Alzheimer disease, Pick disease and senile dementia are all characterized by similar morphological changes, both macroscopic and microscopic, and similar psychiatric symptoms. All three should, therefore, be viewed as aspects of one disease, which is termed Alzheimer-type dementia. Nothing contradicts the view that immune complexes take part in the etiology of Alzheimer-type dementia. There are various types of immune complexes and so their points of action in the organism may vary. There might be two main means of preventing Alzheimer-type dementia: the first could be named the serological (basic) and the second relying on pharmacotherapy (additional). Pharmacological prevention of disease might be aided by the use of parasympathomimetic drugs, e.g. pilocarpine.