Effectiveness of Cognitive Remediation Interventions for Schizophrenia in Asian Population: A Systematic Review and Meta-analysis of Randomized Controlled Trials
Authors: Kantipudi Suvarna Jyothi , Venkatasubramanian Pratiksha , Rattehalli Ranganath 
Published: November 2024

Background:
Cognitive deficits are an integral part of schizophrenia, with negatively impacting functionality. Current treatments, primarily pharmacological, do not adequately address these cognitive impairments. Cognitive remediation (CR) interventions, designed to improve cognitive functions, have shown promising outcomes. However, most research has been conducted in western contexts, necessitating a review of CR effectiveness in the Asian populations. This systematic review aims to provide comprehensive update on the effectiveness of CR interventions in improving cognition among individuals with schizophrenia in Asian countries. The meta-analysis aims to synthesize and summarize the relevant CR studies to obtain a pooled estimate of effectiveness.

Methods:
A systematic search of three databases, PubMed, Ovid MEDLINE, and EMBASE, was conducted from the date of inception to March 19, 2024, for eligible records using prespecified search criteria. Primary studies with a randomized controlled trial (RCT) design, conducted on individuals aged 18–65 years, diagnosed with schizophrenia in Asian countries, comparing CR interventions with other non-pharmacological interventions or treatment as usual, reporting cognitive outcomes, using standardized tools, and published in English were included in the study. The review excluded unpublished RCTs, low-quality studies, open-label studies, cohort studies, studies focusing on noncognitive outcomes, and those lacking a clear comparison arm. The quality of the studies was assessed using the Cochrane risk of bias 2 (RoB2) tool by two independent reviewers. Meta-analyses were performed using R version 4.3.0 software using meta package to synthesize the overall impact of CR interventions on cognitive outcomes.

Results and Discussion:
This systematic review included 17 studies with 1272 participants, conducted in China, Japan, Hong Kong, Taiwan, Iran, Korea, and Singapore. The interventions varied in type and format. These were delivered through group and individual sessions, both in-person and computer-based, with varied duration. Quality assessment done with RoB2 tool indicated high-risk concerns in 14 of the studies. The meta-analysis of four studies on composite cognitive scores using the brief assessment of cognition in schizophrenia showed a significant positive effect of CR interventions (standardized mean difference [SMD] = 0.89, 95% confidence interval [CI]: 0.35 to 1.43). For executive functioning, the meta-analysis of three studies indicated no significant improvement (SMD = 0.75, 95% CI: −0.11 to 1.61).

Conclusion:
CR is an effective intervention for improving cognitive functions in individuals with schizophrenia in Asia based on the meta-analysis conducted, akin to evidence from western countries. However, quality concerns and high heterogeneity among the included studies underscore the need for standardized protocols and uniform outcome measures to enhance the reliability of future research.