Study Protocol: Pegasus: psychotherapy incorporating horses for ‘therapy-resistant’ adolescents with autism spectrum disorders, a study with series of randomised, baseline controlled n-of-1 trials

Abstract Background For people with autism spectrum disorder (ASD), daily life can be highly stressful with many unpredictable events that can evoke emotion dysregulation (ED): a strong difficulty with appropriately negative affect regulation. For some of the patients with ASD, treatment as usual does not prove to be effective for ED. They may be at risk of life-long impairment, development of other disorders and loss of motivation for most regular forms of therapy. A highly promising method that may prove effective for therapy-resistant individuals with ASD is Psychotherapy incorporating horses (PIH). PIH uses the interactions of the horse and the patients on the ground and does not include horseriding. While often met with prejudgment and scepticism, reports from parents and therapists as well as a recent systematic review suggest that PIH may have beneficial effects on youths with ASD. Therefore, we examine clinical outcomes both in the short and in the long terms of PIH offered to adolescents with ASD and severe ED despite regular therapy. Methods A total of 35 adolescents aged 11–18 years with ASD will receive PIH during 15 sessions once a week with randomization to five different groups differentiating in baseline phase from 2 to 6 weeks. PIH uses horses to promote social awareness and self-awareness as well as relationship management and self-management. The primary outcome is the response to treatment on the Emotion Dysregulation Index (EDI). The secondary outcome measures include ASD symptom severity, quality of life, self-esteem, global and family functioning, and goal attainment. Assessments take place at the baseline (T0), at the end of baseline phase A (T1), after completion of intervention phase B (T2), after the end of post-measurement phase C (T3) and after one year (T4). Qualitative interviews of participants, parents and therapists will be held to reveal facilitators and barriers of PIH and a cost-effectiveness study will be performed. Discussion This study aims at contributing to clinical practice for adolescents with ASD and persistent emotion regulation problems despite 1.5 year of treatment by offering Psychotherapy incorporating horses in a study with series of randomised, baseline controlled n-of-1 trials. Trial registration www.ClinicalTrials.gov NCT05200351, December 10th 2021.