There are many different kinds of neurodegenerative disease, such as prion diseases, Alzheimer's,
Parkinson's, Huntington's, and ALS.
Some of these conditions injure particular kinds of cells, others are more widespread.
Degeneration is typically the result of apoptosis, which is triggered by collections (aggregates) of
misfolded proteins that disrupt normal cellular function.
Transmissible spongiform encephalopathy
Contagious brain disease, such as mad cow and Creutzfeldt-Jacob disease, whose degenerative
process gives the brain a sponge-like appearance
Caused by accumulation of misfolded prion protein
Spongiform means that when they die their brain resembles a sponge
Their brain has holes in it due to neurons that are not there anymore
Protein that can exist in two forms that differ only in their three-dimensional shape
The prion protein is at risk of being misfolded
When a misfolded protein bumps into another well-folded one, it can cause this one to
also become misfolded
This creates clumps of misfolded proteins that all bind together
Accumulation of misfolded prion protein is responsible for transmissible spongiform
However, they are not the most prominent of the degenerative disorders
Sporadic disease (another word for idiopathic diseases)
Disease that is not obviously caused by heredity or an infectious agent
Has an unknown cause
Prion protein diseases can be genetic or sporadicand both forms can be transmitted to others
by means of a simple misfolded prion protein
But prion proteins often fall under the sporadic category
Can be transmitted when an individual eats the neural tissue of another individual
This cannot be prevented by cooking the neural tissue So once there is an outbreak, it becomes very dangerous
Misfolded proteins often encourage more misfolding to occur. Thus, most neurodegenerative
diseases can easily spread from neuron to neuron and from brain to brain.
Bottom panel: anytime regular prion proteins was made in the cell, it would immediately be
degraded even if the protein was well folded
Loss of cognitive abilities such as memory, perception, verbal ability, and judgment that is
caused by an organic brain disorder.
Common causes are multiple strokes and Alzheimer's disease
Alzheimers is a form of dementia
Dementia is typically seen in old age
Blanket term for several different types of degenerative disorders
Degenerative brain disorder typically caused by misfolded b-amyloid protein
Clump together in the brain and causes neurons to undergo apoptosis
You dont have holes in the brain in this case because the clumps dont dissipate
Causes progressive memory loss, motor deficits, and eventual death
Occurs in approximately 10 percent of the population above the age of sixty-five and almost 50 percent
of people older than eighty-five years Produces severe degeneration within and around the hippocampus, neocortex (especially the
association cortex of the frontal and temporal lobes), and other places
Degeneration produces progressive loss of memory and other mental functions
Brain of Alzheimers patient versus normal brain
Alzheimers disease (AD) is characterised by progressive memory loss and other mental functions.
Protein found in excessive amounts in brains of patients with Alzheimer's disease
When it clumps together because it is misfolded, it forms amyloid plaques
Extracellular deposit containing a dense core of -amyloid protein surrounded by degenerating
axons and dendrites and activated microglia and reactive astrocytes
Start to be surrounded by other neural tissues (axons, dendrites, etc.)
Protein that is a component of microtubules, part of the cell's transport mechanism. Tau
protein becomes hyper-phosphorylated in Alzheimer's disease, which disrupts transport.
In Alzheimers, the Tau proteins have tons of phosphate groups put on them
They break down over time and reforms neurofibrillary tangles
Dying neuron containing intracellular accumulations of twisted Tau protein filaments that
formerly served as cell's internal skeleton
This begins to clump up as well -amyloid precursor protein (APP)
Protein that is the precursor for -amyloid protein. The gene for this protein is located on
chromosome 21, which is the one duplicated (triplicated) in down syndrome.