Abstract
An etiological hypothesis was proposed for Alzheimer''s disease (malnutrition with or without malabsorption); this may explain clinical and biological phenomena which occur in this disease. A search through the literature revealed that all people suffering from Down''s syndrome (and who all develop Alzheimr''s disease after 40 yr of age) also suffer from malnutrition. This hypothesis may explain the anatomical and neurobiochemical perturbations and the inefficacy of choline. Consequent nutritional treatment of the disease is proposed.