Dementia

Originating from the Latin word demens, meaning “without a mind,” the term dementia historically designated social and intellectual deterioration associated with old age. However, beginning in the late 19th century, the medical characterization of dementia increased in specificity with the rise of biological sciences and the advent of new technologies to study the brain. As a diagnostic category, the term now encompasses about 70 different conditions associated with abnormal cognitive decline. Seminal in this evolution was the 1906 description by German neuropathologist Alois Alzheimer of a presenile form of dementia in a younger woman in her early 50s. In 1910, famous psychiatrist Emil Kraepelin reviewed Alzheimer's findings and claimed them to be suggestive of a new condition he called “Alzheimer's disease” to distinguish it from senile dementia, a disease experts then believed to occur only at a later stage in life. Later research revealed that Alzheimer's disease and senile dementia shared similar clinical and histological features, and by the 1970s, the medical community reached a consensus to use the term Alzheimer's disease to designate both conditions, irrespective of age of onset.

The 1980s marked the development of standardized diagnostic criteria under the impetus of the Alzheimer Disease and Related Disorders Association and the National Institute of Neurological and Communicative Diseases. This development allowed more precise clinical identifications of distinct forms of dementia, including Alzheimer's disease, vascular dementia, and Pick's disease, among others. It also permitted more accurate estimates of the number of dementia cases within the general population.

Current findings put the prevalence of dementia in Western countries at between 2 and 9 percent of people over the age of 65, with rates for those age 85 years and over as high as 50 percent. Alzheimer's disease is by far the most common form of dementia and accounts for approximately three quarters of all cases. In the United States alone, the Alzheimer Society reports that Alzheimer's disease currently affects an estimated 4.5 million Americans, and projections for 2050 put this number at between 11.3 and 16 million. Worldwide, dementia affects an estimated 28 million individuals, a figure projected to increase to 80 million by 2040. These estimates make dementia one of the most common causes of morbidity in elderly people.