More than 55 million people worldwide have dementia (see stats here); Alzheimer’s disease makes up nearly 70% of all cases. Old age is the greatest risk factor in developing Alzheimer’s, though genetic components can lead to early onset.
History
The first case of Alzheimer’s disease dates back to the turn of the 20th century when Dr. Alois Alzheimer came across 51-year-old Auguste Deter, struggling with sudden memory issues and aggressive, irrational behavior.
After Deter’s death, Alzheimer examined her brain and found it had a strange collection of molecular pileups.
In a twist of fate, Alzheimer’s findings were lost until 1995, when they were rediscovered and published in a translated version.
Causes
Scientists now know these “pileups” are created by two distinct molecular formations: plaques and tangles.
Plaques are made from the amyloid beta peptide, or A-beta, which forms when an amyloid precursor protein is split. The sticky A-beta can aggregate into complex molecules that pile up near neurons and elsewhere in the brain.
Tangles are misfolded proteins known as tau proteins. Regular tau helps support healthy neurons. Misfolded tau proteins congregate inside neurons and spread across synapses into healthy neurons, where they can cause healthy tau to misfold.
It is unknown which molecule—plaques or tangles (or both, or something else)—is the primary driver of Alzheimer’s. See a deep dive into the debate here.
As neurons lose their ability to communicate and die off, the brain shrinks. This shrinkage starts in the hippocampus, a part of the brain associated with memory and learning, and leads to impaired memory, communication, and decision-making.
Treatment
Historically, Alzheimer’s disease could only be diagnosed for certain once a person’s brain was analyzed after death. Currently, there’s no cure for Alzheimer’s, and there’s no single test to detect it.
Patients may now receive a diagnosis through medical examinations, including neuropsychological testing, brain imaging, and blood tests, the latter of which may assist with early diagnosis.
Treatments tend to focus on slowing the formation of, or breaking up, plaques or tangles. Some treatments have been shown to modestly slow the progression of symptoms, but none have halted or reversed the disease.
Referenced Resources
- Alzheimer’s disease is the leading cause of dementia and risks rise after age 65
- Five to ten percent of Alzheimer’s cases are early-onset
- The first identification of Alzheimer’s was made in 1906
- Read the original 1907 paper on the first known Alzheimer’s patient
- “Plaques” and “tangles” are top potential causes of Alzheimer’s—but questions remain
- Alzheimer’s can cause brain shrinkage of between 10% and 30%
- More than 200 drug trials for Alzheimer’s have failed or been abandoned since 2010
- Early-onset Alzheimer’s can appear as early as age 30
