Neural changes following equine-assisted therapy for posttraumatic stress disorder: A longitudinal multimodal imaging study

Xi Zhu, Benjamin Suarez-Jimenez, Sigal Zilcha-Mano, Amit Lazarov, Shay Arnon, Ari L Lowell, Maja Bergman, Matthew Ryba, Allan J Hamilton, Jane F Hamilton, J Blake Turner, John C Markowitz, Prudence W Fisher, Yuval Neria, Xi Zhu, Benjamin Suarez-Jimenez, Sigal Zilcha-Mano, Amit Lazarov, Shay Arnon, Ari L Lowell, Maja Bergman, Matthew Ryba, Allan J Hamilton, Jane F Hamilton, J Blake Turner, John C Markowitz, Prudence W Fisher, Yuval Neria

Abstract

Background: While effective treatments for posttraumatic stress disorder (PTSD) exist, many individuals, including military personnel and veterans fail to respond to them. Equine-assisted therapy (EAT), a novel PTSD treatment, may complement existing PTSD interventions. This study employs longitudinal neuro-imaging, including structural magnetic resonance imaging (sMRI), resting state-fMRI (rs-fMRI), and diffusion tensor imaging (DTI), to determine mechanisms and predictors of EAT outcomes for PTSD.

Method: Nineteen veterans with PTSD completed eight weekly group sessions of EAT undergoing multimodal MRI assessments before and after treatment. Clinical assessments were conducted at baseline, post-treatment and at 3-month follow-up.

Results: At post-treatment patients showed a significant increase in caudate functional connectivity (FC) and reduction in the gray matter density of the thalamus and the caudate. The increase of caudate FC was positively associated with clinical improvement seen immediately at post-treatment and at 3-month follow-up. In addition, higher baseline caudate FC was associated with greater PTSD symptom reduction post-treatment.

Conclusions: This exploratory study is the first to demonstrate that EAT can affect functional and structural changes in the brains of patients with PTSD. The findings suggest that EAT may target reward circuitry responsiveness and produce a caudate pruning effect from pre- to post-treatment.

Trial registration: ClinicalTrials.gov NCT03068325.

Keywords: PTSD; equine assisted therapy; neuroimaging; resting state fMRI.

Conflict of interest statement

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

© 2021 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.

Figures

FIGURE 1
FIGURE 1
Networks identified by ICA
FIGURE 2
FIGURE 2
Within‐BGN showed significant increased connectivity after treatment
FIGURE 3
FIGURE 3
The association between changes of resting state caudate connectivity and PCL changes
FIGURE 4
FIGURE 4
Baseline resting state caudate connectivity predicting the PCL changes

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