Deep Cervical Lymphovenous Anastomosis for Moderate Alzheimer's Disease (LYMVA-AD)

Study Design and Objectives This is an interventional, multicenter, randomized, parallel-group, open-label and endpoint-blinded clinical trial. The primary objective is to verify the efficacy and safety of deep cervical lymphovenous anastomosis (LVA) in patients with moderate Alzheimer's disease. The secondary objectives include analyzing the changes of cognitive function, caregiver burden and cerebral amyloid-beta deposition within 12 months after intervention, and exploring the variation characteristics of peripheral blood biomarkers.

Study Population Eligible participants are patients diagnosed with probable Alzheimer's dementia consistent with 2011 NIA-AA clinical criteria and 2018 NIA-AA biomarker framework. Inclusion criteria: age 50 to 80 years; MMSE score between 10 and 20 points (moderate cognitive impairment); progressive cognitive decline for more than 6 months; no clinical improvement after more than six months of drug treatment; having a designated companion who can accompany follow-up and provide informed consent. Subjects with severe organ dysfunction, recent intracranial injury, drug allergy to study related reagents, PET contraindications or other severe mental disorders will be excluded.

Intervention and Control Measures Participants are randomly assigned to two groups by EDC system at a 1:1 ratio. Intervention group: Bilateral deep cervical lymphovenous anastomosis plus conventional symptomatic treatment for Alzheimer's disease. The operation is performed under surgical microscope with indocyanine green (ICG) lymphatic tracing technology. Postoperative routine anti-inflammatory treatment and rehabilitation training will be conducted.

Control group: Receive only standard drug treatment and routine rehabilitation training for Alzheimer's disease, without surgical intervention.

Evaluation Indicators and Time Points The primary outcome measure is the change of CDR-SB score from baseline to 12 months after randomization. Secondary outcome measures include changes in CDR-SB score at 1 month and 6 months, changes in MMSE and ZBI scores at 1, 6 and 12 months, and changes of Aβ-PET Centiloid value at 12 months. Exploratory indicators cover peripheral blood Aβ42, Aβ40, Aβ42/40 ratio, t-tau, p-tau and other biomarkers at each follow-up time point.

All assessments will be conducted at baseline, 1 month (±7 days), 6 months (±15 days) and 12 months (±15 days) after randomization. All adverse events, vital signs, laboratory tests, electrocardiogram and imaging findings will be continuously collected to evaluate the safety profile of the surgical procedure.

Randomization and Blinding Method Randomization is implemented via electronic data capture (EDC) system. Due to the nature of surgical intervention, participants, surgeons and clinical researchers cannot be blinded. However, all outcome assessors and statistical analysts are fully blinded to group allocation to reduce assessment bias. All raters will be shielded from patients' surgical scars during scale evaluation.

Statistical Analysis The full analysis set (FAS) will be adopted for primary efficacy analysis based on the intention-to-treat principle. Per-protocol set (PPS) will be used for sensitivity analysis, and safety analysis will be performed based on safety analysis set (SAS). Mixed-effects model for repeated measures (MMRM) and analysis of covariance (ANCOVA) will be applied for data analysis. Missing data will be handled by last observation carried forward (LOCF) method. Subgroup analyses stratified by APOEε4 status, age and baseline cognitive level will also be performed.

Ethical Requirements The whole study complies with the Declaration of Helsinki and relevant Chinese clinical research regulations. The study has been reviewed and approved by the Ethics Committee of the First Affiliated Hospital of Army Medical University. Written informed consent will be obtained from each participant or their legal surrogate before any study-related procedures. Vulnerable population protection measures are strictly implemented for patients with cognitive impairment.