To test the effects of 6 month additional intervention of ORIENT diet versus usual medical treatment for Intracranial / Carotid Stenosis on cognitive decline, multi-mode MRI image markers and serum and fecal biomarkers in a randomized controlled trial of 120 patients with intracranial / carotid stenosis, who are aged older than 40 years and without dementia.

Oriental Intervention for Enhanced Neurocognitive Health (ORIENT) diet in Patients With Intracranial / Carotid Stenosis is designed to test the impact of a 6-month intervention utilizing a culturally adapted version of the MIND diet, named as the ORIENT diet, on 120 older patients (aged 40 years and above and without dementia) diagnosed with intracranial/carotid stenosis (defined as ≥ 50% stenosis in unilateral intracranial/carotid artery as detected by vascular imaging diagnostic techniques, such as magnetic resonance angiography). The ORIENT diet retains the core components of the DASH, Mediterranean, and MIND diets, but incorporates adjustments according to evidence derived from Asian prospective cohorts and Chinese dietary practices. Participants in the intervention group will receive standard medical treatment in conjunction with the ORIENT diet intervention, while those in the control group will undergo standard medical treatment and receive usual dietary advice. The study's primary objective is to assess the influence of the ORIENT diet on cognitive function and brain macro- and microstructural integrity in patients with intracranial/carotid stenosis. This will be achieved through the administration of neuropsychological assessments and multi-modal magnetic resonance imaging at 6-month intervals until the completion of the trial. The investigation will explore potential mediators and modifiers of the intervention's effects by examining various cardiovascular risk factors, serum and fecal biomarkers, and underlying biological mechanisms.

Inclusion Criteria:

• Patients aged ≥ 40 years
• ≥ 50% stenosis in unilateral intracranial / carotid artery
• Written informed consent available
• Willingness to complete all assessments and participate in follow-up
• Adequate Visual and auditory acuity to undergo neuropsychological testing

Exclusion Criteria:

• Previous history of major head trauma and any intracranial surgery
• Intracranial abnormalities, such as intracerebral hemorrhage, subarachnoid hemorrhage and other space occupying lesions
• Extrapyramidal symptoms or mental illness which may affect neuropsychological measurement
• Severe loss of vision, hearing, or communicative ability
• Nuts, berries, olive oil, or fish allergies
• Patients presenting a malignant disease with life expectancy < 3 years
• Participation in an ongoing investigational drug study

Exit Criteria:

• Not meet the inclusion criteria
• For any poor adherence, not comply with the requirements of the follow-up, or safety reasons determined by investigator
• Any adverse or serious adverse events during the study period judged by Investigator