# Veterans with documented PTSD completed up to eight trauma-informed warm-water therapy sessions and average PCL-M symptom scores fell by 14.4 points in a retrospective study that could not separate the pool treatment from other influences

> In a heated pool, veterans with documented PTSD were guided through slow supported movements and breath cues with close one-to-one care. A 2025 retrospective study indexed by PubMed reported that the group who completed follow-up testing had much lower symptom scores after...

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Byline: ARGO.net Editorial Team
Published: 2026-08-08T03:15:03+00:00
Categories: Explainer, Health

![A man preparing for an indoor pool therapy or exercise session](https://www.argo.net/wp-content/uploads/2026/08/aquatic_physical_therapy_rehabilitation_pool.jpg)

In a heated pool, veterans with documented PTSD were guided through slow supported movements and breath cues with close one-to-one care. A [2025 retrospective study indexed by PubMed](https://pubmed.ncbi.nlm.nih.gov/40266503/) reported that the group who completed follow-up testing had much lower symptom scores after the program than they had before it.

The headline number was a **14.4 point drop** on the **PCL-M**, the PTSD Checklist Military Version. Among the 86 participants who completed at least four sessions and had post-testing, average scores moved from a baseline group mean of 56.2 into a post-treatment mean of 39.3. The paper also reported that 64 percent of those 86 participants improved by at least 10 points, while 36 percent improved by at least 20 points.

The result is encouraging, yet the study design leaves a large caution around cause. The trial was **single-arm**, retrospective and conducted without a randomized control or wait-list group. The authors also state that participants were allowed to continue other mental health treatments while receiving the aquatic sessions, so the score changes cannot be assigned to the warm-water program alone.

## PTSD symptoms were the central outcome

PTSD psychology sits at the center of the paper. The outcome was not pain, flexibility, or general wellness. It was change in trauma-related symptoms measured with the PCL-M, a 17-item questionnaire developed for military experiences. The official [VA PCL-M form](https://www.ptsd.va.gov/professional/assessment/documents/APCLM.pdf) shows how the scale asks about intrusive memories, avoidance, emotional numbing and hypervigilance over the past month.

The study enrolled **111 participants** during calendar year 2023. About 91 percent were veterans rather than active-duty personnel, the average age was 41.1 years, 26.1 percent were women and just over one fifth reported being homeless or in transitional living circumstances. Every participant had a prior PTSD diagnosis documented by medical or military records or by a physician letter, although the research team did not perform a fresh structured diagnostic interview.

The design only shows symptom change within a group that already had clinically recognized trauma symptoms. The study then tracked whether their self-reported symptom burden changed after treatment. It did not establish a new diagnosis and it did not compare the aquatic program with standard psychotherapy, medication, or another structured control condition.

The score thresholds also need context. The current [National Center for PTSD guidance on the checklist family](https://www.ptsd.va.gov/professional/assessment/adult-sr/ptsd-checklist.asp) explains that a 10-point change is commonly used as an indicator of response. That helps explain why the paper highlighted the share of participants who improved by 10 points or more instead of only reporting the group average.

## What happened in the pool each week

The intervention was a form of **trauma-informed aquatic therapy** related to **WATSU**, or water shiatsu. Sessions were delivered individually by licensed practitioners in a temperature-controlled pool at the Healing Wave Aquatics facility in San Diego. Each visit lasted about 50 to 60 minutes and the full program was designed for up to eight weekly sessions over roughly 8 to 10 weeks.

The paper describes a program built around safety, trust and careful attention to body signals. Practitioners manually guided participants through supported positions and gentle movements, while adjusting pace and sequence to each person's comfort, emotional state and structural needs. The stated goal was to promote relaxation and a sense of security that might ease trauma symptoms without asking participants to relive the traumatic event directly.

Because the sessions were tailored, the treatment was deliberately **non-standardized**. One participant could receive a different mix of positions, touch cues and movement pacing from another. That flexible design may fit real-world care, especially for people with trauma histories, yet it also makes it harder to know exactly which ingredients might have helped and which ingredients would need to be reproduced in a future trial.

The broader WATSU literature offers some background without settling the PTSD question. A [systematic review and meta-analysis of passive hydrotherapy](https://pmc.ncbi.nlm.nih.gov/articles/PMC7069616/) found signals of benefit across pain, physical function and mental issues, while also rating the evidence as low to moderate at best and calling for better randomized trials. The veteran PTSD paper sits squarely in that early-evidence zone.

## How large the score changes were

The average change was large enough to attract attention even after the design limits are kept in view. For the 86 participants with at least four sessions and post-testing, the paper reported a mean PCL-M change of 14.4 points with **p < 0.001**. It also reported a Hedges's g effect size of 0.99, which is generally treated as a large effect in group-level statistical terms.

The distribution of change is also useful. Averages can hide the fact that some people improve a great deal while others barely change or even worsen. In this study, 55 of the 86 post-tested participants improved by at least 10 points and 31 improved by at least 20 points. Those are meaningful shares of the completer group, although they still leave a substantial minority who did not reach those thresholds.

Attrition matters here. Twenty-five of the 111 enrolled participants discontinued treatment before completing four sessions and did not enter the main post-test analysis. The authors report no significant baseline demographic differences between early discontinuers and completers on several measured variables. Attrition can still shape results because people who stay in any treatment often differ in motivation, logistics, symptom volatility, or expectations.

The paper also reported very high satisfaction, with an average comfort rating of 4.9 out of 5 and a modal rating of 5 out of 5 across 780 sessions where satisfaction data were collected. High satisfaction is valuable for feasibility, especially in PTSD care where people may stop treatment early. Satisfaction does not show efficacy on its own, though, because a calming or supportive setting can feel beneficial even when a study has not isolated the active treatment mechanism.

## Why the study cannot prove the water treatment caused the drop

The strongest limitation is the absence of a comparison group. A veteran with PTSD can improve over two months for many reasons. Those include regression toward the mean, concurrent therapy, medication changes and supportive contact. Simple passage of time can matter too. Symptom fluctuation and hopeful expectation can also play a role.

Without randomization or a matched control, the study cannot tell how much of the observed improvement came from the warm water. It also cannot separate therapeutic touch, individualized attention and factors completely outside the pool.

The authors are unusually direct on this point. They say future studies need methods that control for **nonspecific treatment factors** such as warm water, therapeutic environment and physical touch. That is the key psychological caution in the paper. Trauma symptoms may respond to feeling safe and attended to. They may also respond to being soothed, yet those ingredients are broader than WATSU itself and a better trial would need to test whether the aquatic format adds something specific beyond them.

The study also allowed **concurrent mental health treatment**. Participants could keep receiving other PTSD or mental health care while they were in the aquatic program. That decision increases real-world relevance, because many veterans combine services in practice. It weakens internal validity at the same time, because overlapping care could explain part of the PCL-M improvement.

Another limit is measurement timing. The PCL-M is a self-report tool based on symptoms over the past month. It can show clinically important change, yet it remains different from a clinician-administered PTSD interview. The study itself notes that Healing Wave Aquatics was still using the PCL-M in 2023 and switched to the newer PCL-5 in 2024, which means the paper sits at a bridge point between older and current checklist practice.

## Provider conflict and naturalistic design both need to stay visible

The paper's conflict statement should remain in view whenever the findings are summarized. Thomas Rutledge reported no conflict, while coauthor Elizabeth Berg was identified as the executive director of Wave Academy, also known as Healing Wave Aquatics, the organization that provided the treatment and the data used in the manuscript. That disclosure does not invalidate the results, yet it raises the importance of independent replication.

The same section of the paper makes clear that the program was studied in a naturalistic way rather than under tight laboratory control. Participants were referred from the community or sought treatment themselves. The intervention was adapted person by person. That design may increase **external validity**, because it resembles actual service delivery. It lowers **internal validity**, because the trial conditions were not built to isolate one clean causal factor.

There is another subtle issue in the wording of the summary numbers. Baseline scores were reported for all 111 enrollees, while the post-treatment average of 39.3 came from those who completed at least four sessions and had follow-up data. The paper's main within-person change analysis is based on the 86 completers and that is the defensible number to emphasize when discussing treatment response. Mixing the full baseline group with the completer follow-up group can make the improvement sound more straightforward than the actual paired analysis supports.

No adverse events were observed in the reported sample and that is relevant because PTSD treatment can be hard to tolerate for some patients. Even so, safety and efficacy are different questions. A warm and carefully supervised pool experience may be low risk for many participants, while still requiring stronger evidence before it can be ranked alongside better studied PTSD interventions.

## Where this fits beside established PTSD care

The authors frame the treatment as **non-exposure-based**, meaning it aims to ease symptoms without directly revisiting traumatic memories in the way some established therapies do. That may appeal to veterans who do not respond to trauma-focused treatment or who are reluctant to begin it. The appeal should not be confused with proof of equal effectiveness.

The [2023 VA and DoD PTSD guideline](https://www.healthquality.va.gov/guidelines/mh/ptsd/) remains the more authoritative map for clinical care. It summarizes evidence-based recommendations across assessment and treatment, including structured psychotherapies and other interventions that have been tested more rigorously. The aquatic study does not challenge that hierarchy. It proposes one additional option worth testing more carefully.

From a psychological perspective, the most plausible contribution of the pool program may be that it creates conditions associated with down-regulation. Those conditions include warmth, buoyancy, predictable support and controlled breathing. A therapist also adjusts touch and movement to a participant's cues. Those conditions may reduce arousal and help some people feel safe enough to loosen persistent defensive patterns. The present study, however, did not measure the mechanism directly, so that explanation remains an informed interpretation rather than a demonstrated pathway.

That is why the next step needs to be more exacting and less promotional. A stronger trial could compare trauma-informed aquatic therapy with another warm-water intervention, with usual care, or with a wait-list group. It could also track medication use, outside therapy and longer-term follow-up. Until those studies exist, the current paper supports cautious interest for veterans seeking additional options, while leaving the core claim where it belongs: **promising preliminary evidence** rather than proof.