<P> Prevalence of AD in populations is dependent upon different factors including incidence and survival . Since the incidence of AD increases with age, it is particularly important to include the mean age of the population of interest . In the United States, Alzheimer prevalence was estimated to be 1.6% in 2000 both overall and in the 65--74 age group, with the rate increasing to 19% in the 75--84 group and to 42% in the greater than 84 group . Prevalence rates in less developed regions are lower . The World Health Organization estimated that in 2005, 0.379% of people worldwide had dementia, and that the prevalence would increase to 0.441% in 2015 and to 0.556% in 2030 . Other studies have reached similar conclusions . Another study estimated that in 2006, 0.40% of the world population (range 0.17--0.89%; absolute number 26.6 million, range 11.4--59.4 million) were afflicted by AD, and that the prevalence rate would triple and the absolute number would quadruple by 2050 . </P> <P> The ancient Greek and Roman philosophers and physicians associated old age with increasing dementia . It was not until 1901 that German psychiatrist Alois Alzheimer identified the first case of what became known as Alzheimer's disease, named after him, in a fifty - year - old woman he called Auguste D. He followed her case until she died in 1906, when he first reported publicly on it . During the next five years, eleven similar cases were reported in the medical literature, some of them already using the term Alzheimer's disease . The disease was first described as a distinctive disease by Emil Kraepelin after suppressing some of the clinical (delusions and hallucinations) and pathological features (arteriosclerotic changes) contained in the original report of Auguste D. He included Alzheimer's disease, also named presenile dementia by Kraepelin, as a subtype of senile dementia in the eighth edition of his Textbook of Psychiatry, published on 15 July, 1910 . </P> <P> For most of the 20th century, the diagnosis of Alzheimer's disease was reserved for individuals between the ages of 45 and 65 who developed symptoms of dementia . The terminology changed after 1977 when a conference on AD concluded that the clinical and pathological manifestations of presenile and senile dementia were almost identical, although the authors also added that this did not rule out the possibility that they had different causes . This eventually led to the diagnosis of Alzheimer's disease independent of age . The term senile dementia of the Alzheimer type (SDAT) was used for a time to describe the condition in those over 65, with classical Alzheimer's disease being used to describe those who were younger . Eventually, the term Alzheimer's disease was formally adopted in medical nomenclature to describe individuals of all ages with a characteristic common symptom pattern, disease course, and neuropathology . </P> <P> Dementia, and specifically Alzheimer's disease, may be among the most costly diseases for society in Europe and the United States, while their costs in other countries such as Argentina, and South Korea, are also high and rising . These costs will probably increase with the ageing of society, becoming an important social problem . AD - associated costs include direct medical costs such as nursing home care, direct nonmedical costs such as in - home day care, and indirect costs such as lost productivity of both patient and caregiver . Numbers vary between studies but dementia costs worldwide have been calculated around $160 billion, while costs of Alzheimer's disease in the United States may be $100 billion each year . </P>

Where did the term alzheimer's come from