Postural Sway Abnormalities in Schizotypal Personality Disorder

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.

Motor function in early onset schizophrenia-A 2-year follow-up study

AIM

Motor symptoms primarily assessed by clinical rating are documented across the schizophrenia spectrum, but no studies have examined the longitudinal course of these symptoms in adolescents using tests that control for the natural maturational process. The aim is therefore to compare fine and gross motor function using age-adjusted tests in adolescents with schizophrenia and controls across a 2-year period, and examine if clinical correlates contribute to changes in motor function in adolescents with schizophrenia.

METHOD

Motor function assessed by two age-adjusted tests was compared in 25 adolescents with schizophrenia and age- and sex-matched controls over a 2-year period using t-tests, Cohen's D and χ2 tests. Linear mixed models with a random intercept at patient level were used to assess changes between baseline and follow-up. The latter approach was adopted to assess the association between changes and potential predictors as age, sex, complications during labour/delivery, childhood motor function, symptoms severity, executive function and antipsychotics.

RESULT

All measures of motor function but one significantly differentiated adolescents with schizophrenia from controls with large effect sizes at 2-year follow-up. The overall scores did not change during follow-up, whereas two resembling motor areas of the tests significantly improved in adolescents with schizophrenia. The severity of schizophrenia, sex and IQ revealed association with the changes.

CONCLUSION

The finding of both stability and improvements from diagnosis to follow-up in adolescents with schizophrenia and the differences between adolescents with and without schizophrenia argue in favour of the neurodevelopment hypothesis and highlights the need for assessing motor function.

Effect of dual tasking on postural control in individuals with schizophrenia

OBJECTIVE

To investigate the effect of dual tasking on postural control in individuals with schizophrenia.

METHODS

Fifteen outpatients with schizophrenia and 15 healthy controls were included. Postural control was assessed with postural sway velocity (PSV) using Balance Master System during three different tasks: single task (standing on a force platform), cognitive task (categorical verbal fluency) and motor task (holding a cup of water) in four conditions: on firm surface with eyes open (1) and closed (2), on foam surface with eyes open (3) and closed (4).

RESULTS

Individuals with schizophrenia presented higher PSV during single standing on foam surface with eyes open and closed. During the cognitive task, they showed higher PSV on foam surface with eyes closed. During the motor task PSV in schizophrenia group was higher on firm surface with eyes closed and on foam surface with eyes open and closed. Individuals with schizophrenia showed higher PSV during cognitive task on firm surface with eyes closed compared to the single task.

CONCLUSIONS

Dual tasking results in a deterioration in postural control in individuals with schizophrenia. A cognitive task specifically alters postural control in the absence of visual information suggesting a possible sensorimotor dysfunction in this population.

Disembodiment and Language in Schizophrenia: An Integrated Psychopathological and Evolutionary Perspective

Different hypotheses have flourished to explain the evolutionary paradox of schizophrenia. In this contribution, we sought to illustrate how, in the schizophrenia spectrum, the concept of embodiment may underpin the phylogenetic and developmental pathways linking sensorimotor processes, the origin of human language, and the construction of a basic sense of the self. In particular, according to an embodied model of language, we suggest that the reuse of basic sensorimotor loops for language, while enabling the development of fully symbolic thought, has pushed the human brain close to the threshold of a severe disruption of self-embodiment processes, which are at the core of schizophrenia psychopathology. We adopted an inter-disciplinary approach (psychopathology, neuroscience, developmental biology) within an evolutionary framework, to gain an integrated, multi-perspectival model on the origin of schizophrenia vulnerability. A maladaptive over-expression of evolutionary-developmental trajectories toward language at the expense of embodiment processes would have led to the evolutionary "trade-off" of a hyper-symbolic activity to the detriment of a disembodied self. Therefore, schizophrenia psychopathology might be the cost of long-term co-evolutive interactions between brain and language.

Altered functional connectivity of cerebellar networks in first-episode schizophrenia

Introduction

Abnormalities of the cerebellum have been displayed to be a manifestation of schizophrenia (SCH) which is a detrimental psychiatric disorder. It has been recognized that the cerebellum contributes to motor function, sensorimotor function, cognition, and other brain functions in association with cerebral functions. Multiple studies have observed that abnormal alterations in cerebro-cerebellar functional connectivity (FC) were shown in patients with SCH. However, the FC of cerebellar networks in SCH remains unclear.

Methods

In this study, we explored the FC of cerebellar networks of 45 patients with first-episode SCH and 45 healthy control (HC) subjects by using a defined Yeo 17 network parcellation system. Furthermore, we performed a correlation analysis between cerebellar networks' FC and positive and negative symptoms in patients with first-episode SCH. Finally, we established the classification model to provide relatively suitable features for patients with first-episode SCH concerning the cerebellar networks.

Results

We found lower between-network FCs between 14 distinct cerebellar network pairs in patients with first-episode SCH, compared to the HCs. Significantly, the between-network FC in N2-N15 was positively associated with positive symptom severity; meanwhile, N4-N15 was negatively associated with negative symptom severity. Besides, our results revealed a satisfactory classification accuracy (79%) of these decreased between-network FCs of cerebellar networks for correctly identifying patients with first-episode SCH.

Conclusion

Conclusively, between-network abnormalities in the cerebellum are closely related to positive and negative symptoms of patients with first-episode SCH. In addition, the classification results suggest that the cerebellar networks can be a potential target for further elucidating the underlying mechanisms in first-episode SCH.

Comparing the Movement Assessment Battery for Children with the Bruininks‐Oseretsky Test of Motor Proficiency in adolescents with and without schizophrenia

BACKGROUND

As motor impairments have implications for health and functioning, they need to be addressed early, not only in childhood but also in adolescence, the period in which mental disorders as schizophrenia, typically develops. Further, the possible prognostic value of motor impairments in schizophrenia highlights the importance. The Bruininks-Oseretsky Test of Motor Proficiency (BOT-2) and the Movement Assessment Battery for Children (MABC-2) assess adolescent motor performance. However, MABC-2 is not valid past age 16 and has no sex-norms. Further, while the concurrent validity between the tests and their ability to distinguish between clinical and non-clinical groups has been established in children, however they have not been established in adolescence.

PURPOSE

To compare the ability of MABC-2 and BOT-2 to distinguish between adolescents with and without schizophrenia, to examine the concurrent validity between tests, to examine the agreement between tests in classifying adolescents "at risk" or scoring "below average" and to examine the influence of age and sex on MABC-2.

METHOD

Motor performance assessed by BOT-2 and MABC-2 was compared in 25 adolescents with schizophrenia (14-18) and age- and sex-matched controls using t-test, Cohen's D and false discovery rate's q-value. The associations between tests were assessed using Pearson's correlation and Lin's concordance correlation coefficient. The Kappa coefficient was used to assess the agreement between tests in classifying "risk/below average" and linear regression was adopted to assess the influence of age/sex on MABC-2.

RESULTS

MABC-2 and BOT-2 significantly distinguished adolescents with schizophrenia from controls with large effect size. A strong association (p > 0.001) was found between the tests. The tests revealed moderate agreement in identifying "risk" or scoring "below average". Only sex influenced MABC-2 scores.

CONCLUSION

MABC-2 and BOT-2 are both useful for assessing motor performance and distinguishing between adolescents with and without schizophrenia, although BOT-2 provides a more detailed picture of the challenges in adolescent with schizophrenia.

The growth and development of research on personality disorders: A bibliometric study

This study objective was to investigate publication trends on personality disorders (PD) and to identify patterns of historical development. Publication rates were determined using the Results by Year Timeline feature of PubMed. Time series autoregressive integrated moving average models were used to analyse the publication rates for PDs in quinquennial periods beginning in 1980 and ending in 2019 and to predict the number of publications in the 2024-2029 period. More than 300 articles on antisocial and borderline PD are being published each year, and the models suggest an accelerating growth rate. Approximately 100 articles are being published on average every year on schizotypal PD, and the regression model indicates linear growth in the near future. The mean number of publications per year for obsessive-compulsive, narcissistic and avoidant PDs is in the range of 10-30 with the corresponding models indicating linear growth. Fewer than 10 articles are being published each year on dependent, paranoid, histrionic and schizoid PD, whereas dependent PD shows modest growth and paranoid PD rates tended to stability, histrionic and schizoid PD exhibit declining rates. Personality disorders are a group of conditions with diverse etiological, prognostic, therapeutic, legal, research, social and cultural implications that influence publication rates.

Posture, gait and self‐disorders: An empirical study in individuals with schizophrenia

AIM

In schizophrenia, subjectively perceived disruptions of the sense of the Self (also referred to as "self-disorders") seem to be intimately associated with a perturbation of the implicit awareness of one's own body. Indeed, an early impairment of the motor system, including posture and gait, is now considered a marker of schizophrenia neurodevelopmental substrate and appears more pronounced in early-onset schizophrenia. Therefore, the present study was aimed at: (1) investigating a possible relationship between self-disorders, symptom dimensions and postural and gait profile in schizophrenia; (2) identifying a specific motor profile in early-onset conditions.

METHODS

A total of 43 schizophrenia outpatients and 38 healthy controls underwent an exhaustive investigation of posture and gait pattern. The positive and negative syndrome scale (PANSS), the examination of anomalous self experience scale (EASE) and the abnormal involuntary movement scale (AIMS) were administered to the schizophrenia group. Subsequently, schizophrenia patients were divided into early and adult-onset subgroups and compared with respect to their motor profile.

RESULTS

We found an association between specific postural patterns (impaired sway area), a general disruption of the gait cycle and subjective bodily experiences (concerning the loss of bodily integrity, cohesion and demarcation). Only motor parameters (increased sway area and gait cadence reduction) differentiated between early and adult-onset patients.

CONCLUSION

The results of the present study hint at a link between motor impairment and self-disturbances in schizophrenia and candidate a specific motor profile as a possible marker of early-onset forms.

Effects of multitask training on cognition and motor control in people with schizophrenia spectrum disorders

Schizophrenia spectrum disorder (SSD) is a disabling mental illness that causes considerable deficits in motor and cognitive functions. The purpose of this study was to examine the effects of combining traditional multitask training (TMT) and video games--a new form of multitask training (video game multitask training VGMT)--on cognition and motor control performance in people with SSD. This was a quasi-experimental, pretest-posttest design study. A total of 25 patients participated in this study voluntarily (13 males and 12 females, average age = 59.61 years, SD– 11.46 years). All participants underwent two stages of training. The first stage involved TMT, and the second stage involved VGMT. Each training stage was 12 weeks long, with sessions twice a week that lasted for 40 minutes. Cognition, upper extremity motor and postural control performance, and functional mobility and subjective balance confidence were measured at three times: before and after the first-stage training and after the second-stage training. The results revealed that TMT and the combination of TMT and VGMT improved SSD patient’s cognition, upper extremity motor control, functional mobility and postural control performance. The subjective confidence of balance during the performance of daily activities was also mildly improved. Training with multitasks in the form of video games tended to further improve the outcome measures. Patients with SSD could benefit from regular participation in various forms of multitasking activities. Whether video games training are better than TMT in improving the functional ability of people with SSD needs further investigation.

Study protocol registration: Clinicaltrials.gov, ID: NCT04629898. Registered brief title: Level of Immersion of Virtual Reality and Cognition and Motor Performance in Patients of Schizophrenia Spectrum Disorder.

Tool-use Extends Peripersonal Space Boundaries in Schizophrenic Patients

BACKGROUND AND HYPOTHESIS

A primary disruption of the bodily self is considered a core feature of schizophrenia (SCZ). The "disembodied" self might be underpinned by inefficient body-related multisensory integration processes, normally occurring in the peripersonal space (PPS), a plastic sector of space surrounding the body whose extent is altered in SCZ. Although PPS is a malleable interface marking the perceptual border between self and others, no study has addressed the potential alteration of its plasticity in SCZ. We investigated the plasticity of PPS in SCZ patients after a motor training with a tool in the far space.

STUDY DESIGN

Twenty-seven SCZ patients and 32 healthy controls (HC) underwent an audio-tactile task to estimate PPS boundary before (Session 1) and after (Session 3) the tool-use. Parameters of PPS, including the size and the slope of the psychometric function describing audio-tactile RTs as a function of the audio-tactile distances, were estimated.

STUDY RESULTS

Results confirm a narrow PPS extent in SCZ. Surprisingly, we found PPS expansion in both groups, thus showing for the first time a preserved PPS plasticity in SCZ. Patients experienced a weaker differentiation from others, as indicated by a shallower PPS slope at Session 1 that correlated positively with negative symptoms. However, at Session 3, patients marked their bodily boundary in a steeper way, suggesting a sharper demarcation of PPS boundaries after the action with the tool.

CONCLUSIONS

These findings highlight the importance of investigating the multisensory and motor roots of self-disorders, paving the way for future body-centred rehabilitation interventions that could improve patients' altered body boundary.

Motor impairments in early onset schizophrenia

AIM

Motor impairments are frequent both at and before diagnosis. In childhood, impairments in general fine and gross motor function are among others identified using test batteries, and while elements of coordination are assessed in onset schizophrenia, the assessment of general motor functions is absent. Thus, we aimed to assess general motor function including childhood motor function in adolescents with schizophrenia in comparison with healthy controls and examine clinical correlates to general motor function.

METHOD

General fine and gross motor function was assessed using two standardized age-normed test batteries and a questionnaire in 25 adolescents with schizophrenia compared with age and gender-matched controls using t-test and χ² -test. Stepwise linear regression assessed potential developmental predictors on motor function including complications during childbirth, reported childhood motor function, executive function including false discovery rate q-values. Associations with schizophrenia symptom severity, executive function, cognitive function were assessed using Pearson's correlation and the impact of antipsychotic medication using t-test.

RESULT

All measures of motor function but one significantly differentiated adolescents with schizophrenia from healthy controls. The presence of schizophrenia (β =4.41, β = 10.96), explained the main part of the variance however, childhood motor function (β = .08) also added significantly to motor function. Executive function (β = -.45) was important for childhood motor function. Severity of schizophrenia was associated with strength (p < .0011) and manual coordination (p = .0295), and receiving antipsychotics affected manual dexterity (p = .0378).

CONCLUSION

The documentation of significant differences in general motor function in early onset schizophrenia compared with healthy controls highlights the need for general motor assessments and potential interventions.

Impaired Sensorimotor Adaption in Schizophrenia in Comparison to Age-Matched and Elderly Controls

BACKGROUND

The "cognitive dysmetria hypothesis" of schizophrenia proposes a disrupted communication between the cerebellum and cerebral cortex, resulting in sensorimotor and cognitive symptoms. Sensorimotor adaptation relies strongly on the function of the cerebellum.

OBJECTIVES

This study investigated whether sensorimotor adaptation is reduced in schizophrenia compared with age-matched and elderly healthy controls.

METHODS

Twenty-nine stably treated patients with schizophrenia, 30 age-matched, and 30 elderly controls were tested in three motor adaptation tasks in which visual movement feedback was unexpectedly altered. In the "rotation adaptation task" the perturbation consisted of a rotation (30° clockwise), in the "gain adaptation task" the extent of the movement feedback was reduced (by a factor of 0.7) and in the "vertical reversal task," up- and downward pen movements were reversed by 180°.

RESULTS

Patients with schizophrenia adapted to the perturbations, but their movement times and errors were substantially larger than controls. Unexpectedly, the magnitude of adaptation was significantly smaller in schizophrenia than elderly participants. The impairment already occurred during the first adaptation trials, pointing to a decline in explicit strategy use. Additionally, post-adaptation aftereffects provided strong evidence for impaired implicit adaptation learning. Both negative and positive schizophrenia symptom severities were correlated with indices of the amount of adaptation and its aftereffects.

CONCLUSIONS

Both explicit and implicit components of sensorimotor adaptation learning were reduced in patients with schizophrenia, adding to the evidence for a role of the cerebellum in the pathophysiology of schizophrenia. Elderly individuals outperformed schizophrenia patients in the adaptation learning tasks.

Postural sway correlates with cognition and quality of life in Parkinson's disease

Background

The severity of Parkinson's disease (PD) is difficult to assess objectively owing to the lack of a robust biological marker of underlying disease status, with consequent implications for diagnosis, treatment and prognosis. The current standard tool is the Unified Parkinson's Disease Rating Scale (MDS-UPDRS), but this is hampered by variability between observers and within subjects. Postural sway has been shown to correlate with complex brain functioning in other conditions. This study aimed to investigate the relationship between postural sway, MDS-UPDRS and other non-motor measures of disease severity in patients with PD.

Method

25 patients with PD and 18 age-matched controls participated in the study. All participants underwent assessment of postural sway using a force plate, with eyes open and closed. In addition, participants underwent tests of cognition and quality of life: Montreal Cognitive Assessment (MoCA), Neuropsychiatry Unit Cognitive Assessment (NUCOG) and, for the patients, the Parkinson's Disease Questionnaire (PDQ-39-1), and assessment of clinical status using the motor component of the MDS-UPDRS.

Results

Patients swayed significantly more than controls. This was most obvious in the eyes-closed condition. Sway path length showed strong correlations with PDQ-39-1, MoCA and the verbal fluency component of the NUCOG, and, to a lesser degree, with the UPDRS-III in patients with PD.

Conclusion

These results suggest that motor and non-motor symptoms of PD are associated in patients, and, in particular, that postural sway shows potential as a possible measure of underlying disease status in PD, either alone or in combination with other measures.

Posture and gait in the early course of schizophrenia

While correlations between postural stability deficits and schizophrenia are well documented, information on dynamic motor alterations in schizophrenia are still scarce, and no data on their onset are available yet. Therefore, the aim of this study was i) to measure gait pattern(s) in patients with schizophrenia; ii) to identify posture and gait alterations which could potentially be used as a predictive clinical tool of the onset of the disorder. Body composition, posture and gait parameters were assessed in a group of 30 patients with schizophrenia and compared to 25 healthy subjects. Sway area was significantly higher in the schizophrenia group compared to controls regardless of whether the participants were in eyes open or eyes closed condition. Gait cadence and speed were significantly lower in patients with schizophrenia, while stride length was similar. We concluded that the combination of an increased sway area (independent from eye closure) and a gait cadence reduction—in the presence of normal gait speed and stride length—might be considered peculiar postural and gait profile characteristic of early schizophrenia.

Cerebellar-cortical dysconnectivity in resting-state associated with sensorimotor tasks in schizophrenia

Abnormalities of cerebellar function have been implicated in the pathophysiology of schizophrenia. Since the cerebellum has afferent and efferent projections to diverse brain regions, abnormalities in cerebellar lobules could affect functional connectivity with multiple functional systems in the brain. Prior studies, however, have not examined the relationship of individual cerebellar lobules with motor and nonmotor resting‐state functional networks. We evaluated these relationships using resting‐state fMRI in 30 patients with a schizophrenia‐spectrum disorder and 37 healthy comparison participants. For connectivity analyses, the cerebellum was parcellated into 18 lobular and vermal regions, and functional connectivity of each lobule to 10 major functional networks in the cerebrum was evaluated. The relationship between functional connectivity measures and behavioral performance on sensorimotor tasks (i.e., finger‐tapping and postural sway) was also examined. We found cerebellar–cortical hyperconnectivity in schizophrenia, which was predominantly associated with Crus I, Crus II, lobule IX, and lobule X. Specifically, abnormal cerebellar connectivity was found to the cerebral ventral attention, motor, and auditory networks. This cerebellar–cortical connectivity in the resting‐state was differentially associated with sensorimotor task‐based behavioral measures in schizophrenia and healthy comparison participants—that is, dissociation with motor network and association with nonmotor network in schizophrenia. These findings suggest that functional association between individual cerebellar lobules and the ventral attentional, motor, and auditory networks is particularly affected in schizophrenia. They are also consistent with dysconnectivity models of schizophrenia suggesting cerebellar contributions to a broad range of sensorimotor and cognitive operations.

Postural Control and Verbal and Visual Working Memory Correlates in Nonclinical Psychosis

INTRODUCTION

Motor and cognitive abnormalities are well documented in psychosis spectrum disorders. Evidence suggests these deficits could be pronounced because of disruptions in the cerebellar-thalamic-cortical-cerebellar (CTCC) circuit, a network thought to be heavily implicated in motor and higher cognitive functioning. Although significant research has been done on this topic in individuals with schizophrenia and those at a clinical high risk for psychosis, much less is known about deficits at the lower end of the spectrum.

METHODS

In this study, we extended the understanding of motor abnormalities across the psychosis continuum by examining postural sway deficits in the nonclinical psychosis (NCP) population. Furthermore, we linked these deficits to verbal and visual working memory. High-NCP (n = 37) and low-NCP control (n = 31) participants completed an instrumental balance task, highly sensitive to subtle variations in postural sway, along with a brief working memory battery.

RESULTS

We found that high-NCP participants presented with increased postural sway area (i.e., worse postural control) relative to low-NCP controls on a difficult condition (with limited proprioceptive cues), but not on an easier condition. Furthermore, results indicated that the sway area was correlated with poorer performance on working memory tasks in the high-NCP group.

CONCLUSION

These findings suggest that CTCC circuit abnormalities are present across the lower end of the psychosis spectrum and that they may be contributing to a range of motor and cognitive behaviors seen in the population. However, evidence suggests that the signs are subtle, and that sensitive assessment devices and challenging conditions may be necessary for detection.