Severity in sustained attention impairment and clozapine-resistant schizophrenia: a retrospective study

Ying-Chieh Peng,Wei J. Chen,An-Sheng Lin,Hung-Yu Chan

doi:10.1186/s12888-019-2204-6

Abstract

BackgroundAmong patients with treatment-resistant schizophrenia (TRS), some exhibited further clozapine resistance (CR). This study aimed to investigate whether greater severity of treatment resistance in schizophrenia is associated with greater impairments in sustained attention.MethodsPatients with a DSM-IV-defined schizophrenia were recruited from a psychiatric center in northern Taiwan (April 2010 to October 2010). Both TRS and CR were determined retrospectively from participants’ medical records following the consensus guidelines. The patients were divided into three groups: 102 non-TRS, 48 TRS without CR, and 54 TRS with CR. They underwent both undegraded and degraded Continuous Performance Tests (CPT), and their performance scores (d′) were standardized against a community sample to derive age-, sex-, and education-adjusted z scores.ResultsThe TRS with CR group had significantly lower adjusted z scores of d′ on both undegraded and degraded CPTs than the other two groups. Meanwhile, the differences between the TRS without CR group and the non-TRS group were not significant. Multivariable linear regression analyses with adjustment for covariates revealed a trend of gradient impairments on the degraded CPT from non-TRS to TRS without CR and to TRS with CR. The proportions of attentional deficits (an adjusted z score of ≤ − 2.5) on the degraded CPT also exhibited a significant trend, from 36.3% in the non-TRS group to 62.5% in the TRS without CR group and to 83.3% in the TRS with CR group.ConclusionsGreater severity of treatment resistance in schizophrenia was associated with greater impairments in sustained attention, indicating some common vulnerability.

Highlights

Among patients with treatment-resistant schizophrenia (TRS), some exhibited further clozapine resistance (CR)
The aims of the study were to investigate whether greater impairments on the Continuous Performance Test (CPT) were associated with more treatment resistance in schizophrenia
Our results revealed a gradient impairment in sustained attention from non-TRS to TRS without CR and to TRS with CR, regardless of continuous CPT performance scores or the proportion of binary CPT deficits

Summary

Introduction

Among patients with treatment-resistant schizophrenia (TRS), some exhibited further clozapine resistance (CR). Despite extensive progress in the treatment of schizophrenia, approximately 30% of patients of schizophrenia show poor responses to treatment, denoted as treatmentresistant schizophrenia (TRS) [1, 2]. Clozapine has remained the gold standard treatment of TRS since its efficacy was described in a randomized trial [6]. An estimated 30% of patients receiving clozapine have unsatisfactory responses and are known to have ultra-treatment-resistant schizophrenia [7], super-refractory schizophrenia [8], or clozapine-resistant schizophrenia [5]. A great deal of research has profiled that TRS has neurochemical and structural abnormalities different from non-TRS or treatment-responsive schizophrenia [8, 14,15,16,17,18]. TRS patients have been reported to have certain minor physical anomalies and craniofacial features [19] and more neurological soft signs [20]

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