Overview

Alzheimer's disease (AD), one of the most common causes of dementia in Singapore and the developed world, is a neurodegenerative disorder with high socioeconomic impact. Accumulation of neurotoxic proteins (ie. amyloid, tau) are purported to lead to neuroinflammation, synaptic dysfunction and cognitive decline. The available pharmacotherapy provide limited symptomatic control, modest effect on disease progression with significant risk of side effects. Patients with AD eventually run out of effective pharmacotherapy and deteriorate.

Recent evidence implicated the glymphatic system, meningeal lymphatics of the brain, and downstream drainage to the cervical lymphatic system in the accumulation of neurotoxic proteins in AD. This presented the opportunity for extra-cranial intervention, and has since been demonstrated in preclinical models. Based on these development, Xie and colleagues pioneered the deep cervical lymph node to venous bypass (DCLNV-BP) procedure with very promising early outcomes. The observed improvement had been attributed to enhanced clearance of the neurotoxic proteins. Knowledge gap and clinical equipoise remain, and clinical trials are required to understand the safety, mechanism of action, patient selection, and long-term outcomes.

In this proof of concept study, the investigators aim to assess safety and preliminary efficacy of DCLNV-BP in AD. An approach using objective clinical assessments, biomarkers and neuroimaging, to assess safety, evaluate preliminary efficacy and elucidate the possible mechanism underlying the observed effects, is undertaken. Since there are limited effective treatment for AD, this procedure is potentially ground breaking if it proves to halt progression or even improve patients' cognition, function and behaviour. Indirectly, this will have enormous health economic benefit for Singapore and the developed world that is facing the silver tsunami. Findings from this pilot study will lay the groundwork for future trials and research collaboration in AD and other neurodegenerative diseases.

Eligibility

Inclusion Criteria:

• Diagnosis of mild-moderate Alzheimer's disease (based on NIA-AA criteria);
• Mini-Mental State Examination (MMSE) score 12-22;
• Both participants and caregiver are able to understand English or Mandarin
• Ability to provide informed consent or have a legally authorised representative to provide informed consent;
• Good family support for post-treatment care and rehabilitation;
• Fit for general anaesthesia/deep sedation and surgery (ASA 1-2; excluding the diagnosis of Alzheimer's Disease).

Exclusion Criteria:

• Severe, confluent vascular burden on neuroimaging (eg. Fazeka 3);
• Cognitive decline due to prior infection or autoimmune diseases;
• History of major cerebrovascular events or significant cardiovascular diseases;
• Inability to have the head turned passively by at least 40 degrees;
• Previous neck lymph node surgery or irradiation;
• Active infection or malignancy;
• Any contraindications to surgery or lumbar puncture
• Any contraindication to MRI/PET scan (eg. metallic implant that are not MRI-safe, known radiotracer allergy)
• Experimental Alzheimer's Disease treatment within the past 6 months. • Current use of monoclonal antibodies treatment (eg. lecanemab/donanemab)