CASP6 and Alzheimer disease: The results of the study revealed that (1) Casp6 activity is highest in and mostly restricted to the AON of the olfactory bulb and co-exists with Tau, but not Aβ, AD pathology, (2) Casp6 activity increases in the AON with the progression of disease and appears to be higher than that of Casp6 activity in the ERC, and (3) active Casp6 levels in the AON are negatively associated with cognitive performance.