Post-stroke cognitive impairment (PSCI) refers to a clinical syndrome characterized by cognitive impairment that occurs after a stroke event and persists for at least 24 weeks. Due to the early recovery of conditions such as delirium and transient cognitive impairment after stroke, the diagnosis of PSCI often requires cognitive assessment at 12 to 24 weeks post-stroke to determine the severity of cognitive impairment. It can be classified according to the severity of cognitive impairment as post-stroke cognitive impairment no dementia (PSCIND) and post-stroke dementia (PSD). Recent large international cohort studies have reported an incidence rate of PSCI ranging from 24% to 53.4%, and patients with PSCI have a significantly higher mortality rate compared to those without cognitive impairment. Guidelines such as American Heart Association/American Society of Anesthesiologists (AHA/ASA) and the Chinese "Expert Consensus on the Management of Post-Stroke Cognitive Impairment" propose integrating cognitive impairment and stroke intervention strategies. Early comprehensive intervention and treatment for high-risk individuals after stroke, aiming to delay or prevent the progression from PSCIND to PSD, are the primary goals in the current treatment of PSCI. However, there is currently a lack of large randomized controlled trials (RCTs) for PSCI, and research is still needed to determine whether cognitive-enhancing drugs can reduce the risk of PSCI occurrence and improve outcomes and prognosis for PSCI patients. A randomized, double-blind, multicenter clinical study involving 281 non-dementia vascular cognitive impairment (VCI) patients showed that the overall cognitive scores of patients treated with donepezil for 24 weeks significantly improved compared to the placebo group.

The aim of this study is to evaluate the effectiveness of donepezil in the treatment of post-stroke cognitive impairment. It will be a multicenter, randomized, double-blind, placebo-controlled trial with a 48-week treatment duration. The study will observe the difference in PSCI incidence rate between the donepezil treatment group and the conventional stroke treatment group at 24 weeks and evaluate the improvement in post-stroke cognitive impairment after 6 months of donepezil treatment compared to conventional treatment.

This study will be conducted in two stages: the first stage (0-24 weeks) aims to assess whether donepezil can reduce the risk of PSCI occurrence and will be a multicenter, randomized, double-blind, placebo-controlled study. The second stage (24-48 weeks) aims to evaluate whether donepezil can improve the prognosis of PSCI patients and will also be a multicenter, randomized, double-blind, placebo-controlled study.

Inclusion Criteria:

First stage:

• Acute ischemic stroke (AIS) symptom onset within 14 days Signs and symptoms consistent with the diagnosis of an acute ischemic stroke by CT/MRI.
• Age >= 60 years，
• Baseline NIHSS 3-18.
• Patient can complete questionnaire survey, physical examination, cranial MRI and other medical examinations
• Patient/legally authorized representative has signed the Informed Consent Form

Second stage:

• Patient with stage I diagnosis of PSCI.
• Patient can complete questionnaire survey, physical examination, cranial MRI and other medical examinations.
• Patient/legally authorized representative has signed the Informed Consent Form

Exclusion Criteria:

First stage:

• Patients who had been diagnosed with dementia prior to stroke
• Other related factors affecting cognitive function: central nervous system infection, neurodegenerative diseases, trauma, poisoning, intracranial space occupying lesions, metabolic diseases, etc.
• Other serious central nervous system diseases: Parkinson's disease, epilepsy, multiple sclerosis, motor neurone disease, immune-related encephalomyelopathy, etc.
• Serious mental illness: anxiety disorder, depression, delirium, schizophrenia, bipolar disorder, mental retardation, which is diagnosed or controlled by medication.
• Uncorrectable visual and hearing impairments and inability to complete neuropsychological tests
• Severe liver and kidney dysfunction
• The presence of a malignant tumor or other serious/life-threatening disease that could cause the subject's death within 12 months.
• Current known alcohol or illicit drug abuse or dependence
• Patients undergoing thrombectomy, thrombolysis, carotid endarterectomy, or other surgical procedures during the acute infarction.
• Using cholinesterase inhibitors, N-methyl-D-aspartate (NMDA) receptor antagonists, or Sodium oligomannate (GV-971).
• Allergic to any component of butylphthalein
• Pregnancy or lactation, have the possibility of becoming pregnant, and who plan to become pregnant
• Participants in other interventional clinical trials
• MRI contraindications (e.g., claustrophobia, hypersensitivity to contrast media, etc.)

Second stage:

• During the first phase of follow-up, participants' compliance was poor, with study medication compliance less than 80% or greater than 120%; Follow-up was less than 24 weeks or did not complete the follow-up within the follow-up window..
• Recurrent stroke in the first stage