RCAN1 and Alzheimer disease: Taken together, these findings imply that balanced expression of RCAN1 is necessary for normal diurnal and circadian regulation of locomotor activity in mice and suggest that changes to RCAN1 levels observed in DS, AD, and normal aging [5, 7] may contribute to the diurnal and circadian dysfunctions associated with these conditions [28, 35, 40, 67].