tDCS for Catatonic Depression in Down Syndrome: A Pilot Study

This study evaluates the efficacy of transcranial direct current stimulation (tDCS) for depression with catatonia in individuals with Down syndrome (DS). 62 patients will be randomized to receive 15 sessions of active or sham tDCS. The primary objective is to measure changes in depressive/catatonic symptoms using the Bush-Francis Catatonia Rating Scale (BFCRS). Secondary objectives include safety, cognitive effects, EEG correlates, and biological markers (cortisol, BDNF, cytokines). The study aims to provide a non-pharmacological therapeutic alternative for this population

Justification: Depression is common in individuals with Down syndrome (DS), often accompanied by catatonia, and is under-treated. Conventional treatments are limited by tolerability and linguistic difficulties. Transcranial direct current stimulation (tDCS), safe and effective, has never been tested in DS.

Hypothesis: tDCS is effective and safe for depression with catatonia in DS, improving mood, cognition, and motor symptoms.

Objectives:

Primary: To evaluate the clinical efficacy of 15 sessions of bifrontal tDCS on depression with catatonia in DS (Bush-Francis Catatonia Rating Scale (BFCRS)).

Secondary: To evaluate safety, long-term clinical and cognitive effects (1 and 3 months), EEG correlates, and biological effects (cortisol, BDNF, cytokines).

Methodology: Multicenter (2 sites), randomized, double-blind, placebo-controlled study. 30 DS patients will receive 15 sessions of active tDCS (2 mA, 20 min, anode over left DLPFC, cathode over right DLPFC) or sham tDCS.

Outcomes:

Primary: Changes in depressive/catatonic symptoms (BFCRS) between Day 0 and Day 5.

Secondary: Safety, clinical (MADRS, UPDRS), cognitive (SIB), EEG, and biological (blood, saliva) assessments.

Target Population: Men and women with DS with a depressive episode and catatonia (30 patients).

Inclusion Criteria: DS, age \> 18 years, major depression with catatonia (DSM-5), informed consent.

Exclusion Criteria: Pregnancy, contraindication to tDCS, refusal. Statistical Analyses: ANOVA or mixed models for BFCRS scores. Justification for Inclusion: To provide a safe, non-pharmacological therapeutic alternative.

Withdrawal Criteria: Withdrawal of consent, severe pathology. Procedures: Clinical, cognitive, EEG, and biological (blood, saliva) assessments at Day 0, Day 1, Day 5, 1 and 3 months.

Recruitment: 6 sites (CH Vinatier Lyon, CHU Nantes, CHU Dijon, CHU Clermont Ferrand, CH Rouen, GHU Neurosciences Paris). EEG and biological analyses at Lyon and Paris only.

Number of Subjects: 62 patients (31 per group). Duration: Inclusion (24 months), individual participation (3 months), total study (27 months).

Locations: CH Le Vinatier (Lyon), CHU Nantes, CHU Dijon, CHU Clermont Ferrand, CH Rouen, GHU Neurosciences Paris.

Benefit-Risk Ratio: Pioneering study on tDCS in DS, aiming for a safe alternative to current treatments and a better understanding of neurobiological mechanisms.

Eligibility Criteria:
Inclusion Criteria:

* Patient with Down syndrome
* Age \> 18
* Diagnosis of Major Depressive Disorder MDD with catatonic symptoms according to the DSM-5 criteria
* Informed consent signed by the patient, by the patient under curatorship, or by the legal representative in the case of a patient under guardianship.
* Person affiliated to the French social security system or equivalent

Exclusion Criteria:

* Pregnancy (checked with a pregnancy test)
* Contraindication for tDCS(i.e., cochlear implant)
* Refusal of the patients or their legal representatives
* Other persons protected under the CSP (judicial safeguard, family habilitation)