SIRT3 and Alzheimer disease: Sirt3 mRNA levels were initially elevated in hippocampal tissues of early symptomatic 6 month-old AD PDAPP mice (which overexpress a human amyloid beta (Aβ) precursor protein (APP) carrying the V717F mutation), but this increase in SIRT3 expression returns to normal levels by 26 months of age (Weir et al., 2012).