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.