Efficacy and Safety of Sodium Oligomannate in the Prevention of PSCI

Inclusion Criteria: * 1.The first occurrence of ischemic stroke, which met the diagnostic criteria of the Chinese Guidelines for the Diagnosis and Treatment of Acute Ischemic Stroke 2018, was confirmed by CT or MR; 2. The onset of illness was less than 7 days after admission, aged 18-80 years; 3. Clear consciousness, able to cooperate with cognitive and other tests, NIHSS score ≤15; 4. Before onset, the patient's cognitive level was normal, daily life and social activities were normal; 5. Stay in the current place of residence for more than 3 years; 6. With cognitive assessment, MoCA \< 22 (years of education \< 12, +1) after correction, and signed the informed consent. Exclusion Criteria: * 1.Unable to cooperate with neuropsychological examination due to various reasons (such as consciousness disorders, vision disorders, hearing disorders, etc.); 2. Combined with other diseases (such as intracranial mass, demyelinating disease, intracranial infection, neurodegenerative disease, epilepsy, severe heart, liver, kidney, blood system or other system diseases, etc.); 3. Used antibiotics 3 months before onset; 4. A history of alcohol abuse, drug use, or serious mental illness (including major depression (HAMD \> 10)) before onset of illness, 5. No stool was collected within 7 days of onset.