HCRT and Alzheimer disease: In line with these data, deregulation of the orexinergic system has been documented in AD patients, who show increases in orexin-A (OX-A) levels in the CSF (Osorio et al., 2016; Gabelle et al., 2017; Shimizu et al., 2020), and in AD animal models (Liu et al., 2018; Zhao et al., 2022).