BDNF and Alzheimer disease: Pathogenesis of AD involves complex interactions between susceptible genes (filaggrin genes), immunological factors (immunoglobulin E, eosinophils, T helper cells, chemokines), skin barrier defects, infections, neuroendocrine factors (brain derived neurotrophic factor) and environmental factors (weather change, food and aeroallergens) [1,2,15,16].