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.