In addition to PD, the loss of the hypocretin neurons in the LH area is also identified in the brains of patients with Alzheimer’s disease (AD; Fronczek et al., 2012), post-traumatic injury (Baumann et al., 2009), and Dementia with Lewy bodies (DLB; Kasanuki et al., 2014). Here, HCRT is linked to Parkinson disease.