[Relation of dementia, Alzheimer's disease and aging].

Relation of dementia, Alzheimer's disease and brain aging was analyzed in a group of 50 persons who decreased at the age of 90 or more. Each of them were investigated according to 87 clinical a pathological variable features. The group has remained the world biggest for the time being. Final diagnosis of Alzheimer's disease is a histological one. Author proved that it depended on criteria lacking of world wide standardization. Various criteria could show the Alzheimer's disease as a phenomenon either not increasing in the 10th decade and differing from aging, or increasing and close or equal to aging. Statistical analysis of author's data could distinguish between non-demented and seriously demented individuals according to the number of plaques. A quasi-selective amnesia of old persons which is taken for a "benign senile forgetfulness" could be a sign of evolving Alzheimer's disease. Dementia is an unevitable condition for the diagnosis of Alzheimer's disease. This is without doubt important for a clinical diagnosis and not for a morphological expression of biological event. Author presume there exists an Alzheimer's disease under clinical threshold which combined with a clinically manifest disease does increase with the age and inflicts on 9 per cent of population in the 10th decade. Alzheimer's disease seems to be a fundamental biological event at least related to brain aging. A productive research problem might be to find out why "Alzheimer" features measured by common methods avoid 10 per cent of population in the 10th decade.