THE IMMEDIATE EFFECTS OF MOUNTED VS. UNMOUNTED HUMAN-EQUINE INTERACTIONS ON PHYSIOLOGICAL AND BEHAVIORAL INDICATORS OF SELF-REGULATION IN AUTISTIC YOUTH

Abstract

Autistic youth can experience impairments to self-regulation, defined as one’s capability to evaluate and modify behaviors and emotions to produce goal-oriented actions. Interventions targeting self-regulation development have evidential support for improving quality of life for autistic youth. Research in equine assisted services (EAS) has demonstrated efficacy to improve self-regulation behaviors in autistic youth. Occupational therapy in an equine environment and therapeutic riding, two specific types of EAS, have shown such improvements and preliminary evidence suggests these services may have immediate impacts on participants’ physiology (autonomic arousal and cortisol levels). Past Studies have not yet compared the behavioral and physiological effects of mounted vs unmounted interactions with a horse. The purpose of this study is to examine behavioral and physiological self-regulation indicators in autistic youth during and immediately after mounted and unmounted human-equine interactions. The study utilized a Williams Design Crossover trial in which all participants experienced a series of three conditions: 1) mounted equine interaction (riding), 2) unmounted equine interaction (grooming), and 3) a no-horse control condition. Youth were randomized to the order in which they participated in each of these three conditions. During the sessions, participants wore electrocardiogram monitors to assess heartrate variability, an indicator of the sympathetic branch of the autonomic nervous system. Heartrate variability was quantified using a time domain metric called root mean square of successive differences (RMSSD). Participants also wore electrodermal activity monitors to measure electrodermal activity, an indicator of sympathetic nervous system arousal. Saliva samples were also collected and assayed for cortisol, a hormone that reflects stress-related changes in the body. Finally, parents completed surveys 24-hours post session to report on their child’s emotional reactivity, dysphoria, irritability, and hyperactivity following the session. At the pre-session, youth demonstrated significantly greater cortisol concentrations during the no-horse condition, but differences in EDA or RMSSD were not observed between conditions at this time. During the intervention, EDA increased during the no horse condition but decreased during both the mounted and unmounted conditions; EDA was significantly lower at post-session in the mounted and unmounted conditions than the no-horse control. RMSSD decreased (indicating decreased parasympathetic activity) across all conditions and returned to near pre-session levels at post-session. Cortisol concentrations significantly reduced in the no horse control condition but remained relatively stable in the mounted and unmounted condition. A day after the intervention, participants demonstrated reduced irritability, dysphoria, and emotional reactivity after the mounted and unmounted equine interaction compared to the no horse control condition. Interacting with horses, mounted and unmounted, are both feasible activities to improve self-regulation for autistic youth. The real horse seemed to induce a calm, relaxed state at the beginning of the lesson (e.g., decreased sympathetic nervous system activity). However, as the lesson progressed, and cognitive demands increased, youth demonstrated an increase in autonomic arousal in all conditions. The learning activities in the mounted, unmounted, and no horse conditions required optimal arousal for the increased mental effort (e.g., increased sympathetic nervous system activity, decreased parasympathetic nervous system activity). Even with the increase cognitive demand, no distress was experienced by the participants, observed in a decrease in cortisol at the end of the lesson. Additionally, interacting with the real horse had a 24-hour effect on autistic youths’ behavior. Reduced irritability, dysphoria, and emotional reactivity observed by parents suggests improvements to self-regulation. Autistic individuals who cannot participate in therapeutic riding lessons can still benefits from unmounted horse interactions. Unmounted programming requires more attention to improve the overall accessibility of EAS. Future research is needed to appreciate the nuances of the human-equine interaction. This project was funded by the Human Animal Bond Research Institute.