Alzheimer's disease was originally named after Dr. Aloysius "Alois" Alzheimer, who was a German doctor that specialized in psychiatry and neuropathology. The term "Alzheimer's disease" was first coined in a book written by Dr. Emil Kraepelin, an accomplished German psychiatrist and said mentor of Dr. Alzheimer.

Dr. Alzheimer was born in Markbreit am Main Germany on June 14, 1864, and went on to become a doctor after earning his degree from Würzburg University. The case that eventually led to the nomenclature for the disease we now know as Alzheimer's disease began with a woman named Frau Auguste D, a 51 year old patient who was admitted to the Municipal Mental Asylum, the hospital where Dr. Alzheimer was a physician. The patient exhibited worsening behavioral and cognitive symptoms such as short term memory loss, auditory hallucinations, paranoia and aggressiveness. Dr. Alzheimer began to study the patient. At the time of the patient's death in 1906, Dr. Alzheimer had begun working at the Anatomical Laboratory of the Royal Psychiatric Clinic at a university in Munich, where he worked with Dr. Emil Kraepelin. After her death, the patient's brain and records were sent to the clinic for further research.

While Dr. Alzheimer's observations were not classified as new discoveries in the medical field, he identified in the woman's brain characteristics associated with patients who have experienced severe dementia. Dr. Alzheimer identified characteristics such as a thinning cerebral cortex, peculiar clumps now called amyloid plaques and entangled bundles of fibers that came to be known as neurofibrillary tangles. Such changes in the brain had previously been observed, and a common speculation is that Dr. Alzheimer did not make a clear attempt to classify his findings as a new disease. However, a speech on his reported findings in 1906 is believed by many to be the first collective presentation linking the symptoms of presenile dementia with the physical changes that had taken place in a patient's brain.

Nonetheless, in Handbook of Psychiatry (eighth edition), Dr. Kraepelin commented on the findings from the autopsy and included use of the phrase "Alzheimer's disease" in his description. In 1911, Dr. Alzheimer used the term again in a paper. Though many argue to this day that Dr. Alzheimer was not responsible for the discovery of the disease, the term "Alzheimer's disease" caught on. Within a few years, the name Alzheimer's disease was well known and began to be used by physicians for diagnosis.

Other characteristics have since been discovered that help physicians identify likely cases of Alzheimer's disease, though there are no definite means of diagnosing the disease until after death.