Comparison of the Effectiveness of Computer-Based Cognitive Rehabilitation and Transcranial Direct Current Stimulation (tDCS) on Improving Cognitive Functions in Patients with Chronic Schizophrenia

The aim of this study is to compare the effectiveness of computer-based cognitive rehabilitation and transcranial direct current stimulation (tDCS) in improving cognitive functions, including attention, working memory, response inhibition, and impulse control, in patients with schizophrenia.

This study is a randomized, single-blind, three-arm clinical trial (cognitive rehabilitation, tDCS, and control) with a parallel design. Fifty-four patients will be randomly assigned using block randomization stratified by age and gender through SPSS version 26, with allocation concealed in sealed opaque envelopes.

The study will be conducted at a rehabilitation center for patients with chronic psychiatric disorders. After screening, participants will be randomly assigned to one of three groups: cognitive rehabilitation, tDCS, or control. Sessions will be conducted by a trained therapist in a quiet setting, and participants will be blinded to group allocation (single-blind design).

Participants were patients with schizophrenia spectrum disorder aged 20 to 60 years who were clinically stable and provided informed consent. Those with severe neurological or cognitive disorders, brain injury, epilepsy, or acute psychotic episodes were excluded.

Participants were randomly assigned to three groups: the first received computer-based cognitive rehabilitation using the Captain’s Log software, the second underwent transcranial direct current stimulation (tDCS), and the control group received only routine pharmacological treatment and standard care.

Improvement of cognitive functions including attention, working memory, response inhibition, cognitive flexibility, and impulse control; reduction of positive and negative symptoms of schizophrenia.

In this study, randomization of participants was performed after assessing the inclusion criteria and obtaining informed consent. A block randomization method with a block size of six was used to ensure a balanced distribution of participants across the three study groups (computer-based cognitive rehabilitation, transcranial direct current stimulation, and control). The unit of randomization was the individual, and no cluster randomization was applied. To control for demographic variables such as age and gender, stratified randomization was implemented. The allocation sequence was generated by the study statistician using SPSS version 26 and a table of random numbers, and the final assignment was conducted through numbered, opaque, sealed envelopes to maintain allocation concealment and prevent potential bias in the assignment process.

A single-blind design was implemented in this study. Participants were unaware of their allocation to one of the three groups (transcranial direct current stimulation, computer-based cognitive rehabilitation, or control group) to minimize potential bias due to expectancy effects. The researchers, intervention administrators, outcome assessors, and data analysts were aware of the group assignments, as full blinding was not feasible given the nature of the interventions. However, all participants were treated under similar environmental conditions, session schedules, and researcher interactions to minimize subjective bias across groups.

Raw data from neuropsychological test scores (including N-Back, Simple Stroop, and Continuous Performance Test) will be available in Excel format after de-identification of participants. Shared data will include only outcome-related variables (primary and secondary) and will not contain any personal or identifiable information of patients.

Access to the data will begin six months after publication of the study results in a scientific journal and will remain available for five years thereafter.

The data will be available to researchers and academic staff from universities and research centers who submit a written request and specify a clear research purpose.

The data may be used only for research and educational purposes. Any commercial use or redistribution without written permission from the study investigators is prohibited. Requests must include a research proposal, study objectives, and a confidentiality agreement.

Requests for access to study data or related documents should be directed to the corresponding researcher via email.

Data access requests will be reviewed by the principal investigator upon receipt via email. The research purpose and eligibility of the applicant will be evaluated. Upon approval and signing of a confidentiality and data use agreement, anonymized data will be shared within 4 weeks.