Evaluation of Cerogrin for Auricular Vagus Nerve Stimulation in Vascular Dementia or Vascular Mild Cognitive Impairment

Inclusion Criteria * Adults aged 55 to 89 years. * Diagnosed with vascular dementia or vascular mild cognitive impairment within 1 year before screening, with subcortical lesions confirmed on MRI. * For both diagnoses: * Severe white matter hyperintensity on MRI (Fazekas scale: deep white matter ≥ 2.5 cm or caps/bands ≥ 1.0 cm). * Z-score \< -1.0 SD in at least one cognitive domain (adjusted for education, age, and sex). * For vascular dementia: independence in daily living impaired. * For vascular mild cognitive impairment: independence in daily living preserved. * K-MMSE-II score ≥ 18 and CDR score 0.5 to 1.0 at screening. * Stable cognitive-enhancing medication (if applicable) for ≥4 weeks before baseline. * Availability of a caregiver (at least 8 hours/week contact). * Females of childbearing potential: agreement to use medically acceptable contraception during the study. * Provided written informed consent. * Willingness to comply with study protocol. Exclusion Criteria * Dementia other than vascular dementia (e.g., Alzheimer's disease, Lewy body dementia, frontotemporal dementia). * Conditions causing cognitive decline (e.g., uncontrolled metabolic diseases, CNS infections, cerebrovascular disease, traumatic brain injury, Parkinson's disease). * Severe psychiatric disorders (e.g., major depression, schizophrenia, substance abuse). * Serious unstable physical conditions. * MRI contraindications (e.g., claustrophobia, metal implants, contrast agent allergy). * Auricular skin disease or condition preventing device use. * Inability to comply with study procedures. * Pregnancy or breastfeeding. * Participation in other clinical trials within 30 days before screening. * Any other condition deemed inappropriate for participation by the investigator.