Motoric neurological soft signs and psychopathological symptoms in schizophrenic psychoses

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.

Schizophrenia polygenic risk score in psychosis proneness

Schizophrenia (SZ) is a complex disorder with a highly polygenic inheritance. It can be conceived as the extreme expression of a continuum of traits that are present in the general population often broadly referred to as schizotypy. However, it is still poorly understood how these traits overlap genetically with the disorder. We investigated whether polygenic risk for SZ is associated with these disorder-related phenotypes (schizotypy, psychotic-like experiences, and subclinical psychopathology) in a sample of 253 non-clinically identified participants. Polygenic risk scores (PRSs) were constructed based on the latest SZ genome-wide association study using the PRS-CS method. Their association with self-report and interview measures of SZ-related traits was tested. No association with either schizotypy or psychotic-like experiences was found. However, we identified a significant association with the Motor Change subscale of the Comprehensive Assessment of At-Risk Mental States (CAARMS) interview. Our results indicate that the genetic overlap of SZ with schizotypy and psychotic-like experiences is less robust than previously hypothesized. The relationship between high PRS for SZ and motor abnormalities could reflect neurodevelopmental processes associated with psychosis proneness and SZ.

Brain functional connectivity mirrors genetic pleiotropy in psychiatric conditions

Pleiotropy occurs when a genetic variant influences more than one trait. This is a key property of the genomic architecture of psychiatric disorders and has been observed for rare and common genomic variants. It is reasonable to hypothesize that the microscale genetic overlap (pleiotropy) across psychiatric conditions and cognitive traits may lead to similar overlaps at the macroscale brain level such as large-scale brain functional networks. We took advantage of brain connectivity, measured by resting-state functional MRI to measure the effects of pleiotropy on large-scale brain networks, a putative step from genes to behaviour. We processed nine resting-state functional MRI datasets including 32 726 individuals and computed connectome-wide profiles of seven neuropsychiatric copy-number-variants, five polygenic scores, neuroticism and fluid intelligence as well as four idiopathic psychiatric conditions. Nine out of 19 pairs of conditions and traits showed significant functional connectivity correlations (rFunctional connectivity), which could be explained by previously published levels of genomic (rGenetic) and transcriptomic (rTranscriptomic) correlations with moderate to high concordance: rGenetic-rFunctional connectivity = 0.71 [0.40-0.87] and rTranscriptomic-rFunctional connectivity = 0.83 [0.52; 0.94]. Extending this analysis to functional connectivity profiles associated with rare and common genetic risk showed that 30 out of 136 pairs of connectivity profiles were correlated above chance. These similarities between genetic risks and psychiatric disorders at the connectivity level were mainly driven by the overconnectivity of the thalamus and the somatomotor networks. Our findings suggest a substantial genetic component for shared connectivity profiles across conditions and traits, opening avenues to delineate general mechanisms-amenable to intervention-across psychiatric conditions and genetic risks.

The Impact of Antipsychotic Treatment on Neurological Soft Signs in Patients with Predominantly Negative Symptoms of Schizophrenia

Schizophrenia is a complex and incompletely elucidated pathology that affects sensorimotor function and also produces numerous therapeutic challenges. The aims of this cross-sectional study were to identify the profile of neurological soft signs (NSS) in patients with predominantly negative symptoms of schizophrenia (PNS) compared with patients with schizophrenia who do not present a predominance of negative symptoms (NPNS) and also to objectify the impact of treatment on the neurological function of these patients. Ninety-nine (n = 99; 56 females and 43 males) patients diagnosed with schizophrenia according to DSM-V were included; these patients were undergoing antipsychotic (4 typical antipsychotics, 86 atypical antipsychotics, and 9 combinations of two atypical antipsychotics) or anticholinergic treatment (24 out of 99) at the time of evaluation, and the PANSS was used to identify the patients with predominantly negative symptoms (n = 39), the Neurological Evaluation Scale (NES) was used for the evaluation of neurological soft signs (NSS), and the SAS was used for the objectification of the extrapyramidal side effects induced by the neuroleptic treatment, which was converted to chlorpromazine equivalents (CPZE). The study's main finding was that, although the daily dose of CPZE did not represent a statistically significant variable, in terms of neurological soft signs, patients with PNS had higher rates of NSS.

Examining Motor Anticipation in Handwriting as an Indicator of Motor Dysfunction in Schizophrenia

Dysfunction in motor skills can be linked to alterations in motor processing, such as the anticipation of forthcoming graphomotor sequences. We expected that the difficulties in motor processing in schizophrenia would be reflected in a decrease of motor anticipation. In handwriting, motor anticipation concerns the ability to write a letter while processing information on how to produce the following letters. It is essential for fast and smooth handwriting, that is, for the automation of graphomotor gestures. In this study, we examined motor anticipation by comparing the kinematic characteristics of the first l in the bigrams ll and ln written on a digitiser. Previous studies indicated that the downstroke duration of the first l is modulated by the anticipation of the local constraints of the following letter. Twenty-four adult individuals with diagnosis of schizophrenia and 24 healthy adults participated in the study. The classic measures of duration (sec), trajectory (cm), and dysfluency (velocity peaks) were used for the kinematic analysis of the upstroke (US) and downstroke (DS). In the control group, the duration of the downstroke of the l was longer in ln than ll (US: ln = ll; DS: ln > ll) whereas no differences were found for the group with schizophrenia. Likewise, the control group showed a longer DS trajectory for the l of ln than ll in downstrokes, while the group of patients failed to show this effect. These results suggest that the motor alterations in patients with schizophrenia could also affect their ability for motor anticipation.

Characterizing the sensorimotor domain in schizophrenia spectrum disorders

The rapidly evolving field of sensorimotor neuroscience reflects the scientific and clinical relevance of sensorimotor abnormalities as an intrinsic component of the disease process, e.g., in patients with schizophrenia spectrum disorders (SSD). Despite previous efforts, however, prevalence rates and relationships between different categories of sensorimotor abnormalities in SSD patients are still subject of ongoing debate. In this study, we examined five different categories of the sensorimotor domain (Neurological soft signs (NSS), parkinsonism, catatonia, akathisia, and tardive dyskinesia) according to well-established clinical ratings scales and the respective cut-off criteria in a sample of 131 SSD patients. We used a collection of statistical methods to better understand prevalence, overlap and heterogeneity, as well as psychopathological and cognitive correlates of sensorimotor abnormalities. 97.7% of the SSD patients considered by this study exhibited at least one categorically defined sensorimotor abnormality that tended to co-vary within three different sensorimotor subgroups (moderate, hyperkinetic and hypokinetic). Finally, hyperkinetic and hypokinetic groups differed significantly in their neurocognitive performance compared with the moderate group. The results suggest different patterns of clinical overlap, highlight the relationship between sensorimotor and cognitive domain and provide clues for further neurobiological studies.

Movement markers of schizophrenia: a detailed analysis of patients' gait patterns

Motor abnormalities occur in the majority of persons with schizophrenia but are generally neglected in clinical care. Psychiatric diagnostics fail to include quantifiable motor variables and few assessment tools examine full-body movement. We assessed full-body movement during gait of 20 patients and 20 controls with motion capture technology, symptom load (PANSS, BPRS) and Neurological Soft Signs (NSS). In a data-driven analysis, participants' motion patterns were quantified and compared between groups. Resulting movement markers (MM) were correlated with the clinical assessment. We identified 16 quantifiable MM of schizophrenia. While walking, patients and controls display significant differences in movement patterns related to posture, velocity, regularity of gait as well as sway, flexibility and integration of body parts. Specifically, the adjustment of body sides, limbs and movement direction were affected. The MM remain significant when controlling for medication load. They are systematically related to NSS. Results add assessment tools, analysis methods as well as theory-independent MM to the growing body of research on motor abnormalities in schizophrenia.

Association of visual motor processing and social cognition in schizophrenia

Patients with schizophrenia have difficulties in social cognitive domains including emotion recognition and mentalization, and in sensorimotor processing and learning. The relationship between social cognitive deficits and sensorimotor function in patients with schizophrenia remains largely unexplored. With the hypothesis that impaired visual motor processing may decelerate information processing and subsequently affects various domains of social cognition, we examined the association of nonverbal emotion recognition, mentalization, and visual motor processing in schizophrenia. The study examined mentalization using the verbal subset of the Chinese version of Theory of Mind (CToM) Task, an equivalent task of the Faux Pas Test; emotion recognition using the Diagnostic Analysis of Nonverbal Accuracy 2-Taiwan version (DANVA-2-TW), and visual motor processing using a joystick tracking task controlled for basic motor function in 34 individuals with chronic schizophrenia in the community and 42 healthy controls. Patients with schizophrenia had significantly worse performance than healthy controls in social cognition, including facial, prosodic emotion recognition, and mentalization. Visual motor processing was also significantly worse in patients with schizophrenia. Only in patients with schizophrenia, both emotion recognition (mainly in prosodic modality, happy, and sad emotions) and mentalization were positively associated with their learning capacity of visual motor processing. These findings suggest a prospective role of sensorimotor function in their social cognitive deficits. Despite that the underlying neural mechanism needs further research, our findings may provide a new direction for restoration of social cognitive function in schizophrenia by enhancing visual motor processing ability.

Neurological soft signs (NSS) and gray matter volume (GMV) in first-episode psychosis: An analysis of NSS motor subscores

We aimed to study the correlations between gray matter volume and the motor subscores of NSS in first-episode psychosis patients with both, whole brain and region of interest analyses. The structural MRIs of 81 first-episode psychosis patients were analyzed by using voxel-based morphometry (VBM) for SPM. NSS were assessed using the Heidelberg scale. Significant decreases of gray matter volume were correlated to high NSS total scores and, more specifically, frontal, subcortical and cerebellar areas were significantly correlated with increased scores of the subscores Motor Coordination (MoCo) and Complex Motor Tasks (CMT). When applying a stricter statistical correction, only the frontal gyrus and caudate nucleus survived for MoCo; whereas the precentral and superior frontal gyri survived for CMT. When doing regional analyses, using as masks the structures deemed as significant by the whole brain analyses and applying the FWE-correction, the superior frontal gyrus, thalamus and caudate nucleus correlated negatively with MoCo; and the precentral and superior frontal gyri, thalamus and caudate nucleus showed inverse correlations with CMT. These results suggest that cerebral cortex, subcortical structures (thalamus and striatum) and cerebellum are inversely correlated to both motor NSS subscores, the first time a study describes this relationship for all the relevant structures simultaneously. For its part, ROI proves to be effective demonstrating that subcortical structures (thalamus and caudate) are the most affected by motor NSS.

Effects of different types of sensory signals on reaching performance in persons with chronic schizophrenia

Previous studies have reported movement abnormalities in persons with schizophrenia. This study aimed to examine the differences between persons with chronic schizophrenia and healthy control participants in reaching movement and the effects of sensory signals on reaching performance in persons with chronic schizophrenia. A counter-balanced repeated-measures design was employed. Twenty persons with schizophrenia and 20 age- and gender-matched control participants were recruited in this study. Reaching performance was measured in three types of sensory signal conditions (visual, auditory, and no signal), i.e., two externally triggered and one self-initiated movement were assessed in reaction time/inter-response interval, movement time, peak velocity, percentage of time in which peak velocity occurred, and movement units. The results revealed significant main effects of group in reaction time/inter-response interval (p = 0.003), movement time (p < 0.001), peak velocity (p < 0.001), and movement units (p < 0.001). The persons with chronic schizophrenia demonstrated slower response to signals and in self-initiated movement, increased movement time, and less forceful and less smooth movement compared to healthy control participants when performing the reaching task. The interaction effect between group and signal in reaction time/inter-response interval was also significant (p < 0.001). The inter-response interval for self-initiated reaching was the shortest in healthy controls. Conversely, the inter-response interval for self-initiated reaching was the longest in persons with schizophrenia. The main effect of the signal on movement time was significant (p < 0.001). The movement time of reaching was longer in response to the auditory signal than in response to visual or self-initiated. The differences in percentages of time in which peak velocity occurred between persons with schizophrenia and healthy controls (p > 0.01) and across the three conditions (p > 0.01) were non-significant. Neither duration of illness nor antipsychotic dosage was significantly associated with reaching performance (all p > 0.01). In conclusion, these findings indicate that reaching movement in persons with chronic schizophrenia is slower, less forceful, and less coordinated compared to healthy control participants. In addition, persons with chronic schizophrenia also had shorter inter-response interval for self-initiated movement and shorter movement time in auditory signal condition, independent of duration of illness and antipsychotic dosage.

Neurological soft signs (NSS) and brain morphology in patients with chronic schizophrenia and healthy controls

Subtle abnormalities in sensory integration, motor coordination and sequencing of complex motor acts or neurological soft signs (NSS) are characteristic phenomena in patients with schizophrenia at any stage of the illness. Previous MRI studies in schizophrenia found NSS to be associated with cortical, thalamic and cerebellar changes. Since these studies mainly focused on first-episode or recent onset schizophrenia, the cerebral correlates of NSS in chronic schizophrenia remained rather unclear. 49 middle-aged patients with chronic schizophrenia with a mean duration of illness of 20.3 ± 14.0 years and 29 healthy subjects matched for age and sex were included. NSS were examined on the Heidelberg Scale and correlated to grey matter (GM) by using whole brain high resolution magnetic resonance imaging (3 Tesla) with SPM12/CAT12 analyses. As expected, NSS in patients were significantly (p≤0.001) elevated in contrast to healthy controls, a finding, which not only applied to NSS total score, but also to the respective subscales "motor coordination", "sensory integration", "complex motor tasks", "right/left and spatial orientation" and "hard signs". Within the patient group NSS total scores were significantly correlated to reduced GM in right lingual gyrus, left parahippocampal gyrus, left superior temporal gyrus, left thalamus (medial dorsal nucleus) and left posterior lobe of the cerebellum (declive). Respective negative associations could also be revealed for the subscales "motor coordination", "complex motor tasks" and "right/left and spatial orientation". These findings remained significant after FWE-correction for multiple comparisons and were confirmed when years of education, chlorpromazine-equivalents or variables indicating the severity of psychopathology were introduced as additional covariates. According to our results lingual, parahippocampal, superior temporal, inferior and middle frontal gyri, thalamus and cerebellum have to be considered as important sites of NSS in chronic schizophrenia. That these findings only applied for patients but not healthy controls may indicate a different pathogenesis of NSS.

Neurological soft signs in schizophrenia spectrum disorders are not confounded by current antipsychotic dosage

Neurological soft signs (NSS) have garnered increasing attention in psychiatric research on motor abnormalities in schizophrenia spectrum disorders (SSD). However, it remains unclear whether the assessment of NSS severity could have been confounded by current antipsychotic dosage. In this study, we recruited 105 patients with SSD that underwent a comprehensive motor assessment evaluating NSS and extrapyramidal motor symptoms (EPMS) by means of standardized instruments. Current antipsychotic dosage equivalence estimates were determined by the classical mean dose method (doses equivalent to 1 mg/d olanzapine). We used multiple regression analyses to describe the relationship between NSS, EPMS and antipsychotic medication. In line with our expectations, current antipsychotic dosage had no significant effects on NSS total score (p = 0.27), abnormal involuntary movements (p = 0.17), akathisia (p = 0.32) and parkinsonism (p = 0.26). Further, NSS total score had a significant effect on akathisia (p = 0.003) and parkinsonism (p = 0.0001, Bonferroni corr.), but only marginal effect on abnormal involuntary movements (p = 0.08). Our results support the notion that NSS are not significantly modulated by current antipsychotic dosage in SSD. The associations between NSS, akathisia and parkinsonism, as revealed by this study, support the genuine rather than medication-dependent origin of particular motor abnormalities in SSD.

12-Month stability of neurological soft signs in stabilized patients with schizophrenia

Objective: Neurological soft signs (NSS) are a group of minor non-localizable neurological abnormalities found more often in patients with schizophrenia. The aim of the current study was to investigate their temporal stability and relationship to the overall outcome over a 12-month period. Material and methods: The study sample included 133 stabilized patients suffering from schizophrenia (77 males and 56 females; aged 33.55 ± 11.22 years old). The assessment included the application at baseline and after 12 months of the Neurological Evaluation Scale (NES), and a number of scales assessing the clinical symptoms and adverse effects. The statistical analysis included ANOVA, exploratory t-test and Pearson correlation coefficients with Bonferroni correction. Results: In stabilized patients, NSS are stable over a 12-month period with only the subscale of NES-sensory integration manifesting a significant worsening, while, in contrast, most of the clinical variables improved significantly. There was no relationship of NES scores with the magnitude of improvement. The only significant negative correlation was between NES-motor coordination and Positive and Negative Syndrome Scale-GP change at 1 year. Discussion: The results of the current study suggest that after stabilization of patients with schizophrenia, there are probably two separate components, a 'trait' which is stable over a 12-month period, and a 'degenerative' component with a tendency to worsen probably in parallel with the progression of the illness and in correlation with the worsening of negative symptoms. However, the statistical support of the 'degenerative' component is weak. Significant outcomes Neurological softs signs are stable over a 12-month period, with the exception of 'sensory integration' which manifests significant improvement irrespective of treatment response. They do not respond to treatment with antipsychotics. They do not constitute a prognostic factor to predict improvement over a period of 1 year. Neurological soft signs constitute a trait symptom of schizophrenia which is stable though time. Limitations All the subjects have been previously hospitalized which may represent a more severe form of schizophrenia. Also, all patients were under antipsychotic and some also under benzodiazepine medications. Patients with comorbid somatic disorders were excluded which may decrease generalizability of results.

Differential contributions of brainstem structures to neurological soft signs in first- and multiple-episode schizophrenia spectrum disorders

Neurological soft signs (NSS) are frequently found in patients with schizophrenia spectrum disorders (SSD) at any stage of the disease. Brainstem structures are crucial for motor control, integration of sensory input and coordination of automatic motor actions. It is unclear whether disease duration has an impact on NSS/brainstem volume relationships. We tested the hypothesis that volumes of brainstem structures differ between first-episode psychosis (FEP) and multiple-episodes psychosis (MEP) patients with SSD, and that alterations of these structures are associated with NSS. T1-weighted structural MRI data at 3 T were obtained from 92 right-handed SSD patients (27 FEP and 65 MEP). FreeSurfer vers. 6.0 was used for segmentation of brainstem structures including the medulla oblongata, pons, superior cerebellar pedunculus (SCP), and midbrain. Multiple regression analyses were used to describe the relationship between brainstem structures and distinct NSS subdomains. In FEP, pons volume had a significant effect on NSS total score (p = 0.001, Bonferroni corr.). Further, medulla oblongata (p = 0.001, Bonferroni corr.) and pons (p = 0.001, Bonferroni corr.) volumes had a significant effect on NSS motor coordination score. In MEP, significant associations between brainstem structures and NSS levels were not found. The present data support the notion that brainstem structures play an important role in the expression of NSS in SSD individuals with FEP, in contrast to individuals with MEP. Our study also emphasizes the need of better characterizing episode-specific brainstem correlates of NSS in SSD.

Neurological soft signs (NSS) and cognitive impairment in chronic schizophrenia

Recent studies indicate that neurological soft signs (NSS) in schizophrenia are associated with generalized cognitive impairments rather than changes in specific neuropsychological domains. However, the majority of studies solely included first-episode patients or patients with a remitting course and did not consider age, course, education or severity of global cognitive deficits as potential confounding variables. Therefore, we examined NSS with respect to cognitive deficits in chronic schizophrenia, i.e. patients who are particularly vulnerable to both, NSS and cognitive impairments.

Eighty patients with chronic schizophrenia (43.36 ± 15a) and 60 healthy controls (47.52 ± 14.8a) matched for age, sex and years of education were examined on the Heidelberg NSS scale and a broad neuropsychological battery including short term, working, logical and autobiographic memory (AM), theory of mind (ToM), psychomotor speed and cognitive flexibility.

When contrasted with the controls, patients showed significantly higher NSS scores and impairments in all neuropsychological domains but short-term memory. NSS were significantly associated with all neuropsychological domains considered but short-term memory and semantic AM. Except for episodic AM (which was significantly correlated with NSS in patients only) these correlations applied to both groups and were confirmed when age, years of education and severity of global cognitive deficits (Mini Mental State Examination) were controlled for.

Results demonstrate that NSS reflect a rather wide range of cognitive impairments in schizophrenia, which also involves episodic AM and ToM. These associations were not accounted for by age, education or severity of global cognitive deficits and facilitate the clinical usage of NSS as a screening instrument.

Motor dysfunction as an intermediate phenotype across schizophrenia and other psychotic disorders: Progress and perspectives

Primary motor abnormalities (PMA), as found in patients with schizophrenia, are quantitatively and qualitatively distinct markers of motor system abnormalities. PMA have been often referred to phenomena that are present across schizophrenia-spectrum disorders. A dysfunction of frontoparietal and subcortical networks has been proposed as core pathophysiological mechanism underlying the expression of PMA. However, it is unclear at present if such mechanisms are a common within schizophrenia and other psychotic disorders. To address this question, we review recent neuroimaging studies investigating the neural substrates of PMA in schizophrenia and so-called "nonschizophrenic nonaffective psychoses" (NSNAP) such as schizophreniform, schizoaffective, brief psychotic, and other unspecified psychotic disorders. Although the extant data in patients with schizophrenia suggests that further investigation is warranted, MRI findings in NSNAP are less persuasive. It is unclear so far which PMA, if any, are characteristic features of NSNAP or, possibly even specific for these disorders. Preliminary data suggest a relationship between relapsing-remitting PMA in hyper-/hypokinetic cycloid syndromes and neurodegenerative disorders of the basal ganglia, likely reflecting the transnosological relevance of subcortical abnormalities. Despite this evidence, neural substrates and mechanisms underlying PMA that are common in schizophrenia and NSNAP cannot be clearly delineated at this stage of research. PMA and their underlying brain circuits could be promising intermediate phenotype candidates for psychotic disorders, but future multimodal neuroimaging studies in schizophrenia and NSNAP patients and their unaffected first-degree relatives are needed to answer fundamental transnosologic questions.

Motor abnormalities and cognitive impairment in first-episode psychosis patients, their unaffected siblings and healthy controls

Motor abnormalities (MAs) may be already evidenced long before the beginning of illness and are highly prevalent in psychosis. However, the extent to which the whole range of MAs are related to cognitive impairment in psychosis remains understudied. This study aimed to examine comparatively the relationships between the whole range of motor abnormalities and cognitive impairments in the first-episode of psychosis (FEP), their unaffected siblings and healthy control subjects. Fifty FEP patients, 21 of their healthy siblings and 24 age- and sex matched healthy controls were included. Motor assessment included catatonic, extrapyramidal and neurological soft signs (NSS) by means of standardized instruments. An exhaustive neuropsychological battery was also performed to extract the 7 cognitive dimensions of MATRICS initiative. Higher scores on NSS but not on extrapyramidal and catatonic signs showed significant associations with worse cognitive performance in the three study groups. However, the pattern of associations regarding specific cognitive functions was different among the three groups. Moreover, extrapyramidal signs showed significant associations with cognitive impairment only in FEP patients but not in their unaffected siblings and healthy controls. Catatonic signs did not show any significant association with cognitive functioning in the three study groups. These findings add evidence to the associations between motor abnormalities, particularly NSS and extrapyramidal signs, and cognitive impairment in first-episode psychosis patients. In addition, our results suggest that the specific pattern of associations between MAs and cognitive functioning is different in FEP patients from those of the unaffected siblings and healthy subjects.

Neurological Soft Signs in Schizophrenia: An Update on the State- versus Trait-Perspective

BACKGROUND

Neurological soft signs (NSS) represent minor neurological signs, which indicate non-specific cerebral dysfunction. In schizophrenia, their presence has been documented extensively across all stages of the disease. Until recently, NSS were considered an endophenotype or a trait phenomenon. During the past years, however, researchers report fluctuations of the NSS scores.

AIMS

To further clarify the question whether NSS exhibit state or trait components or both, studies that have investigated NSS longitudinally were reviewed.

METHOD

Studies which have assessed NSS longitudinally in adults suffering from schizophrenia, were searched for. The time frame was January 1966 to June 2017. Studies on teenagers were excluded because of interferences between brain maturation and pathology.

RESULTS

Twenty-nine follow-up studies were identified. They included patients during different stages of their illness and mainly used established instruments for NSS assessment. Patients with a first episode or a remitting course predominantly show a decrease of NSS over time, whereas a worsening of NSS can be found in the chronically ill. It was shown that change of NSS total scores over time is predominantly caused by motor system subscales and to a lesser extent by sensory integration scales. With respect to medication, the majority of studies agree on a relationship between medication response and improvement of NSS while the type of antipsychotic does not seem to play a major role. Moreover, where information on side-effects is given, it does not favor a strong relationship with NSS. However, NSS seem to correlate with negative and cognitive symptoms.

CONCLUSION

Studies manifest a conformity regarding the presence of NSS in schizophrenia patients on the one hand. On the other hand, fluctuations of NSS scores have been widely described in subgroups. Taken together results strongly support a state-trait dichotomy of NSS. Thus, the usage of NSS as an endophenotype has to be called into question.

Neurological Soft Signs and Psychopathology in Chronic Schizophrenia: A Cross-Sectional Study in Three Age Groups

As established in a wealth of studies subtle motor and sensory neurological abnormalities or neurological soft signs (NSS) are frequently found in patients with schizophrenia at any stage of their illness. However, the potential impact of chronicity and age on NSS was scarcely investigated. Therefore, we assessed NSS in 90 patients with subchronic (n = 22) or chronic (n = 68) schizophrenia and in 60 healthy controls who were assigned to three age groups (18-29, 30-49, and +50 years). NSS were measured on the Heidelberg Scale, psychopathological symptoms including apathy were rated on established instruments. As demonstrated by analysis of variance, NSS scores in patients were significantly (p < 0.05) increased relative to healthy controls. Significant age effects arose in all NSS subscores, with older subjects scoring well above the younger ones. These age effects were more pronounced in patients than controls, indicating that NSS in chronic schizophrenia exceed age-associated changes. Moreover, the NSS scores in patients were significantly associated with duration of illness, thought disturbance, positive symptoms, and apathy. These results were confirmed after age/duration of illness and years of education were partialed out and via regression analyses. Our findings conform to the hypothesis that NSS are associated with chronicity of the disorder as indicated by the correlations of NSS with both, duration of illness and apathy. The correlations between NSS and positive symptoms/thought disturbance correspond to the fluctuation of positive symptoms during the course of the disorder. The significantly more pronounced age effects on NSS in patients may either point to ongoing cerebral changes or to a greater susceptibility of patients toward physiological age effects, which may be mediated among other factors by a lower cognitive reserve.

Neurological soft signs in first-episode schizophrenia: State- and trait-related relationships to psychopathology, cognition and antipsychotic medication effects

BACKGROUND

Neurological soft signs (NSS) are proposed to represent both state- and trait-related features of schizophrenia.

METHOD

We assessed the course of NSS with the Neurological Evaluation Scale (NES) over 12months of standardised treatment in 126 patients with first-episode schizophrenia, schizophreniform or schizoaffective disorder, and evaluated their state- and trait-related associations with psychopathology, functionality, cognition and antipsychotic treatment. We considered change scores from baseline to be state-related and endpoint scores to be trait-related.

RESULTS

Significant effects for time were recorded for all NSS domains. For state-related change-scores greater improvements in sensory integration were predicted by more improvement in working memory (p=0.01); greater improvements in motor sequencing scores were predicted by more improvement in working memory (p=0.005) and functionality (p=0.005); and greater improvements in NES Total score were predicted by more improvement in disorganised symptoms (p=0.02). There were more substantial associations between trait-related endpoint scores than for state-related change scores. For endpoint scores lower composite cognitive score predicted poorer sensory integration (p=0.001); higher Parkinsonism score predicted poorer motor co-ordination (p=0.0001); lower composite cognitive score (p=0.001) and higher Parkinsonism score (p=0.005) predicted poorer motor sequencing; higher Parkinsonism score (p=0.0001) and disorganised symptoms (p=0.04), and lower composite cognitive score (p=0.0007) predicted higher NES total score.

CONCLUSIONS

NSS improved with treatment, but were weakly associated with improvements in psychopathology. Studies investigating NSS as trait-markers should ensure that patients have been optimally treated at the time of testing, and should take possible effects of extrapyramidal symptoms into account.

Psychiatric symptoms mediate the effects of neurological soft signs on functional outcomes in patients with chronic schizophrenia: A longitudinal path-analytic study

Neurological soft signs (NSS) in motor coordination and sequencing occur in schizophrenia patients and are an intrinsic sign of the underlying neural dysfunctions. The present longitudinal study explored the relationships among NSS, psychiatric symptoms, and functional outcomes in 151 Chinese patients with chronic schizophrenia across a 6-month period. The participants completed neurological assessments at baseline (Time 1), psychiatric interviews at Time 1 and 3-month follow-up (Time 2), and self-report measures on daily functioning at 6-month follow-up (Time 3). Two possible (combined and cascading) path models were examined on predicting the functional outcomes. Direct and indirect effects of Time 1 NSS on Time 3 functional outcomes via Time 2 psychiatric symptoms were evaluated using path analysis under bootstrapping. Motor coordination and sequencing NSS did not have significant direct effects on functional outcomes. Motor coordination NSS exerted significant and negative indirect effects on functional outcomes via psychiatric symptoms. These results contribute to a better understanding of the determinants of functional outcomes by showing significant indirect pathways from motor coordination NSS to functional outcomes via psychiatric symptoms. That motor sequencing NSS did not affect functional outcomes either directly or indirectly may be explained by their trait marking features.

Manual Dexterity in Schizophrenia-A Neglected Clinical Marker?

Impaired manual dexterity is commonly observed in schizophrenia. However, a quantitative description of key sensorimotor components contributing to impaired dexterity is lacking. Whether the key components of dexterity are differentially affected and how they relate to clinical characteristics also remains unclear. We quantified the degree of dexterity in 35 stabilized patients with schizophrenia and in 20 age-matched control subjects using four visuomotor tasks: (i) force tracking to quantify visuomotor precision, (ii) sequential finger tapping to measure motor sequence recall, (iii) single-finger tapping to assess temporal regularity, and (iv) multi-finger tapping to measure independence of finger movements. Diverse clinical and neuropsychological tests were also applied. A patient subgroup (N = 15) participated in a 14-week cognitive remediation protocol and was assessed before and after remediation. Compared to control subjects, patients with schizophrenia showed greater error in force tracking, poorer recall of tapping sequences, decreased tapping regularity, and reduced degree of finger individuation. A composite performance measure discriminated patients from controls with sensitivity = 0.79 and specificity = 0.9. Aside from force-tracking error, no other dexterity components correlated with antipsychotic medication. In patients, some dexterity components correlated with neurological soft signs, Positive and Negative Syndrome Scale (PANSS), or neuropsychological scores. This suggests differential cognitive contributions to these components. Cognitive remediation lead to significant improvement in PANSS, tracking error, and sequence recall (without change in medication). These findings show that multiple aspects of sensorimotor control contribute to impaired manual dexterity in schizophrenia. Only visuomotor precision was related to antipsychotic medication. Good diagnostic accuracy and responsiveness to treatment suggest that manual dexterity may represent a useful clinical marker in schizophrenia.

Postural Sway and Clinical Characteristics in Patients with Psychotic Disorders: A Review

Postural instability is a feature that is frequently observed in patients with psychotic disorders. Previous studies applied rating scales or behavioral test to assess postural instabilities. Recently, a pressure-sensitive platform has been used to study detailed characteristics of postural sway and regulation. However, characteristics of posturography indices in patients with psychotic disorders have not been well documented. To integrate the findings from studies that assessed postural sway using posturography in patients with psychotic disorders, we conducted a systematic review. Following database literature search, we identified nine eligible articles. Assessment conditions and indices of postural stability varied between studies. Postural control was associated with negative and general psychopathology in two studies. Two studies reported associations between posturographic variables and medication dose, whereas four studies reported no associations. This review identified the need to develop standards to assess postural sway in patients with psychiatric disorders. Further studies need to report associations between postural sway and confounding factors.

Motor dysfunction within the schizophrenia-spectrum: A dimensional step towards an underappreciated domain

At the beginning of the 20th century, genuine motor abnormalities (GMA) were considered to be intricately linked to schizophrenia. Subsequently, however, GMA have been increasingly regarded as unspecific transdiagnostic phenomena or related to side effects of antipsychotic treatment. Despite possible medication confounds, within the schizophrenia spectrum GMA have been categorized into three broad categories, i.e. neurological soft signs, abnormal involuntary movements and catatonia. Schizophrenia patients show a substantial overlap across a broad range of distinct motor signs and symptoms suggesting a prominent involvement of the motor system in disease pathophysiology. There have been several attempts to increase reliability and validity in diagnosing schizophrenia based on behavior and neurobiology, yet relatively little attention has been paid to the motor domain in the past. Nevertheless, accumulating neuroscientific evidence suggests the possibility of a motor endophenotype in schizophrenia, and that GMA could represent a specific dimension within the schizophrenia-spectrum. Here, we review current neuroimaging research on GMA in schizophrenia with an emphasis on distinct and common mechanisms of brain dysfunction. Based on a dimensional approach we show that multimodal neuroimaging combined with fine-grained clinical examination can result in a comprehensive characterization of structural and functional brain changes that are presumed to underlie core GMA in schizophrenia. We discuss the possibility of a distinct motor domain, together with its implications for future research. Investigating GMA by means of multimodal neuroimaging can essentially contribute at identifying novel and biologically reliable phenotypes in psychiatry.

Abnormal visuomotor processing in schizophrenia

Subtle disturbances of visual and motor function are known features of schizophrenia and can greatly impact quality of life; however, few studies investigate these abnormalities using simple visuomotor stimuli. In healthy people, electrophysiological data show that beta band oscillations in sensorimotor cortex decrease during movement execution (event-related beta desynchronisation (ERBD)), then increase above baseline for a short time after the movement (post-movement beta rebound (PMBR)); whilst in visual cortex, gamma oscillations are increased throughout stimulus presentation. In this study, we used a self-paced visuomotor paradigm and magnetoencephalography (MEG) to contrast these responses in patients with schizophrenia and control volunteers. We found significant reductions in the peak-to-peak change in amplitude from ERBD to PMBR in schizophrenia compared with controls. This effect was strongest in patients who made fewer movements, whereas beta was not modulated by movement in controls. There was no significant difference in the amplitude of visual gamma between patients and controls. These data demonstrate that clear abnormalities in basic sensorimotor processing in schizophrenia can be observed using a very simple MEG paradigm.

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Visual and motor deficits in schizophrenia are rarely investigated.

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We use MEG to non-invasively assess the neural basis of these deficits.

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Patients showed abnormalities in neuronal oscillations in motor cortex.

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Beta band power, reflecting cortical inhibition, was reduced after movements.

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Increased movement frequency may be a behavioural compensation for this reduction.

Neurological soft signs in aging, mild cognitive impairment, and Alzheimer's disease - the impact of cognitive decline and cognitive reserve

OBJECTIVES

Neurological soft signs (NSS), i.e., minor motor and sensory changes, are a common feature in severe psychiatric disorders. We sought to establish the frequency of NSS in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) on basis of a large population-based sample and to identify their neuropsychological correlates including cognitive reserve.

METHODS

Neurological soft signs were examined using an abbreviated version of the Heidelberg NSS Scale in 221 "old" participants born between 1930 and 1932 (63 with MCI, 15 with AD, 143 healthy old controls) and 256 healthy "young" participants (born between 1950 and 1952) of the population-based interdisciplinary longitudinal study of aging. Subjects received thorough neuropsychological testing; years of school education were used as a proxy for cognitive reserve.

RESULTS

Neurological soft signs scores were significantly (p < 0.001) higher in the AD patients (5.6 ± 3.11) than in the healthy old controls (2.8 ± 1.90) and in the MCI patients (3.0 ± 1.96). This result was confirmed after years of school education, which were inversely correlated (r = -0.25; p < 0.001) with NSS were entered as a covariate. In the patients, but not in the controls, NSS were significantly correlated with deficits in executive functioning and visuospatial functioning. Comparison of NSS scores between "old" (2.84 ± 1.9) and "young" (2.46 ± 1.97) controls yielded only minor, non-significant differences after education (13.86 ± 3.0 vs. 14.61 ± 2.48 years, respectively) was controlled for.

CONCLUSION

Our results demonstrate that NSS are frequently found in mild AD, but not in MCI. NSS refer to frontal-executive deficits and visuospatial dysfunction rather than age per se and can be partly compensated for by cognitive reserve.

Neurological soft signs might be endophenotype candidates for patients with deficit syndrome schizophrenia

BACKGROUND

Schizophrenia is a chronic, disabling, disorder that affects approximately 1% of the population. The nature of schizophrenia is heterogeneous, and unsuccessful efforts to subtype this disorder have been made. Deficit syndrome schizophrenia (DS) is a clinical diagnosis that has not been placed in main diagnostic manuals. In this study, we aimed to investigate and compare neurological soft signs (NSS) in DS patients, non-deficit schizophrenia (NDS) patients, and healthy controls (HCs). We suggest that NSS might be an endophenotype candidate for DS patients.

METHODS

Sixty-six patients with schizophrenia and 30 HCs were enrolled in accordance with our inclusion and exclusion criteria. The patients were sub-typed as DS (n=24) and NDS (n=42) according to the Schedule for the Deficit Syndrome. The three groups were compared in terms of sociodemographic and clinical variables and total scores and subscores on the Physical and Neurological Examination for Soft Signs (PANESS). Following the comparison, a regression analysis was performed for predictability of total PANESS score and its subscales in the diagnosis of DS and NDS.

RESULTS

The groups were similar in terms of age, sex, and smoking status. The results of our study indicated that the total PANESS score was significantly higher in the DS group compared to the NDS and HC groups, and all PANESS subscales were significantly higher in the DS group than in the HC group. The diagnosis of DS was predicted significantly by total PANESS score (P<0.001, odds ratio =9.48, 95% confidence interval: 0.00-4.56); the synergy, graphesthesia, stereognosis, motor tasks, and ability to maintain posture subscales were found to be significant predictors.

CONCLUSION

This study confirms that NSS were higher in patients with DS. In addition, we suggest that our results might support the notion of DS as a different and distinct type of schizophrenia. NSS might also be a promising candidate as an endophenotype for DS. However, large sampled, multicentric studies are needed to clarify the place of NSS as an endophenotype in DS.

Neurological soft signs in the clinical course of schizophrenia: results of a meta-analysis

Neurological soft signs (NSS) comprise subtle deficits in sensory integration, motor coordination, and sequencing of complex motor acts, which are typically observed in the majority of schizophrenia patients, including chronic cases and neuroleptic-naïve first-episode patients. However, recent studies clearly demonstrate that NSS are not a static feature of schizophrenia but vary in the clinical course of the disorder. This effect was investigated in a meta-analysis based on 17 longitudinal studies published between 1992 and 2012. Studies included between 10 and 93 patients with schizophrenia spectrum disorders (total number 787) with follow-up periods between 2 and 208 weeks. Beside the Neurological Examination Scale, the Cambridge Neurological Inventory and the Heidelberg NSS Scale were used to assess NSS. All but three studies found NSS to decrease in parallel with remission of psychopathological symptoms. This effect was more pronounced in patients with a remitting compared to a non-remitting, chronic course (Cohen's d 0.81 vs. 0.15) and was significantly correlated with length of the follow-up period (r = -0.64) but not with age (r = 0.28). NSS scores did not decrease to the level typically observed in healthy controls. From a clinical perspective, NSS may therefore be used to identify subjects at risk to develop schizophrenia and to monitor disease progression.

Neurological soft signs and brainstem morphology in first-episode schizophrenia

BACKGROUND

Minor motor and sensory deficits or neurological soft signs (NSS) have frequently been reported in patients with schizophrenia at any stage of their illness. NSS have been demonstrated to correlate with neuroanatomical abnormalities in various brain regions. Despite its important role in the integration and coordination of automatic motor actions, the brainstem has so far rather been ignored in previous neuroimaging studies on NSS in schizophrenia.

METHOD

We investigated 21 right-handed first-episode schizophrenia patients using high-resolution magnetic resonance imaging at 3 T. The severity of NSS was measured with the Heidelberg Scale. Associations between NSS and both brainstem volume and shape changes were examined.

RESULTS

Higher NSS scores were significantly associated with structural alterations in the brainstem. According to volume measurements higher NSS scores correlated with global changes of the brainstem. Using shape analyses these associations referred to regionally specific morphometric alterations predominantly in the midbrain and pons.

CONCLUSION

The findings suggest that brainstem morphometric alterations are associated with the severity of NSS in patients with first-episode schizophrenia. They further indicate the involvement of the brainstem in the pathogenesis of schizophrenia.

Neurological abnormalities in recent-onset schizophrenia and asperger-syndrome

BACKGROUND

Neurological abnormalities including a variety of subtle deficits such as discrete impairments in sensory integration, motor coordination (MOCO), and sequencing of complex motor acts are frequently found in patients with schizophrenia (SZ) and commonly referred to as neurological soft signs (NSS). Asperger-syndrome (AS) is characterized by sensory-motor difficulties as well. However, the question whether the two disorders share a common or a disease-specific pattern of NSS remains unresolved.

METHOD

A total of 78 age- and education-matched participants [26 patients with recent-onset SZ, 26 individuals with AS, and 26 healthy controls (HC)] were recruited for the study. Analyses of covariance (ANCOVAs), with age, years of education, and medication included as covariates, were used to examine group differences on total NSS and the five subscale scores. Discriminant analyses were employed to identify the NSS subscales that maximally discriminate between the three groups.

RESULTS

Significant differences among the three groups were found in NSS total score and on the five NSS subscales. The clinical groups differed significantly in the NSS subscale MOCO. The correct discriminant rate between patients with SZ and individuals with AS was 61.5%. The correct discriminant rate was 92.3% between individuals with AS and HC, and 80.8% between SZ patients and HC, respectively.

CONCLUSION

Our findings provide new evidence for the presence of NSS in AS and lend further support to previously reported difficulties in movement control in this disorder. According to the present results, SZ and AS seem to be characterized by both quantitative and qualitative NSS expression.

Benzodiazepines, benzodiazepine-like drugs, and typical antipsychotics impair manual dexterity in patients with schizophrenia

Impaired dexterity is a major psychomotor deficit reported in patients with schizophrenia. In the present study, the Purdue pegboard test was used to compare the manual dexterity in patients with schizophrenia and healthy controls. We also examined the influence of antipsychotics, benzodiazepines, and benzodiazepine-like drugs on manual dexterity. Subjects were 93 patients with schizophrenia and 93 healthy controls, matched for sex and age distributions. Control subjects scored significantly higher on all scores of Purdue pegboard than patients with schizophrenia. Age, PANSS negative symptom scale, typical antipsychotic dose, and use of benzodiazepines and/or benzodiazepine-like drugs were negatively correlated with the pegboard scores in patients with schizophrenia. The present results indicate that patients with schizophrenia have impaired gross and fine fingertip dexterity compared to healthy controls. The use of typical antipsychotics and benzodiazepines and/or benzodiazepine-like drugs, but not atypical antipsychotics, had significant negative impact on dexterity in patients with schizophrenia. Psychiatrists should be aware that some psychotropic medications may enhance the disability caused by the impairment of dexterity in patients with schizophrenia.

Dynamics of neurological soft signs and its relationship to clinical course in patients with first-episode schizophrenia

The aim of the study was to assess the dynamics of neurological soft signs (NSS) over four years from the clinical onset of schizophrenia, depending on the clinical course of the disease, and to evaluate the relationship of NSS to symptomatic dimensions in patients with first-episode schizophrenia. Sixty-eight patients with first-episode schizophrenia were included in the trial. The clinical status was assessed using Positive and Negative Syndrome Scale (PANSS) at the same time as the neurological examination, at admission to the hospital for first-episode schizophrenia and at a check-up examination four years later. The assessment of NSS using the Neurological Evaluation Scale (NES) coincided with the assessment of the clinical condition of the patients. According to the Andreasen remission criterion of schizophrenia, after four years we found that 57% of patients' were remitters and 43% were non-remitters. During the monitoring period, in remitters total NES score and sensory integration/sequencing of motor acts items of the NES decreased. In non-remitters, increase in the total NES score and the 'others' item of the NES was observed. A connection between the dynamics of NSS and the clinical course of schizophrenia, over the period of four years, and a relationship between NSS and negative schizophrenia symptoms was found.

Parsing the components of the psychomotor syndrome in schizophrenia

OBJECTIVE

Catatonia, extrapyramidal signs, psychomotor slowing, and (motoric) neurological soft signs are well-known psychomotor symptoms in schizophrenia. This study aims at investigating the interrelations between these symptoms. In addition, associations between psychomotor symptoms, clinical symptoms, and cognitive functioning will be studied.

METHOD

An extensive test battery containing psychomotor (Bush Francis Catatonia Rating Scale; St Hans Rating Scale; Salpêtrière Retardation Rating Scale; Neurological Evaluation Scale) and clinical (Positive and Negative Syndrome Scale; Calgary Depression Scale) rating scales as well as instrumental psychomotor tests (Line Copying Task; Finger Tapping Task) and cognitive tasks (Symbol Digit Substitution Test; Stroop Colour Word Test; Continuous Performance Test; Letter Number Sequencing) was administered to a sample of 124 patients with schizophrenia or schizoaffective disorder.

RESULTS

Correlational analyses showed that two clusters emerge from our data: first, a psychomotor poverty cluster referring to the interrelations between catatonia, parkinsonism, psychomotor slowing, and negative symptoms; second, a cluster containing motoric neurological soft signs, which were found to be correlated with cognitive functioning.

CONCLUSION

Psychomotor abnormalities are highly prevalent phenomena in schizophrenia that have to be considered as a heterogeneous construct. However, longitudinal and neurobiological research is needed to further explore the precise nature of the interrelations found in this study.

Neurological soft signs and subcortical brain morphology in recent onset schizophrenia

BACKGROUND

Minor motor and sensory deficits or neurological soft signs (NSS) are frequently found in patients with schizophrenia at any stage of their illness. The thalamus and basal ganglia are accepted as being important for both motor control and integration of sensory input. However, whether NSS are related to alterations of these brain regions remains controversial.

METHOD

Twenty patients with recent onset schizophrenia were investigated using high-resolution magnetic resonance imaging (MRI) at 3 Tesla. NSS were examined on the Heidelberg Scale after remission of acute symptoms and related to both volumetric and shape measurements of thalamus, caudate nucleus, putamen, and globus pallidus, respectively. Age, education, medication and duration of illness were considered as potential confounders.

RESULTS

NSS were associated with structural alterations predominantly in the thalamus, the left caudate nucleus, and in the right globus pallidus. According to shape analyses these associations referred to regionally specific morphometric alterations rather than to global atrophy of the respective structures.

CONCLUSION

Our findings provide new insights into the association of NSS with brain morphometric alterations and lend further support to an involvement of multiple subcortical regions in schizophrenia.

Neurological soft signs in schizophrenia - The past, the present and the future

Clinical neurological abnormalities in patients with schizophrenia have been generally called "Neurological Soft Signs" (NSS). Studies have consistently shown increased NSS in patients with schizophrenia as compared to healthy persons. Early studies were limited by possible confounds of prior neuroleptic medications and illness chronicity. Studies in first episode never treated schizophrenia patients have addressed these confounds. The clinical significance of these findings and the correlation with cognitive dysmetria is the focus of the current review. Relevant literature was obtained using PUBMED and MEDLINE search (1980-2008) and a direct search of reference list of pertinent journal articles. In a 2003 study, neuroleptic-naive schizophrenia patients had significantly more NSS than controls. Patients who were more neurologically impaired had more negative symptoms. Higher NSS scores in treatment-naive schizophrenia patients and the absence of correlation between NSS and illness duration lends support to a neurodevelopmental pathogenesis for schizophrenia. The finding of incoordination and cerebellar signs in most studies also supports the "cognitive dysmetria" explanatory model for schizophrenia. A significant subgroup of patients with schizophrenia may have more neuropathological abnormalities, which predisposes them for a more severe and chronic course of illness. These patients may potentially be identified by clinical neurological examination, which might be very important for prognostication and evolving better methods of treatment for these patients. NSS, by themselves or as a composite index with other neurobiological parameters, hold potential as a candidate endophenotype for schizophrenia.

Neurological signs and morphological cerebral changes in schizophrenia: An analysis of NSS subscales in patients with first episode psychosis

Neurological soft signs (NSS) comprise a broad range of minor motor and sensory deficits which are frequently found in schizophrenia. However, the cerebral changes underlying NSS are only partly understood. We therefore investigated the cerebral correlates of NSS by using magnetic resonance imaging (MRI) in 102 patients with first episode schizophrenia. NSS were assessed after remission of acute psychotic symptoms using the Heidelberg scale (HS), which consists of five NSS subscales ("motor coordination", "complex motor tasks", "orientation", "integrative functions", and "hard signs"). Correlations between NSS scores and cerebral changes were established by optimized voxel-based morphometry. NSS total scores were significantly associated with reduced gray matter densities in the precentral and postcentral gyri, the inferior parietal lobule and the inferior occipital gyrus. Both of the NSS subscales "motor coordination" and "complex motor tasks", referred to motor strip changes but showed differential correlations with parietal, insular, cerebellar or frontal sites, respectively. The NSS subscales "orientation" and "integrative functions" were associated with left frontal, parietal, and occipital changes or bihemispheric frontal changes, respectively. The NSS subscale "hard signs" was associated with deficits in the right cerebellum and right parastriate cortex. Repeated analyses for white matter changes revealed similar results. These findings confirm the associations between NSS and cerebral changes in areas important for motor and sensory functioning. This variety of cerebral sites corresponds to the heterogeneity of NSS and are consistent with the hypothesis that NSS reflect both a rather generalized cerebral dysfunction and localized deficits specific for particular signs.

Neurological soft signs in schizophrenia: a meta-analysis

BACKGROUND

Neurological soft signs (NSS) are hypothesized as candidate endophenotypes for schizophrenia, but their prevalence and relations with clinical and demographic data are unknown. The authors undertook a quantification (meta-analysis) of the published literature on NSS in patients with schizophrenia and healthy controls. A systematic search was conducted for published articles reporting NSS and related data using standard measures in schizophrenia and healthy comparison groups.

METHOD

A systematic search was conducted for published articles reporting data on the prevalence of NSS in schizophrenia using standard clinical rating scales and healthy comparison groups. Meta-analyses were performed using the Comprehensive Meta-analysis software package. Effect sizes (Cohen d) indexing the difference between schizophrenic patients and the healthy controls were calculated on the basis of reported statistics. Potential moderator variables evaluated included age of patient samples, level of education, sample sex proportions, medication doses, and negative and positive symptoms.

RESULTS

A total of 33 articles met inclusion criteria for the meta-analysis. A large and reliable group difference (Cohen d) indicated that, on average, a majority of patients (73%) perform outside the range of healthy subjects on aggregate NSS measures. Cognitive performance and positive and negative symptoms share 2%-10% of their variance with NSS.

CONCLUSIONS

NSS occur in a majority of the schizophrenia patient population and are largely distinct from symptomatic and cognitive features of the illness.

Potential Endophenotype for Schizophrenia: Neurological Soft Signs

Introduction: Neurological soft signs (NSS) are suggested as a candidate endophenotype for schizophrenia. This article aims to review relevant literature and discuss the role of NSS in understanding schizophrenia. Methods: This is an update on a review article published in 2003. Articles from 2003 onwards were specifically reviewed and discussed with relevance to the role of NSS as endophenotype for schizophrenia. Results: Consistent data suggest an excess of NSS in schizophrenic patients. NSS appear to be related to schizophrenic symptoms, in particular negative symptoms and disorganisation. Information on NSS and demographic correlates is scarce, and the confounding effects between age, education and intelligence on NSS constitute an important gap in current knowledge. Longitudinal data suggest NSS as both a trait and state variable in the course of disease. NSS are not specific with regard to diagnosis, although there are claims that individual sub-components may be more specific. The weight of evidence raises question on the specificity of NSS for schizophrenia. Conclusions: The usefulness and feasibility of NSS as a specific endophenotype target for schizophrenia is unclear. However, NSS remain an important feature and symptom correlate of schizophrenia. Future research should focus on delineating the effects of NSS from those of confounding demographic variables, and the stability of NSS over the course of illness to elucidate its role in schizophrenia. Key words: Diagnostic specificity, Neurological examination abnormalities, Psychotic symptoms, Review, Trait

Neurological signs and involuntary movements in schizophrenia: intrinsic to and informative on systems pathobiology

While it has long been considered whether the pathobiology of schizophrenia extends beyond its defining symptoms to involve diverse domains of abnormality, in the manner of a systemic disease, studies of neuromotor dysfunction have been confounded by treatment with antipsychotic drugs. This challenge has been illuminated by a new generation of studies on first-episode schizophrenia before initiation of antipsychotic treatment and by opportunities in developing countries to study chronically ill patients who have remained antipsychotic naive due to limitations in provision of psychiatric care. Building from studies in antipsychotic-naive patients, this article reviews 2 domains of neuromotor dysfunction in schizophrenia: neurological signs and involuntary movements. The presence and characteristics of neurological signs in untreated vis-à-vis treated psychosis indicate a vulnerability marker for schizophrenia and implicate disruption to neuronal circuits linking the basal ganglia, cerebral cortex, and cerebellum. The presence and characteristics of involuntary movements in untreated vis-à-vis treated psychosis indicate an intrinsic feature of the disease process and implicate dysfunction in cortical-basal ganglia-cortical circuitry. These neuromotor disorders of schizophrenia join other markers of subtle but pervasive cerebral and extracerebral, systemic dysfunction, and complement current concepts of schizophrenia as a disorder of developmentally determined cortical-basal ganglia-thalamo-cortical/cerebellar network disconnectivity.

Fewer neurological soft signs among first episode psychosis patients with heavy cannabis use

BACKGROUND

Although neurological soft signs (NSS) have been consistently associated with schizophrenia and a variety of risk factors, few studies have focused on the association between NSS and environmental factors such as cannabis use, particularly in patients with first episode psychosis.

METHODS

We administered the Neurological Evaluation Scale (NES) to 92 patients during their first episode of functional psychosis. Psychopathology was assessed with the Positive And Negative Syndrome Scale (PANSS) and the family history of psychotic disorder was established on the basis of the Family Interview for Genetic Studies (FIGS). We also assessed lifetime cannabis and cocaine use utilizing that specific section of the Composite International Diagnostic Interview. The outcome variable was the presence of high NSS, defined by a score above the median split of the NES score (>21).

RESULTS

Most patients (80/92, 87%) presented a non-affective psychosis. The presence of high NSS showed a significant independent association with not having been a heavy cannabis user (OR=8.3; 95% CI, 2.4-33.3), family history of psychosis (OR=4.3; 95% CI, 1.2-14.9), male sex (OR=4.0; 95% CI, 1.2-14.0), lower score in verbal fluency and higher score in negative symptoms (both p<0.01).

CONCLUSION

Our cross-sectional results support the hypothesis that potentially different pathways associated with the emergence of first episode psychosis may exist, including neurological premorbid alteration and environmental cannabis abuse.

Impairment of motor dexterity in schizophrenia assessed by a novel finger movement test

Schizophrenia is characterized by a series of serious mental disturbances, including social, cognitive, and emotional dysfunctions. Although motor dysfunctions as well as the cognitive impairments in schizophrenia have been noted since the era of Kraepelin, little attention has been paid to motor dysfunctions until recently. Here, we examined the characteristics of motor dysfunctions and their relationship to other cognitive functions in schizophrenia. Subjects were 27 patients who met the DSM-IV criteria for schizophrenia and 49 healthy volunteers. A series of motor tests, i.e., pegboard, mirror drawing, normal drawing, and finger movement tests, were administered, and cognitive functions were assessed with the Wechsler Adult Intelligence Scale Revised, the Wechsler Memory Scale Revised and the Wisconsin Card Sorting Test. The finger movement test is a novel motor test that we developed to assess motor dexterity independent of motor speed. A stepwise discriminant analysis revealed that the finger movement and delayed recall tests were able to distinguish patients and controls most effectively. The scores of these two tests showed no correlation. Educational level was correlated with the delayed recall score, but not with the finger movement score. A significant difference was observed in the finger movement test score between inpatients and outpatients. There was no significant correlation between dosage of antipsychotic drugs and finger movement score in the patient group. The present results suggest that impairment in motor dexterity is a major characteristic of schizophrenia, which might be independent of cognitive functions.

The role of the cerebellum in schizophrenia: an update of clinical, cognitive, and functional evidences

The role of the cerebellum in schizophrenia has been highlighted by Andreasen's hypothesis of "cognitive dysmetria," which suggests a general dyscoordination of sensorimotor and mental processes. Studies in schizophrenic patients have brought observations supporting a cerebellar impairment: high prevalence of neurological soft signs, dyscoordination, abnormal posture and propioception, impaired eyeblink conditioning, impaired adaptation of the vestibular-ocular reflex or procedural learning tests, and lastly functional neuroimaging studies correlating poor cognitive performances with abnormal cerebellar activations. Despite those compelling evidences, there has been, to our knowledge, no recent review on the clinical, cognitive, and functional literature supporting the role of the cerebellum in schizophrenia. We conducted a Medline research focusing on cerebellar dysfunctions in schizophrenia. Emphasis was given to recent literature (after 1998). The picture arising from this review is heterogeneous. While in some domains, the role of the cerebellum seems clearly defined (ie, neurological soft signs, posture, or equilibrium), in other domains, the cerebellar contribution to schizophrenia seems limited or indirect (ie, cognition) if present at all (ie, affectivity). Functional models of the cerebellum are proposed as a background for interpreting these results.