In addition, participants who directly touched dogs or cats through animal visiting programs and had sensory interactions with animals showed decreased cortisol levels compared with other groups that did not interact with animals (Pendry and Vandagriff, 2019); however, as these mechanisms were not confirmed by directly applying AAI to animal models or patients with AD, future studies are required for confirming the direct effect of AAI on Aβ deposition and tau hyperphosphorylation using positron emission tomography in preclinical or patients with prodromal AD. This evidence concerns the gene MAPT and Alzheimer disease.