Motor Abnormalities and Basal Ganglia in Schizophrenia: Evidence from Structural Magnetic Resonance Imaging

Spatiotemporal dynamics of functional connectivity and association with molecular architecture in schizophrenia

Schizophrenia is a self-disorder characterized by disrupted brain dynamics and architectures of multiple molecules. This study aims to explore spatiotemporal dynamics and its association with psychiatric symptoms. Resting-state functional magnetic resonance imaging data were collected from 98 patients with schizophrenia. Brain dynamics included the temporal and spatial variations in functional connectivity density and association with symptom scores were evaluated. Moreover, the spatial association between dynamics and receptors/transporters according to prior molecular imaging in healthy subjects was examined. Patients demonstrated decreased temporal variation and increased spatial variation in perceptual and attentional systems. However, increased temporal variation and decreased spatial variation were revealed in higher order networks and subcortical networks in patients. Specifically, spatial variation in perceptual and attentional systems was associated with symptom severity. Moreover, case-control differences were associated with dopamine, serotonin and mu-opioid receptor densities, serotonin reuptake transporter density, dopamine transporter density, and dopamine synthesis capacity. Therefore, this study implicates the abnormal dynamic interactions between the perceptual system and cortical core networks; in addition, the subcortical regions play a role in the dynamic interaction among the cortical regions in schizophrenia. These convergent findings support the importance of brain dynamics and emphasize the contribution of primary information processing to the pathological mechanism underlying schizophrenia.

Structural correlates of sensorimotor dysfunction in heavy cannabis users

Sensorimotor dysfunction has been previously reported in persons with cannabis dependence. Such individuals can exhibit increased levels of neurological soft signs (NSS), particularly involving motor coordination and sensorimotor integration. Whether such abnormalities may also apply to non-dependent individuals with heavy cannabis use (HCU) is unknown, as much as the neural correlates underlying such deficits. In this study, we investigated associations between NSS and gray matter volume (GMV) in males with HCU and male controls. Twenty-four persons with HCU and 17 controls were examined using standardized assessment of NSS and structural magnetic resonance imaging (MRI) at 3 T. GMV was calculated using voxel-based morphometry algorithms provided by the Computational Anatomy Toolbox (CAT12). Individuals with HCU showed higher NSS total scores compared to controls. In particular, significant NSS-subdomain effects were found for "motor coordination" (MoCo), "complex motor tasks" (CoMT), and "hard signs" (HS) expression in HCU (p < 0.05, Bonferroni-corrected). Compared to controls, persons with HCU showed significant NSS/GMV interactions in putamen and inferior frontal cortex (MoCo), right cerebellum (CoMT) and middle and superior frontal cortices, and bilateral precentral cortex and thalamus (HS). In between-group analyses, individuals with HCU showed lower GMV in the right anterior orbital and precentral gyrus, as well as higher GMV in the right superior frontal gyrus and left supplementary motor cortex compared to controls. The data support the notion of abnormal sensorimotor performance associated with HCU. The data also provide a neuromechanistic understanding of such deficits, particularly with respect to aberrant cortical-thalamic-cerebellar-cortical circuit.

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.

Functional Connectivity Between Sensory-Motor Subnetworks Reflects the Duration of Untreated Psychosis and Predicts Treatment Outcome of First-Episode Drug-Naïve Schizophrenia

BACKGROUND

Somatic symptoms and motor abnormalities have been consistently reported as typical symptoms of schizophrenia, but evidence linking impaired functional connectivity among the primary sensory-motor network and its associations to schizophrenia is largely lacking. The present study aims to examine abnormal functional connectivity in the sensory-motor network in schizophrenia and its associations with the duration of untreated psychosis and medication treatment effects. We hypothesize that patients with schizophrenia suffer from disrupted functional connectivity between the sensory-motor subnetworks. The degree of impairment in the connectivity could reflect the duration of untreated psychosis and predict outcomes of medication treatment.

METHODS

At baseline, resting-state functional magnetic resonance imaging data were acquired from 60 first-episode patients with drug-naïve schizophrenia (36 were female) and 60 matching normal control subjects (31 were female). After 2 months, 23 patients who received medication treatment and 32 normal control subjects were rescanned. Functional connectivity among subnetworks in the sensory-motor system was compared between the groups and correlated with the duration of untreated psychosis and the treatment outcome.

RESULTS

Patients with schizophrenia showed significantly disrupted functional connectivity in the sensory-motor network. The degree of impairment reflected the duration of untreated psychosis and motor-related symptoms. It further predicted the improvement of positive scores after medication.

CONCLUSIONS

These findings suggest that functional connectivity in the sensory-motor network could indicate the severity of neural impairment in schizophrenia, and it deserves more attention in the search for neuroimaging markers for evaluating neural impairment and prognosis.

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 dysfunction as research domain across bipolar, obsessive-compulsive and neurodevelopmental disorders

Although genuine motor abnormalities (GMA) are frequently found in schizophrenia, they are also considered as an intrinsic feature of bipolar, obsessive-compulsive, and neurodevelopmental disorders with early onset such as autism, ADHD, and Tourette syndrome. Such transnosological observations strongly suggest a common neural pathophysiology. This systematic review highlights the evidence on GMA and their neuroanatomical substrates in bipolar, obsessive-compulsive, and neurodevelopmental disorders. The data lends support for a common pattern contributing to GMA expression in these diseases that seems to be related to cerebello-thalamo-cortical, fronto-parietal, and cortico-subcortical motor circuit dysfunction. The identified studies provide first evidence for a motor network dysfunction as a correlate of early neurodevelopmental deviance prior to clinical symptom expression. There are also first hints for a developmental risk factor model of these mental disorders. An in-depth analysis of motor networks and related patho-(physiological) mechanisms will not only help promoting Research Domain Criteria (RDoC) Motor System construct, but also facilitate the development of novel psychopharmacological models, as well as the identification of neurobiologically plausible target sites for non-invasive brain stimulation.

Motor clusters reveal differences in risk for psychosis, cognitive functioning, and thalamocortical connectivity: evidence for vulnerability subtypes

Abnormal development of parallel cortical-striatal networks may contribute to abnormal motor, cognitive, and affective behavior prior to the onset of psychosis. Partitioning individuals at clinical high-risk (CHR) using motor behavior may provide a novel perspective on different etiological pathways or patient subtypes. A K-means cluster analysis was conducted in CHR (N=69; 42% female, mean age=18.67 years) young adults using theoretically distinct measures of motor behavior. The resulting subtypes were then compared on positive and negative symptoms at baseline, and 2-year risk of psychosis conversion. CHR participants were followed for 2 years to determine conversion to psychosis. CHR subtypes and healthy controls (N=61; 57% female, mean age=18.58 years) were compared on multiple cognitive domains and cortical-striatal connectivity. Results suggest 3 vulnerability subtypes of CHR individuals with different profiles of motor performance, symptoms, risk for conversion to psychosis, cognition, and thalamocortical connectivity. This approach may reflect a novel strategy for promoting tailored risk assessment as well as future research developing individualized medicine.

Objective and quantitative equilibriometric evaluation of individual locomotor behaviour in schizophrenia: Translational and clinical implications

Psychiatry is the only medical specialty that lacks clinically applicable biomarkers for objective evaluation of the existing pathology at a single-patient level. On the basis of an original translational equilibriometric method for evaluation of movement patterns, we have introduced in the everyday clinical practice of psychiatry an easy-to-perform computerized objective quantification of the individual locomotor behaviour during execution of the Unterberger stepping test. For the last 20 years, we have gradually collected a large database of more than 1000 schizophrenic patients, their relatives, and matched psychiatric, neurological, and healthy controls via cross-sectional and longitudinal investigations. Comparative analyses revealed transdiagnostic locomotor similarities among schizophrenic patients, high-risk schizotaxic individuals, and neurological patients with multiple sclerosis and cerebellar ataxia, thus suggesting common underlying brain mechanisms. In parallel, intradiagnostic dissimilarities were revealed, which allow to separate out subclinical locomotor subgroups within the diagnostic categories. Prototypical qualitative (dysmetric and ataxic) locomotor abnormalities in schizophrenic patients were differentiated from 2 atypical quantitative ones, manifested as either hypolocomotion or hyperlocomotion. Theoretical analyses suggested that these 3 subtypes of locomotor abnormalities could be conceived as objectively measurable biomarkers of 3 schizophrenic subgroups with dissimilar brain mechanisms, which require different treatment strategies. Analogies with the prominent role of locomotor measures in some well-known animal models of mental disorders advocate for a promising objective translational research in the so far over-subjective field of psychiatry. Distinctions among prototypical, atypical, and diagnostic biomarkers, as well as between neuromotor and psychomotor locomotor abnormalities, are discussed. Conclusions are drawn about the translational and clinical implications of the new approach and its future perspectives.

Tardive Dyskinesia Associated with Atypical Antipsychotics: Prevalence, Mechanisms and Management Strategies

All antipsychotics, including the atypical antipsychotics (AAPs), may cause tardive dyskinesia (TD), a potentially irreversible movement disorder, the pathophysiology of which is currently unknown. The prevention and treatment of TD remain major challenges for clinicians. We conducted a PubMed search to review the prevalence and etiology of and management strategies for TD associated with AAPs. TD prevalence rates varied substantially between studies, with an estimated prevalence of around 20% in patients using AAPs. The risk of TD is lower with AAPs than with typical antipsychotics (TAPs) but remains a problem because AAPs are increasingly being prescribed. Important risk factors associated with TD include the duration of antipsychotic use, age, and ethnicity other than Caucasian. Theories about the etiology of TD include supersensitivity of the dopamine receptors and oxidative stress, but other neurotransmitters and factors are probably involved. Studies concerning the management of TD have considerable methodological limitations. Thus, recommendations for the management of TD are based on a few trials and clinical experience, and no general guidelines for the management of TD can be established. The best management strategy remains prevention. Caution is required when prescribing antipsychotics, and regular screening is needed for early detection of TD. Other strategies may include reducing the AAP dosage, switching to clozapine, or administering vesicular monoamine transporter (VMAT)-2 inhibitors. In severe cases, local injections of botulinum toxin or deep brain stimulation may be considered. More clinical trials in larger samples are needed to gather valid information on the effect of interventions targeting TD.

Altered Coupling Between Resting-State Cerebral Blood Flow and Functional Connectivity in Schizophrenia

BACKGROUND

Respective changes in resting-state cerebral blood flow (CBF) and functional connectivity in schizophrenia have been reported. However, their coupling alterations in schizophrenia remain largely unknown.

METHODS

89 schizophrenia patients and 90 sex- and age-matched healthy controls underwent resting-state functional MRI to calculate functional connectivity strength (FCS) and arterial spin labeling imaging to compute CBF. The CBF-FCS coupling of the whole gray matter and the CBF/FCS ratio (the amount of blood supply per unit of connectivity strength) of each voxel were compared between the 2 groups.

RESULTS

Whole gray matter CBF-FCS coupling was decreased in schizophrenia patients relative to healthy controls. In schizophrenia patients, the decreased CBF/FCS ratio was predominantly located in cognitive- and emotional-related brain regions, including the dorsolateral prefrontal cortex, insula, hippocampus and thalamus, whereas an increased CBF/FCS ratio was mainly identified in the sensorimotor regions, including the putamen, and sensorimotor, mid-cingulate and visual cortices.

CONCLUSION

These findings suggest that the neurovascular decoupling in the brain may be a possible neuropathological mechanism of schizophrenia.

Brain anatomy of symptom stratification in schizophrenia: a voxel-based morphometry study

BACKGROUND

Although some Magnetic Resonance Imaging (MRI) studies have investigated the relationship between clinical severity and neuroanatomical alterations in patients with schizophrenia (SCZ), the biological signature associated with illness severity in schizophrenia is still uncertain. Therefore, this study aims to investigate structural brain abnormalities in SCZ, with particular regards to the identification of potential deficits associated with the severity of illness.

METHODS

In total, 1.5T MRI data were acquired for 61 subjects with SCZ and 59 matched healthy controls (HC). The patient group was divided in two sub-groups based on clinical severity, one composed of 34 mild-to-moderately ill patients, and the other of 27 severely ill patients, and compared with matched HC.

RESULTS

The whole group of patients with SCZ had significantly reduced grey matter (GM) volumes in the left inferior and middle temporal gyrus compared to HC (p < 0.05, pFWE corrected). Furthermore, compared to HC, patients with mild-to-moderate illness showed decreased GM volumes in the inferior and middle temporal gyrus, whereas those with severe illness had reduced GM volumes in the middle temporal gyrus and cerebellum bilaterally (all p < 0.001 uncorrected). No differences were observed between the two sub-groups of patients.

CONCLUSION

The results showed significant GM volume reductions in temporal regions in patients with SCZ compared to matched HC, confirming the role of these regions in the pathophysiology of SCZ. Furthermore, specific cerebellar grey matter volume reductions were identified in patients with severe illness, which may contribute to stratifying patients with SCZ according to their clinical phenotype expression, ultimately helping in guiding targeted therapeutic/rehabilitation interventions.

A case for motor network contributions to schizophrenia symptoms: Evidence from resting-state connectivity

Though schizophrenia (SCZ) is classically defined based on positive symptoms and the negative symptoms of the disease prove to be debilitating for many patients, motor deficits are often present as well. A growing literature highlights the importance of motor systems and networks in the disease, and it may be the case that dysfunction in motor networks relates to the pathophysiology and etiology of SCZ. To test this and build upon recent work in SCZ and in at-risk populations, we investigated cortical and cerebellar motor functional networks at rest in SCZ and controls using publically available data. We analyzed data from 82 patients and 88 controls. We found key group differences in resting-state connectivity patterns that highlight dysfunction in motor circuits and also implicate the thalamus. Furthermore, we demonstrated that in SCZ, these resting-state networks are related to both positive and negative symptom severity. Though the ventral prefrontal cortex and corticostriatal pathways more broadly have been implicated in negative symptom severity, here we extend these findings to include motor-striatal connections, as increased connectivity between the primary motor cortex and basal ganglia was associated with more severe negative symptoms. Together, these findings implicate motor networks in the symptomatology of psychosis, and we speculate that these networks may be contributing to the etiology of the disease. Overt motor deficits in SCZ may signal underlying network dysfunction that contributes to the overall disease state. Hum Brain Mapp 38:4535-4545, 2017. © 2017 Wiley Periodicals, Inc.

Motor system dysfunction in the schizophrenia diathesis: Neural systems to neurotransmitters

Motor control is a ubiquitous aspect of human function, and from its earliest origins, abnormal motor control has been proposed as being central to schizophrenia. The neurobiological architecture of the motor system is well understood in primates and involves cortical and sub-cortical components including the primary motor cortex, supplementary motor area, dorsal anterior cingulate cortex, the prefrontal cortex, the basal ganglia, and cerebellum. Notably all of these regions are associated in some manner to the pathophysiology of schizophrenia. At the molecular scale, both dopamine and γ-Aminobutyric Acid (GABA) abnormalities have been associated with working memory dysfunction, but particularly relating to the basal ganglia and the prefrontal cortex respectively. As evidence from multiple scales (behavioral, regional and molecular) converges, here we provide a synthesis of the bio-behavioral relevance of motor dysfunction in schizophrenia, and its consistency across scales. We believe that the selective compendium we provide can supplement calls arguing for renewed interest in studying the motor system in schizophrenia. We believe that in addition to being a highly relevant target for the study of schizophrenia related pathways in the brain, such focus provides tractable behavioral probes for in vivo imaging studies in the illness. Our assessment is that the motor system is a highly valuable research domain for the study of schizophrenia.

White matter microstructure variations contribute to neurological soft signs in healthy adults

OBJECTIVE

Neurological soft signs (NSS) are core features of psychiatric disorders with significant neurodevelopmental origin. However, it is unclear whether NSS correlates are associated with neuropathological processes underlying the disease or if they are confounded by medication. Given that NSS are also present in healthy persons (HP), investigating HP could reveal NSS correlates, which are not biased by disease-specific processes or drug treatment. Therefore, we used a combination of diffusion MRI analysis tools to provide a framework of specific white matter (WM) microstructure variations underlying NSS in HP.

METHOD

NSS of 59 HP were examined on the Heidelberg Scale and related to diffusion associated metrics. Using tract-based spatial statistics (TBSS), we studied WM variations in fractional anisotropy (FA) as well as radial (RD), axial (AD), and mean diffusivity (MD). Using graph analytics (clustering coefficient-CC, local betweenness centrality -BC), we then explored DTI-derived structural network variations in regions identified by previous MRI studies on NSS.

RESULTS

NSS scores were negatively associated with RD, AD and MD in corpus callosum, brainstem and cerebellum (P < 0.05, corr.). NSS scores were negatively associated with CC and BC of the pallidum, the superior parietal gyrus, the precentral sulcus, the insula, and the cingulate gyrus (P < 0.05, uncorr.).

CONCLUSION

The present study supports the notion that WM microstructure variations in subcortical and cortical sensorimotor regions contribute to NSS expression in young HP. Hum Brain Mapp 38:3552-3565, 2017. © 2017 Wiley Periodicals, Inc.

Instrumental measurements of spontaneous dyskinesia and schizotypy in subjects with auditory verbal hallucinations and healthy controls

Spontaneous dyskinesia is associated with non-affective psychosis. Few studies investigated dyskinesia in individuals with subclinical psychotic experiences. We examined dyskinesia using instrumental measurements of force variability in 34 individuals with frequent auditory verbal hallucinations but without a clinical psychotic disorder and 31 matched healthy controls. Schizotypy was assessed using the Schizotypal Personality Questionnaire. We found a positive correlation between dyskinesia and schizotypy in the total group. In addition, when using a cut-off point based on the 95th percentile of force variability in the control group, we found a greater proportion of subjects with dyskinesia in the group with auditory verbal hallucinations than in the control subjects. Current findings are in agreement with the concept of psychosis as a continuous phenomenon and with movement disorders being an integral part of psychosis.

Evidence for Distinguishable Treatment Costs among Paranoid Schizophrenia and Schizoaffective Disorder

BACKGROUND

Schizophrenia spectrum disorders result in enormous individual suffering and financial burden on patients and on society. In Germany, there are about 1,000,000 individuals suffering from schizophrenia (SZ) or schizoaffective disorder (SAD), a combination of psychotic and affective symptoms. Given the heterogeneous nature of these syndromes, one may assume that there is a difference in treatment costs among patients with paranoid SZ and SAD. However, the current the national system of cost accounting in psychiatry and psychosomatics in Germany assesses all schizophrenia spectrum disorders within one category.

METHODS

The study comprised a retrospective audit of data from 118 patients diagnosed with paranoid SZ (F20.0) and 71 patients with SAD (F25). We used the mean total costs as well as partial cost, i.e., mean costs for medication products, mean personal costs and mean infrastructure costs from each patient for the statistical analysis. We tested for differences in the four variables between SZ and SAD patients using ANCOVA and confirmed the results with bootstrapping.

RESULTS

SAD patients had a longer duration of stay than patients with SZ (p = .02). Mean total costs were significantly higher for SAD patients (p = .023). Further, we found a significant difference in mean personnel costs (p = .02) between patients with SZ and SAD. However, we found no significant differences in mean pharmaceutical costs (p = .12) but a marginal difference of mean infrastructure costs (p = .05) between SZ and SAD. We found neither a common decrease of costs over time nor a differential decrease in SZ and SAD.

CONCLUSION

We found evidence for a difference of case related costs of inpatient treatments for paranoid SZ and SAD. The differences in mean total costs seem to be primarily related to the mean personnel costs in patients with paranoid SZ and SAD rather than mean pharmaceutical costs, possibly due to higher personnel effort and infrastructure.

Additive sex-specific influence of common non-synonymous DISC1 variants on amygdala, basal ganglia, and white cortical surface area in healthy young adults

The disrupted-in-schizophrenia-1 (DISC1) gene is known for its role in the development of mental disorders. It is also involved in neurodevelopment, cognition, and memory. To investigate the association between DISC1 variants and brain morphology, we analyzed the influence of the three common non-synonymous polymorphisms in DISC1 on specific brain structures in healthy young adults. The volumes of brain regions were determined in 145 subjects by magnetic resonance imaging and automated analysis using FreeSurfer. Genotyping was performed by high resolution melting of amplified products. In an additive genetic model, rs6675281 (Leu607Phe), rs3738401 (Arg264Gln), and rs821616 (Ser704Cys) significantly explained the volume variance of the amygdala (p = 0.007) and the pallidum (p = 0.004). A higher cumulative portion of minor alleles was associated with larger volumes of the amygdala (p = 0.005), the pallidum (p = 0.001), the caudate (p = 0.024), and the putamen (p = 0.007). Sex-stratified analysis revealed a strong genetic effect of rs6675281 on putamen and pallidum in females but not in males and an opposite influence of rs3738401 on the white cortical surface in females compared to males. The strongest single association was found for rs821616 and the amygdala volume in male subjects (p < 0.001). No effect was detected for the nucleus accumbens. We report-to our knowledge-for the first time a significant and sex-specific influence of common DISC1 variants on volumes of the basal ganglia, the amygdala and on the cortical surface area. Our results demonstrate that the additive model of all three polymorphisms outperforms their single analysis.

Cerebellar contributions to neurological soft signs in healthy young adults

Neurological soft signs (NSS) are frequently found in psychiatric disorders of significant neurodevelopmental origin, e.g., in patients with schizophrenia and autism. Yet NSS are also present in healthy individuals suggesting a neurodevelopmental signature of motor function, probably as a continuum between health and disease. So far, little is known about the neural mechanisms underlying these motor phenomena in healthy persons, and it is even less known whether the cerebellum contributes to NSS expression. Thirty-seven healthy young adults (mean age = 23 years) were studied using high-resolution structural magnetic resonance imaging (MRI) and "resting-state" functional MRI at three Tesla. NSS levels were measured using the "Heidelberg Scale." Cerebellar gray matter volume was investigated using cerebellum-optimized voxel-based analysis methods. Cerebellar function was assessed using regional homogeneity (ReHo), a measure of local network strength. The relationship between cerebellar structure and function and NSS was analyzed using regression models. There was no significant relationship between cerebellar volume and NSS (p < 0.005, uncorrected for height, p < 0.05 corrected for spatial extent). Positive associations with cerebellar lobule VI activity were found for the "motor coordination" and "hard signs" NSS domains. A negative relationship was found between lobule VI activity and "complex motor task" domain (p < 0.005, uncorrected for height, p < 0.05 corrected for spatial extent). The data indicate that in healthy young adults, distinct NSS domains are related to cerebellar activity, specifically with activity of cerebellar subregions with known cortical somatomotor projections. In contrast, cerebellar volume is not predictive of NSS in healthy persons.

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.