Introduction: Animal-assisted therapy (AAT) is an emerging treatment for patients with severe disorders of consciousness that can lead to a rise in vegetative, emotional and motoric reactions. The aim of this pilot study is to investigate the effect of animal presence and contact on awareness and reactivity in patients in a minimally conscious state (MCS), reflected via brain activity. The results shall lead to a better understanding of MCS patients’ inner perception and their reaction to animal interaction. This could be used for ongoing development of treatment concepts.
Methodology: Three MCS patients (mean age = 44; SD = 12.16) and three healthy adults (mean age = 40.33; SD = 18.17) participated in this randomized, controlled within-subject study with repeated measurement. Participants were measured during six sessions over a period of two weeks, with three experimental (small therapy dog, guinea pig or rabbit present) and three control sessions (robotic toy animal present). Each session consisted of five different phases: Two baselines, watching animal, animal on lap, stroking animal. Participant’s neurovascular response was measured using a portable, non-invasive, functional near-infrared spectroscopy (fNIRS) device. During the sessions, blood oxygen levels (O2Hb, HHb, total Hb) served as a correlate for brain activity.
Main Results: One MCS patient and one healthy control subject had to be excluded from analysis due to corrupt data. The remaining four participants all showed the largest hemodynamic response to direct animal contact, when either the live or the robotic animal was placed on their lap or when it was stroked. One patient and two control subjects, showed a stronger response while stroking the live animal in comparison to stroking the robotic animal. All participants showed an inverted hemodynamic response when both animals, live and robotic, were stroked. In all other phases the hemodynamic response matched the typical fNIRS response.
Principal Conclusions and Implications for the Field: The data indicates that MCS patients and healthy control subjects react to the presence of and contact with an animal, leading to a measurable difference in their neurovascular reaction. fNIRS can therefore serve as a noninvasive method for investigating the benefits on brain activity during an animal-assisted therapy session in MCS patients. Even though the number of participants is limited, the results indicate that AAT can be a reasonable treatment for DOC patients.