TRPA1 and Alzheimer disease: A hypothesis which considered TRP receptors as an important activator of AD would be consistent with the description of AD as “the itch that rashes” [39] since peripheral itch from TRPA1 would send afferent signals of itch to the brain, but the resultant inflammatory mediators might not be released until the efferent signals were returned to the skin after the scratching occurred [15].