Course of neurological soft signs in first-episode schizophrenia: Relationship with negative symptoms and cognitive performances.

Raymond C K Chan,Ya Wang,Fu-Lei Geng,Ruben C Gur,Karen S Y Hung,Raquel E Gur,Simon S Y Lui,Karen K Y Ho,Eric F C Cheung

doi:10.1038/srep11053

Abstract

This prospective study examined the course of neurological soft signs (NSS) in patients with first-episode schizophrenia and its relationship with negative symptoms and cognitive functions. One hundred and forty-five patients with first-episode schizophrenia were recruited, 29 were classified as having prominent negative symptoms. NSS and neuropsychological measures were administered to all patients and 62 healthy controls at baseline. Patients were then followed-up prospectively at six-month intervals for up to a year. Patients with prominent negative symptoms exhibited significantly more motor coordination signs and total NSS than patients without prominent negative symptoms. Patients with prominent negative symptoms performed worse than patients without negative symptoms in working memory functions but not other fronto-parietal or fronto-temporal functions. Linear growth model for binary data showed that the prominent negative symptoms were stable over time. Despite general improvement in NSS and neuropsychological functions, the prominent negative symptoms group still exhibited poorer motor coordination and higher levels of NSS, as well as poorer working memory than patients without prominent negative symptoms. Two distinct subtypes of first-episode patients could be distinguished by NSS and prominent negative symptoms.

Highlights

This prospective study examined the course of neurological soft signs (NSS) in patients with firstepisode schizophrenia and its relationship with negative symptoms and cognitive functions
The prevalence of the deficit syndrome was estimated to be about 15% in first-episode schizophrenia patients and about 25–30% in patients with chronic schizophrenia17; whereas the prevalence of persistent negative symptoms varied from 13.2% to 27% in first-episode schizophrenia according to various operational definitions18
The present findings generally confirm results from previous studies examining the prevalence of NSS in first-episode schizophrenia24,26–30

Summary

Introduction

This prospective study examined the course of neurological soft signs (NSS) in patients with firstepisode schizophrenia and its relationship with negative symptoms and cognitive functions. A recent meta-analysis on NSS in schizophrenia suggests that NSS are associated with specific brain structural and functional connectivity changes, mainly involving the cerebello-thalamo-prefrontal network proposed by Andreasen et al.9 These regions and neural connections overlap with neural substrates thought to be related to the deficit syndrome of schizophrenia or persistent negative symptoms. Mittal et al. showed that ultra-high risk individuals exhibit a decrease in factional anisotropy value in the superior cerebellar peduncle pathway on follow-up after 12 months as compared to healthy controls, there was no significant difference in the integrity of this pathway at baseline Taken together, these findings suggest that negative symptoms share common neural substrates with NSS in schizophrenia, especially in the cerebello-thalamo-prefrontal connection. It is unclear whether the findings were confounded by chronicity of illness or antipsychotic medication effect

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