Abstract
The understanding of mental deterioration associated with old age has undergone several changes over the past two centuries, and has spurred major scientific debates. In the 19th century, this disorder was still considered an inevitable part of aging.
The beginning of the 20th century offered a histological explanation for presenile dementia, and Alois Alzheimer was credited as the discoverer of a new disease that bears his name to date. In the last quarter of the 20th century, findings of Alois Alzheimer were applied massively to late-onset dementia as well, thereby virtually excluding natural intellectual impairment as an explanation to dementia.
In contradiction to the original concept provided by Alzheimer, amyloid plaques and neurofibrillary tangles are now being considered as the cause of psychological depreciation at all ages, and the presence of these is interpreted as a disease. The present review is aimed at disputing these common views and suggests that continuing with this approach may prove to be increasingly counterproductive.
Instead, the present review offers an unbiased view without any preconceived ideas, which considers a long list of natural biological failures that inevitably accompany every human life, such as micro-injuries, microinfarcts, leukoaraiosis, as a consequence of partial failing of the cerebral blood flow, microbleeds, glycemic fluctuations in diabetics, influences of alcohol and toxins, decreasing anisotropy, increasing mean diffusivity on MRIs, and others.