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Home / Equine Research Bank / Int J Environ Res Public Health / Using Functional Near-Infrared Spectroscopy to Elucidate Neu...
International journal of environmental research and public health2025; 22(8); 1294; doi: 10.3390/ijerph22081294

Using Functional Near-Infrared Spectroscopy to Elucidate Neurophysiological Mechanism of Action of Equine-Assisted Services: Proof-of-Concept Study.

Abstract: Equine-assisted services (EAS) are used for civilian and military trauma survivors to reduce depression and posttraumatic stress symptoms. While early scientific evidence supports the benefits of EAS, the neurophysiological mechanisms underlying these benefits are unknown. The specific aims of this exploratory study were to determine (1) whether functional near-infrared spectroscopy (fNIRS) neuroimaging can be used to explore neural responses of EAS veteran participants and (2) the correlation between neural responses and psychological outcomes of the participants interacting with equines. Fifteen veterans participated in a 2-day EAS program consisting of four randomized activities. An fNIRS sensor cap was used to measure the oxygenated (OHb), deoxygenated (hHb), and total hemoglobin (tHb) of the participants during each activity. The results indicated no significant differences for OHb and tHb across the visits or activities, however, a significant difference in hHb was observed. There was an increase in hHb during the activities that included an equine, which indicated a greater cognitive load and attention. Further, data from pre-/post-psychometric assessments showed a significant improvement in participants' trait anxiety, psychological flexibility, and positive and negative affect after interacting with the horse. Preliminary data revealed a potential association between the cognitive attention and psychological health of participants during an EAS session.
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Publication Date: 2025-08-19 PubMed ID: 40869879PubMed Central: PMC12386777DOI: 10.3390/ijerph22081294Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study investigated whether functional near-infrared spectroscopy (fNIRS) can be used to measure brain activity during equine-assisted services (EAS) in veterans and explored how these neural responses relate to improvements in psychological outcomes such as anxiety and affect.

Introduction to Equine-Assisted Services and Research Focus

  • EAS are therapeutic activities involving horses, used to help trauma survivors, including military veterans, to reduce symptoms of depression and posttraumatic stress disorder (PTSD).
  • Although prior studies show EAS benefits, the brain mechanisms underlying these positive effects are not yet clearly understood.
  • The study aimed to explore neurophysiological responses during EAS using functional near-infrared spectroscopy (fNIRS), a non-invasive neuroimaging technique that measures brain oxygenation changes.
  • Specifically, the study investigated:
    • Whether fNIRS could be effectively applied to veterans participating in EAS to capture neural activity.
    • The relationship between neural activity during EAS and psychological measures such as anxiety, flexibility, and mood.

Study Design and Methods

  • Participants:
    • 15 veterans with trauma-related symptoms took part in the study.
  • Intervention:
    • A 2-day EAS program where participants completed four different randomized activities, some involving direct interaction with horses and others not.
  • Data Collection:
    • fNIRS sensor caps recorded hemoglobin metrics during each activity:
      • Oxygenated hemoglobin (OHb)
      • Deoxygenated hemoglobin (hHb)
      • Total hemoglobin (tHb)
    • Psychometric assessments were administered before and after the EAS sessions measuring:
      • Trait anxiety
      • Psychological flexibility
      • Positive and negative affect (mood)

Key Findings

  • Neural Measures:
    • No significant changes were found in oxygenated (OHb) and total hemoglobin (tHb) levels during the activities across visits.
    • Significant increase in deoxygenated hemoglobin (hHb) was observed during activities involving interaction with the horses, suggesting higher cognitive load and mental attention during these tasks.
  • Psychological Outcomes:
    • Participants showed significant improvements in:
      • Trait anxiety – indicating reduced general anxiety
      • Psychological flexibility – suggesting better adaptive coping mechanisms
      • Positive and negative affect – improved mood and emotional state
  • Potential Correlations:
    • Preliminary data indicated a possible association between increased cognitive attention (as measured by hHb changes) during EAS and enhanced psychological health.
    • This suggests that neural engagement during horse interaction may relate to therapeutic benefits.

Implications and Conclusions

  • This study demonstrates that fNIRS is a feasible tool to assess brain activity during EAS activities in trauma-affected veterans.
  • The observed increase in deoxygenated hemoglobin during horse-related tasks points to heightened cognitive effort or attention when engaging with equines.
  • Improved psychological outcomes post-EAS support the potential utility of equine-assisted therapies for mental health amelioration in trauma survivors.
  • The correlation between neural markers of attention and psychological improvement provides preliminary evidence toward understanding the neurophysiological mechanism of action in EAS.
  • Future larger-scale studies can build on these findings to confirm these relationships and optimize EAS protocols for maximum therapeutic effect.

Cite This Article

APA
Lanning BA, Smith CM, Ugale C, Nazarenko E, Marchand WR. (2025). Using Functional Near-Infrared Spectroscopy to Elucidate Neurophysiological Mechanism of Action of Equine-Assisted Services: Proof-of-Concept Study. Int J Environ Res Public Health, 22(8), 1294. https://doi.org/10.3390/ijerph22081294

Publication

International journal of environmental research and public health
ISSN: 1660-4601
NlmUniqueID: 101238455
Country: Switzerland
Language: English
Volume: 22
Issue: 8
PII: 1294

Researcher Affiliations

Lanning, Beth A
  • Department of Public Health, Baylor University, Waco, TX 76655, USA.
Smith, Cory M
  • Department of Health, Human Performance and Recreation, Baylor University, Waco, TX 76655, USA.
Ugale, Cierra
  • Department of Health, Human Performance and Recreation, Baylor University, Waco, TX 76655, USA.
Nazarenko, Elena
  • Whole Health Service, VA Salt Lake City Health Care System, 500 Foothill Drive, Salt Lake City, UT 84108, USA.
Marchand, William R
  • Whole Health Service, VA Salt Lake City Health Care System, 500 Foothill Drive, Salt Lake City, UT 84108, USA.
  • Department of Psychiatry, University of Utah, 501 Chipeta Way, Salt Lake City, UT 84108, USA.
  • Department of Animal, Dairy and Veterinary Sciences, Utah State University, 0500 Old Main Hill, Logan, UT 84322, USA.

MeSH Terms

  • Spectroscopy, Near-Infrared / methods
  • Humans
  • Male
  • Animals
  • Horses
  • Equine-Assisted Therapy
  • Female
  • Adult
  • Middle Aged
  • Veterans / psychology
  • Proof of Concept Study
  • Stress Disorders, Post-Traumatic / therapy
  • Hemoglobins / analysis
  • Depression / therapy

Grant Funding

  • 1001663 / Horses and Humans Research Foundation

Conflict of Interest Statement

The authors declare no conflicts of interest.

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