In addition, a decline in cAMP-dependent protein kinase A (PKA) signaling, another CaMKK2 upstream kinase (Wayman et al., 1997; Cao et al., 2011), contributes to the etiology of several neurodegenerative diseases, including AD and PD (Dagda and Das Banerjee, 2015). This evidence concerns the gene CAMKK2 and Alzheimer disease.