[Presentation of illness in the elderly: a simple explanation for a complex problem]

Illness presentation in the elderly is often complex and atypical. This may cause negative health outcomes. In the standard medical model of diagnosis, there is a 1:1 correspondence between clinical signs and symptoms and a pathological disease process. This model can be only applied to some presentations of illness in the elderly. For this reason Linda Fried, 'grande dame' of geriatric medicine in the United States, developed four complementary generic diagnostic models, taking into account social and functional aspects as well as clinical symptoms. Here we present these models for a broader audience, since not only geriatricians but all physicians are being confronted with a growing population of older patients.