Assessment of Transcranial Alternating Current Stimulation's Clinical Efficacy in Treating Cognitive Impairment of Idiopathic Inflammatory Demyelinating Diseases

Inclusion Criteria: * Age: 18-60 years old. * Diagnosis: Patients with neuromyelitis optica spectrum disease, multiple sclerosis and other inflammatory demyelinating diseases of the central nervous system that meet the diagnostic criteria. * Medications have been stable for at least three months. Exclusion Criteria: * Recurrence has been recorded in the past 3 months. * Have a pacemaker or other metal implant in the body. * Impaired skin integrity at the site of electrode placement. * Previous organic brain disease such as epilepsy, hydrocephalus, central nervous system tumors, brain injury, or intracranial infection. * Combined with severe or unstable organic diseases, such as heart, liver and kidney and other organ dysfunction. * Pregnant or lactating women, those who are planning to become pregnant in the near future. * Patient compliance is poor. * In the opinion of the investigator, there is a situation that is not suitable to participate in this study.