Even thought our findings need to be replicated, our study suggests that the identification of neural abnormalities involved in anxiety, schizophrenia and schizophrenia-anxiety may lead to an improved diagnosis and management of these conditions.

Medial frontal gyrus alterations in schizophrenia: relationship with duration of illness and executive dysfunction

Executive functioning is consistently impaired in schizophrenia, and it has been associated with reduced gray matter volume in prefrontal areas. Abnormalities in prefrontal brain regions have also been related to the illness duration. The aim of the study was to investigate the effect of executive functioning decline and chronicity in prefrontal regions of patients with schizophrenia. Participants comprised 33 schizophrenic patients, 18 with duration of illness (DoI) shorter than 10 years and 15 with duration of illness longer than 10 years. In addition, 24 healthy controls served as a comparison group. Participants performed the Wisconsin Card Sorting Test (WCST) and underwent structural magnetic resonance imaging. Patients with longer DoI showed significant reduction of gray matter volume in the left medial frontal gyrus compared with healthy controls. Moreover, there was a trend for greater gray matter volume decrease in patients with a longer illness duration compared with patients with shorter illness duration. There was no interaction between the volume of the left medial frontal gyrus performance on the WCST. The present study supports the hypothesis that medial frontal gyrus alterations in schizophrenia are sensitive to duration of illness. These alterations were not associated with executive functioning.

Abnormal causal connectivity by structural deficits in first-episode, drug-naive schizophrenia at rest

Anatomical deficits and resting-state functional connectivity (FC) alterations in prefrontal-thalamic-cerebellar circuit have been implicated in the neurobiology of schizophrenia. However, the effect of structural deficits in schizophrenia on causal connectivity of this circuit remains unclear. This study was conducted to examine the causal connectivity biased by structural deficits in first-episode, drug-naive schizophrenia patients. Structural and resting-state functional magnetic resonance imaging (fMRI) data were obtained from 49 first-episode, drug-naive schizophrenia patients and 50 healthy controls. Data were analyzed by voxel-based morphometry and Granger causality analysis. The causal connectivity of the integrated prefrontal-thalamic (limbic)-cerebellar (sensorimotor) circuit was partly affected by structural deficits in first-episode, drug-naive schizophrenia as follows: (1) unilateral prefrontal-sensorimotor connectivity abnormalities (increased driving effect from the left medial prefrontal cortex [MPFC] to the sensorimotor regions); (2) bilateral limbic-sensorimotor connectivity abnormalities (increased driving effect from the right anterior cingulate cortex [ACC] to the sensorimotor regions and decreased feedback from the sensorimotor regions to the right ACC); and (3) bilateral increased and decreased causal connectivities among the sensorimotor regions. Some correlations between the gray matter volume of the seeds, along with their causal effects and clinical variables (duration of untreated psychosis and symptom severity), were also observed in the patients. The findings indicated the partial effects of structural deficits in first-episode, drug-naive schizophrenia on the prefrontal-thalamic (limbic)-cerebellar (sensorimotor) circuit. Schizophrenia may reinforce the driving connectivities from the left MPFC or right ACC to the sensorimotor regions and may disrupt bilateral causal connectivities among the sensorimotor regions.

Schizophrenia and cortical blindness: protective effects and implications for language

The repeatedly noted absence of case-reports of individuals with schizophrenia and congenital/early developed blindness has led several authors to argue that the latter can confer protective effects against the former. In this work, we present a number of relevant case-reports from different syndromes that show comorbidity of congenital and early blindness with schizophrenia. On the basis of these reports, we argue that a distinction between different types of blindness in terms of the origin of the visual deficit, cortical or peripheral, is crucial for understanding the observed patterns of comorbidity. We discuss the genetic underpinnings and the brain structures involved in schizophrenia and blindness, with insights from language processing, laying emphasis on the three structures that particularly stand out: the occipital cortex, the lateral geniculate nucleus (LGN), and the pulvinar. Last, we build on previous literature on the nature of the protective effects in order to offer novel insights into the nature of the protection mechanism from the perspective of the brain structures involved in each type of blindness.

Disrupted modular architecture of cerebellum in schizophrenia: a graph theoretic analysis

Recent studies of schizophrenia have revealed cognitive and memory deficits that are accompanied by disruptions of neuronal connectivity in cortical and subcortical brain regions. More recently, alterations of topological organization of structural networks in schizophrenia are also being identified using graph theoretical analysis. However, the role of the cerebellum in this network structure remains largely unknown. In this study, global network measures obtained from diffusion tensor imaging were computed in the cerebella of 25 patients with schizophrenia and 36 healthy volunteers. While cerebellar global network characteristics were slightly altered in schizophrenia patients compared with healthy controls, the patients showed a retained small-world network organization. The modular architecture, however, was changed mainly in crus II. Furthermore, schizophrenia patients had reduced correlations between modularity and microstructural integrity, as measured by fractional anisotropy (FA) in lobules I-IV and X. Finally, FA alterations were significantly correlated with the Positive and Negative Syndrome Scale symptom scores in schizophrenia patients. Taken together, our data suggest that schizophrenia patients have altered network architecture in the cerebellum with reduced local microstructural connectivity and that cerebellar structural abnormalities are associated symptoms of the disorder.

Multivariate neuroanatomical classification of cognitive subtypes in schizophrenia: a support vector machine learning approach

Heterogeneity in the structural brain abnormalities associated with schizophrenia has made identification of reliable neuroanatomical markers of the disease difficult. The use of more homogenous clinical phenotypes may improve the accuracy of predicting psychotic disorder/s on the basis of observable brain disturbances. Here we investigate the utility of cognitive subtypes of schizophrenia - 'cognitive deficit' and 'cognitively spared' - in determining whether multivariate patterns of volumetric brain differences can accurately discriminate these clinical subtypes from healthy controls, and from each other. We applied support vector machine classification to grey- and white-matter volume data from 126 schizophrenia patients previously allocated to the cognitive spared subtype, 74 cognitive deficit schizophrenia patients, and 134 healthy controls. Using this method, cognitive subtypes were distinguished from healthy controls with up to 72% accuracy. Cross-validation analyses between subtypes achieved an accuracy of 71%, suggesting that some common neuroanatomical patterns distinguish both subtypes from healthy controls. Notably, cognitive subtypes were best distinguished from one another when the sample was stratified by sex prior to classification analysis: cognitive subtype classification accuracy was relatively low (<60%) without stratification, and increased to 83% for females with sex stratification. Distinct neuroanatomical patterns predicted cognitive subtype status in each sex: sex-specific multivariate patterns did not predict cognitive subtype status in the other sex above chance, and weight map analyses demonstrated negative correlations between the spatial patterns of weights underlying classification for each sex. These results suggest that in typical mixed-sex samples of schizophrenia patients, the volumetric brain differences between cognitive subtypes are relatively minor in contrast to the large common disease-associated changes. Volumetric differences that distinguish between cognitive subtypes on a case-by-case basis appear to occur in a sex-specific manner that is consistent with previous evidence of disrupted relationships between brain structure and cognition in male, but not female, schizophrenia patients. Consideration of sex-specific differences in brain organization is thus likely to assist future attempts to distinguish subgroups of schizophrenia patients on the basis of neuroanatomical features.

Dissociation of functional and anatomical brain abnormalities in unaffected siblings of schizophrenia patients

OBJECTIVE

Schizophrenia patients and their unaffected siblings share similar brain functional and structural abnormalities. However, no study is engaged to investigate whether and how functional abnormalities are related to structural abnormalities in unaffected siblings. This study was undertaken to examine the association between functional and anatomical abnormalities in unaffected siblings.

METHODS

Forty-six unaffected siblings of schizophrenia patients and 46 age-, sex-, and education-matched healthy controls underwent structural and resting-state functional magnetic resonance imaging scanning. Voxel-based morphometry (VBM), amplitude of low-frequency fluctuation (ALFF) and fractional ALFF (fALFF) were utilized to analyze imaging data.

RESULTS

The VBM analysis showed gray matter volume decreases in the fronto-temporal regions (the left middle temporal gyrus and right inferior frontal gyrus, orbital part) and increases in basal ganglia system (the left putamen). Functional abnormalities measured by ALFF and fALFF mainly involved in the fronto-limbic-sensorimotor circuit (decreased ALFF in bilateral middle frontal gyrus and the right middle cingulate gyrus, and decreased fALFF in the right inferior frontal gyrus, orbital part; and increased ALFF in the left fusiform gyrus and left lingual gyrus, and increased fALFF in bilateral calcarine cortex). No significant correlation was found between functional and anatomical abnormalities in the sibling group.

CONCLUSIONS

A dissociation pattern of brain regions with functional and anatomical abnormalities is observed in unaffected siblings.

SIGNIFICANCE

Our findings suggest that brain functional and anatomical abnormalities might be present independently in unaffected siblings of schizophrenia patients.

Juggling revisited - a voxel-based morphometry study with expert jugglers

Juggling is a highly interesting tool to investigate neuroplasticity associated with motor-learning. Several brain-imaging studies have reported changes in regional brain morphology in visual association cortices in individuals learning how to juggle a three-ball cascade. However, to our knowledge there are no studies that investigated expert jugglers, looking for specific features in regional brain morphology related to this highly specialized skill. Using T1-weighted images and voxel-based morphometry we investigated in a cross-sectional study design 16 expert jugglers, able to juggle at least five balls and an age- and gender-matched group of non-jugglers. We hypothesized that expert jugglers would show higher gray matter density in regions involved in visual motion perception and eye-hand coordination. Images were pre-processed and analyzed using SPM8. Age was included in the analyses as covariate of no interest. As compared to controls jugglers displayed several clusters of higher, regional gray matter density in the occipital and parietal lobes including the secondary visual cortex, the hMT+/V5 area bilaterally and the intraparietal sulcus bilaterally. Within the jugglers group we also found a correlation between performance and regional gray matter density in the right hMT+/V5 area. Our study provides evidence that expert jugglers show increased gray matter density in brain regions involved in visual motion perception and eye-hand coordination, i.e. brain areas that have previously been shown to undergo dynamic changes in terms of gray matter increases in subjects learning a basic three-ball cascade. The extent to which transient increases in beginners and the differences in experts and non-experts are based on the same neurobiological correlates remains to be fully elucidated.