Neurodegenerative pathologies are devastating diseases that not only seriously compromise health, but also impair human personality. The most dramatic are various forms of dementia, of which the most frequent is senile dementia or Alzheimer's disease. In an Alzheimer patient, the progressive degeneration of several neurons occurs, particularly in some areas of the cerebral cortex where typical neuropathological hallmarks are the neurofibrillary tangles and the neuritic plaques, mainly made up of a modified form of the amyloid protein (Fig. 1).

Disease symptoms start with memory impairment and evolve later with dramatic alterations of intellectual ability and loss of control over body functions. In most cases, Alzheimer's disease becomes patent in the elderly and its incidence dramatically increases with aging: at 70 years of age, approximately 5% of the population is affected, but the percentage jumps to 25% at 85 years of age.

Fig. 2: Estimated progression of cases of Alzheimer disease in the United States (millions of persons affected). (Credit: Eric H. Chudler - "Neuroscience for kids")

As demonstrated by the graph of Fig. 2, the improvement of health and living conditions, together with longer life expectancy, unavoidably lead to an increase of Alzheimer patients, who at present cannot be effectively treated, except with some accessory drugs. It has been said that the disease, which tends to aggravate when health and social conditions improve, is like a time-bomb of civilization. Perspective therapies, so far largely theoretical,are based on the possibility to perform transplants with young cells that could substitute those undergoing degeneration, similarly to what has been done with some success for Parkinson's disease during the past years.