Characterization of neurological soft signs in a Brazilian sample of stable patients with schizophrenia

Neurological soft signs and neurocognitive deficits in remitted patients with schizophrenia, their first-degree unaffected relatives, and healthy controls

Neurological soft signs (NSS) and neurocognitive deficits (ND) are highly prevalent in schizophrenia, and have been separately proposed as candidate endophenotypes of schizophrenia. However, few relevant studies focus on remitted patients with schizophrenia (RP) and integrate NSS and ND as a composite endophenotype. This study aimed to explore the NSS and ND and examine the comparative relationship between them in RP, their first-degree unaffected relatives (FDR), and healthy controls, furthermore, to seek potential endophenotypes subitems of NSS and ND and create a composite endophenotype. 86 RP, 86 FDR, and 86 healthy controls were included. NSS and ND were independently assessed with Cambridge Neurological Inventory and MATRICS^TM Consensus Cognitive Battery. RP had more NSS and ND than FDR in all subitems except disinhibition, information processing speed, working memory, and visual memory. Similarly, FDR presented poorer performance than controls in all subscales except disinhibition, sensory integration, working memory, and visual memory. Six subitems of NSS and ND met the criteria of endophenotype and the three groups were most accurately classified (71.2%) with these subitems working as a composite endophenotype. Moreover, information processing speed, attention, and social cognition were associated with sensory integration in RP and FDR. These findings add evidences that certain subitems of NSS and ND might be the endophenotypes of schizophrenia and integrating these endophenotypes may prove useful in identifying schizophrenia and high-risk individuals. Furthermore, sensory integration and specific cognitive domains covary, hence suggesting an overlap of compromised underlying neural systems.

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.