HCRT and neurodegenerative disease: The age-associated increased levels of orexin in the brain of killifish likely resemble those reported in course of mammalian neurodegenerative processes (Zhao et al. 2022) and can be interpreted as a manifestation of the neurodegenerative-like phenotype identified in the brains of the old killifish brain, corroborating the hypothesis that the trajectory of brain ageing in this fish resembles that of humans with neurodegenerative diseases (de Bakker and Valenzano 2023).