NCT06530290: Mirtazapine for Anxiety in Parkinson's Disease

NCT06530290: Mirtazapine for Anxiety in Parkinson's Disease

Overview

NCT06530290: Mirtazapine for Anxiety in Parkinson's Disease

Overview

This Phase 2 clinical trial (NCT06530290) evaluates mirtazapine, a noradrenergic and specific serotonergic antidepressant, for the treatment of anxiety in Parkinson's disease (PD)[@nct06530290]. Anxiety is one of the most common non-motor symptoms in PD, affecting up to 40% of patients, yet treatment options remain limited due to the sensitivity of PD patients to traditional anxiolytic medications.

Mirtazapine represents a promising therapeutic approach because it modulates both noradrenergic and serotonergic systems—pathways known to be affected in PD—and has a favorable side effect profile compared to traditional SSRIs and benzodiazepines.

Trial Details

| Attribute | Value |
|-----------|-------|
| NCT ID | NCT06530290 |
| Phase | Phase 2 |
| Status | Recruiting |
| Intervention | Mirtazapine (15 mg once daily) |
| Condition | Parkinson's Disease, Anxiety |
| Participants | 64 (estimated) |
| Sponsor | Leila Dargahi, PharmD PhD |
| Location | Shahid Beheshti University of Medical Sciences, Tehran, Iran |
| Start Date | June 2022 |
| Primary Completion | December 2025 |
| Completion | June 2026 |

Parkinson's Disease and Anxiety

Prevalence and Impact

Anxiety disorders in Parkinson's disease represent a significant non-motor complication:

• Prevalence: 25-40% of PD patients meet criteria for anxiety disorders
• Types: Generalized anxiety disorder (GAD), panic disorder, social anxiety
• Underdiagnosis: Often unrecognized due to overlap with motor symptoms[@bruneau2011]

Neurobiological Basis

The neurobiological basis of anxiety in PD involves multiple neurotransmitter systems:

Dopaminergic dysfunction:

• Loss of dopaminergic neurons in the substantia nigra affects mesocortical pathways
• Reduced dopamine in prefrontal cortex contributes to anxiety symptoms
• Correlation between striatal dopamine deficiency and anxiety severity

• Locus coeruleus degeneration is an early feature of PD
• Norepinephrine modulation of anxiety circuits is impaired
• The noradrenergic system regulates stress response and arousal[@ressler2004]

• Raphe nuclei are affected in PD
• Serotonin regulates mood and anxiety
• SSRIs show modest efficacy in PD anxiety[@menza2010]

Current Treatment Challenges

Current treatment options for anxiety in PD have significant limitations:

| Treatment | Limitations |
|-----------|-------------|
| SSRIs/SNRIs | Limited efficacy, potential worsen motor symptoms |
| Benzodiazepines | Risk of falls, sedation, cognitive impairment |
| Buspirone | Modest efficacy |
| CBT | Access barriers, variable response |

This highlights the need for novel therapeutic approaches like mirtazapine that can target multiple neurotransmitter systems simultaneously.

Mirtazapine: Pharmacology

Mechanism of Action

Mirtazapine is a tetracyclic antidepressant with a unique pharmacological profile:

Primary mechanisms:

• Alpha-2 adrenergic autoreceptor antagonism: Increases norepinephrine release
• 5-HT2 receptor antagonism: Enhances serotonergic transmission
• 5-HT3 receptor antagonism: Reduces side effects (nausea, insomnia)

Advantages for PD

Mirtazapine has several properties that make it attractive for PD anxiety:

Clinical Experience in PD

Prior studies have evaluated mirtazapine in Parkinson's disease:

Depression in PD:

• Mirtazapine has shown efficacy for PD depression
• Improved mood without worsening motor symptoms
• Good tolerability in PD populations[@chen2017]

• Sedating properties can improve sleep fragmentation
• May reduce nighttime disability
• Does not worsen periodic limb movements

Trial Design

Study Population

Inclusion criteria:

• Men and women over 17 years old
• Parkinson's disease diagnosis (UKPDSBB criteria)
• Mild/moderate PD (Hoehn and Yahr score 1-3)
• Self-report or clinical diagnosis of anxiety
• Signed informed consent

• Pregnant or lactating women
• Disease onset less than 1 year
• Unstable PD medication (last 2 weeks)
• Deep brain stimulation (DBS)
• Other neurodegenerative diseases (MSA, Huntington's)
• Major depressive disorder
• SSRIs, SNRIs, benzodiazepines, β-blockers (last 4 weeks)
• MAO inhibitors
• Alcohol/substance abuse
• Acute stress (last 3 months)
• Suicide history
• Cardiovascular disease
• Liver/kidney disorders

Treatment Arms

The trial uses a randomized, double-blind, placebo-controlled design:

| Arm | Intervention | Dose | Duration |
|-----|--------------|------|----------|
| Treatment | Mirtazapine | 15 mg daily | 12 weeks |
| Control | Placebo | N/A daily | 12 weeks |

Primary Endpoints

Anxiety assessment:

• Hamilton Anxiety Rating Scale (HAM-A) at baseline, week 4, and week 12
• Parkinson Anxiety Scale (PAS) at baseline, week 4, and week 12

• 14 items, scored 0-4 each
• Total score range: 0-56
• Mild anxiety: 14-17
• Moderate anxiety: 18-24
• Severe anxiety: ≥25

Secondary Endpoints

| Outcome | Instrument | Timepoints |
|---------|------------|------------|
| Depression | Hamilton Depression Rating Scale (HAM-D) | Baseline, week 4, week 12 |
| Fatigue | Parkinson's Disease Fatigue Scale (PDFS) | Baseline, week 4, week 12 |
| Sleep | Parkinson's Disease Sleep Scale (PDSS) | Baseline, week 4, week 12 |
| Quality of Life | PDQL Questionnaire | Baseline, week 4, week 12 |

Scientific Rationale

Targeting Noradrenergic Dysfunction

The rationale for mirtazapine in PD anxiety centers on its noradrenergic effects:

α2-adrenoceptor antagonism:

• Increases norepinephrine release in the prefrontal cortex
• Enhances anxiety regulation in limbic circuits
• May compensate for locus coeruleus degeneration

• Direct pharmacological targeting of the impaired system
• Unlike SSRIs, which primarily affect serotonin
• Potential for greater efficacy in PD-specific anxiety[@nutt2008]

Serotonergic Modulation

The serotonergic effects of mirtazapine provide additional benefits:

• 5-HT2A antagonism: May reduce anxiety and improve mood
• 5-HT2C antagonism: Anxiolytic effects
• 5-HT3 antagonism: Reduces nausea and other GI side effects
• Enhanced serotonergic transmission without serotonin release

Sleep Benefits

PD patients frequently experience sleep fragmentation:

• Mirtazapine's H1 antagonism promotes sleep
• May improve overnight motor symptoms
• Could enhance daytime function
• Does not disrupt sleep architecture

Non-Motor Symptoms in Parkinson's Disease

Comprehensive Burden

Parkinson's disease involves numerous non-motor symptoms that impact quality of life:

| Category | Symptoms |
|----------|----------|
| Neuropsychiatric | Depression, anxiety, apathy, psychosis |
| Sleep | Insomnia, RBD, restless legs, daytime sleepiness |
| Autonomic | Orthostatic hypotension, constipation, urinary dysfunction |
| Sensory | Hyposmia, pain, visual disturbances |
| Cognitive | Executive dysfunction, memory impairment, dementia[@kalia2015] |

Anxiety as a Therapeutic Target

Treating anxiety in PD provides multiple benefits:

Safety Considerations

Mirtazapine Safety Profile

Mirtazapine's established safety profile supports its evaluation in PD:

Common adverse effects:

• Somnolence (due to H1 antagonism)
• Weight gain
• Dry mouth
• Constipation
• Dizziness

• Orthostatic hypotension (α2 blockade)
• Rare neutropenia (requires monitoring)
• Suicidal ideation (monitor in vulnerable patients)

PD-Specific Considerations

Special considerations for the PD population:

Motor effects:

• Monitor for worsening of motor symptoms
• May interact with dopaminergic medications
• Generally considered motor-safe

• Consider impact on cognition
• Monitor for sedation
• May affect driving safety

• Monitor blood pressure
• Assess orthostatic symptoms
• Review cardiac history

Drug Interactions

Key interactions to monitor in PD patients:

• May enhance sedative effects of dopaminergic medications
• Potential interaction with MAO-B inhibitors
• Caution with other serotonergic agents
• Monitor with drugs affecting QT interval

Future Directions

Implications for PD Treatment

If successful, this trial could establish mirtazapine as a first-line treatment for PD anxiety:

Clinical practice impact:

• Provides evidence-based option for anxiety
• Addresses an unmet need in PD care
• May improve overall treatment outcomes

• Combination with dopaminergic therapy
• Comparison with SSRIs/SNRIs
• Long-term efficacy and safety
• Effects on disease progression

Biomarker Development

Future studies may incorporate:

• Neuroimaging markers of anxiety circuits
• CSF neurotransmitter levels
• Genetic predictors of response
• Autonomic function measures

Conclusion

The NCT06530290 trial represents an important step in addressing anxiety in Parkinson's disease, one of the most common and debilitating non-motor symptoms. By evaluating mirtazapine—a noradrenergic and serotonergic modulator—this trial tests a mechanistically targeted approach that addresses the neurobiological basis of PD anxiety.

The scientific rationale is compelling: mirtazapine directly enhances noradrenergic neurotransmission, which is impaired due to locus coeruleus degeneration in PD, while also providing serotonergic modulation and sleep benefits. The established safety profile of mirtazapine in general populations supports its evaluation in the often-medically complex PD patient population.

Given the high prevalence of anxiety in PD and the limitations of current treatment options, successful results from this trial could significantly improve the standard of care for Parkinson's disease patients suffering from anxiety.

See Also

• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Anxiety Disorders in Neurodegeneration](/mechanisms/anxiety-neurodegeneration)
• [Noradrenergic System](/mechanisms/noradrenergic-system)
• [Serotonin and Parkinson's Disease](/mechanisms/serotonin-parkinsons)
• [Clinical Trials Dashboard](/clinical-trials/dashboard)
• [Non-Motor Symptoms in PD](/mechanisms/non-motor-symptoms-pd)
• [Mirtazapine](/therapeutics/mirtazapine)

External Links

• [ClinicalTrials.gov - NCT06530290](https://clinicaltrials.gov/study/NCT06530290)
• [Shahid Beheshti University of Medical Sciences](https://www.sbmu.ac.ir/)

References