An interventional study of Web-based Think/No-Think retrieval-suppression training in Posttraumatic Stress Disorder (PTSD), sponsored by Palo Alto Veterans Institute for Research. Completed at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-23.
Sponsored by Palo Alto Veterans Institute for Research · Not applicable, Interventional, and Other
Intrusive memories of trauma are a core and often persistent symptom of posttraumatic stress disorder (PTSD). This study tested whether veterans with PTSD could take part in a computer-based training program that teaches people to stop unwanted memories from coming to mind (the Think/No-Think procedure). Veterans listed personally significant negative and positive events, learned a cue word for each, and then practiced suppressing the negative events and vividly recalling the positive ones over three consecutive days, in person or remotely. The study measured whether veterans could be recruited and retained, whether they completed the training, how acceptable they found it, and whether it was safe. It also explored changes in anxiety, worry, mood, wellbeing, and depressive symptoms, and in how vivid and distressing the trained memories were.
This single-site feasibility study adapted a web-based Think/No-Think retrieval-suppression training program, previously tested in the general population, for veterans with PTSD. At an introductory session, participants gave consent, completed baseline questionnaires, and received instructions for generating 40 personally significant events (20 negative, 20 positive), each with a cue (Hint) word and a key-detail (Response) word. After stimulus preparation (1 to 3 days), participants completed three consecutive training days. On Day 1 they rated each event and learned the 40 cue-detail pairs. On each training day they completed four runs of the Training Task: on No-Think trials (negative events) they recognized the event but stopped it from coming to mind without substituting other thoughts; on Think trials (positive events) they recalled the event and imagined it vividly. Untrained events of each valence served as baseline items. On Day 3 participants completed a cued-recall test, re-rated event vividness and affect, and completed post-training questionnaires.
The protocol was revised during the study through IRB-approved amendments. Initially, participants were randomly assigned to one of four instruction conditions that differed only in the suppression strategy offered (flexible strategy, visual focus, breath focus, or heart-centered visualization), and sessions were held in person. From December 2025, all sessions could be held remotely and all participants received the flexible-strategy instruction, with the structured strategies suggested as optional aids. From February 2026, positive and negative events could be drawn from the past, present, or future rather than only past negative and future positive events.
2,284 studies on the registry are indexed under Stress Disorders, Post-Traumatic; 557 are open to participants now.
This study's enrollment of 11 is below the median of 70 across 1,897 interventional studies indexed under Stress Disorders, Post-Traumatic.
Browse Stress Disorders, Post-Traumatic studies →Palo Alto Veterans Institute for Research is the lead sponsor of 52 studies on the registry; 9 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Participants generate 40 personally significant events, learn cue-detail word pairs, and complete three consecutive days of web-based Think/No-Think training (No-Think trials for negative events, Think trials for positive events).
Behavioral: Web-based Think/No-Think retrieval-suppression training
Each training day comprises four runs in which 16 trained events (8 Think, 8 No-Think) are each presented three times (192 trials per day); each cue is shown for 5 seconds. On No-Think trials, participants keep their attention on the cue while preventing the associated memory from coming to mind, without substituting other thoughts.
Recruitment
Number of eligible veterans enrolled (consented) during the recruitment period, against the target of 20 completers.
Time frame: Recruitment period (November 2025 to July 2026)
Retention
Percentage of consented participants who complete all study sessions.
Time frame: From consent through Training Day 3 (about 5 days)
Protocol adherence
Percentage of participants who begin training and complete all three training days.
Time frame: Training Days 1 to 3
Number of participants rating the suppression strategy as useful outside the laboratory
Single post-training yes/no item: "Do you think that the suppression strategy you learned through the course of this training is useful or helpful to use outside the lab in your own life?" Reported as the number and percentage of participants answering Yes; a higher percentage indicates greater acceptability.
Time frame: End of Training Day 3
Number of completers whose training was delivered on the protocol-specified schedule
Delivery was recorded as per protocol when stimulus preparation was followed by three training days on consecutive days, as specified in the protocol. Reported as the number and percentage of completers; a higher percentage indicates greater fidelity of delivery.
Time frame: From stimulus preparation through Training Day 3 (about 5 days)
Adverse events
Number of participants with serious adverse events.
Time frame: From consent through Training Day 3
Number of participants likely to re-use the suppression strategy, assessed by a 5-point rating item
Single post-training item: "How likely are you to re-use the suppression strategy you learned to decrease your anxiety or thoughts about the negative events in your life?" Rated from 1 (Very unlikely) to 5 (Very likely); minimum 1, maximum 5; higher scores indicate greater likelihood of re-use (a better outcome). Reported as the number and percentage of participants rating Likely (4) or Very likely (5).
Time frame: End of Training Day 3
Self-rated effectiveness at stopping thoughts about upsetting events, assessed by a 5-point rating item
Participants rated how effectively they could stop thoughts about their upsetting events at the beginning of training (Training Day 1, rated retrospectively) and at the end of training (Training Day 3). Each rating ranges from 1 (Not at all effective) to 5 (Extremely effective); higher scores indicate better self-rated effectiveness (a better outcome).
Time frame: End of Training Day 3
Number of completers confirming the suppression-strategy instruction they were assigned, assessed by a post-training yes/no item
After training, participants were shown the strategy instruction for their assigned condition and asked to confirm (Yes/No) that it was the strategy they had practiced. Reported as the number and percentage answering Yes; a higher percentage indicates more accurate delivery of the assigned instruction.
Time frame: Training Day 3
Warwick-Edinburgh Mental Well-being Scale (WEMWBS)
Change in total score (range 14 to 70; higher scores indicate better well-being).
Time frame: Baseline (introductory session) and end of Training Day 3 (about 5 days)
Positive and Negative Affect Schedule (PANAS)
Change in positive affect and negative affect subscale scores (10 items each, rated 1 to 5; each subscale range 10 to 50). Higher positive-affect scores indicate a better outcome; higher negative-affect scores indicate a worse outcome.
Time frame: Baseline (introductory session) and end of Training Day 3 (about 5 days)
State-Trait Anxiety Inventory, state form (STAI-S)
Change in total score (range 20 to 80; higher scores indicate more anxiety).
Time frame: Baseline (introductory session) and end of Training Day 3 (about 5 days)
Penn State Worry Questionnaire-Past Day (PSWQ-PD)
Change in total score (range 0 to 60; higher scores indicate more worry).
Time frame: Baseline (introductory session) and end of Training Day 3 (about 5 days)
Beck Depression Inventory-II (BDI-II)
Change in total score (20-item version without the suicidal-thoughts item; range 0 to 60; higher scores indicate more depressive symptoms).
Time frame: Baseline (introductory session) and end of Training Day 3 (about 5 days)
Event vividness ratings
Change in vividness ratings (1 to 5) of trained versus untrained events, from Training Day 1 to Training Day 3.
Time frame: Training Day 1 and Training Day 3
Event affect ratings
Change in distress (negative events) or joy (positive events) ratings (1 to 5), from Training Day 1 to Training Day 3.
Time frame: Training Day 1 and Training Day 3
Cued recall
Percentage of Response Words recalled for trained versus untrained events on Training Day 3.
Time frame: Training Day 3
PTSD Checklist for DSM-5 (PCL-5) total score
20 items rated 0 (Not at all) to 4 (Extremely) for how much each problem bothered the participant, in relation to their worst event, during the past week (adapted from the standard past-month time frame). Total score range 0 to 80; higher scores indicate more severe PTSD symptoms (a worse outcome).
Time frame: Training Day 3
Cambridge Selective Forgetting Inventory (CSFI)
32 items rated 0 to 3; total score range 0 to 96. Higher scores indicate a greater self-reported tendency to forget or disengage from unpleasant memories.
Time frame: Baseline (introductory session)
Plan to share: Undecided — De-identified data may be made available by the investigators on reasonable request, subject to VA data-sharing policy.
Ran from Nov 2025 to primary completion in Jul 2026, 8 months.
Of 911 non-industry interventional studies with no phase under Stress Disorders, Post-Traumatic, half reached primary completion within 35 months of starting (the median), counting those still running; a quarter within 17 and three quarters within 53. This study's 8 months is below that.
Counting every sponsor, half of 937 studies reached it within 35 months; a quarter within 17 and three quarters within 53.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Palo Alto Veterans Institute for Research