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Randomized, Triple-Blind, and Parallel-Controlled Trial of Transcranial Direct Current Stimulation for Cognitive Rehabilitation after Stroke
Published on: June 6, 2025
Transcranial direct current stimulation (tDCS) for cognitive impairment in schizophrenia: A systematic review and
Lorena García-Fernández1, Alberth Patricio Muñoz-Gualan2, Verónica Romero-Ferreiro3
1Clinical Medicine Department, Universidad Miguel Hernández, Alicante, Spain; Psychiatry Department, Hospital Universitario de San Juan, Alicante, Spain; CIBERSAM-ISCIII (Biomedical Research Networking Centre for Mental Health), Spain; Foundation for the Promotion of Health and Biomedical Research of the Valencian Community (FISABIO), Valencia, Spain.
Background:
Cognitive deficits represent a core symptom domain in schizophrenia, with limited responsiveness to pharmacological interventions. Transcranial direct current stimulation (tDCS) has emerged as a promising non-invasive neuromodulatory technique targeting cognitive enhancement. This systematic review and meta-analysis synthesized randomized controlled trials (RCTs) assessing the efficacy of tDCS on cognitive outcomes in schizophrenia.
Methods:
A comprehensive literature search identified 33 RCTs (n = 1372) evaluating cognitive effects of tDCS in patients with schizophrenia or schizoaffective disorder. Studies varied in montage, intensity, duration, and session count. Risk of bias was assessed using the Jadad scale and Cochrane RoB 2 tool. Quantitative meta-analyses were conducted across eight cognitive domains using multilevel random-effects models.
Results:
Working memory and verbal learning were the most frequently improved domains. Meta-analytic results revealed a statistically significant effect in verbal learning (Hedges' g = 0.26, p = .034), with negligible heterogeneity. Other domains (e.g., working memory, processing speed, problem solving) showed small, non-significant trends toward improvement, while attention and social cognition demonstrated inconsistent or null effects. Outcomes were influenced by stimulation parameters, with ≥10 sessions and DLPFC-targeted montages associated with better efficacy. Methodological heterogeneity and moderate risk of bias were prevalent.
Conclusions:
tDCS shows domain-specific potential for cognitive enhancement in schizophrenia, particularly in verbal learning. However, the small effect sizes, high heterogeneity, and limited methodological rigor of included trials warrant cautious interpretation. Future research should emphasize standardized protocols, robust trial designs, and integration with cognitive remediation strategies.
