Not all PTSD therapies keep veterans in treatment, study warns

Group-based exposure therapy, intensive outpatient programs show lower dropout rates

American Psychological Association

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About a quarter of U.S. service members and veterans who start psychotherapy for post-traumatic stress disorder quit before they finish treatment. But not all therapies are equal in their appeal, with some effective approaches reporting the highest dropout rates, according to research published by the American Psychological Association.

PTSD affects about 7% of veterans at some point in their lives, slightly higher than the rate seen in the general U.S. adult population, according to the U.S. Department of Veterans Affairs. Beyond PTSD’s emotional impact, the American Heart Association notes that it can also raise the risk of heart disease and stroke, two conditions that disproportionately affect veterans.

“Behind every statistic is a person who may be struggling to stay the course in treatment,” said lead author Elizabeth A. Penix-Smith, PhD, of Idaho State University and a National Research Council fellow at the Walter Reed Army Institute of Research. “By learning more about the patterns of who drops out and why, we can shape PTSD care so that it meets veterans where they are at.”

In a meta-analysis of 181 studies covering 232 PTSD treatments and more than 124,000 military participants, researchers found an average of 25.6% of veterans and service members dropped out before finishing the recommended course of treatment for all PTSD therapies. However, rates differed significantly among the therapies.

Weekly trauma-focused approaches such as cognitive processing therapy and prolonged exposure had the highest dropout rates: 40.1% and 34.7%, respectively. Virtual reality exposure therapy also showed high dropout (37.2%). In contrast, present-centered therapy and mindfulness-based stress reduction showed lower dropout rates of 16.1% and 20%. Dropout rates from intensive outpatient versions of trauma-focused treatments ranged from 5.5% to 8.5%.

Researchers also discovered that group-based exposure therapy, which encourages teamwork and connection before diving into trauma work, kept participants engaged better than most therapies, with only 6.9% dropping out.

Dropout was especially high (46.4%) in programs treating PTSD alongside substance use disorders, compared with lower rates (23.2%) for programs targeting both PTSD and depression.

“This study provides better benchmarks for how often people disengage from different PTSD treatments,” Penix-Smith said. “It highlights which therapies may be easier for some service members and veterans to stick with.”

The findings, published in the journal Psychological Trauma: Theory, Research, Practice, and Policy, reveal that while some trauma-focused therapies remain highly effective, they may also see more clients leaving treatment early.

“Dropout rates remain a significant challenge in PTSD care for military populations,” said Penix-Smith. “Identifying which protocols are more sustainable can help clinicians tailor care and policymakers prioritize treatments that keep patients engaged.”

Penix-Smith suggests that when therapists use treatments with higher dropout rates, they should try proven ways to keep clients engaged—such as building trust, tracking progress and respecting what each client prefers.

“Our study findings underscore the importance of investing in interventions for preventing dropout or identifying methods for matching clients to their optimal treatment to reduce dropout,” Penix-Smith said. “By focusing on approaches that are a good fit and by providing the right support along the way, we can make real progress in helping them recover from trauma.”

Article: “The Protocol Matters: A Meta-analysis of Psychotherapy Dropout from Specific PTSD Treatment Approaches in U.S. Service Members and Veterans,” by Elizabeth A. Penix-Smith, PhD, Idaho State University, and Joshua K. Swift, PhD, Idaho State University. Psychological Trauma: Theory, Research, Practice, and Policy, published online Nov. 17, 2025.

Note: The views expressed are those of the authors and should not be construed to represent the positions of the U.S. Army and Department of Defense. 

Contact: Elizabeth A. Penix-Smith, PhD, can be reached at eapenix@gmail.com.

The American Psychological Association, in Washington, D.C., is the largest scientific and professional organization representing psychology in the United States. APA’s membership includes  173,000 researchers, educators, clinicians, consultants and students. Through its divisions in 54 subfields of psychology and affiliations with 60 state, territorial and Canadian provincial associations, APA works to advance the creation, communication and application of psychological knowledge to benefit society and improve lives.

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DOI

10.1037/tra0002070 

Method of Research

Meta-analysis

Subject of Research

People

Article Title

The Protocol Matters: A Meta-Analysis of Psychotherapy Dropout From Specific PTSD Treatment Approaches in U.S. Service Members and Veterans

Article Publication Date

17-Nov-2025

 

A microbial blueprint for climate-smart cows

Gut genes may hold key to lowering methane

University of California - Davis

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Each year, a single cow can belch about 200 pounds of methane. The powerful greenhouse gas is 27 times more potent at trapping heat in the atmosphere than carbon dioxide. For decades, scientists and farmers have tried to find ways to reduce methane without stunting the animal’s growth or productivity. 

Recent research at University of California, Davis, has shown that feeding cows red seaweed can dramatically cut the amount of methane that is produced and released into the environment. Until now, however, scientists did not fully understand how red seaweed changes the interactions among the thousands of microbes in the cow’s gut, or rumen. 

A new collaborative study by researchers at UC Davis, the University of California, Berkeley, and the Innovative Genomics Institute, or IGI, sheds light on that process and reveals which microbes in the cow’s gut might help reduce methane. The new insights bring the multidisciplinary team, composed of microbiologists, animal and computer scientists, closer to engineering the gut microbes of cows to produce less methane, offering a long-term solution that would not depend on seaweed feed additives. The study was published in Microbiome.

Seaweed transforms the cow gut

Scientists have previously shown that red seaweed of the genus Asparagopsis blocked a key enzyme found in methane-producing microbes in the cow’s gut. In the current study, researchers discovered that seaweed turned certain microbial genes on and off, a sign that these genes play a key role in how red seaweed helps cut methane from cows. As these genes switched on and off in the cow’s gut, hydrogen briefly built up. The team also identified a rumen bacterium that belongs to the genus Duodenibacillus that can use some of the hydrogen. 

“That’s important because too much hydrogen can lead to acidosis in the rumen, which can harm the animal,” said project leader and corresponding author Matthias Hess, a microbiologist and professor in the UC Davis Department of Animal Science and an IGI investigator. “Instead, this organism uses the hydrogen and converts it to succinate, a compound the animal can eventually use to make protein.”

Hess said the findings could open the door to engineering communities of hydrogen-hungry microbes that might outcompete methane-producing microbes.

“Hydrogen is a key energy source in the rumen, specifically for methane-producing microbes," said principal investigator Spencer Diamond, with the IGI. "This study helps us better understand how other microbes that naturally occur in the rumen can divert this hydrogen away from methanogens and towards bacteria that may make animals more efficient.” 

Scientists extracted fluid from the rumens of eight cows: four that were fed a regular diet and four that were also given a seaweed additive for 14 days. Cows that ate the seaweed cut their methane emissions by 60%, increased their hydrogen production by 367%, and increased their feed efficiency by up to 74%.

Researchers were also able to reconstruct the genome of Duodenibacillus, a bacterium that has not yet been isolated in a lab. By looking at the bacterium’s complete genetic code, they could understand its role in hydrogen consumption, how it may compete with other hydrogen-utilizing microorganisms, and how it functions in the cow’s rumen more globally. Efforts are now underway to try and isolate this specific Duodenibacillus species for further study.

Other authors of the study include Ermias Kebreab, Pedro Romero and Breanna Roque of UC Davis; Pengfan Zhang of the Innovative Genomics Institute at UC Berkeley; and Nicole Shapiro and Emiley Eloe-Fadrosh of the U.S. Department of Energy Joint Genome Institute. Authors Matthias Hess and Ermias Kebreab are also principal investigators at the IGI. 

This work was supported in part by Lyda Hill Philanthropies, Acton Family Giving, the Valhalla Foundation, Hastings/Quillin Fund - an advised fund of the Silicon Valley Community Foundation, the CH Foundation, Laura and Gary Lauder and Family, the Sea Grape Foundation, the Emerson Collective, Mike Schroepfer and Erin Hoffman Family Fund - an advised fund of Silicon Valley Community Foundation, and the Anne Wojcicki Foundation through The Audacious Project at the Innovative Genomics Institute. The work was also supported by the Shurl and Kay Curci Foundation and by the Office of Science of the U.S. Department of Energy. 

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Journal

Microbiome

DOI

10.1186/s40168-025-02251-2 

Subject of Research

Animals

Article Title

Red seaweed supplementation suppresses methanogenesis in the rumen, revealing potentially advantageous traits among hydrogenotrophic bacteria

Article Publication Date

13-Nov-2025

COI Statement

Breanna Roque (BR) works for FutureFeed a company working on red seaweed based strategy to reduce enteric methane. However, all work performed as part of this study was not impacted or influenced in anyway by the position BR holds with FutureFeed.

 

Bridging the gap to bionic motion: challenges in legged robot limb unit design, modeling, and control

Beijing Institute of Technology Press Co., Ltd

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image: 

Unlike traditional mobile robots, legged robots leverage their distinctive “leg” structures to traverse obstacles and adapt to uneven terrain, demonstrating exceptional mobility when confronted with pronounced undulations or soft ground. Their excellent terrain adaptability and high flexibility enable them to perform tasks in complex and unstructured environments that are challenging for wheeled or tracked robots to accomplish.

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Credit: Jinyuan Liu, Zhejiang University.

In recent years, robots have increasingly become integral in enhancing human life, particularly with the growing demand for mobile robots with high payload-to-weight ratios and dynamic capabilities. Traditional wheeled or tracked robots are difficult to operate stably in complex real-world environments, which has driven research on legged robots. Legged robots leverage their distinctive “leg” structures to traverse obstacles and adapt to uneven terrain, demonstrating exceptional mobility when confronted with pronounced undulations or soft ground. However, research on legged robots faces a series of difficulties. From the hardware manufacture perspective, leg structures are required to not only support the robot’s weight, but also generate sufficient actuation force to drive the entire system. Furthermore, the impact force generated when the foot lifts off or contacts the ground can affect the internal structure, thereby making impact mitigation a critical consideration in the overall design process. From the control perspective, legged robots exhibit substantially greater kinematic and dynamic complexity compared to wheeled or tracked counterparts. This poses a significant challenge to the control architecture, requiring high-precision, real-time coordination between multiple joints and actuators.

Due to the reasons mentioned above, the construction and analysis of complete legged robotic systems remain inherently complex and challenging. “Compared to the complete multi-legged robots (MLRs), single-legged robots (SLRs) feature simpler configurations and typically admit a dynamic gait: hopping. Its hopping period can effectively characterize the behavior of multi legged and single legged structures, making it easier to tackle structural design and dynamic control problems.” said the author Jinyuan Liu, a researcher at Zhejiang University, “Therefore, we systematically review the mechanical structure, applications, modeling, and control strategies of SLRs, and outline key challenges and future directions, with the aim of narrowing the gap between engineering implementation and biomimetic motion.”

This article takes the single-leg robot (SLR) as a representative “lower-limb unit” for legged robots and develops a systematic review along four axes—structure, modeling, control, and challenges/prospects. On the hardware side, the article organizes SLRs by structure and actuation–elasticity configuration: (i) telescoping designs, centered on a linear prismatic degree of freedom, feature simple mechanisms and planning and suit planar/spatial jumping and baseline validation; and (ii) articulated designs, which biomimetically incorporate multiple joints and are further subdivided by actuation–elastic coupling into rigid (RALR), parallel elastic (PEALR), series elastic (SEALR), and variable stiffness (VSELR) variants. A performance–cost comparison is provided—for example, SEALR attenuates landing impacts and improves efficiency at the expense of structural complexity, whereas VSELR offers adaptability but increases control difficulty and mechanical heft—and a data-oriented survey of representative quadruped platforms (e.g., ANYmal, SpotMini, Cheetah) is used to bridge the path from single-leg to multi-leg systems. At the modeling level, the article delineates two principal lines for SLR research: the SLIP template models and the articulated reduced models. The former capture the core center-of-mass/ground-reaction dynamics via a spring-loaded inverted pendulum and extend to 1/2/3-DoF and other scenarios; the latter perform controlled structural simplifications that facilitate task-level controller design and comparative evaluation. On the control side, the article systematically compares model-based (e.g., VMC/IDC, MPC) and model-free (e.g., CPG, reinforcement learning) strategies: model-based methods offer interpretability and principled constraint handling but depend on accurate models, are sensitive to noise, and incur notable computational cost; model-free methods exhibit adaptability in high-DoF, nonlinear systems, yet face challenges in training cost, interpretability, and practical deployment—especially in transferring from simulation to hardware. Subsequently, the article summarizes the main Sim-to-Real bottlenecks—performance degradation due to sensor noise, actuation delays, and contact uncertainty—and the prevailing remedies, including domain randomization, high-fidelity simulators, and imitation learning, along with guidance for selecting among control strategies.

Finally, the article outlines a multi-pronged research agenda toward “bionic motion”: bio-inspired structures, lightweight fabrication (topology optimization, generative design, multi-material additive processes), auxiliary mechanisms (reaction wheels/tails, grasping, jump-fly hybrids), and new materials (high-energy-density elastomers, SMAs/soft actuators), emphasizing tight integration with intelligent control (including privileged-information RL and large-scale planning) to enhance stability, efficiency, and generality in real-world, complex environments.

However, SLRs still face practical gaps—model–reality mismatch under contact uncertainty, complexity–weight and reliability trade-offs in articulated/elastic actuation, energy and thermal limits during high-power transients, real-time compute burdens for whole-body coordination, and limited scalability from SLR templates to multi-leg systems in unstructured terrains. “Therefore, future research should pursue tightly coupled advances in morphology, materials, and control: bio-inspired structures; lightweight fabrication (topology optimization, generative design, multi-material additive processes); auxiliary mechanisms (reaction wheels/tails, grasping, jump-fly hybrids); and new materials (high-energy-density elastomers, SMAs/soft actuators)—all integrated with intelligent control, including privileged-information RL and large-scale planning, to enhance stability, efficiency, and generality in real-world, complex environments,” said Jinyuan Liu.

Authors of the paper include Junhui Zhang, Jinyuan Liu, Huaizhi Zong, Pengyuan Ji, Lizhou Fang, Yong Li, Huayong Yang, and Bing Xu.

This work was supported by the National Natural Science Foundation of China (grant no. U24B2049) and the National Natural Science Foundation of China (grant no. U21A20124).

The paper, “Bridging the Gap to Bionic Motion: Challenges in Legged Robot Limb Unit Design, Modeling, and Control” was published in the journal Cyborg and Bionic Systems on Aug. 19, 2025, at DOI: 10.34133/cbsystems.0365.

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Journal

Cyborg and Bionic Systems

 

Wastewater from most countries favours non-resistant bacteria

University of Gothenburg

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Joakim Larsson, Professor at the University of Gotheburg, and director at CARe, Centre for Antibiotic Resistance Research.

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Credit: Photo: Johan Wingborg, University of Gothenburg

Municipal wastewater contains a large range of excreted antibiotics and has therefore long been suspected to be a spawning ground for antibiotic-resistant bacteria. Now, a study published in Nature Communications led by a team from the University of Gothenburg provides a more nuanced picture.

By testing the potential of untreated municipal wastewater from 47 countries to select for resistant E. coli, the researchers show that while some samples indeed do so, most instead suppress them. 

“What we found most intriguing is the widespread disadvantages for resistant E. coli in wastewaters from most countries,” says Professor Joakim Larsson, senior author of the study and director of CARe. “This suggests that municipal wastewater treatment plants may not always be breeding grounds for resistance, as sometimes perceived.”

To understand what drives these patterns, the researchers also measured 22 antibiotics and 20 antibacterial biocides in all samples. While some antibiotics exceeded thresholds predicted to select for resistance in certain bacteria, none stood out as a clear driver of resistance in E. coli. Chemical patterns often correlated only weakly with the observed selection outcomes, suggesting that complex mixtures—or unmeasured compounds—may influence which bacteria thrive. 

Why, then, does resistance often come at a disadvantage in wastewater?

“Resistance often comes with a cost to the bacterium,” Joakim Larsson explains. “If there is not enough antibiotic present, the sensitive ones often grow better. It might also have something to do with particular adaptations of certain E. coli lineages to the sewage environment.”

The study validated their findings using both synthetic communities of 340 diverse E. coli strains and by using natural wastewater microbial communities, showing similar patterns of both selection and deselection. Together, these results challenge common assumptions about municipal wastewater and highlight the complexity of resistance dynamics in real-world environments.

Researchers emphasize that although some wastewater clearly can select for resistance, the widely observed suppression of resistant strains may help reduce the risk of resistance evolution and transmission in many settings.

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Journal

Nature Communications

DOI

10.1038/s41467-025-65670-7 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

Antibiotic resistance selection and deselection in municipal wastewater from 47 countries

Article Publication Date

13-Nov-2025