Nabilone for Agitation Blinded Intervention Trial (NAB-IT) is a Phase 3 randomized, double-blind, placebo-controlled clinical trial evaluating the efficacy and safety of nabilone (a synthetic cannabinoid) for the treatment of agitation in patients with Alzheimer's disease (AD). The trial is conducted by Sunnybrook Health Sciences Centre in Toronto, Canada.
| Field | Value |
|-------|-------|
| NCT Number | [NCT04516057](https://clinicaltrials.gov/study/NCT04516057) |
| Phase | Phase 3 |
| Status | Recruiting |
| Sponsor | Sunnybrook Health Sciences Centre |
| Collaborator | Alzheimer's Drug Discovery Foundation |
| Start Date | February 1, 2021 |
| Primary Completion | April 2027 (Estimated) |
| Enrollment | 112 participants (Estimated) |
Agitation is highly prevalent in Alzheimer's disease and is one of the most distressing and challenging-to-treat neuropsychiatric symptoms. It is associated with:
Nabilone is a synthetic cannabinoid that targets the endocannabinoid system[@wu2022]:
| Treatment | Mechanism | Efficacy | Safety |
|-----------|-----------|----------|--------|
| Nabilone | CB1/CB2 agonist | Moderate | Requires monitoring |
| Risperidone | D2 antagonist | Moderate | Extrapyramidal effects |
| Quetiapine | Multi-receptor | Low-moderate | Sedation, metabolic |
| trazodone | 5-HT antagonist | Low | Sedation |
Nabilone (brand name: Cesamet) is a synthetic cannabinoid that is Health Canada-approved to treat chemotherapy-induced nausea and vomiting. It is a cannabinoid receptor agonist that acts on the CB1 and CB2 receptors.
Pharmacology:
The foundational pilot study demonstrated:
Common Adverse Effects:
Agitation is one of the most common and distressing neuropsychiatric symptoms in Alzheimer's disease, affecting 40-60% of patients across disease stages. It encompasses a heterogeneous group of behaviors including:
| Category | Examples |
|----------|----------|
| Physical aggression | Hitting, kicking, biting, pushing |
| Verbal aggression | Yelling, screaming, threatening |
| Non-aggressive agitation | Pacing, fidgeting, repetitive behaviors |
| Disinhibition | Inappropriate sexual behavior, screaming |
Agitation significantly impacts quality of life:
| Impact Area | Consequence |
|-------------|-------------|
| Patient wellbeing | Increased distress, reduced quality of life |
| Caregiver burden | Physical and emotional exhaustion |
| Institutionalization | Primary driver of nursing home placement |
| Healthcare costs | Increased hospitalizations, medication use |
| Mortality | Associated with increased mortality risk |
| Treatment | Efficacy | Limitations |
|-----------|----------|-------------|
| Non-pharmacological | Moderate | Requires training, time-intensive |
| Antipsychotics | Modest | Black box warning, mortality risk |
| SSRIs | Variable | Slow onset, side effects |
| Benzodiazepines | Limited | Sedation, fall risk, dependence |
| Cannabinoids | Under investigation | Regulatory issues, safety concerns |
The biological basis of agitation in AD involves multiple systems:
The endocannabinoid system (ECS) is a complex neuromodulatory system involved in various physiological processes. It consists of:
| Component | Function |
|-----------|----------|
| Endocannabinoids | Anandamide, 2-AG |
| Cannabinoid receptors | CB1, CB2 |
| Metabolic enzymes | FAAH, MAGL |
| Transport proteins | FABP, ABC |
The CB1 receptor is one of the most abundant G-protein-coupled receptors in the brain[@manuel2023]:
| Region | Density | Function |
|--------|---------|----------|
| Hippocampus | High | Memory, learning |
| Cerebellum | High | Motor coordination |
| Basal ganglia | High | Movement control |
| Prefrontal cortex | Moderate | Executive function |
| Amygdala | Moderate | Emotion regulation |
CB2 receptors are primarily found in peripheral immune cells but are also expressed in brain microglia[@bachs2020]:
| Cell Type | CB2 Expression | Function |
|-----------|-----------------|----------|
| Microglia | Induced | Neuroinflammation modulation |
| Astrocytes | Low-Moderate | Glial function |
| Neurons | Very low | Unknown |
| Function | Mechanism |
|----------|-----------|
| Memory | Synaptic plasticity modulation |
| Emotion | Amygdala function |
| Pain | Nociceptive processing |
| Appetite | Hypothalamic regulation |
| Sleep | Sleep-wake cycle |
Alterations in the ECS have been documented in AD:
| Finding | Implication |
|---------|-------------|
| Reduced CB1 density | Memory dysfunction |
| Elevated 2-AG | Inflammatory response |
| CB2 upregulation | Immune modulation |
| FAAH alterations | Endocannabinoid tone |
Nabilone (Cesamet) is a synthetic cannabinoid with specific pharmacology:
| Property | Value |
|----------|-------|
| CB1 affinity | High agonist |
| CB2 affinity | High agonist |
| Half-life | 35-50 hours |
| Onset | 1-2 hours |
| Peak | 2-4 hours |
| Metabolism | CYP3A4, CYP2C19 |
| Excretion | Feces (65%), urine (20%) |
| Parameter | Recommendation |
|-----------|----------------|
| Starting dose | 0.5 mg |
| Titration | 0.5 mg increments |
| Maximum | 2 mg/day |
| Frequency | BID or daily |
| Administration | Oral, with/without food |
| Interaction | Effect | Management |
|-------------|--------|------------|
| CYP3A4 inhibitors | Increased levels | Dose reduction |
| CYP3A4 inducers | Decreased levels | Avoid |
| CNS depressants | Additive sedation | Caution |
| Anticholinergics | Additive effects | Avoid |
The trial uses quadruple-masking:
| Phase | Duration | Purpose |
|-------|----------|---------|
| Screening | 2-4 weeks | Eligibility confirmation |
| Baseline | Day 0 | Pre-treatment assessments |
| Treatment | 8 weeks | Active intervention |
| Washout | 2 weeks | Drug clearance |
| Follow-up | 8 weeks | Long-term assessment |
| Visit | Timing | Assessments |
|-------|--------|-------------|
| V1 | Screening | Medical history, cognitive testing |
| V2 | Baseline | CMAI, NPI-NH, safety |
| V3 | Week 2 | Efficacy, safety, PK |
| V4 | Week 4 | Full assessment, labs |
| V5 | Week 8 | Primary endpoint, safety |
| V6 | Week 10 | Washout |
| V7 | Week 16 | Follow-up |
The CMAI is the primary endpoint:
| Domain | Items | Scoring |
|--------|-------|---------|
| Physical aggression | 8 | 29-203 total |
| Verbal aggression | 6 | Higher = worse |
| Non-aggressive behavior | 15 | |
| Subscale | Items | Examples |
|----------|-------|----------|
| Physically aggressive | 1-8 | Hitting, kicking |
| Verbally aggressive | 9-14 | Cursing, screaming |
| Non-aggressive | 15-29 | Pacing, complaining |
Comprehensive behavioral assessment:
| Domain | Maximum Score |
|--------|---------------|
| Delusions | 12 |
| Hallucinations | 12 |
| Agitation | 12 |
| Depression | 12 |
| Anxiety | 12 |
| Apathy | 12 |
| Disinhibition | 12 |
| Irritability | 12 |
| Motor disturbance | 12 |
| Nighttime behavior | 12 |
| Appetite | 12 |
| Total | 144 |
| Domain | Items | Score |
|--------|-------|-------|
| Orientation | 10 | 10 |
| Registration | 3 | 3 |
| Attention | 5 | 5 |
| Recall | 3 | 3 |
| Language | 8 | 8 |
| Visuospatial | 1 | 1 |
| Total | | 30 |
| Event | Frequency | Management |
|-------|-----------|------------|
| Sedation | 30-40% | Dose reduction |
| Dizziness | 20-30% | Fall precautions |
| Dry mouth | 15-25% | Hydration |
| Weight gain | 10-15% | Monitoring |
| Constipation | 10-15% | Laxatives |
| Confusion | 5-10% | Assessment |
| Event | Monitoring | Reporting |
|-------|------------|------------|
| Cardiovascular | Vital signs, ECG | Immediate |
| Psychiatric | Mood, behavior | Regular |
| Respiratory | Pulse ox | Per protocol |
| Falls | Incidence tracking | Continuous |
| Contraindication | Rationale |
|------------------|-----------|
| Psychosis | Exacerbation risk |
| Substance abuse | Dependence |
| Severe cardiac disease | Arrhythmia risk |
| Hepatic impairment | Metabolism |
| Treatment | Mechanism | CMAI Effect | Key Limitation |
|-----------|-----------|-------------|----------------|
| Nabilone | CB1/CB2 agonist | Moderate | Requires monitoring |
| Risperidone | D2 antagonist | Moderate | Extrapyramidal effects |
| Quetiapine | Multi-receptor | Low-moderate | Sedation, metabolic |
| Trazodone | 5-HT antagonist | Low | Sedation |
| Citalopram | SSRI | Variable | Slow onset |
| Intervention | Evidence | Implementation |
|--------------|----------|----------------|
| Music therapy | Moderate | Easy |
| Validation therapy | Moderate | Training needed |
| Exercise | Moderate | Physical ability |
| Sensory modulation | Variable | Staff training |
| Environmental modification | Variable | Cost |
Nabilone is approved in Canada for:
If approved:
| Component | Cost |
|-----------|------|
| Nabilone (monthly) | $200-400 |
| Monitoring visits | $100-200 |
| Lab work | $50-100 |
| Total | $350-700/month |
| Treatment | Monthly Cost | Effectiveness |
|-----------|--------------|---------------|
| Nabilone | $350-700 | Moderate |
| Risperidone | $50-100 | Moderate |
| Quetiapine | $100-200 | Low-moderate |
| Hospitalization | $5000+ | High |
| Factor | Criteria |
|--------|-----------|
| Diagnosis | AD with agitation |
| Severity | Moderate agitation (CMAI > 50) |
| Cognitive | sMMSE < 24 |
| Failure | Non-pharmacological failed |
| Contraindications | None |
| Factor | Reason |
|--------|--------|
| Active psychosis | Exacerbation risk |
| Cardiovascular disease | Arrhythmia risk |
| Substance abuse history | Dependence risk |
| Severe liver disease | Metabolism |
| Focus | Duration | Endpoints |
|-------|----------|-----------|
| Safety | 12 months | SAEs |
| Durability | 6 months | CMAI maintenance |
| Tolerability | 12 months | AE rate |
| Area | Priority |
|------|----------|
| Severe agitation | High |
| Long-term safety | High |
| Combination therapy | Moderate |
| Biomarkers | Moderate |
| Pre-symptomatic | Low |
Cannabinoids have been studied in PDP:
If approved, implementation pathway:
Key points for caregivers:
The NAB-IT trial represents an important step in addressing agitation in Alzheimer's disease, a highly prevalent and challenging symptom with limited treatment options. Nabilone's unique mechanism targeting the endocannabinoid system offers a novel approach that may provide benefits beyond traditional pharmacological interventions.
The trial's rigorous design, including quadruple blinding and comprehensive outcome measures, will provide high-quality evidence for nabilone's efficacy and safety in this population. Given the significant impact of agitation on patients, caregivers, and healthcare systems, any effective treatment would represent a major advance in dementia care.
Success in this trial would not only provide a new therapeutic option but also advance our understanding of the endocannabinoid system's role in neuropsychiatric symptoms of dementia, potentially opening doors for additional cannabinoid-based therapies in neurodegenerative diseases.