December 14, 2016

Equine-Assisted Therapy Linked to Functional Brain Changes in Children with Attention-Deficit/Hyperactivity Disorder

A pilot study finds that equine-assisted therapy may have the potential to improve symptoms of ADHD in children due to the fact that it produces connectivity changes in certain areas of the brain.
By Laurie Anne Walden, DVM, ELS
The results of a pilot study suggest that equine-assisted therapy produces connectivity changes in certain areas of the brain. These changes may explain how equine-assisted therapy can improve symptoms of attention-deficit/hyperactivity disorder (ADHD), say the authors. The study was recently published in Clinical Psychopharmacology and Neuroscience.
 
Although the sample size and design of the pilot study do not allow for broad conclusions to be drawn, write the authors, “this study showed a potential mechanism for how EAA/T [equine-assisted activities and therapy] has a positive influence on ADHD.” According to the authors, this is the first study to show the effects of equine-assisted therapy on functional connectivity in the brain.
 
Researchers in Seoul, Republic of Korea, recruited 22 children diagnosed with ADHD to participate in 12 weeks of equine-assisted therapy. The final analysis included data from 10 children (exclusions were an inability to undergo magnetic resonance imaging [MRI], administration of methylphenidate or atomoxetine, and failure to complete the full 12 weeks of therapy). Nine of the children were boys and one was a girl. Their mean age was 8.3 ± 1.3 years.
 
The equine-assisted therapy program consisted of 24 sessions (twice weekly for 12 weeks) provided by hippotherapy specialists. The hour-long sessions were conducted in an indoor arena and included grooming, tacking, feeding, and riding. The children were accompanied by their parents, side walkers, and a leader and wore protective equipment. The horses and ponies were trained and experienced in hippotherapy.
 
The investigators evaluated the participants about 2 weeks before and 2 weeks after the therapy program. They used rating scales to measure symptom severity, clinical improvement, and motor coordination. At the same time, they obtained MRI brain scans (high-resolution T1 images followed by resting functional whole-brain MRI scans) for each participant. They used the processed MRI data to calculate regional homogeneity (ReHo), a measure of local connectivity within specific regions of the brain.
 
After 12 weeks of equine-assisted therapy, mean symptom severity and clinical improvement scores had improved. Motor coordination scores did not significantly change after therapy.
 
ReHo significantly decreased after therapy in two areas of the brain: the right precuneus and the pars orbitalis. The precuneus is an area of the parietal lobe thought to be involved in self-consciousness and episodic memory retrieval. It is part of the default mode network, a neural system that is most active when the brain is resting. Changes in connectivity in the default mode network have been implicated in the development of ADHD, and previous MRI studies of participants with ADHD have shown atypical connections in the precuneus, say the authors. In this study, the ReHo change in the right precuneus after equine-assisted therapy was significantly correlated with lower symptom severity scores.
 
The pars orbitalis is located in the inferior frontal gyrus, which plays a role in behavior inhibition and executive motor control. The authors suggest that a decrease in ReHo in the inferior frontal gyrus could mediate the effect of equine therapy on inhibitory control.
 
The authors discussed three study limitations. The study included only participants with ADHD, with no comparison group of children without ADHD. The investigators collected data from participants only in the resting state, so no conclusions could be drawn about task-related performance. Because the study was limited to a single 12-week therapy program, long-term effects of equine therapy could not be analyzed. The authors recommend further controlled studies with larger sample sizes.
 
“In conclusion, the current study found that EAA/T in ADHD participants is associated with subsequent resting-state functional signal changes in the right precuneus and pars orbitalis clusters,” write the authors. They suggest that improvement in ADHD symptoms after equine-assisted therapy could be related to dysfunctional modulation in the default mode network.
 
The authors report no conflicts of interest. The study was conducted by the Korea Racing Authority and was partly funded by the Korea Advanced Institute of Science and Technology.
 
Dr Laurie Anne Walden received her doctorate in veterinary medicine from North Carolina State University. After an internship in small animal medicine and surgery at Auburn University, she returned to North Carolina, where she has been in small animal primary care practice for over 20 years. Dr. Walden is also a board-certified editor in the life sciences and owner of Walden Medical Writing, LLC. She works as a full-time freelance medical writer and editor and continues to see patients a few days each month.

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