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: 1. Is personalized tACS stimulation of the DMN associated with reduced rumination 24 hours after stimulation? 2. Does a reduction in rumination result in lower feelings of entrapment and suicidal ideation? 3. Does personalized tACS stimulation of the DMN lead to a reduction of DMN alpha connectivity? 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: * Receive either active or sham tACS stimulation during stimulation sessions, but all participants will receive active tACS at least once. * Complete self-report measures of rumination, entrapment, and suicidal ideation before and after stimulation. * Undergo EEG recordings to assess changes in DMN alpha connectivity. This clinical trial will be preceded by a pilot study in healthy participants with an anticipated completion of data collection in August 2025.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
50
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).
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
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.
Time frame: 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.
Time frame: Visit 2 to visit 3 (24 hours)
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.
Time frame: 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"
Time frame: 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"
Time frame: 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"
Time frame: 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"
Time frame: 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"
Time frame: 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".
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: Visits 2-5 (24 hours)
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.