Previous research on human postmortem AD brains has revealed neuronal cell loss and reduced vasopressin levels in the SCN (Swaab et al., 1985; Hofman and Swaab, 1994; Stopa et al., 1999), and there is in vitro evidence for severe disruption of the circadian clock by the presence of Abeta (Schmitt et al., 2017), though the extent of clock gene expression changes in the SCN of AD patients is unknown. The gene discussed is CLOCK; the disease is Alzheimer disease.