Neurological Soft Signs Are Associated With Altered Cerebellar-Cerebral Functional Connectivity in Schizophrenia

Psychomotor slowing in schizophrenia is associated with aberrant postural control

Motor abnormalities, including psychomotor slowing, are prevalent in a large proportion of individuals with schizophrenia. While postural control deficits have been observed in this population, the impact of motor abnormalities on postural stability remains unclear. This study aimed to objectively evaluate postural stability in patients with and without psychomotor slowing and healthy controls. Seventy-three schizophrenia patients with psychomotor slowing (PS; Salpêtrière Retardation Rating Scale (SRRS) ≥ 15), 25 schizophrenia patients without psychomotor slowing (non-PS; SRRS < 15), and 27 healthy controls (HC) performed four conditions on the Kistler force plate: eyes open (EO), eyes closed (EC), head reclined with eyes open (EOHR), and head reclined with eyes closed (ECHR). Larger sway areas and higher Root Mean Square (RMS) values indicate lower postural stability, while a lower Complexity Index (CI) reflects reduced adaptability, flexibility, and dynamic functioning of postural control. PS exhibited larger sway areas and higher RMS compared to the other groups. Both PS and non-PS showed reduced complexity in postural control compared to healthy controls, without differences between the two patient groups. Reduced postural stability and complexity were associated with greater expert-rated motor abnormalities, as well as more severe negative symptoms. Additionally, lower complexity was linked to reduced physical activity levels. These findings suggest that psychomotor slowing is associated with lower postural stability, potentially reflecting impaired cerebellar function. Furthermore, the loss of complexity in postural control highlights reduced flexibility, adaptability, and efficiency in the postural control network of individuals with schizophrenia.

Disrupted emotion regulation and spontaneous neural activity in panic disorder: a resting-state fMRI study

Background

Emotional dysregulation, particularly unconscious catastrophic cognitions, plays a pivotal role in the genesis of panic disorder (PD). However, no studies have yet applied the percentage of amplitude fluctuation (PerAF) metric in resting-state functional magnetic resonance imaging to examine spontaneous neural functioning and its relation to catastrophic cognitions in PD.

Objectives

To explore the interplay between resting-state neural activity, functional connectivity (FC), and unconscious emotion regulation in individuals with PD.

Design

Cross-sectional study.

Methods

The study encompassed 51 participants, including 26 PD patients and 25 healthy individuals. The PerAF algorithm was employed to explore the local spontaneous neural activity in PD. Regions exhibiting aberrant spontaneous neural activity were used as seed points for whole-brain FC analysis. Correlations were utilized to examine associations between local neural activity patterns and neurocognitive assessments in PD.

Results

The study revealed that compared to healthy individuals, PD patients exhibited elevated PerAF values in key emotion-regulation-related brain regions, including the ventromedial prefrontal cortex (vmPFC), striatum, amygdala, dorsomedial prefrontal cortex (dmPFC), and cerebellum. In addition, the resting-state FC between vmPFC and precuneus, as well as between the cerebellum and precuneus, was weakened in PD patients. Furthermore, positive associations were noted between PerAF measurements of vmPFC and amygdala and catastrophizing scores.

Conclusion

PD involves regional and network-level alterations in resting-state brain activity. The fronto-striatal-limbic circuits play a critical role in catastrophic-style emotion regulation in PD patients. Reduced FC within the default mode network and cerebellum-default mode network may signify a coordination anomaly in introspection and cognitive activities in PD. These findings complement the model of implicit emotion regulation in PD and suggest potential intervention targets.

A Comparative Study of Frontal and Cerebellar Lobe Volumes Between Patients With First-Episode Schizophrenia and Healthy Controls and Its Association With Psychopathology and Neurological Soft Signs in Patients

Objectives Our study aimed to investigate the fronto-cerebellar volumes in both patients and controls, as well as explore their relationship with symptomatology. Our primary objectives were to compare the frontal and cerebellar lobe volumetric measurements between patients with first-episode schizophrenia (FES) and healthy controls and to assess the relationship of these volumes with psychopathology, cognition, and neurological soft signs in FES patients. The secondary objective was to explore the association of fronto-cerebellar lobe volumes with socio-demographic factors among patients and controls, as well as the duration of untreated illness (DUI) among patients. Materials and methods This was a cross-sectional, case-control study involving 60 participants, including 30 antipsychotic-naïve FES patients and 30 healthy controls. Participants underwent MRI scanning to measure frontal and cerebellar lobe volumes using the volBrain platform. Additionally, FES patients were assessed using the Positive and Negative Syndrome Scale (PANSS), Montreal Cognitive Assessment-Basic (MoCA-B), and Brief Motor Scale (BMS). Pearson's correlation, independent sample t-tests, multivariate linear regression, and binomial logistic regression were used to analyze the relationships between brain volumes, clinical assessments, and socio-demographic factors. Results No significant differences in frontal volumes were found between the two groups, while cerebellar volumes were significantly smaller in FES patients (p=0.004), particularly in younger males (p=0.026). Frontal volumes were negatively correlated with age in both groups (p=0.012), which remained robust in patients even after controlling for their gender, education, and DUI (p=0.012, aR2=0.221). Cerebellar volume reduction was associated with a higher likelihood of being classified as a patient (p=0.029). BMS was significantly correlated with frontal lobe volumes, especially in motor sequencing (MoSe), after adjusting for age, gender, and education (p=0.009). BMS MoSe scores were also significantly positively correlated with the DUI (r=0.415, p=0.023) and PANSS-General Psychopathology (GP) (r=0.494, p=0.005). MoCA-B scores were significantly lower in females than males (p=0.016), while PANSS-GP was significantly negatively correlated with age (r=-0.432, p=0.017). Conclusion Frontal and cerebellar volumes were differentially impacted in FES, with cerebellar atrophy being a significant distinguishing feature of the disorder. Frontal atrophy was associated with motor dysfunction but did not appear to influence psychopathology or cognition significantly in the early stages. The independent effects of frontal and cerebellar volumes, as shown by the lack of correlation between them, may suggest that these brain regions undergo separate pathological processes in schizophrenia, with frontal functional changes impacting motor function and cerebellar structural changes contributing to broader psychiatric symptoms, thereby warranting further exploration involving larger sample size.

A Lightweight Multi-Mental Disorders Detection Method Using Entropy-Based Matrix from Single-Channel EEG Signals

Background: Mental health issues are increasingly prominent worldwide, posing significant threats to patients and deeply affecting their families and social relationships. Traditional diagnostic methods are subjective and delayed, indicating the need for an objective and effective early diagnosis method. Methods: To this end, this paper proposes a lightweight detection method for multi-mental disorders with fewer data sources, aiming to improve diagnostic procedures and enable early patient detection. First, the proposed method takes Electroencephalography (EEG) signals as sources, acquires brain rhythms through Discrete Wavelet Decomposition (DWT), and extracts their approximate entropy, fuzzy entropy, permutation entropy, and sample entropy to establish the entropy-based matrix. Then, six kinds of conventional machine learning classifiers, including Support Vector Machine (SVM), k-Nearest Neighbors (kNN), Naive Bayes (NB), Generalized Additive Model (GAM), Linear Discriminant Analysis (LDA), and Decision Tree (DT), are adopted for the entropy-based matrix to achieve the detection task. Their performances are assessed by accuracy, sensitivity, specificity, and F1-score. Concerning these experiments, three public datasets of schizophrenia, epilepsy, and depression are utilized for method validation. Results: The analysis of the results from these datasets identifies the representative single-channel signals (schizophrenia: O1, epilepsy: F3, depression: O2), satisfying classification accuracies (88.10%, 75.47%, and 89.92%, respectively) with minimal input. Conclusions: Such performances are impressive when considering fewer data sources as a concern, which also improves the interpretability of the entropy features in EEG, providing a reliable detection approach for multi-mental disorders and advancing insights into their underlying mechanisms and pathological states.

Accelerated Cortical Thinning in Schizophrenia Is Associated With Rare and Common Predisposing Variation to Schizophrenia and Neurodevelopmental Disorders

BACKGROUND

Schizophrenia is a highly heritable disorder characterized by increased cortical thinning throughout the life span. Studies have reported a shared genetic basis between schizophrenia and cortical thickness. However, no genes whose expression is related to abnormal cortical thinning in schizophrenia have been identified.

METHODS

We conducted linear mixed models to estimate the rates of accelerated cortical thinning across 68 regions from the Desikan-Killiany atlas in individuals with schizophrenia compared with healthy control participants from a large longitudinal sample (ncases = 169 and ncontrols = 298, ages 16-70 years). We studied the correlation between gene expression data from the Allen Human Brain Atlas and accelerated thinning estimates across cortical regions. Finally, we explored the functional and genetic underpinnings of the genes that contribute most to accelerated thinning.

RESULTS

We found a global pattern of accelerated cortical thinning in individuals with schizophrenia compared with healthy control participants. Genes underexpressed in cortical regions that exhibit this accelerated thinning were downregulated in several psychiatric disorders and were enriched for both common and rare disrupting variation for schizophrenia and neurodevelopmental disorders. In contrast, none of these enrichments were observed for baseline cross-sectional cortical thickness differences.

CONCLUSIONS

Our findings suggest that accelerated cortical thinning, rather than cortical thickness alone, serves as an informative phenotype for neurodevelopmental disruptions in schizophrenia. We highlight the genetic and transcriptomic correlates of this accelerated cortical thinning, emphasizing the need for future longitudinal studies to elucidate the role of genetic variation and the temporal-spatial dynamics of gene expression in brain development and aging in schizophrenia.

Altered static and dynamic cerebellar-cerebral functional connectivity in acute pontine infarction

This study investigates abnormalities in cerebellar-cerebral static and dynamic functional connectivity among patients with acute pontine infarction, examining the relationship between these connectivity changes and behavioral dysfunction. Resting-state functional magnetic resonance imaging was utilized to collect data from 45 patients within seven days post-pontine infarction and 34 normal controls. Seed-based static and dynamic functional connectivity analyses identified divergences in cerebellar-cerebral connectivity features between pontine infarction patients and normal controls. Correlations between abnormal functional connectivity features and behavioral scores were explored. Compared to normal controls, left pontine infarction patients exhibited significantly increased static functional connectivity within the executive, affective-limbic, and motor networks. Conversely, right pontine infarction patients demonstrated decreased static functional connectivity in the executive, affective-limbic, and default mode networks, alongside an increase in the executive and motor networks. Decreased temporal variability of dynamic functional connectivity was observed in the executive and default mode networks among left pontine infarction patients. Furthermore, abnormalities in static and dynamic functional connectivity within the executive network correlated with motor and working memory performance in patients. These findings suggest that alterations in cerebellar-cerebral static and dynamic functional connectivity could underpin the behavioral dysfunctions observed in acute pontine infarction patients.

Cerebellar dysconnectivity in schizophrenia and bipolar disorder is associated with cognitive and clinical variables

BACKGROUND

Abnormal cerebellar functional connectivity (FC) has been implicated in the pathophysiology of schizophrenia (SCZ) and bipolar disorder (BD). However, the patterns of cerebellar dysconnectivity in these two disorders and their association with cognitive functioning and clinical symptoms have not been fully clarified. In this study, we examined cerebellar FC alterations in SCZ and BD-I and their association with cognition and psychotic symptoms.

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) data of 39 SCZ, 43 BD-I, and 61 healthy controls from the Consortium for Neuropsychiatric Phenomics dataset were examined. The cerebellum was parcellated into ten functional networks, and seed-based FC was calculated for each cerebellar system. Principal component analyses were used to reduce the dimensionality of the diagnosis-related FC and cognitive variables. Multiple regression analyses were used to assess the relationship between FC and cognitive and clinical data.

RESULTS

We observed decreased cerebellar FC with the frontal, temporal, occipital, and thalamic areas in individuals with SCZ, and a more widespread decrease in cerebellar FC in individuals with BD-I, involving the frontal, cingulate, parietal, temporal, occipital, and thalamic regions. SCZ had increased within-cerebellum and cerebellar frontal FC compared to BD-I. In BD-I, memory and verbal learning performances, which were higher compared to SCZ, showed a greater interaction with cerebellar FC patterns. Additionally, patterns of increased cortico-cerebellar FC were marginally associated with positive symptoms in patients.

CONCLUSIONS

Our findings suggest that shared and distinct patterns of cortico-cerebellar dysconnectivity in SCZ and BD-I could underlie cognitive impairments and psychotic symptoms in these disorders.

The pathobiology of psychomotor slowing in psychosis: altered cortical excitability and connectivity

Psychomotor slowing is a frequent symptom of schizophrenia. Short-interval intracortical inhibition assessed by transcranial magnetic stimulation demonstrated inhibitory dysfunction in schizophrenia. The inhibitory deficit results from additional noise during information processing in the motor system in psychosis. Here, we tested whether cortical inhibitory dysfunction was linked to psychomotor slowing and motor network alterations. In this cross-sectional study, we included 60 patients with schizophrenia and psychomotor slowing determined by the Salpêtrière Retardation Rating Scale, 23 patients without slowing and 40 healthy control participants. We acquired single and double-pulse transcranial magnetic stimulation effects from the left primary motor cortex, resting-state functional connectivity and diffusion imaging on the same day. Groups were compared on resting motor threshold, amplitude of the motor evoked potentials, as well as short-interval intracortical inhibition. Regression analyses calculated the association between motor evoked potential amplitudes or cortical inhibition with seed-based resting-state functional connectivity from the left primary motor cortex and fractional anisotropy at whole brain level and within major motor tracts. In patients with schizophrenia and psychomotor slowing, we observed lower amplitudes of motor evoked potentials, while the short-interval intracortical inhibition/motor evoked potentials amplitude ratio was higher than in healthy controls, suggesting lower cortical inhibition in these patients. Patients without slowing also had lower amplitudes of motor evoked potentials. Across the combined patient sample, cortical inhibition deficits were linked to more motor coordination impairments. In patients with schizophrenia and psychomotor slowing, lower amplitudes of motor evoked potentials were associated with lower fractional anisotropy in motor tracts. Moreover, resting-state functional connectivity between the primary motor cortex, the anterior cingulate cortex and the cerebellum increased with stronger cortical inhibition. In contrast, in healthy controls and patients without slowing, stronger cortical inhibition was linked to lower resting-state functional connectivity between the left primary motor cortex and premotor or parietal cortices. Psychomotor slowing in psychosis is linked to less cortical inhibition and aberrant functional connectivity of the primary motor cortex. Higher neural noise in the motor system may drive psychomotor slowing and thus may become a treatment target.

Clinical and Sociodemographic Correlations with Neurological Soft Signs in Hospitalized Patients with Schizophrenia: A Preliminary Longitudinal Study

Schizophrenia is a severe, chronic neuropsychiatric disorder characterized by symptoms that profoundly impact behavior, cognition, perception, and emotions, leading to a reduced quality of life and physical impairment. Given the complexity of schizophrenia, there is a pressing need for clinical markers and tools to predict its course, enhance disease staging, facilitate early intervention, improve differential diagnosis, and tailor individualized treatment approaches. Previous studies focused on the relationship between neurological soft signs (NSS) and factors such as age, illness duration, and symptomatology, indicating NSS as state markers improving in parallel with psychotic symptom remission or predicting treatment resistance. However, there is a lack of consensus on NSS assessment tools, hindering routine clinical monitoring despite diagnostic and prognostic potential. The present longitudinal study involved 81 psychiatric inpatients diagnosed with schizophrenia. Patients were assessed at three time points: baseline, 1 month, and 6 months. The examination included the use of scales to evaluate psychotic and neurological symptoms, as well as the identification of adverse extrapyramidal reactions caused by neuroleptic treatment. The progression of NSS was correlated to both the symptomatology and the sociodemographic data of the patients. The main findings from the present investigation revealed a statistical correlation between NSS and psychopathological symptoms, especially with negative symptoms of schizophrenia. However, it is important to note that neuroleptic side effects only had a limited impact on NSS. Therefore, instead of being linked to extrapyramidal symptoms caused by neuroleptics, NSS appears to be more frequently related with symptoms of schizophrenia. Our findings provide further support for their strong association with the course of schizophrenia, independent of treatment side effects, thus emphasizing their potential as reliable assessment tools in both research and clinical settings.

Abnormal resting-state effective connectivity in large-scale networks among obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is a chronic mental illness characterized by abnormal functional connectivity among distributed brain regions. Previous studies have primarily focused on undirected functional connectivity and rarely reported from network perspective.

METHODS

To better understand between or within-network connectivities of OCD, effective connectivity (EC) of a large-scale network is assessed by spectral dynamic causal modeling with eight key regions of interests from default mode (DMN), salience (SN), frontoparietal (FPN) and cerebellum networks, based on large sample size including 100 OCD patients and 120 healthy controls (HCs). Parametric empirical Bayes (PEB) framework was used to identify the difference between the two groups. We further analyzed the relationship between connections and Yale-Brown Obsessive Compulsive Scale (Y-BOCS).

RESULTS

OCD and HCs shared some similarities of inter- and intra-network patterns in the resting state. Relative to HCs, patients showed increased ECs from left anterior insula (LAI) to medial prefrontal cortex, right anterior insula (RAI) to left dorsolateral prefrontal cortex (L-DLPFC), right dorsolateral prefrontal cortex (R-DLPFC) to cerebellum anterior lobe (CA), CA to posterior cingulate cortex (PCC) and to anterior cingulate cortex (ACC). Moreover, weaker from LAI to L-DLPFC, RAI to ACC, and the self-connection of R-DLPFC. Connections from ACC to CA and from L-DLPFC to PCC were positively correlated with compulsion and obsession scores (r = 0.209, p = 0.037; r = 0.199, p = 0.047, uncorrected).

CONCLUSIONS

Our study revealed dysregulation among DMN, SN, FPN, and cerebellum in OCD, emphasizing the role of these four networks in achieving top-down control for goal-directed behavior. There existed a top-down disruption among these networks, constituting the pathophysiological and clinical basis.

Revisiting reward impairments in schizophrenia spectrum disorders: a systematic review and meta-analysis for neuroimaging findings

BACKGROUND

Abnormal reward functioning is central to anhedonia and amotivation symptoms of schizophrenia (SCZ). Reward processing encompasses a series of psychological components. This systematic review and meta-analysis examined the brain dysfunction related to reward processing of individuals with SCZ spectrum disorders and risks, covering multiple reward components.

METHODS

After a systematic literature search, 37 neuroimaging studies were identified and divided into four groups based on their target psychology components (i.e. reward anticipation, reward consumption, reward learning, effort computation). Whole-brain Seed-based d Mapping (SDM) meta-analyses were conducted for all included studies and each component.

RESULTS

The meta-analysis for all reward-related studies revealed reduced functional activation across the SCZ spectrum in the striatum, orbital frontal cortex, cingulate cortex, and cerebellar areas. Meanwhile, distinct abnormal patterns were found for reward anticipation (decreased activation of the cingulate cortex and striatum), reward consumption (decreased activation of cerebellum IV/V areas, insula and inferior frontal gyri), and reward learning processing (decreased activation of the striatum, thalamus, cerebellar Crus I, cingulate cortex, orbitofrontal cortex, and parietal and occipital areas). Lastly, our qualitative review suggested that decreased activation of the ventral striatum and anterior cingulate cortex was also involved in effort computation.

CONCLUSIONS

These results provide deep insights on the component-based neuro-psychopathological mechanisms for anhedonia and amotivation symptoms of the SCZ spectrum.

Movement initiation and preparation in subjects with schizophrenia - The amplitude of the readiness potential as a biological marker for negative symptom severity

OBJECTIVE

Despite extensive research, the etiology of negative symptoms is not well understood. Preliminary findings are linking motor disturbances to negative symptom severity. We aimed to further the understanding to what extent motor movement preparation influences negative symptom severity.

METHODS

In a cohort of 31 subjects with schizophrenia and 20 control subjects we recorded the readiness potential amplitude over Cz during spontaneous movements of the right and left thumb. We further assessed negative and positive symptom severity (scale for the assessment of negative and positive symptoms) as well as neurological soft signs (NSS).

RESULTS

In subjects with schizophrenia the severity of negative symptoms was best predicted by the readiness potential amplitude and the NSS subdomain motor coordination. The correlation between deficits in motor coordination and negative symptom severity was partially mediated by the readiness potential amplitude in subjects with schizophrenia.

CONCLUSIONS

Deficits in motor processing are linked to negative symptom severity in schizophrenia. The readiness potential may represent a biological marker of these basal deficits. In combination with the assessment of NSS, the readiness potential may be a marker of the course of negative symptom severity and help clarifying interdependencies between (pre)frontal networks for action initiation and coordination, as well as negative symptoms.

A tablet-based quantitative assessment of manual dexterity for detection of early psychosis

Background

We performed a pilot study on whether tablet-based measures of manual dexterity can provide behavioral markers for detection of first-episode psychosis (FEP), and whether cortical excitability/inhibition was altered in FEP.

Methods

Behavioral and neurophysiological testing was undertaken in persons diagnosed with FEP (N = 20), schizophrenia (SCZ, N = 20), autism spectrum disorder (ASD, N = 20), and in healthy control subjects (N = 20). Five tablet tasks assessed different motor and cognitive functions: Finger Recognition for effector (finger) selection and mental rotation, Rhythm Tapping for temporal control, Sequence Tapping for control/memorization of motor sequences, Multi Finger Tapping for finger individuation, and Line Tracking for visuomotor control. Discrimination of FEP (from other groups) based on tablet-based measures was compared to discrimination through clinical neurological soft signs (NSS). Cortical excitability/inhibition, and cerebellar brain inhibition were assessed with transcranial magnetic stimulation.

Results

Compared to controls, FEP patients showed slower reaction times and higher errors in Finger Recognition, and more variability in Rhythm Tapping. Variability in Rhythm Tapping showed highest specificity for the identification of FEP patients compared to all other groups (FEP vs. ASD/SCZ/Controls; 75% sensitivity, 90% specificity, AUC = 0.83) compared to clinical NSS (95% sensitivity, 22% specificity, AUC = 0.49). Random Forest analysis confirmed FEP discrimination vs. other groups based on dexterity variables (100% sensitivity, 85% specificity, balanced accuracy = 92%). The FEP group had reduced short-latency intra-cortical inhibition (but similar excitability) compared to controls, SCZ, and ASD. Cerebellar inhibition showed a non-significant tendency to be weaker in FEP.

Conclusion

FEP patients show a distinctive pattern of dexterity impairments and weaker cortical inhibition. Easy-to-use tablet-based measures of manual dexterity capture neurological deficits in FEP and are promising markers for detection of FEP in clinical practice.

Clinical anatomy of the precuneus and pathogenesis of the schizophrenia

Recent evidence has shown that the precuneus plays a role in the pathogenesis of schizophrenia. The precuneus is a structure of the parietal lobe's medial and posterior cortex, representing a central hub involved in multimodal integration processes. Although neglected for several years, the precuneus is highly complex and crucial for multimodal integration. It has extensive connections with different cerebral areas and is an interface between external stimuli and internal representations. In human evolution, the precuneus has increased in size and complexity, allowing the development of higher cognitive functions, such as visual-spatial ability, mental imagery, episodic memory, and other tasks involved in emotional processing and mentalization. This paper reviews the functions of the precuneus and discusses them concerning the psychopathological aspects of schizophrenia. The different neuronal circuits, such as the default mode network (DMN), in which the precuneus is involved and its alterations in the structure (grey matter) and the disconnection of pathways (white matter) are described.

Neurological Soft Signs in Schizophrenia, a Picture of the Knowledge in the Last Decade: A Scoping Review

(1) Background: Neurological Soft Signs (NSS) are subtle neurological abnormalities that are more common in schizophrenia patients than in healthy individuals and have been regularly observed in neuroleptic-naive first-episode patients, supporting the hypothesis that they are an intrinsic component of schizophrenia. (2) Methods: a review of articles published in the last ten years (from January 2013 to January 2023) was carried out on articles published in ScienceDirect and PubMed, by following the PRISMA Statement extension for scoping reviews (PRISMA-ScR), which evaluated the impact of NSS in correlation with the symptomatology, neuroleptic treatment, and the cerebral structural changes of patients with schizophrenia. (3) Results: thirty articles were included, among them twelve included MRI structural evaluation and four studies with a longitudinal design. (4) Conclusions: interest in researching NSS has increased in recent years, but questions remain about their origin and relationship to schizophrenia symptoms, thus this study aims to fill in information gaps in the hope that future research will help provide individualized treatment. It is suggested that NSS in schizophrenia might have an inherited genetic relationship pattern, thus being in line with a trait viewpoint. Most of the research revealed that schizophrenia patients had higher NSS scores than healthy controls, however, they were rather similar to their first-degree relatives, thus, also arguing in favor of a trait perspective. The greatest improvement in scores is seen in those with a remitting course, as shown by declining NSS ratings concurrent with symptomatology.

Cerebellar Functional Dysconnectivity in Drug-Naïve Patients With First-Episode Schizophrenia

BACKGROUND

Cerebellar functional dysconnectivity has long been implicated in schizophrenia. However, the detailed dysconnectivity pattern and its underlying biological mechanisms have not been well-charted. This study aimed to conduct an in-depth characterization of cerebellar dysconnectivity maps in early schizophrenia.

STUDY DESIGN

Resting-state fMRI data were processed from 196 drug-naïve patients with first-episode schizophrenia and 167 demographically matched healthy controls. The cerebellum was parcellated into nine functional systems based on a state-of-the-art atlas, and seed-based connectivity for each cerebellar system was examined. The observed connectivity alterations were further associated with schizophrenia risk gene expressions using data from the Allen Human Brain Atlas.

STUDY RESULTS

Overall, we observed significantly increased cerebellar connectivity with the sensorimotor cortex, default-mode regions, ventral part of visual cortex, insula, and striatum. In contrast, decreased connectivity was shown chiefly within the cerebellum, and between the cerebellum and the lateral prefrontal cortex, temporal lobe, and dorsal visual areas. Such dysconnectivity pattern was statistically similar across seeds, with no significant group by seed interactions identified. Moreover, connectivity strengths of hypoconnected but not hyperconnected regions were significantly correlated with schizophrenia risk gene expressions, suggesting potential genetic underpinnings for the observed hypoconnectivity.

CONCLUSIONS

These findings suggest a common bidirectional dysconnectivity pattern across different cerebellar subsystems, and imply that such bidirectional alterations may relate to different biological mechanisms.

Neurological and cerebellar soft signs in bipolar disorder: The role of staging, type and history of psychotic symptoms

AIM

Bipolar disorder (BD) patients show neurological abnormalities in form of neurological and cerebellar soft signs (NSS and CSS). NSS represents heterogeneous group of symptoms representing i.a. deficits of motor coordination, sequencing of complex motor acts and sensory integration. CSS were introduced as group of the neurological deficits of posture, gait, kinetic functions, eye movements and speech, associated more specifically to cerebellar abnormalities than NSS. Studies show significant effect size variability of those symptoms in BD group suggesting the existence of differing subpopulations. The aim of our study was to evaluate the effect of BD type, stage and the history of psychotic symptoms (HoPS) on the severity of CSS and NSS as none of the previous studies had verified the role of those categories.

METHODS

This study involved 181 participants: 116 euthymic BD patients (66 BD I, 50 BD II) and 65 healthy controls (HC). CSS was assessed with the International Cooperative Ataxia Rating Scale and NSS with Neurological Evaluation Scale. Patients were divided into early and late stage of the disorder according to Kapczinski's criteria. Rater was blind to patients' stage, type and HoPS.

RESULTS

Staging was related to vast majority of CSS and NSS scores. HoPS was related to oculomotor deficits. The effect of BD type was the least significant. Late stage BD showed more severe CSS and NSS than HC in every measure. There were no differences between early stage BD and HC, apart of posture and gait disturbances. Except of sensory integration scores, late stage BD showed higher CSS and NSS rates than early stage patients.

CONCLUSION

In this hitherto the largest study of neurological abnormalities in BD we have shown significant role of staging in CSS and NSS severity. Progression criteria based on inter-episode psychosocial functioning may stand as unrecognised factor responsible for variability observed in previous studies evaluating neurological abnormalities in BD. Our study suggests that in clinical practice NSS and CSS may be potentially used as easy-to-assess biological marker of BD staging. Observed severity of neurological impairments of BD patients may more likely correspond to the disease progression than to BD type and HoPS.

Functional correlates of neurological soft signs in heavy cannabis users

Sensorimotor dysfunction has been previously reported in persons with cannabis dependence. Such individuals can exhibit increased levels of neurological soft signs (NSS), particularly involving motor coordination, sensorimotor integration and complex motor task performance. Abnormal NSS levels can also be detected in non-dependent individuals with heavy cannabis use (HCU), yet very little is known about the functional correlates underlying such deficits. Here, we used resting-state functional magnetic resonance imaging (MRI) to investigate associations between NSS and intrinsic neural activity (INA) in HCU (n = 21) and controls (n = 26). Compared with controls, individuals with HCU showed significantly higher NSS across all investigated subdomains. Three of these subdomains, that is, motor coordination, sensorimotor integration and complex motor task behaviour, were associated with specific use-dependent variables, particularly age of onset of cannabis use and current cannabis use. Between-group comparisons of INA revealed lower regional homogeneity (ReHo) in left precentral gyrus, left inferior occipital gyrus, right triangular pat of the inferior frontal gyrus and right precentral gyrus in HCU compared with controls. In addition, HCU showed also higher ReHo in right cerebellum and left postcentral gyrus compared with controls. Complex motor task behaviour in HCU was significantly related to INA in postcentral, inferior frontal and occipital cortices. Our findings indicate abnormal ReHo in HCU in regions associated with sensorimotor, executive control and visuomotor-integration processes. Importantly, we show associations between ReHo, cannabis-use behaviour and execution of complex motor tasks. Given convergent findings in manifest psychotic disorders, this study suggests an HCU endophenotype that may present with a cumulative risk for psychosis.

Altered intrinsic cerebellar-cerebral functional connectivity is related to negative symptoms in patients with first-episode psychosis

BACKGROUND

Negative symptoms in schizophrenia include cognitive and affective dysfunction, such as diminished expression and amotivation. Although the cerebellar posterior hemisphere and vermis are involved in cognitive and affective functioning, previous studies on the neural mechanism of negative symptoms have mostly been confined to the cerebral cortex. This study aimed to investigate whether resting-state cerebellar-cerebral functional connectivity (FC) is altered in first-episode psychosis (FEP) patients and whether this connectivity is related to negative symptoms.

METHODS

Resting-state functional magnetic resonance images were obtained from 38 FEP patients and 100 healthy controls (HCs). Using the posterior hemisphere and vermis of the cerebellum as seeds, whole-brain FC was compared between FEP patients and HCs. As cerebellar-parietal cortex connectivity is associated with negative symptoms and sociocognitive dysfunctions in schizophrenia patients, its correlation with negative symptoms was explored in FEP patients.

RESULTS

FEP patients showed hyperconnectivity between the cerebellum and bilateral frontal pole (FP), occipital pole, fusiform gyrus, right lingual gyrus, central opercular cortex, anterior middle temporal gyrus, precuneus, and subcallosal cortex. Hypoconnectivity was found between the cerebellum and left FP, right anterior supramarginal gyrus (aSMG), and cerebellum crus I. FC between the left crus II and right aSMG was negatively correlated with the severity of negative symptoms and diminished expression.

CONCLUSIONS

Altered FC between the cerebellum and cerebral regions related to cognitive, affective, and sensory processing was found in FEP patients and was connected to negative symptoms. These results suggest that the cerebellum plays a role in the pathophysiology of negative symptoms in schizophrenia.

Structural network alterations and their association with neurological soft signs in schizophrenia: Evidence from clinical patients and unaffected siblings

BACKGROUND

Grey matter abnormalities and neurological soft signs (NSS) have been found in schizophrenia patients and their unaffected relatives. Evidence suggested that NSS are associated with grey matter morphometrical alterations in multiple regions in schizophrenia. However, the association between NSS and structural abnormalities at network level remains largely unexplored, especially in the schizophrenia and unaffected siblings.

METHOD

We used source-based morphometry (SBM) to examine the association of structural brain network characteristics with NSS in 62 schizophrenia patients, 25 unaffected siblings, and 60 healthy controls.

RESULTS

Two components, namely the IC-5 (superior temporal gyrus, inferior frontal gyrus and insula network) and the IC-10 (parahippocampal gyrus, fusiform, thalamus and insula network) showed significant grey matter reductions in schizophrenia patients compared to healthy controls and unaffected siblings. Further association analysis demonstrated separate NSS-related grey matter covarying patterns in schizophrenia, unaffected siblings and healthy controls. Specifically, NSS were negatively associated with IC-1 (hippocampus, caudate and thalamus network) and IC-5 in schizophrenia, but with IC-3 (caudate, superior and middle frontal cortices network) in unaffected siblings and with IC-5 in healthy controls.

CONCLUSION

Our results confirmed the key cortical and subcortical network abnormalities and NSS-related grey matter covarying patterns in the schizophrenia and unaffected siblings. Our findings suggest that brain regions implicating genetic liability to schizophrenia are partly separated from brain regions implicating neural abnormalities.

Progress in sensorimotor neuroscience of schizophrenia spectrum disorders: Lessons learned and future directions

The number of neuroimaging studies on movement disorders, sensorimotor, and psychomotor functioning in schizophrenia spectrum disorders (SSD) has steadily increased over the last two decades. Accelerated by the addition of the "sensorimotor domain" to the Research Domain Criteria (RDoC) framework in January 2019, neuroscience research on the role of sensorimotor dysfunction in SSD has gained greater scientific and clinical relevance. To draw attention to recent rapid progress in the field, we performed a triennial systematic review (PubMed search from January 1st^, 2018 through December 31st^, 2020), in which we highlight recent neuroimaging findings and discuss methodological pitfalls as well as challenges for future research. The identified magnetic resonance imaging (MRI) studies suggest that sensorimotor abnormalities in SSD are related to cerebello-thalamo-cortico-cerebellar network dysfunction. Longitudinal and interventional studies highlight the translational potential of the sensorimotor domain as putative biomarkers for treatment response and as targets for non-invasive neurostimulation techniques in SSD.

[The sensorimotor domain in the research domain criteria system: progress and perspectives]

Over the past three decades research interest in hypokinetic, hyperkinetic, sensorimotor and psychomotor abnormalities in mental disorders has steadily increased. This development has led to an increasing number of scientific initiatives that have not only highlighted the clinical need for early detection of extrapyramidal motor symptoms, tardive dyskinesia and catatonia but also provided numerous neurobiological findings and clinically relevant results based on the pathology of the sensorimotor system in patients with mental disorders. In view of these developments in January 2019 the National Institute of Mental Health (NIMH) research domain criteria (RDoC) initiative introduced a sixth domain called the sensorimotor domain to address deficits in the sensorimotor system and associated behavioral abnormalities. To draw attention to the rapid progress just since the introduction of the sensorimotor domain, a 2-year (1 January 2019-18 February 2021) systematic review is presented highlighting recent neuroimaging findings and discussing challenges for future research. In summary, aberrant sensorimotor processing in mental disorders is associated with dysfunction of the cerebello-thalamo-motor cortex network, which interacts with (social)cognitive and affective systems. Initial longitudinal and interventional studies highlight the translational potential of the sensorimotor domain.

Different trajectories of neurological soft signs progression between treatment-responsive and treatment-resistant schizophrenia patients

Schizophrenia patients exhibit subtle and non-localizing neurological abnormalities, known as neurological soft signs (NSS). Life-span evidence suggests that NSS vary along the course of schizophrenia. An association between NSS and treatment response has been proposed, suggesting that NSS reflect the underlying neuropathology development in schizophrenia. However, few studies have investigated the relationship between NSS and treatment resistance in first-episode schizophrenia patients. We conducted a longitudinal study on 52 first-episode schizophrenia patients, who were assessed at baseline, the sixth month, and the fifth year using the abridged version of the Cambridge Neurological Inventory. The trajectories of NSS between 29 treatment-responsive patients (with full symptomatic remission) and 23 treatment-resistant patients (who received clozapine) were compared using mixed model ANOVA. We also controlled for the effect of age and estimated IQ, using a mixed ANCOVA model. Although the two schizophrenia groups had comparable NSS at the baseline, their trajectories of NSS differed significantly. Compared with their treatment-responsive counterparts, treatment-resistant schizophrenia patients had worsening of NSS over time. Our findings support the potential utility of NSS in identifying treatment resistance in first-episode schizophrenia. Progressive worsening of NSS in treatment-resistant schizophrenia patients may reflect the development of underlying neuropathology. Further studies using large samples of treatment-resistant schizophrenia patients are needed.