In the AD cortex, SIRT1 (silent-mating-type information regulation 2 homolog 1) deacetylation of BMAL1 (brain and muscle ARNT-like protein 1) declines dramatically and NAD+ (nicotinamide adenine dinucleotide) synthesis also declines, resulting in more muted oscillations of PER2 (period 2) as AKT (serine/threonine-protein kinase) and AMPK (AMP-activated protein kinase) circadian rhythms collapse; within the hippocampus, the temporal variation in CREB (cyclic AMP Response Element-Binding) activation disappears under diurnal conditions that decrease the ability to consolidate memory [38]. This evidence concerns the gene AKT1 and Alzheimer disease.