This study is a double-blind, randomized, controlled intervention study aimed at exploring whether high-frequency transcranial alternating current stimulation (Hi-tACS) can improve cognitive impairment in patients with schizophrenia.

Schizophrenia is a chronic, severe mental disorder characterized by a high suicide rate and significant disability. Cognitive impairment is one of the core symptoms of schizophrenia, with approximately 98% of patients experiencing a decline in cognitive function compared to pre-illness levels. Research has found that individuals with schizophrenia show significant impairments in seven domains, including reaction time, attention, working memory, verbal learning and memory, visual learning and memory, logical reasoning, and social cognition.

Pharmacological treatment remains the primary approach for managing schizophrenia. However, cognitive impairment in individuals with schizophrenia often does not respond well to medication. Additionally, electroconvulsive therapy (ECT) may have potential cognitive side effects. Transcranial alternating current stimulation (tACS), a form of noninvasive brain stimulation, has been found in several studies to improve cognition. However, its effectiveness is not yet clear.

Conventional tACS utilizes weak currents below 4mA, which can only directly stimulate certain cortical areas and indirectly stimulate deep brain structures. Moreover, the targeting of specific brain regions can be complex, and users may experience a sensation of heat on the skin where the electrodes come into contact.High-frequency transcranial alternating current stimulation (Hi-tACS) employs electrical currents greater than 10mA, typically ranging from 10-15mA. Unlike conventional tACS, Hi-tACS can apply stimulation to the entire brain, potentially enhancing its therapeutic effects. Moreover, Hi-tACS does not require precise targeting and is generally well-tolerated without any discomfort during the stimulation. It is considered a promising and potentially safe treatment modality for cognitive impairment in schizophrenia.

Inclusion Criteria:

1. Meets the diagnostic criteria for schizophrenia according to DSM-5.
2. Age ≥ 18 years old.
3. Right-handed.
4. Willing to participate in this study and sign an informed consent form. If the participant is unable to read and sign the informed consent form due to lack of capacity, a legal guardian must act as a proxy during the informed consent process and sign the form.
5. Clinically stable, receiving antipsychotic medication treatment with a stable dose for 4 weeks without any changes.
6. Montreal Cognitive Assessment score ≥ 10 points.

Exclusion Criteria:

1. Psychotic disorders caused by split affective disorder, bipolar disorder, intellectual disability, anxiety spectrum disorders, drugs, alcohol, and other psychoactive substances according to DSM-V diagnostic criteria.
2. Those with severe or unstable organic diseases, with a history of brain tumors or epilepsy.
3. Those who have received MECT or TMS treatment within 1 month before enrollment.
4. Skin integrity at the electrode placement site is compromised. Allergy to electrode gel or adhesive.
5. Implants of metal or electronic devices (such as pacemakers, cochlear implants, deep brain stimulators, aneurysm clips, internal fixation devices after ventriculoperitoneal shunt surgery, etc.).
6. Participation in any other clinical trials within 1 month prior to baseline.
7. Pregnant and lactating women.
8. The investigator believes that there are inappropriate conditions for participating in this study.