Similar to AD in other age groups, both immunoglobulin (Ig)E-mediated allergic (extrinsic) and non-IgE-allergic (intrinsic) forms exist in elderly AD, and the most frequent environmental allergens involved in the extrinsic form are house dust mites (e.g. Dermatophagoides species), followed by pollens and foods.1,4 Skin manifestations in elderly AD basically match those of adult AD, although the reverse sign of lichenified eczema around unaffected folds of the elbows and knees is more common than the classic sign of localized lichenification in those folds.1,2. The gene discussed is IGHE; the disease is Alzheimer disease.