Etiology and Pathogenesis:
Eleanor P Lavretsky
Fredda L Leiter
Lissy F Jarvik
On the whole, it is evident that we are dealing
with a peculiar, little-known disease process.
In recent years these particular disease-processes
have been detected in great numbers. This fact
should stimulate us to further study and analysis
of this particular disease. We must not be satis-
fied to force it into the existing group of well‐
known disease patterns. It is clear that there ex-
ist many more mental diseases than our
Life expectancy has increased dramatically during this century due to many factors, including the discovery of cures for many infectious diseases, the development of sophisticated medical and surgical technologies, and the promotion of healthier lifestyles. Many people now reach an age at which degenerative diseases of the brain, particularly Alzheimer's disease, become common. Dementia, the loss of our most human qualities—reasoning, memory, and language—formerly was accepted as the natural consequence of reaching advanced old age. A grandparent who became confused and forgetful suffered from "hardening of the arteries in the brain." In the past, two etiologic factors were thought to be responsible for initiating the dementing process: advanced age and arteriosclerosis or atherosclerosis. It is now obvious that they are neither necessary nor sufficient for the development of dementia.
Old age is an important risk factor for Alzheimer's disease, but epidemiplogic studies have demonstrated that a large proportion of individuals do not have dementia, no matter how old they are. The number of individuals at a given time (prevalence) with dementia from all causes ranges from 5% to 10% among persons age 65 and older, and increases exponentially with age. A recent study performed in England demonstrated that new cases per year (incidence) doubled