Previously, it has been demonstrated that there is an increased expression of NGF and amphiregulin in the epidermis, but decreased expression of nerve repulsion factors, semaphorin-3A and anosmin-1, in AD lesions, which can explain the increased nerve density in AD (Tominaga et al., 2009; Tominaga and Takamori, 2014; Kubanov et al., 2015). Here, AREG is linked to Alzheimer disease.