Lecture 26: Alzheimer's Disease Flashcards
Symptoms of Alzheimer’s
- memory loss
- cognitive difficulty
- symptoms worsen as the disease continues to develop
Key differences in normal and “Alzheimer’s” brain
-Alzheimer’s brain:
- shriveled up cortex, messes up memory and thinking
- ventricles grow larger
- brain becomes smaller than normal
What are plaques and tangles composed of?
- plaques: composed of Aβ
- tangles: composed of abnormal tau
What CAUSES neuronal cell death in Alzheimer’s?
-errors in Aβ and tau action
Two pathological changes commonly observed in AD brains
- Senile plaque outside of cell
2. neurofibrillary tangles
How do neurons interact?
-by sending electrical signals throughout the body
What are plaques?
-deposits of a protein fragment called beta-amyloid that build up in the spaces between nerve cells
What are tangles?
-are twisted fibers of another protein called tau that build up inside cells.
Two Types of Alzheimer’s
- Early-onset
- Late-onset
Early-onset AD
- happens to people before age 65, mostly in their 40s and 50s
- rare; only 10% of people with AD
Late-onset
- happens to people age 65+
- most common form
Risk factors for AD
- age
- gender
- family history
- down syndrome
- head injuries
Why was bexarotene tried as an Alzheimer’s drug? What were the results? What was the explanation for these results?
- Used because it lowered brain Aβ, reduced plaque load, and improved behavioral deficits in mouse models of Alzheimer’s disease.
- However, it didn’t work on humans because it does not get across the human blood brain barrier nearly as well as the mouse
Why have AD drugs failed so many times?
- maybe we are giving the drugs too late
- maybe people already “have” AD before any outward symptoms
- maybe the pathological pathway is already underway and irreversible
