Potential mechanisms and research progress of animal-assisted interventions for autism spectrum disorder

Figure 2 Proposed mechanistic framework of animal-assisted intervention for autism spectrum disorder. Animal-assisted intervention may exert its therapeutic effects through four interconnected pathways: Neurobiological regulation (hypothalamic-pituitary-adrenal axis modulation, oxytocin system activation, brain network remodeling, and neuroplasticity enhancement), physiological and immunometabolic modulation (autonomic nervous system regulation, cytokine balance restoration, and mitochondrial function improvement), psychological-behavioral facilitation (emotional security, social motivation, behavioral synchrony, and self-control), and sensorimotor integration (vestibular, proprioceptive, and multisensory input processing). These pathways converge to improve core autism spectrum disorder symptoms. HPA: Hypothalamic-pituitary-adrenal; mPFC: Medial prefrontal cortex; BDNF: Brain-derived neurotrophic factor; mTOR: Mammalian target of rapamycin; AAI: Animal-assisted intervention; HRV: Heart rate variability; IL: Interleukin; TNF-α: Tumor necrosis factor-α; INN: Interneuron network; ATP: Adenosine triphosphate; ASD: Autism spectrum disorder.