This clinical trial evaluates the preliminary effectiveness and safety of Cerogrin, a medical device developed by Neurogrin Inc. for auricular vagus nerve stimulation, in patients with vascular dementia or vascular mild cognitive impairment. Given the limited availability of effective pharmacological treatments for these conditions, the study aims to assess whether Cerogrin can enhance cognitive function through non-invasive neuromodulation.

Twenty-four participants will be randomized to receive either the active Cerogrin device or a sham (non-stimulating) device. Daily use will occur at home for 30 minutes over a four-week intervention period. The full study duration, including baseline assessments and follow-up, will span up to three months. During this period, cognitive function, neural activity, and safety outcomes will be systematically evaluated. This feasibility trial represents a critical step toward expanding therapeutic options for vascular 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.