Can Playing Tetris Reduce Intrusive Memories and Flashbacks After Trauma?

Ask most people whether a 1980s puzzle game could help with the aftermath of a traumatic event and you'll get a raised eyebrow. But the question — can playing Tetris reduce intrusive memories and flashbacks after a traumatic event — has now been tested in a properly controlled clinical trial, published in The Lancet Psychiatry, and the answer is more interesting than "no."

The study followed 99 NHS healthcare workers in the UK who had lived through work-related trauma during the COVID-19 pandemic. These were people who described things like watching a young patient die while resuscitation failed. Many of them were still seeing those moments, uninvited, months later.

What are intrusive memories, exactly?

An intrusive memory is a mental image from a traumatic event that pops suddenly into your mind when you don't want it to. Not a thought about the event — an image. A face, a sound, a split second replaying itself in the mind's eye. People often call them flashbacks.

They're the defining symptom of post-traumatic stress disorder (PTSD), and they're also extremely common in people who don't meet the full criteria for a diagnosis. In one large US study, 95% of people with PTSD reported them. But plenty of people have a handful a week, find them distressing and exhausting, and never get anywhere near a clinic.

That matters, because the researchers behind this trial made a specific bet: intrusive memories aren't just one symptom among many. They sit near the centre of the whole cluster. Turn the volume down on the images, and the rest — the avoidance, the jumpiness, the low mood — might quieten too.

Why Tetris? What does a puzzle game have to do with memory?

The reasoning goes back roughly two decades of laboratory work on how memory functions.

When you deliberately bring a memory to mind, it becomes briefly unstable — a little malleable — before the brain stores it again. During that short window, what you do next may influence how the memory settles. And Tetris makes heavy demands on the same mental machinery you use to picture things: rotating shapes, tracking space, holding a visual pattern in mind.

The idea is that a visual, spatial task competes for the mental resources the intrusive image needs to stay vivid. The memory of the event isn't erased. What's targeted is the tendency for it to burst in unbidden as a picture.

The intervention built on this — the researchers call it an imagery-competing task intervention — is short and oddly undramatic. You briefly call one intrusive image to mind, rate how vivid it feels, then play Tetris for about 20 minutes while deliberately rotating the blocks in your head. That's it. No talking through the trauma in detail. No lengthy narrative.

What did the trial actually find?

Participants first kept a seven-day diary to count their intrusive memories. The median was ten in a week. Half of them were still being exposed to new work-related trauma while the study ran.

They were then randomly split into three groups. One got the Tetris intervention through a secure website, starting with a single one-hour guided session, then used it on their own whenever they wanted. A second group got a carefully matched comparison: same platform, same guided hour, same 20-minute task — but listening to Mozart instead of playing a game. A third group carried on with whatever care they already had.

At four weeks, the Tetris group's median count had fallen to 0.5 intrusive memories in a week. Both comparison groups sat at 5. The statistical models estimated around 70% fewer intrusive memories in the Tetris group than in either comparison group.

The part that surprised even the research team was the durability. At twelve weeks and again at twenty-four weeks, most people in the Tetris group were reporting none at all. By six months, an estimated 70% were free of intrusive memories, compared with 13% of the music group and 20% of the usual-care group. Broader PTSD symptom scores dropped too, and stayed down. Sleep, anxiety, low mood and day-to-day functioning improved at four weeks, though those effects were patchier further out. No harms linked to the intervention showed up.

The research team's own summary is that this is "the first evidence that a single guided-session digital intervention can sustainably reduce intrusive memories and other PTSD symptoms, even for individuals with ongoing trauma exposure."

The full paper is open access: https://doi.org/10.1016/s2215-0366(25)00397-9

Couldn't this just be a placebo effect?

This is the question worth pressing on, and the design anticipated it.

A weakness of many digital mental health studies is that the comparison group gets nothing much — no app, no researcher checking in, no sense of doing something. Then any improvement gets credited to the treatment when it might just be attention and hope.

Here the music group got the guided session, the same platform, the same reminders, the same 20 minutes of structured activity. And here's the detail that makes the finding harder to dismiss: participants rated the music intervention as more believable than Tetris before starting. If expectation were driving the results, the music group should have done better. It didn't.

That doesn't prove the memory-competition explanation is right. But it does make "they just felt cared for" an unlikely full account.

What are the limits of this study?

Quite a few, and they matter.

The sample was small — 99 people randomised, and the trial stopped early once the evidence crossed a pre-set threshold. Early stopping is efficient and was planned in advance, but small trials that end early can overstate how large an effect really is.

The group was also narrow. Almost all participants were healthcare workers, 86% were women, 90% were White. Whether the same thing happens with, say, survivors of assault, road collisions, combat or childhood abuse is an open question. The trauma types here were largely occupational.

About a quarter of participants didn't provide complete data at four weeks, which always introduces uncertainty. Outcomes were self-reported through diaries and questionnaires — reasonable for something as private as an intrusive image, but not the same as an independent assessment. And participants knew they were playing a game rather than listening to music, so they weren't blind to which arm they were in.

Finally, the mechanism findings — that elimination was more likely when the recalled image was less vivid and the game score higher — were exploratory. Interesting, consistent with theory, not confirmed.

One trial rarely settles anything. This one replicates and extends an earlier study from the same team, which strengthens it, but independent replication in different populations is what would make it solid.

What should someone struggling with flashbacks take from this?

Not "go download Tetris and you'll be fine." The intervention tested here wasn't casual gaming. It involved a deliberate, brief retrieval of a specific image, then a structured task, delivered through a monitored platform with a guided first session. Playing a puzzle game to distract yourself from a memory is a different thing entirely, and there's no evidence it does what this protocol did.

What's genuinely encouraging is the direction of travel. Established trauma treatments work well but typically need eight to twelve sessions with a specialist therapist, and they usually ask you to describe what happened in detail. For people on a waiting list, working shifts, or not ready to talk, that's a real barrier. An approach that needs one guided hour from a trained helper without a mental health qualification — and no detailed disclosure — could reach people who currently get nothing.

If intrusive images are part of your life right now, the most useful step is usually to tell someone. That might be a GP or a therapist. It might also be somewhere lower-stakes to start putting words to it — which is part of why Serena exists, as a place to talk things through when the other doors feel closed. She isn't a therapist and isn't a treatment, but she can listen, and sometimes being able to say it out loud once is what makes the next step possible.

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This article is for general information and isn't medical advice. It doesn't describe a treatment you can carry out on your own, and it shouldn't replace a conversation with a qualified clinician about your situation. If you're in crisis or thinking about harming yourself, please contact your local emergency number or a crisis line in your country now.