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Figure 4. Number of Americans age 65 and older living with Alzheimer's disease, 2015-2050. Adapted from "Changing the Trajectory of Alzheimer’s Disease: How a Treatment by 2025 Saves Lives and Dollars," by Alzheimer's Association, 2023.
Figure 5. Alois Alzheimer. Adapted from "Who is Alois Alzheimer?" by Alzheimer's Disease International, 2022.
History of Alzheimer's Disease
History of Alzheimer's Disease
In the early 1900’s, the term ‘Alzheimer’s disease” was coined after a German physician, Alois Alzheimer, discovered a deteriorated cerebral cortex alongside senile plaque formations at neurons and intertwined nerve fibers in the brain of a woman who had been exhibiting mania, agitation, and memory loss prior to her death (Yang et al., 2016). The findings in the autopsy of the decedent, Auguste Deter, led Alzheimer to announce that these cognitive symptoms in life were caused by the deterioration of the cerebral cortex. Four years later, Alois’s co-researcher, Emil Kraeplin, published Alzheimer’s findings in a book and described these symptoms as “Alzheimer’s Disease.”
Processes of Alzheimer's Disease
Processes of Alzheimer's Disease
Research shows that healthy brains function through the work of neurons that process and communicate information throughout the brain and to different parts of the body. Neurons use signals, either chemical or electrical, to communicate this information between one another (National Institute on Aging, 2017). For brains that live with Alzheimer’s, communication amongst these neurons has been interrupted, which eventually leads to the loss of function or death of these cells. Three broad processes are believed to cause neuron loss and dysfunction: the accumulation of amyloid plaques, neurofibrillary tangles, and chronic inflammation.
Figure 6. Stages of Alzheimer's. Adapted from "Brain Atrophy and Alzheimer's," by the Mayo Foundation for Medical Education and Research, 2023.
The three related processes of neuron death and disruption result in the shrinking, or atrophy, of the brain (see fig. 1). As neurons decline in function and/or die, communications across brain cells are disrupted, cells are unable to effectively metabolize oxygen, and the regenerative capacity of neurons severely declines. During the early stages of neuron loss, patients often begin experiencing memory loss followed by deteriorating abilities in “language, reasoning, and social behavior” as the cerebral cortex becomes further damaged (National Institute on Aging, 2017). Atrophy throughout the rest of the brain eventually disrupts an individual’s sleeping patterns, mental health, physical abilities, continence, and communication (National Institute on Aging, 2022).
Severe Alzheimer’s is associated with increasingly critical physical illnesses and decline, little to no awareness or ability to communicate, consistent bedridden states, weight loss, and incapacity to eat or swallow. These symptoms are thought to be caused by brain atrophy, but it is important to recognize the undetermined and complicated nature of this disease. Physical changes to the brain throughout the stages of Alzheimer’s are similar but not identical among all patients. Research is still underway to understand which processes of decline in Alzheimer’s patients are a cause of the disease and which changes are a result of the disease.
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