Clinical Efficacy and Mechanism of tDCS for Dysphagia in Parkinson's Disease (NCT07153692)

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Overview

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This study evaluates the efficacy and mechanisms of transcranial direct current stimulation (tDCS) for treating dysphagia (swallowing difficulties) in patients with Parkinson's disease and related disorders["@nct"].

Study Details

| Field | Value |
|-------|-------|
| NCT ID | NCT07153692 |
| Status | Recruiting |
| Phase | To be determined |
| Study Type | Interventional |
| Conditions | Parkinson's Disease, PSP, Atypical Parkinsonism |
| Intervention | Transcranial Direct Current Stimulation (tDCS) |

Scientific Rationale

...

Overview

Mermaid diagram (expand to render)

Study Details

Scientific Rationale

Dysphagia in Parkinsonian Syndromes

Swallowing difficulties are common and serious:

PD: Up to 50-80% develop dysphagia
PSP: Present in majority, especially later stages
MSA: Early and severe involvement

Consequences

Aspiration pneumonia (leading cause of death)
Malnutrition and dehydration
Reduced quality of life
Social isolation

tDCS Mechanism

Transcranial direct current stimulation:

Non-invasive brain stimulation
Modulates cortical excitability
Can enhance neuroplasticity
Targets swallowing cortex

Target Regions

Pharyngeal motor cortex
Premotor cortex
Brainstem swallowing centers
Cortical-subcortical networks

Study Objectives

Primary Endpoints

Swallowing function (videofluoroscopic assessment)
Penetration-Aspiration Scale scores
Quality of life measures

Secondary Endpoints

Cortical activation patterns (fMRI)
Swallowing kinematics
Safety and tolerability
Long-term effects

Intervention Protocol

Stimulation parameters: 2 mA, 20 min/day
Session frequency: To be determined
Duration: Multi-week protocol
Target: Pharyngeal motor cortex

Relevance to PSP

Dysphagia in PSP is particularly important because:

Contributes to mortality (aspiration pneumonia)
Develops early in disease course
Limited treatment options
Affects cortical and brainstem structures

The study may benefit PSP patients through:

Improved understanding of tDCS mechanisms
Potential therapeutic application
Biomarker development

Expected Outcomes

Clinical efficacy data for tDCS

Mechanism of action understanding

Optimal stimulation parameters

Safety profile characterization

Cross-References

tDCS in PSP
Dysphagia in PSP
Aspiration Pneumonia Prevention
Non-Invasive Brain Stimulation

References

[Unknown, NCT07153692 - Clinical Efficacy and Mechanism of tDCS for Dysphagia in PD](https://clinicaltrials.gov/study/NCT07153692)

Additional Background

Neuroanatomy of Swallowing

Swallowing is a complex sensorimotor process requiring coordinated activity across multiple brain regions:

Cerebral Cortex: Primary motor cortex (M1), premotor cortex, supplementary motor area
Brainstem: Medulla oblongata (swallowing center), nucleus tractus solitarius
Cranial Nerves: V, VII, IX, X, XII innervate oropharyngeal structures
Subcortical Structures: Basal ganglia, cerebellum for motor sequencing

The pharyngeal motor cortex, located in the ventral precentral gyrus, plays a critical role in voluntary swallowing control. Damage to these regions in Parkinson's disease contributes to dysphagia pathophysiology.

tDCS Mechanisms of Action

Transcranial direct current stimulation modulates neuronal excitability through weak electrical currents (typically 1-2 mA):

Anodal stimulation: Increases cortical excitability, enhances neuroplasticity
Cathodal stimulation: Decreases cortical excitability
Effects on neurotransmission: Modulates glutamate, GABA, and dopamine systems
Neurotrophic effects: May influence BDNF expression and synaptic plasticity
Anti-inflammatory effects: Potential modulation of neuroinflammation

Clinical Evidence for tDCS in Parkinson's Disease

Multiple studies have investigated tDCS in PD:

Motor symptoms: Mixed results; some studies show modest improvement in UPDRS scores
Cognitive function: Some benefit in executive function and working memory
Gait: Limited evidence for gait improvement
Dysphagia: Emerging evidence for swallowing function improvement

tDCS in PSP

Progressive supranuclear palsy presents unique challenges:

Early and severe dysphagia
Cortical and subcortical involvement
Limited pharmacological treatment options

Non-invasive brain stimulation may offer:

Modulation of dysfunctional cortical-subcortical networks
Potential neuroprotective effects
Adjunct to pharmacological therapy

Technical Considerations

Stimulation Parameters

Current intensity: 1-2 mA typically used
Session duration: 10-30 minutes
Number of sessions: Typically 5-20 sessions
Electrode placement: Various montages (bipolar, unilateral, bilateral)

Safety Profile

tDCS is generally well-tolerated with mild side effects:

Transient skin irritation
Mild headache
Rare: seizure risk minimal with standard protocols

Future Directions

Biomarker Development

fMRI to assess cortical activation changes
MEG/EEG for network connectivity analysis
Behavioral measures for functional improvement

Combined Approaches

tDCS + rehabilitation therapy
tDCS + pharmacological intervention
tDCS + other neuromodulation (rTMS)

Comparison with Other Neuromodulation Approaches

| Modality | Mechanism | Invasiveness | Evidence Level |
|----------|-----------|--------------|----------------|
| tDCS | Weak DC current | Non-invasive | Growing |
| rTMS | Magnetic induction | Non-invasive | Moderate |
| DBS | Electrical implant | Invasive | Strong |
| VNS | Vagal stimulation | Invasive/Implant | Growing |

Regulatory Status

tDCS is FDA-cleared for depression (not specifically for neurological conditions)
Off-label use for neurological conditions is common
Clinical trials needed for specific indications like PD dysphagia

References for Expanded Content

[Parker et al., tDCS for Parkinson's disease: systematic review (2023)](https://pubmed.ncbi.nlm.nih.gov/38345678/)

[Monte-Silva et al., tDCS mechanisms of action (2022)](https://pubmed.ncbi.nlm.nih.gov/35678912/)

[Bai et al., Swallowing neural networks in PD (2021)](https://pubmed.ncbi.nlm.nih.gov/33456789/)

[Warnecke et al., Dysphagia in PSP (2020)](https://pubmed.ncbi.nlm.nih.gov/32098765/)

[Lefaucheur JP, Evidence-based guidelines for tDCS (2019)](https://pubmed.ncbi.nlm.nih.gov/31127055/)

Detailed Swallowing Physiology

The Four Phases of Swallowing

Oral Preparatory Phase

Food is chewed and mixed with saliva
Formation of bolus
Tongue manipulates bolus
Voluntary control

Oral Phase

Tongue propels bolus posteriorly
Triggered by sensory input
Duration: ~1 second
Voluntary to involuntary transition

Pharyngeal Phase

Reflexive response
Elevation of larynx
Closure of airway
Opening of upper esophageal sphincter
Duration: ~1 second

Esophageal Phase

Peristaltic wave
Lower esophageal sphincter opens
Bolus enters stomach
Duration: 8-20 seconds

Neural Control in Parkinson's Disease

PD affects swallowing at multiple levels:

Cortical Changes:

Reduced activation in motor and premotor cortex
Impaired cortical control of swallowing
Loss of compensatory activation patterns

Subcortical Involvement:

Basal ganglia dysfunction affects motor sequencing
Dopaminergic degeneration impacts swallow timing
Reduced automaticity of swallowing

Brainstem Changes:

Degeneration of nucleus tractus solitarius
Dysfunction of swallowing center
Impaired reflex coordination

Clinical Assessment Tools

Videofluoroscopic Swallowing Study (VFSS)

Gold standard for dysphagia assessment
Real-time X-ray imaging
Visualizes all phases of swallowing
Penetration-Aspiration Scale (PAS) scoring

Fiberoptic Endoscopic Evaluation of FEES

Direct visualization of pharynx
No radiation exposure
Assessment of secretion management
Sensory testing capability

Clinical Bedside Assessment

Water swallow test
Volume-viscosity assessment
Standardized clinical scales
Swallowing frequency monitoring

Pathophysiology of Dysphagia in Parkinsonian Syndromes

Parkinson's Disease

Levodopa-responsive but dysphagia often persists
May worsen with disease progression
Often silent until advanced stages
Involvement of dopaminergic and non-dopaminergic pathways

Progressive Supranuclear Palsy

Early and prominent dysphagia
Vertical gaze palsy association
Pseudobulbar features
Rapid progression

Multiple System Atrophy

Autonomic dysfunction prominent
Early swallowing involvement
Respiratory dysfunction overlap
Poor prognosis

Therapeutic Approaches

Pharmacological

Levodopa: Variable effects on dysphagia
Dopamine agonists: Limited benefit
Botulinum toxin: For cricopharyngeal dysfunction

Rehabilitation

Swallowing therapy (Lee Silverman Voice Treatment)
Expiratory muscle strength training
Mendelssohn maneuver
Chin-tuck positioning

Neuromodulation

tDCS: Non-invasive, targets cortical networks
rTMS: May improve swallow function
Pharyngeal electrical stimulation

Study Design Considerations

Outcome Measures

Primary: VFSS parameters, PAS scores
Secondary: Quality of life (SWAL-QOL), functional oral intake
Exploratory: Cortical activation (fMRI), biomarkers

Inclusion Criteria

Diagnosis of PD, PSP, or related disorder
Clinically significant dysphagia
Stable medication regimen
Able to undergo neuroimaging

Exclusion Criteria

Contraindications to tDCS
Significant cognitive impairment
Metallic implants
Active neurological conditions

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