Alzheimer’s disease

In 1907, when Alois Alzheimer first described the clinical and pathologic findings in the case of 54-year-old Auguste D., her severe and progressive dementia had been grossly obvious, and the pathologic findings were clearly evident.1 Because the condition occurred in a relatively young woman, it was con-sidered a “presenile” disorder, and “Alzheimer’s disease” (named by Kraepelin for his pupil) was considered a rare condition for many decades.

Almost 70 years later, when it was pointed out that the dementia affecting the majority of cognitively impaired elderly people was virtually identical both clinically and pathologically to Alzheimer’s description,2 what had been a rarity was recognized as an important public health problem. Soon, physicians began to look for the cause(s) and treatments for AD, and epidemiologists began to assess the frequency of AD in populations throughout the world. Unfortunately, there was no single, simple test for AD, and it was clear that research into the etiology and treatment of AD needed more reliable diagnostic criteria than those in use at that time.

To address this issue, a Work Group hammered out criteria for possible, probable, and definite AD in 1984.3 These criteria (the National Institute for Neurological and Communicative Diseases and Stroke–AD and Related Disorders Association [NINCDS-ADRDA] criteria) were designed to be conservative and accurate, using adequate severity of AD and careful exclusion of other potential causes of dementia. Their goal was to identify carefully examined patients with AD for therapeutic trials of drugs, for genetic studies, and for case–control analyses of etiologic factors. The NINCDS-ADRDA criteria have proven to be highly reliable for identifying patients with AD in research clinics, where 85 to 90% of diagnoses have typically been confirmed at autopsy.

A large number of epidemiologic studies have since examined the prevalence of AD by age group. …