2-Minute Neuroscience: Alzheimer’s Disease

Welcome to 2 minute neuroscience, where I
simplistically explain neuroscience topics in 2 minutes or less. In this installment I will discuss Alzheimer’s
disease. Alzheimer’s disease is the most common form
of neurodegenerative disease, meaning it is characterized by the degeneration and death
of neurons. It is classified as a type of dementia, a
term that refers to a category of brain disorders that involve memory loss and cognitive impairment. Alzheimer’s most often affects adults over
the age of 65.

The causes of the disease are not well understood
and genetics and environmental factors are thought to be involved. Alzheimer’s disease is associated with neuronal
death throughout the brain, which can be extensive enough that regions of the brain appear atrophied
(or shrunken) compared to a healthy brain. A hallmark sign of Alzheimer’s disease is
the formation of clusters of misfolded proteins both inside and outside of neurons.

One of these proteins, amyloid beta protein,
is found in the extracellular space around neurons in a healthy brain. During Alzheimer’s, however, misfolded forms
of amyloid beta clump together in deposits called amyloid plaques. Another protein called tau protein, which
is normally found inside neurons and involved in maintaining neuronal structure, is also
found in a misfolded state in Alzheimer’s. It accumulates inside neurons in bundles called
neurofibrillary tangles. Although amyloid plaques and neurofibrillary
tangles are hallmark signs of Alzheimer’s disease, it is unclear if they contribute
to the neurodegeneration or are part of the brain’s response to it. The most common treatments for Alzheimer’s
disease involve drugs that inhibit the activity of acetylcholinesterase, an enzyme that breaks
down the neurotransmitter acetylcholine. The drugs, called acetylcholinesterase inhibitors,
increase levels of acetylcholine, which is thought to promote healthy cognition and memory. The effects of these treatments are modest,
however, and they do not stop neurodegeneration in Alzheimers; thus, they are not a cure for
the disease..

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