Home-based tDCS for Prevention of Suicidal Ideation

Number of completed remotely supervised transcranial direct current stimulation (RS-tDCS) sessions, for both active and sham groups: We expect at least 70% of the subjects to complete at least 5 of recommended 10 RS-tDCS sessions.

The C-SSRS (Columbia-Suicide Severity Rating Scale) is a suicidal ideation and behavior rating scale. For the 5 items assessing suicidal ideation intensity, each item is scored 0-5. The total intensity score is the sum of these 5 items (range 0-25), with higher scores indicating greater suicidal ideation. The mean is calculated by the sum of the scores of the participants at Day 14 divided by the number of participants

The C-SSRS (Columbia-Suicide Severity Rating Scale) is a suicidal ideation and behavior rating scale. For the 5 items assessing suicidal ideation intensity, each item is scored 0-5. The total intensity score is the sum of these 5 items (range 0-25), with higher scores indicating greater suicidal ideation. The mean is calculated by the sum of the scores of the participants at Day 30 divided by the number of participants

Outcome measure description: The C-SSRS (Columbia-Suicide Severity Rating Scale) is a suicidal ideation and behavior rating scale. For the 5 items assessing suicidal ideation intensity, each item is scored 0-5. The total intensity score is the sum of these 5 items (range 0-25), with higher scores indicating greater suicidal ideation. The mean is calculated by the sum of the scores of the participants at Day 60 divided by the number of participants

Acceptability of the intervention is assessed based on participants' readiness, self-confidence, and satisfaction with treatment. Specifically, acceptability is determined if at least 60% of participants respond "Strongly agree" or "Agree" to item 11 of the acceptability questionnaire: "Overall, I felt that transcranial electrical stimulation treatment benefited me." The questionnaire uses a 5-point Likert scale: "Strongly agree," "Agree," "Neither agree nor disagree," "Disagree," "Strongly disagree." Higher scores indicate greater perceived acceptability.

Proportion of participants who report no suicidal ideation, defined as answering "No" to both question 1 ("Have you wished you were dead or wished you could go to sleep and not wake up?") and question 2 ("Have you actually had any thoughts of killing yourself?") on the C-SSRS. Higher proportions indicate fewer participants experiencing suicidal ideation.

Proportion of participants who report no suicidal ideation, defined as answering "No" to both question 1 ("Have you wished you were dead or wished you could go to sleep and not wake up?") and question 2 ("Have you actually had any thoughts of killing yourself?") on the C-SSRS. Higher proportions indicate fewer participants experiencing suicidal ideation

Proportion of participants who report no suicidal ideation, defined as answering "No" to both question 1 ("Have you wished you were dead or wished you could go to sleep and not wake up?") and question 2 ("Have you actually had any thoughts of killing yourself?") on the C-SSRS. Higher proportions indicate fewer participants experiencing suicidal ideation.

The Ruminative Responses Scale (RRS) is a 22-item self-report measure assessing rumination. Each item is rated on a 4-point Likert scale: 1 = almost never, 2 = sometimes, 3 = often, 4 = almost always. The total score is calculated by summing the scores of all 22 items (range 22-88), with higher scores indicating greater rumination. The mean is calculated by the sum of the scores of the participants at Day 14 divided by the number of participants

The Ruminative Responses Scale (RRS) is a 22-item self-report measure assessing rumination. Each item is rated on a 4-point Likert scale: 1 = almost never, 2 = sometimes, 3 = often, 4 = almost always. The total score is calculated by summing the scores of all 22 items (range 22-88), with higher scores indicating greater rumination. The mean is calculated by the sum of the scores of the participants at Day 30 divided by the number of participants

The Ruminative Responses Scale (RRS) is a 22-item self-report measure assessing rumination. Each item is rated on a 4-point Likert scale: 1 = almost never, 2 = sometimes, 3 = often, 4 = almost always. The total score is calculated by summing the scores of all 22 items (range 22-88), with higher scores indicating greater rumination. The mean is calculated by the sum of the scores of the participants at Day 60 divided by the number of participants

The Concise Associated Symptoms Tracking (CAST) scale is a 16-item self-report measure assessing symptoms associated with suicidal ideation across five domains: anxiety (3 items, subscore range 3-15), irritability (5 items, subscore range 5-25), mania (4 items, subscore range 4-20), insomnia (2 items, subscore range 2-10), and panic (2 items, subscore range 2-10). Total CAST scores range from 16 to 80. Each item is rated on a 5-point Likert scale: 1 = strongly disagree, 2 = disagree, 3 = neither agree nor disagree, 4 = agree, 5 = strongly agree. Higher scores indicate greater symptom severity. The mean is calculated by the sum of the scores of the participants at Day 14 divided by the number of participants

The Concise Associated Symptoms Tracking (CAST) scale is a 16-item self-report measure assessing symptoms associated with suicidal ideation across five domains: anxiety (3 items, subscore range 3-15), irritability (5 items, subscore range 5-25), mania (4 items, subscore range 4-20), insomnia (2 items, subscore range 2-10), and panic (2 items, subscore range 2-10). Total CAST scores range from 16 to 80. Each item is rated on a 5-point Likert scale: 1 = strongly disagree, 2 = disagree, 3 = neither agree nor disagree, 4 = agree, 5 = strongly agree. Higher scores indicate greater symptom severity. The mean is calculated by the sum of the scores of the participants at Day 30 divided by the number of participants

The Concise Associated Symptoms Tracking (CAST) scale is a 16-item self-report measure assessing symptoms associated with suicidal ideation across five domains: anxiety (3 items, subscore range 3-15), irritability (5 items, subscore range 5-25), mania (4 items, subscore range 4-20), insomnia (2 items, subscore range 2-10), and panic (2 items, subscore range 2-10). Total CAST scores range from 16 to 80. Each item is rated on a 5-point Likert scale: 1 = strongly disagree, 2 = disagree, 3 = neither agree nor disagree, 4 = agree, 5 = strongly agree. Higher scores indicate greater symptom severity. The mean is calculated by the sum of the scores of the participants at Day 60 divided by the number of participants

MADRS is a 10-item clinician-administered questionnaire assessing the following symptoms: 1) Apparent sadness, 2) Reported sadness, 3) Inner tension, 4) Reduced sleep, 5) Reduced appetite, 6) Concentration difficulties, 7) Lassitude, 8) Inability to feel, 9) Pessimistic thoughts, 10) Suicidal thoughts. Each item is scored 0-6, giving a total score range of 0-60. Higher scores indicate more severe depressive symptoms. The mean is calculated by the sum of the scores of the participants at Day 14 divided by the number of participants

MADRS is a 10-item clinician-administered questionnaire assessing the following symptoms: 1) Apparent sadness, 2) Reported sadness, 3) Inner tension, 4) Reduced sleep, 5) Reduced appetite, 6) Concentration difficulties, 7) Lassitude, 8) Inability to feel, 9) Pessimistic thoughts, 10) Suicidal thoughts. Each item is scored 0-6, giving a total score range of 0-60. Higher scores indicate more severe depressive symptoms. The mean is calculated by the sum of the scores of the participants at Day 30 divided by the number of participants

MADRS is a 10-item clinician-administered questionnaire assessing the following symptoms: 1) Apparent sadness, 2) Reported sadness, 3) Inner tension, 4) Reduced sleep, 5) Reduced appetite, 6) Concentration difficulties, 7) Lassitude, 8) Inability to feel, 9) Pessimistic thoughts, 10) Suicidal thoughts. Each item is scored 0-6, giving a total score range of 0-60. Higher scores indicate more severe depressive symptoms. The mean is calculated by the sum of the scores of the participants at Day 60 divided by the number of participants

After each RS tDCS session (up to 10 sessions per participant), seven prespecified side effects itching, burning, headache, fatigue, nervousness, dizziness, and difficulty concentrating were assessed using the RS tDCS Side Effect Rating Scale. Each symptom was rated on a numeric scale from 0 to 10, where 0 indicates not at all and 10 indicates the highest degree of severity.

For each participant and each symptom, ratings were summed across all completed sessions to generate a cumulative symptom specific side effect score, with a theoretical range of 0 to 100. Higher scores indicate greater cumulative side effect burden. Participants contributed all available session ratings with no imputation. For reporting, participant level cumulative scores were averaged across participants for each symptom and summarized as mean and standard deviation.

Predefined, expected side effects associated with RS tDCS were prospectively and systematically collected using a standardized post session side effect questionnaire administered after each RS tDCS session. Solicited side effects included itching, burning, headache, fatigue, nervousness, dizziness, difficulty concentrating, and other expected sensations related to stimulation.

This outcome summarizes the number of participants who reported one or more solicited side effects at any time during the treatment period. These solicited side effect assessments were collected as part of structured safety monitoring and are reported as outcome measures rather than as adverse events. Unsolicited adverse events meeting ClinicalTrials.gov reporting criteria are reported separately in the Adverse Events module.