NCT07218081 is a Phase 1 clinical trial conducted by Augusta University investigating intermittent deep brain stimulation (DBS) of the nucleus basalis of Meynert (NBM) for the treatment of Alzheimer's disease (AD). This trial represents a novel neurostimulation approach targeting the cholinergic system directly, building upon decades of research into both the neurobiology of the basal forebrain and the therapeutic potential of electrical brain stimulation[1].
The NBM (also known as the basal nucleus of Meynert or Ch4) is the primary source of cholinergic innervation to the cortex, playing critical roles in memory, attention, and arousal. In Alzheimer's disease, NBM neurons are among the earliest to degenerate, leading to cortical cholinergic hypofunction that contributes significantly to cognitive decline[2]. This trial aims to directly modulate the remaining cholinergic neurons, potentially restoring cortical tone and slowing disease progression.
| Attribute | Details |
|---|---|
| NCT Number | NCT07218081 |
| Sponsor | Augusta University |
| Intervention | Deep Brain Stimulation of Nucleus Basalis of Meynert |
| Phase | Phase 1 |
| Indication | Alzheimer's Disease |
| Status | Recruiting |
| Location | Augusta University Medical Center |
| Study Start | 2021 |
| Estimated Completion | 2026 |
| Enrollment | 10 participants |
The nucleus basalis of Meynert (NBM) is a collection of cholinergic neurons in the basal forebrain that provides the primary cholinergic innervation to the cerebral cortex. First described by Theodor Meynert in 1872, these neurons form the major component of the basal forebrain cholinergic system (BFCS)[3].
The NBM consists of several subdivisions (Ch1-Ch4) with distinct projection patterns:
| Subdivision | Location | Primary Projections |
|---|---|---|
| Ch1 (medial septum) | Medial septum | Hippocampus |
| Ch2 (vertical diagonal band) | Vertical limb of diagonal band | Hippocampus |
| Ch3 (horizontal diagonal band) | Horizontal limb of diagonal band | Olfactory bulb |
| Ch4 (nucleus basalis) | Substantia innominata | Neocortex, amygdala |
These neurons play crucial roles in:
The cholinergic hypothesis of AD, proposed in the 1980s, posits that loss of basal forebrain cholinergic neurons and the resulting cortical cholinergic hypofunction are major contributors to the cognitive deficits in AD[5]. This hypothesis led to the development of cholinesterase inhibitors (donepezil, rivastigmine, galantamine), which remain the mainstay of symptomatic treatment.
However, the cholinergic hypothesis has evolved to recognize that:
The rationale for NBM-DBS includes multiple mechanisms:
Deep brain stimulation has been used successfully for movement disorders since the 1980s, with the first FDA approvals for Parkinson's disease[7]. The application to AD is more recent, with initial trials targeting the fornix (memory circuit) showing promising but inconsistent results.
The ADvance trial (NCT01074880) tested fornix DBS in patients with mild AD, demonstrating increased cerebral glucose metabolism and slowing of cognitive decline in some analyses. However, the subsequent ADvance II trial did not meet its primary endpoint, highlighting the complexity of neurostimulation for cognitive disorders.
NBM-DBS represents a different approach—directly targeting the source of cholinergic innervation rather than downstream memory circuits. Preclinical work in animal models demonstrated that NBM stimulation could enhance memory performance and promote cholinergic neuron survival[8].
NBM-DBS works through several mechanisms that together may restore or enhance cortical cholinergic function[9]:
| Mechanism | Effect | Evidence |
|---|---|---|
| Neuronal activation | Direct excitation of cholinergic NBM neurons | Animal studies showing increased ACh release |
| Cortical release | Increased acetylcholine in prefrontal cortex and hippocampus | Microdialysis studies in rodents |
| Network synchronization | Modulation of cortical-subcortical circuits | Human neuroimaging studies |
| Neurotrophic effects | Potential promotion of cholinergic neuron survival | Molecular studies |
| Anti-inflammatory | Reduction in neuroinflammation markers | Preclinical data |
DBS for AD has been attempted at several brain targets, each with different mechanisms:
| Target | Indication | Mechanism | Clinical Status |
|---|---|---|---|
| NBM | Alzheimer's | Cholinergic enhancement | Phase 1/2 trials |
| Fornix | Alzheimer's | Memory circuit modulation | Phase 2 completed |
| Subthalamic nucleus | Parkinson's | Motor circuit modulation | Approved |
| Ventral intermediate thalamus | Tremor | Sensorimotor circuit modulation | Approved |
| Anterior cingulate | Depression | Limbic circuit modulation | Approved |
Each target offers different advantages. NBM targeting is unique in its direct approach to the cholinergic system, potentially offering both symptomatic benefit and disease modification[10].
Parameter selection significantly influences outcomes in DBS. Current research focuses on:
The NCT07218081 trial uses intermittent high-frequency stimulation, designed to maximize cholinergic activation while minimizing potential adverse effects from continuous stimulation[11].
The Phase 1 trial includes:
Key Inclusion Criteria:
Key Exclusion Criteria:
| Measure | Type | Timepoints |
|---|---|---|
| Adverse events | Primary safety | Continuous |
| ADAS-Cog | Cognitive function | Baseline, 3, 6, 12 months |
| MMSE | Global cognition | Baseline, 3, 6, 12 months |
| CDR | Dementia severity | Baseline, 6, 12 months |
| CSF biomarkers | Aβ, tau, ACh levels | Baseline, 12 months |
| PET imaging | Cholinergic integrity, glucose metabolism | Baseline, 12 months |
| Neuropsychological battery | Comprehensive cognitive assessment | Baseline, 6, 12 months |
Preclinical research has provided strong rationale for NBM-DBS:
Limited pilot studies and case series have provided preliminary human data:
The phase 1 trial NCT07218081 builds upon this foundation, with rigorous methodology and comprehensive outcome assessment[12].
Comprehensive neuroimaging is performed at baseline:
Key biomarkers tracked during the trial[13]:
| Biomarker | Fluid | Significance |
|---|---|---|
| Aβ42 | CSF | Amyloid pathology |
| Total tau | CSF | Neurodegeneration |
| Phospho-tau | CSF | Tau pathology |
| Acetylcholine | CSF | Cholinergic function |
| NfL | Serum | Neuroaxonal injury |
| GFAP | Serum | Astrocyte activation |
Changes in these biomarkers may provide evidence of disease modification.
| Aspect | NBM-DBS | Cholinesterase Inhibitors |
|---|---|---|
| Mechanism | Direct neural activation | Enzyme inhibition |
| Duration | Long-term, potentially disease-modifying | Requires daily dosing |
| Target specificity | Focal, personalized | Systemic |
| Efficacy | Potential for greater effect | Modest symptomatic benefit |
| Side effects | Surgical risks | GI, cardiac, insomnia |
| Invasiveness | Surgical procedure | Oral medication |
| Reversibility | Fully reversible | Fully reversible |
NBM-DBS represents a fundamentally different approach—rather than compensating for cholinergic loss through pharmacological means, it directly stimulates the remaining cholinergic neurons to enhance their function.
| Approach | Advantages | Limitations | Evidence Level |
|---|---|---|---|
| NBM-DBS | Targets cognitive circuitry, disease modification | Invasive surgery | Phase 1/2 |
| Fornix DBS | Established safety profile | Mixed efficacy | Phase 2 |
| TMS (rTMS) | Non-invasive | Limited penetration | Phase 2/3 |
| tDCS | Home-use possible | Subtle effects | Phase 2 |
| Vagus nerve stimulation | Peripheral, established | Limited cognitive data | Phase 2 |
Patients most likely to benefit from NBM-DBS:
Based on other DBS trials and AD biomarker studies:
As with any DBS procedure:
Careful monitoring and parameter adjustment minimize these risks.
NBM-DBS modulates multiple brain networks[11:1]:
Memory Networks:
Attention Networks:
Autonomic Networks:
DBS produces characteristic electrophysiological changes:
| Measure | Effect | Significance |
|---|---|---|
| Theta power | Increased | Memory encoding |
| Gamma power | Modulated | Cognitive processing |
| Entropy | Increased | Information processing |
| Coherence | Changed | Network integration |
DBS may induce molecular changes:
Neurotrophic Factors:
Neurotransmitter Release:
Inflammatory Modulation:
DBS for AD aims to preserve function and quality of life:
Primary Goals:
Outcome Categories:
| Domain | Measure | Goal |
|---|---|---|
| Cognition | MMSE, ADAS-Cog | Maintain or slow decline |
| Behavior | NPI-NH | Reduce neuropsychiatric symptoms |
| Function | ADL scales | Preserve independence |
| Quality of life | QoL-AD | Maintain well-being |
DBS success depends on caregiver support:
Pre-operative:
Post-operative:
Ongoing:
DBS represents substantial investment but may offer value:
| Cost Component | Estimate |
|---|---|
| Surgical procedure | $50,000-100,000 |
| Device and hardware | $30,000-50,000 |
| Programming visits | $5,000-10,000 |
| Annual maintenance | $5,000-15,000 |
Delayed institutionalization:
Reduced caregiver burden:
Healthcare utilization:
| Intervention | Cost (5 years) | Benefits |
|---|---|---|
| Cholinesterase inhibitors | $15,000-25,000 | Modest symptomatic benefit |
| Anti-amyloid antibodies | $90,000-150,000 | Disease modification |
| NBM-DBS | $100,000-150,000 | Direct neural modulation |
| Standard care | $50,000-100,000 | No specific treatment |
Precise NBM targeting is critical:
Anatomical Landmarks:
Verification Methods:
DBS leads have multiple contacts:
| Feature | Configuration |
|---|---|
| Contacts | 4-8 per lead |
| Spacing | 1.5-7.5 mm |
| Polarity | Anode/cathode |
| Impedance | 500-2000 ohms |
| Parameter | Typical Range |
|---|---|
| Frequency | 130-180 Hz |
| Amplitude | 1-5 mA |
| Pulse width | 60-120 μs |
| Cycle | Continuous or intermittent |
Based on Phase 1 data[12:1]:
Cognitive Outcomes:
Quality of Life:
Neuroimaging:
CSF Biomarkers:
Device Longevity:
Disease Progression:
Combining DBS with medications may enhance outcomes:
With Cholinesterase Inhibitors:
With Anti-Amyloid Therapies:
Multi-target approaches are being explored:
Fornix + NBM DBS:
NBM + Vagus Nerve Stimulation:
Optimal patient selection:
Stimulation optimization:
Mechanistic understanding:
Next-Generation DBS:
Targeting Advances:
| Trial | Phase | Status | Key Features |
|---|---|---|---|
| NCT07218081 | Phase 1 | Recruiting | NBM target |
| ADvance II | Phase 2b | Completed | Fornix target |
| Various | Phase 1/2 | Various | Multi-target |
If Phase 1 is successful, future trials may:
Key biomarker targets for future trials[14]:
The most promising future direction may be combining NBM-DBS with disease-modifying therapies:
This approach addresses both the upstream (Aβ) and downstream (cholinergic) components of AD pathophysiology.
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Cholinergic dysfunction in Alzheimer's disease. Nature Reviews Neuroscience. 2022. ↩︎
A phase I trial of deep brain stimulation of memory circuits. Annals of Neurology. 2013. ↩︎
Acetylcholine and Alzheimer's disease. Reviews in the Neurosciences. 2014. ↩︎
Neural effects of deep brain stimulation for Alzheimer's disease. Brain Stimulation. 2017. ↩︎
The history of deep brain stimulation. World Neurosurgery. 2015. ↩︎
Deep brain stimulation for Alzheimer's disease. Journal of Alzheimer's Disease. 2020. ↩︎
Deep brain stimulation mechanisms in Alzheimer's disease. Brain Stimulation. 2021. ↩︎
Nucleus basalis of Meynert stimulation for dementia. Neurology. 2021. ↩︎
Deep brain stimulation targeting the basal forebrain. Brain. 2023. ↩︎ ↩︎
Phase I trial of NBM DBS for Alzheimer's disease. Alzheimer's & Dementia. 2022. ↩︎ ↩︎
Biomarker changes in NBM DBS. Neurology. 2022. ↩︎
Optimizing DBS parameters for memory enhancement. Nature Reviews Neurology. 2023. ↩︎