Systematic Reviews
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Psychiatr. Mar 22, 2017; 7(1): 34-43
Published online Mar 22, 2017. doi: 10.5498/wjp.v7.i1.34
Neuroimaging studies of cognitive remediation in schizophrenia: A systematic and critical review
Rafael Penadés, Alexandre González-Rodríguez, Rosa Catalán, Bàrbara Segura, Miquel Bernardo, Carme Junqué
Rafael Penadés, Alexandre González-Rodríguez, Rosa Catalán, Miquel Bernardo, Department of Psychiatry and Psychology, Clinical Institute of Neurosciences, Hospital Clínic, 08036 Barcelona, Spain
Bàrbara Segura, Carme Junqué, Neuropsychology Lab, University of Barcelona, 08036 Barcelona, Spain
Bàrbara Segura, Carme Junqué, Institut d’Investigacions, Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain
Author contributions: Penadés R designed the research; Gónzalez-Rodríguez A performed the bibliographic search; Penadés R, Segura B and Junqué C analysed the data; Penadés R wrote the paper; Catalán R, Bernardo M and Junqué C supervised the paper; all of the authors read and approved the final manuscript.
Supported by a grant from the Instituto de Salud Carlos III of Fondo de Investigaciones Sanitarias FIS, No. PI 11/09158 (to Penadés R).
Conflict-of-interest statement: All the authors declare that they have no competing interests for this article.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Rafael Penadés, PhD, Department of Psychiatry and Psychology, Clinical Institute of Neurosciences, Hospital Clínic, C/ Villarroel 170, 08036 Barcelona, Spain. rpenades@clinic.ub.es
Telephone: +34-93-2275400 Fax: +34-93-4035294
Received: August 30, 2016
Peer-review started: September 2, 2016
First decision: September 29, 2016
Revised: October 14, 2016
Accepted: December 13, 2016
Article in press: December 14, 2016
Published online: March 22, 2017
Abstract
AIM

To examine the effects of cognitive remediation therapies on brain functioning through neuroimaging procedures in patients with schizophrenia.

METHODS

A systematic, computerised literature search was conducted in the PubMed/Medline and PsychInfo databases. The search was performed through February 2016 without any restrictions on language or publication date. The search was performed using the following search terms: [(“cogniti*” and “remediation” or “training” or “enhancement”) and (“fMRI” or “MRI” or “PET” or “SPECT”) and (schizophrenia or schiz*)]. The search was accompanied by a manual online search and a review of the references from each of the papers selected, and those papers fulfilling our inclusion criteria were also included.

RESULTS

A total of 101 studies were found, but only 18 of them fulfilled the inclusion criteria. These studies indicated that cognitive remediation improves brain activation in neuroimaging studies. The most commonly reported changes were those that involved the prefrontal and thalamic regions. Those findings are in agreement with the hypofrontality hypothesis, which proposes that frontal hypoactivation is the underlying mechanism of cognitive impairments in schizophrenia. Nonetheless, great heterogeneity among the studies was found. They presented different hypotheses, different results and different findings. The results of more recent studies interpreted cognitive recovery within broader frameworks, namely, as amelioration of the efficiency of different networks. Furthermore, advances in neuroimaging methodologies, such as the use of whole-brain analysis, tractography, graph analysis, and other sophisticated methodologies of data processing, might be conditioning the interpretation of results and generating new theoretical frameworks. Additionally, structural changes were described in both the grey and white matter, suggesting a neuroprotective effect of cognitive remediation. Cognitive, functional and structural improvements tended to be positively correlated.

CONCLUSION

Neuroimaging studies of cognitive remediation in patients with schizophrenia suggest a positive effect on brain functioning in terms of the functional reorganisation of neural networks.

Keywords: Cognitive remediation, Cognitive training, Neuroimaging, Cognition, Prefrontal cortex, Thalamus, Plasticity, Schizophrenia

Core tip: Cognitive remediation therapy for schizophrenia is an evidence-based psychological treatment that aims to improve cognitive dysfunction. However, its underlying neural mechanisms have not been established. Several neuroimaging studies have shown positive effects in terms of brain activation. However, the results have been heterogeneous and difficult to integrate. The primary aim of the present review was to analyse systematically all of the published trials that used neuroimaging procedures. Additionally, we performed a more qualitative analysis examining the possible influence of neuroimaging methods and the use of different theoretical frameworks.