Significantly elevated PACAP levels were measured in traumatic brain injury [21], migraine [22–25], posttraumatic stress disorder (PTSD) [26], and intracerebral bleedings [27, 28], and significantly lower PACAP levels were found in Alzheimer’s disease [29–31] and multiple sclerosis [32]. This evidence concerns the gene ADCYAP1 and early-onset autosomal dominant Alzheimer disease.