Review highlights promise and limits of fNIRS in PTSD care
Bottom line
A new narrative review in BMC Psychiatry argues that functional near-infrared spectroscopy, or fNIRS, may be a practical way to track treatment-related brain changes in people with post-traumatic stress disorder and trauma-related symptoms. The review, published July 23, 2026, identified just four eligible longitudinal studies through January 30, 2026, and found that all focused on non-pharmacologic interventions, including trauma-focused psychotherapy, attention-based cognitive training, and equine-assisted services. Across those studies, repeated fNIRS measurements consistently detected changes in prefrontal cortical activity, but the direction and size of those changes varied by intervention and study design. The authors say that makes fNIRS promising, but still early-stage, as a treatment-monitoring tool. (link.springer.com)
Why it matters: For veterinary professionals, the review is less about immediate clinical adoption and more about where behavioral medicine is heading. fNIRS is noninvasive, portable, and better suited than MRI for repeated measurements in real-world care settings, which could eventually make objective monitoring of treatment response more feasible in psychiatry and, by extension, comparative or translational behavioral research. But the evidence base remains thin: no pharmacologic treatment studies met inclusion criteria, the sample of studies was small, and the authors highlighted major methodological heterogeneity. That caution matters in a field where current PTSD guidelines still center on established trauma-focused psychotherapies, with medications used selectively, rather than biomarker-guided care. (link.springer.com)
What to watch: The next step is whether larger, standardized longitudinal trials, especially those testing medications and multimodal imaging, can show that fNIRS adds clinically useful information beyond symptom scales alone. (link.springer.com)
Key facts
- Study type
- Narrative review
- Journal
- BMC Psychiatry
- Publication date
- July 23, 2026
- Search cutoff
- January 30, 2026
- Studies included
- 4 longitudinal studies
- Population
- Adults with PTSD or trauma-related symptoms
- Interventions studied
- Trauma-focused psychotherapy, attention-based cognitive training, and equine-assisted services
- Main finding
- Repeated fNIRS measurements detected changes in prefrontal cortical activity, but results varied by intervention and study design
- Evidence gap
- No eligible longitudinal pharmacologic studies were found
Functional near-infrared spectroscopy is getting a closer look as a possible tool for monitoring how PTSD treatment changes brain function over time. In a narrative review published July 23, 2026, in BMC Psychiatry, researchers concluded that fNIRS appears clinically feasible and potentially useful for repeated assessment of treatment-related neurofunctional change, particularly in interventions aimed at prefrontal regulatory circuits. At the same time, they emphasized that the field is still immature and far from supporting routine clinical use. (link.springer.com)
That framing reflects a broader problem in PTSD care: symptom burden, illness course, and treatment response can vary widely across patients, while objective biomarkers remain limited. Current PTSD guidelines from the VA/DoD and the American Psychological Association continue to prioritize evidence-based trauma-focused psychotherapies, with selected SSRIs and SNRIs used in some cases, underscoring that treatment still relies mainly on clinical assessment rather than validated neurofunctional monitoring tools. (ptsd.va.gov)
The review team searched PubMed, Web of Science, Scopus, PsycINFO, and the Cochrane Library for studies published through January 30, 2026. Only four studies met eligibility criteria. Those studies evaluated repeated NIRS or fNIRS measurements in adults with PTSD or clinically significant trauma-related symptoms undergoing trauma-focused psychotherapy, attention-based cognitive training, or equine-assisted services. No eligible longitudinal pharmacologic studies were found. Across studies, treatment was associated with modulation of prefrontal cortical hemodynamic activity, but the findings were not uniform, and the authors pointed to substantial variation in paradigms, analytic methods, and intervention types. (link.springer.com)
The practical appeal of fNIRS is straightforward. Unlike MRI-based methods, it is noninvasive, comparatively portable, and more realistic for repeated use in clinical environments. That helps explain why interest in psychiatric treatment monitoring has been growing. A recent scoping review of fNIRS in psychiatric treatment response described an accelerating research trajectory, especially after 2020, but also noted persistent challenges around reproducibility, standardized longitudinal methods, and integration with clinical outcomes. (link.springer.com)
Outside this PTSD-specific review, the wider literature has taken a cautiously optimistic tone. Earlier reviews in psychiatry have described fNIRS as a potential supplement to clinical interviews and symptom measures, not a replacement for established imaging or diagnostic approaches. That is also the position of the BMC Psychiatry authors, who explicitly describe fNIRS as a complementary tool rather than a substitute for functional MRI. (link.springer.com)
Why it matters: For veterinary professionals following clinical research, this is a translational story about measurement, not a practice-changing result. The review highlights growing interest in objective, repeatable biomarkers for behavioral and psychiatric treatment response, but it also shows how far the field remains from standardization. The fact that only four longitudinal studies qualified, and none involved pharmacologic treatment, limits the strength of any conclusions. Still, if fNIRS can eventually help identify which patients are responding, when they are responding, and how neurofunctional changes align with symptoms, it could influence future behavioral medicine research well beyond human psychiatry. (link.springer.com)
There is also a practical lesson in what the review did not find. Despite strong interest in biomarkers, established PTSD care still rests on therapies with proven clinical benefit, not on neuroimaging-guided decision-making. For clinicians, that means fNIRS is best viewed as an emerging research instrument that may improve trial design, patient stratification, or longitudinal monitoring before it ever becomes part of frontline care. (ptsd.va.gov)
What to watch: The field now needs adequately powered longitudinal studies, common acquisition and analysis standards, multimodal imaging strategies, and medication trials that test whether fNIRS measurements actually predict or improve treatment decisions, rather than simply mirror symptom change after the fact. (link.springer.com)