Cortical Thinning in Network-Associated Regions in Cognitively Normal and Below-Normal Range Schizophrenia.

R Walter Heinrichs,Farena Pinnock,Lindsay Hanford,Melissa Parlar,Colin Hawco,Geoffrey B Hall

doi:10.1155/2017/9760905

Abstract

This study assessed whether cortical thickness across the brain and regionally in terms of the default mode, salience, and central executive networks differentiates schizophrenia patients and healthy controls with normal range or below-normal range cognitive performance. Cognitive normality was defined using the MATRICS Consensus Cognitive Battery (MCCB) composite score (T = 50 ± 10) and structural magnetic resonance imaging was used to generate cortical thickness data. Whole brain analysis revealed that cognitively normal range controls (n = 39) had greater cortical thickness than both cognitively normal (n = 17) and below-normal range (n = 49) patients. Cognitively normal controls also demonstrated greater thickness than patients in regions associated with the default mode and salience, but not central executive networks. No differences on any thickness measure were found between cognitively normal range and below-normal range controls (n = 24) or between cognitively normal and below-normal range patients. In addition, structural covariance between network regions was high and similar across subgroups. Positive and negative symptom severity did not correlate with thickness values. Cortical thinning across the brain and regionally in relation to the default and salience networks may index shared aspects of the psychotic psychopathology that defines schizophrenia with no relation to cognitive impairment.

Highlights

Cognitive impairment is highly prevalent in schizophrenia, with dysfunction across multiple abilities observed in 75– 80% of patients [1]
We evaluated cortical thickness in schizophrenia patients as well as in healthy control participants meeting and failing to meet a criterion for cognitive normality based on a widely used neuropsychological test battery [15]
In addition to comparing cortical thickness values across the whole brain, we focused on regions associated with the default mode network (DMN), central executive network (CEN), and salience network (SN)

Summary

Introduction

Cognitive impairment is highly prevalent in schizophrenia, with dysfunction across multiple abilities observed in 75– 80% of patients [1]. It is likely that cognitive performance forms a continuum in the patient population, ranging from impaired to normative values, rather than a discrete or binary disease marker. This does not obviate the potential benefit of studying patients with psychosis who are relatively free of cognitive impairment. Putatively normal range patients may demonstrate task deficits and discrepant performance profiles when compared directly with healthy control groups [3, 4] This is not always the case [5] and absolute performance normality in any clinical population that endures a substantial stress and illness burden may be an unsupportable expectation

Methods

Results

Discussion

Conclusion