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The goal of this clinical trial is to determine whether modulating default mode network (DMN) alpha connectivity using transcranial alternating current stimulation (tACS) can reduce rumination and, in turn, mitigate feelings of entrapment and suicidal ideation in individuals with active suicidal ideation and depression.
The main questions it aims to answer are:
Researchers will compare active tACS stimulation to sham stimulation to assess whether modulating alpha connectivity has a specific effect on rumination, entrapment, suicidal ideation, and DMN alpha connectivity.
Participants will:
This clinical trial will be preceded by a pilot study in healthy participants with an anticipated completion of data collection in August 2025.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Sham tACS | Sham Comparator | Participants assigned to this arm will receive active stimulation during one of the stimulation visits and sham stimulation for the remaining one. Sham will involve 10s ramp-up with the same stimulation protocol as the active one, followed by an immediate 10s ramp-down (no stimulation afterwards). |
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| Active tACS | Experimental | Participants will receive active tACS during all stimulation visits. The stimulation frequency will be adjusted to the individual alpha peak frequency with in-phase stimulation in parieto-occipital brain areas and anti-phase stimulation in frontal brain areas. |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Sham alpha-tACS | Procedure | A sinusoidal ± 2mA current adjusted to the individual alpha peak frequency with in-phase stimulation at parieto-occipital brain areas and anti-phase stimulation in frontal brain areas. The stimulation will involve a 10s ramp-up, followed by an immediate 10s ramp-down (no stimulation afterwards). |
| Measure | Description | Time Frame |
|---|---|---|
| EEG alpha functional connectivity (phase synchronization) | The primary outcome measure will be changes in EEG alpha functional connectivity between pre- and post-stimulation at visit 2 (stimulation visit 1) in the active versus sham group (between-person comparison). EEG alpha functional connectivity will also be assessed at visit 4 (stimulation visit 2). Allowing for between- and within-person comparisons as secondary outcomes. | Pre-stimulation to post-stimulation at visit 2 (up to 1 hour) |
| Response style questionnaire (RSQ-10D) | The primary outcome will be changes in rumination between visit 2 (pre-stimulation) and visit 3 (24 hours post-stimulation) in the active versus sham group (between-person comparison). Rumination will also be assessed at visit 4 and visit 5, allowing for between- and within-person comparisons as secondary outcome measures. The RSQ-10D measures two facets of rumination: brooding and reflection with 5 items each. Scores per facet range from 5 to 20 with higher scores indicating higher rumination. | Visit 2 to visit 3 (24 hours) |
| Measure | Description | Time Frame |
|---|---|---|
| Beck Scale for Suicide Ideation (BSS) | Changes in suicidal ideation between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The BSS is a 19-item scale measuring suicidal ideation, with two additional items assessing a history of suicide attempts. Scores range from 0 to 38 with higher scores indicating higher severity of suicidal ideation. |
| Measure | Description | Time Frame |
|---|---|---|
| EEG alpha power | Changes in EEG alpha power between pre- and post-stimulation at visit 2 (stimulation visit 1) and visit 4 (stimulation visit 2), between- and within-person comparisons. | Visits 2 & 4 (up to 1 hour) |
| EEG: Individual alpha peak frequency |
Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Anna Monn, M.Sc. | Contact | 0041 58 384 34 82 | anna.monn@uzh.ch |
| Name | Affiliation | Role |
|---|---|---|
| Sebastian Olbrich, Prof. Dr. med. | Department of Adult Psychiatry and Psychotherapy, University Hospital of Psychiatry Zurich, University of Zurich, Zurich, Switzerland | Principal Investigator |
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| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 37562347 | Background | Bankwitz A, Ruesch A, Adank A, Hormann C, Villar de Araujo T, Schoretsanitis G, Kleim B, Olbrich S. EEG source functional connectivity in patients after a recent suicide attempt. Clin Neurophysiol. 2023 Oct;154:60-69. doi: 10.1016/j.clinph.2023.06.025. Epub 2023 Jul 22. |
| Label | URL |
|---|---|
| OSF Preregistration | View source |
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Due to ethical considerations and to protect the privacy of study participants, access to data will only be granted following justified requests for research purposes. Deidentified participant data and a data dictionary will then be made available to the requesting person or institution.
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| ID | Term |
|---|---|
| D059020 | Suicidal Ideation |
| D000079562 | Rumination Syndrome |
| D003863 | Depression |
| D001519 | Behavior |
| ID | Term |
|---|---|
| D013405 | Suicide |
| D016728 | Self-Injurious Behavior |
| D001526 | Behavioral Symptoms |
| D005767 | Gastrointestinal Diseases |
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Investigators assessing primary electroencephalography (EEG) outcomes will also be blinded to the assigned study arm.
|
| alpha-tACS | Procedure | Active tACS with a sinusoidal ± 2mA current adjusted to the individual alpha peak frequency with a 10s ramp-up and 10s ramp-down after stimulation. In-phase stimulation will be applied to parieto-occipital brain areas and anti-phase stimulation will be applied to frontal brain areas |
|
| Visits 2-5 (24 hours) |
| Clinical Global Impression of Imminent Suicide Risk (CGI-SR-I) | Changes in risk for suicide between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The CGI-SR-I is a single-item clinician rating scale where 1 indicates "no imminent suicide risk" and 7 indicates "extreme imminent suicide risk" | Visits 2-5 (24 hours) |
| Clinical Global Impression of Imminent Suicide Risk (CGI-SR-I) | Changes in risk for suicide between pre-stimulation at visit 2 and visit 4 and post-stimulation at visit 2 and visit 4, between- and within-person comparisons. The CGI-SR-I is a single-item clinician rating scale where 1 indicates "no imminent suicide risk" and 7 indicates "extreme imminent suicide risk" | Visits 2 & 4 (up to 1 hour) |
| Clinical Global Impression of Suicidality (CGI-SS-R) | Changes in risk for suicide between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The CGI-SS-R is a single-item clinician rating scale where 1 indicates "normal, not at all suicidal" and 7 indicates "among the most extremely suicidal patients" | Visits 2-5 (24 hours) |
| Clinical Global Impression of Suicidality (CGI-SS-R) | Changes in risk for suicide between pre-stimulation at visit 2 and visit 4 and post-stimulation at visit 2 and visit 4, between- and within-person comparisons. The CGI-SS-R is a single-item clinician rating scale where 1 indicates "normal, not at all suicidal" and 7 indicates "among the most extremely suicidal patients" | Visits 2 & 4 (up to 1 hour) |
| Suicidal Intent Visual Analogue Scale (S-VAS) | Changes in suicidal intent between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The S-VAS is a single-item visual analogue scale. Scores range from 0 to 100 with 0 indicating "no urge to kill myself" and 100 indicating "extreme urge to kill myself" | Visits 2-5 (24 hours) |
| Suicidal Intent Visual Analogue Scale (S-VAS) | Changes in suicidal intent between pre-stimulation at visit 2 and visit 4 and post-stimulation at visit 2 and visit 4, between- and within-person comparisons. Scores range from 0 to 100 with 0 indicating "no urge to kill myself" and 100 indicating "extreme urge to kill myself". | Visits 2 & 4 (up to 1 hour) |
| Short Defeat and Entrapment Scale (SDES) | Changes in defeat and entrapment between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The SDES is an 8-item scale measuring defeat and entrapment with 4 items each. Scores range from 0 to 16 per facet (i.e., defeat/entrapment) with higher scores indicating higher defeat and entrapment, respectively. | Visits 2-5 (24 hours) |
| Beck Depression Inventory (BDI-II) | Changes in depressive symptoms between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The BDI is a 21-item scale measuring depressive symptoms. Sum scores range from 0 to 63 with higher scores indicating higher severity of depressive symptoms. | Visits 2-5 (24 hours) |
| Montgomery-Asberg Depression Rating Scale (MADRS) | Changes in depressive symptoms between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The MADRS is a10-item clinician rating scale measuring depressive symptoms. Scores range from 0 to 60 with higher scores indicating higher severity of depressive symptoms. | Visits 2-5 (24 hours) |
Changes in individual alpha peak frequency between pre- and post-stimulation at visit 2 (stimulation visit 1) and visit 4 (stimulation visit 2), between- and within-person comparisons.
| Visits 2 & 4 (up to 1 hour) |
| Beck Hopelessness Scale (BHS) | Changes in hopelessness between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The BHS is a 20-item scale measuring hopelessness. Scores range from 0 to 20 with higher scores indicating increased hopelessness | Visits 2-5 (24 hours) |
| Perceived Burdensomeness Visual Analogue Scale (PB-VAS) | Changes in perceived burdensomeness between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The PB-VAS is a single-item visual analogue scale with the statement "I feel like a burden" where 0 indicates "not at all" and 100 indicates "extremely". | Visits 2-5 (24 hours) |
| Perceived Burdensomeness Visual Analogue Scale (PB-VAS) | Changes in perceived burdensomeness between pre-stimulation at visit 2 and visit 4 and post-stimulation at visit 2 and visit 4, between- and within-person comparisons. The PB-VAS is a single-item visual analogue scale with the statement "I feel like a burden" where 0 indicates "not at all" and 100 indicates "extremely". | Visits 2 & 4 (up to 1 hour) |
| Positive and Negative Affective Schedule (PANAS) | Changes in positive and negative affect between pre-stimulation (visit 2 and visit 4) and post-stimulation (visit 3 and visit 5), between- and within-person comparisons. The PANAS is a 20-item scale measuring positive and negative affect with 10 items each. Scores range from 10 to 50 per domain (i.e. positive & negative affect) where higher scores indicate higher positive or negative affect, respectively. | Visits 2-5 (24 hours) |
| D004066 |
| Digestive System Diseases |
| D001068 | Feeding and Eating Disorders |
| D001523 | Mental Disorders |