Autism Spectrum Disorder (ASD) is a critical public health concern, given its negative quality of life impacts, increasing prevalence rates, and high health care utilization costs. Two-thirds of the ASD population have co-occurring psychiatric disorders. These individuals require intensive interventions to address psychiatrically related aberrant behaviors (e.g., irritability and hyperactivity), which are the source of much of the disability and cost for this population. The goal of this project is to assess physiological mechanisms underlying Therapeutic Horseback Riding?s (THR) previously observed significant positive effects on ASD youth, particularly those with co-occurring psychiatric disorders, and to further evaluate durability, dose, and sub-population effects of the intervention.
Aim 1 : Test the hypothesis that physiological response patterns of salivary cortisol, cardiovascular, and electrodermal activity account for our previously observed significant outcomes (i.e., reduced irritability and hyperactivity, and improved social and communication), and additional outcomes (emotion regulation and caregiver quality of life), in youth ages 6-16 yrs. with ASD and co-occurring psychiatric diagnoses randomized to a 10-week manualized THR intervention compared to a no-horse Barn Activity (BA) control. Our preliminary findings suggest the psychiatrically challenged ASD majority may be more likely to benefit from THR, particularly if outcomes are mediated by physiological arousal.
Aim 2 : Evaluate the durability of Aim 1 outcomes in the THR group compared to the BA control group six-months after the intervention period, given our preliminary evidence for maintenance of initial outcome gains in a six-month follow-up.
Aim 3 : Explore dose and sub-population effects of THR and BA interventions by comparing effect size differences in THR and BA groups to a: (1) 10-week wait-list control group; (2) Hybrid intervention group (five weeks BA followed by five weeks THR); and (3) subsample of the THR study population randomized following psychiatric hospitalization. Our preliminary results, obtained at both PATH international premiere accredited riding centers proposed in the current application demonstrate that peripheral physiological arousal data collection is feasible with ASD youth while engaged in THR. We have also partially replicated our previous results and demonstrated that cortisol is a viable target mediator of THR effects on aberrant behaviors in ASD youth that merits further investigation. Our proposal has the potential to advance the field of human-animal interaction (HAI), specifically THR, for individuals with ASD and co-occurring psychiatric disorders. It also stands to guide future researchers interested in better understanding the physiological mechanisms associated with HAI. Our long-range goal is to empirically establish THR as an ecologically valid, transdiagnostic intervention that targets underlying psychophysiological arousal states in youth with a variety of mental health issues, facilitating acquisition and long-term maintenance of critical life skills that enhance quality of life for individuals and their caregivers.

Public Health Relevance

Having previously demonstrated that a 10-week therapeutic horseback riding (THR) intervention produces significant medium effect size improvements in irritability, hyperactivity, social communication, social cognition, and word fluency in youth with ASD compared to controls, the current proposal will: (1) examine putative physiological mediators hypothesized to contribute to these as well as expanded outcomes; (2) evaluate the six-month durability of outcomes compared to controls; and (3) explore dose and sub-population effects of the intervention. We target a more impaired majority ASD subpopulation, youth ages 6-16 yrs. with psychiatric diagnoses, who may be more likely to benefit from THR given preliminary evidence of stronger positive outcomes of THR in this subgroup. We have demonstrated the feasibility of collecting ambulatory physiological data during THR in the target population, and now seek to determine if THR is a viable adjunctive intervention able to improve biologically measurable arousal states and associated outcomes (i.e., irritability, hyperactivity, social, communication, emotion regulation and caregiver quality of life) for the majority ASD population, those with co-occurring psychiatric diagnoses.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Esposito, Layla E
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Colorado Denver
Schools of Medicine
United States
Zip Code