Alpha tACS for Disorders of Consciousness : a Single Case Experimental Design

NCT07213869 | Not Yet Recruiting

• 2 other identifiers: 69HCL24_09762025-A02086-43
• Study Type: interventional
• Target: 5
• Locations: 1 country
• Sites: 1

Brief Summary

BRIEF SUMMARY \* (Include a statement of the study hypothesis) Avoid all personal pronouns (Limit: 5000 characters) Disorders of consciousness (DoC) following a severe traumatic brain injury represent a major medical challenge, with very limited therapeutic options and many patients remaining in a minimally conscious state or vegetative/unresponsive wakefulness state for months. To date, only two pharmacological treatments (amantadine and zolpidem) have shown partial benefits. Non-invasive neuromodulation techniques such as transcranial direct current stimulation (tDCS) have produced modest but encouraging results. Recent advances in transcranial alternating current stimulation (tACS) have demonstrated its ability to modulate brain oscillations, particularly in the alpha frequency range (8-12 Hz), which plays a central role in large-scale functional connectivity, especially within the default mode network (DMN). Neuroimaging studies suggest alpha activity and DMN connectivity are major correlate of the level of consciousness in DoC. Yet experimental evidence suggests that alpha tACS can enhance alpha power and antero-posterior connectivity in healthy subjects, as well as connectivity within the default mode network (DMN). However, no controlled study has yet evaluated its therapeutic potential in patients with DoC. The present study (SPARC) is a single-center clinical investigation aiming to assess the clinical efficacy of alpha tACS in patients with DoC after traumatic brain injury. The primary hypothesis is that repeated sessions of alpha tACS will improve the level of consciousness, compared to baseline and non-stimulation periods, by reinforcing power and functional connectivity in the alpha band. This trial adopts a Single-Case Experimental Design (SCED), a robust methodology particularly suited to rare and heterogeneous clinical populations such as DoC. Five adult patients (aged 18-70 years) with DoC persisting for 3-12 months post-trauma will be included. Each participant will undergo six consecutive phases over three months: three non-stimulation (baseline/washout) periods and three stimulation periods, each period lasting two weeks, in an A-B-A-B-A-B sequence. This intra-subject design allows each patient to serve as their own control, maximizing sensitivity to individual changes and limiting confounding by clinical heterogeneity. The primary outcome measure is the change in the Simplified Evaluation of Consciousness Disorders (SECONDS) score, a validated clinical scale routinely used in DoC assessment. SECONDS will be measured three times weekly throughout the study. Secondary outcomes include: (1) EEG-based classification of consciousness state using an established machine-learning algorithm, (2) spectral power and functional connectivity changes in the alpha band, and (3) resting-state fMRI measures of DMN connectivity. These multimodal assessments aim both to provide objective evidence of clinical improvement and to explore the underlying neurophysiological mechanisms of tACS. Safety and tolerability are monitored. Previous studies confirm that tACS is safe and well-tolerated, with only minor, transient side effects (tingling, scalp redness, phosphene perception). The study also involves EEG and MRI recordings, both of which are non-invasive and carry only minimal risks. This study, although limited to five patients, is designed to provide rigorous individual-level evidence of efficacy and mechanistic plausibility. If results demonstrate consistent clinical and neurophysiological improvements, they will justify the design of a larger confirmatory trial and contribute to the development of novel therapeutic approaches for this severely disabled population.

Conditions

Disorder of Consciousness

Keywords

disorders of consciousness; tACS; tES; transcranial electric stimulation; traumatic brain injury

Outcome Measures

Primary Outcomes (1)

• Change in SECONDS score (Simplified Evaluation of CONsciousness Disorders) during tACS vs. non-stimulation phases

  The primary endpoint is the evolution of the SECONDS score, a standardized and validated clinical scale (range 1-8) routinely used in disorders of consciousness. Each participant is analyzed individually (single-case time series). Scores during three active stimulation phases will be compared with scores during three non-stimulation phases.

  Assessed 3 times per week throughout the 12-week protocol (across six phases: three stimulation and three non-stimulation periods).

Secondary Outcomes (3)

• EEG-based classification of consciousness state (SVM algorithm)

  Baseline and end of each stimulation and non-stimulation phase (8 EEG recordings per participant over 12 weeks, plus 1-month follow-up).

• Change in alpha spectral power and antero-posterior functional connectivity (EEG)

  Baseline and end of each stimulation and non-stimulation phase (8 EEG recordings per participant over 12 weeks, plus 1-month follow-up).

• Resting-state fMRI connectivity within the Default Mode Network (DMN)

  At study start, after 2 weeks without stimulation, and after 2 weeks of stimulation (3 MRI scans per participant).

Study Arms (1)

Alpha tACS

EXPERIMENTAL

Participants receive Alpha tACS daily, in repeated sessions delivered during three 2-week stimulation periods, alternating with three 2-week no-stimulation (baseline) periods, for a total duration of approximately three months.

Device: Transcranial alternating current stimulation (tACS)

Interventions

Transcranial alternating current stimulation (tACS) DEVICE

Alpha tACS daily, in repeated sessions delivered during three 2-week stimulation periods, alternating with three 2-week no-stimulation (baseline) periods, for a total duration of approximately three months

Alpha tACS

Eligibility Criteria

• Age: 18 Years - 70 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age 18 to 70 years
• No evidence of exit from minimally conscious state (eMCS) according to Coma Recovery Scale-Revised (CRS-R)

You may not qualify if:

• Active epilepsy or major pre-existing central nervous system disorders
• Craniectomy without bone flap replacement, non-healed scalp lesions, intracerebral metallic implants (except titanium), or implanted electronic devices (e.g., pacemaker)
• Contraindications to MRI (non-compatible devices, metallic fragments, recent tattoos, etc.)
• Pregnant or breastfeeding women
• Persons deprived of liberty, under psychiatric care, or not affiliated with a social security/health insurance system

Sponsors & Collaborators

• Hospices Civils de Lyon: lead

Study Sites (1)

Post-Intensive Care Neurorehabilitation Unit (Service de Reeducation Post-Reanimation) in Pierre Wertheimer Neurologic Hospital

Bron, 69029, France

Location

MeSH Terms

Conditions

Consciousness Disorders; Brain Injuries, Traumatic

Interventions

Transcranial Direct Current Stimulation

Condition Hierarchy (Ancestors)

Neurobehavioral Manifestations; Neurologic Manifestations; Nervous System Diseases; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Neurocognitive Disorders; Mental Disorders; Brain Injuries; Brain Diseases; Central Nervous System Diseases; Craniocerebral Trauma; Trauma, Nervous System; Wounds and Injuries

Intervention Hierarchy (Ancestors)

Electric Stimulation Therapy; Therapeutics; Convulsive Therapy; Psychiatric Somatic Therapies; Behavioral Disciplines and Activities; Electroshock; Psychological Techniques

Study Officials

• Caroline HERAULT, Dr

  Hospices Civils de Lyon

  STUDY CHAIR

Central Study Contacts

Caroline HERAULT, DR

CONTACT

04 72 35 78 95; caroline.herault01@chu-lyon.fr

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Single-Case Experimental Design (SCED, A-B-A-B-A-B): Each participant serves as their own control and undergoes six consecutive phases over approximately three months, alternating between baseline (no stimulation) and active stimulation periods (two weeks each). This intra-subject design maximizes sensitivity to individual changes while limiting confounding from clinical heterogeneity.

Study Record Dates

• First Submitted: October 2, 2025
• First Posted: October 9, 2025
• Study Start: January 1, 2026
• Primary Completion (Estimated): June 1, 2028
• Study Completion (Estimated): June 1, 2028
• Last Updated: October 9, 2025

Record last verified: 2025-10

Data Sharing

• IPD Sharing: Will not share

Locations

FR (1)