ADCYAP1 and early-onset autosomal dominant Alzheimer disease: Detailed analyses showed that PACAP levels were reduced in the human entorhinal cortex, mid-temporal, superior frontal, and 16 primary visual cortex at both the mRNA and protein levels associated with pathological signs of Alzheimer’s disease; PACAP levels were reduced more in the amyloid plaque but not in the primary visual cortex, a region spared in most cases of the disease (Wu et al., 2006).