Cognitive decline

Question 1

Define Alzheimer’s disease

Answer 1

A progressive neurodegenerative disease characterised by memory loss, cognitive impairment and functional decline

Question 2

Neuropathophysiology of AD

Answer 2

Amyloid plaques
Neurofibrillary tangles (Tau)
Shrunken cortex
*Hippocampal and cortical (grey matter) atrophy

Question 3

Familial Alzheimer’s disease mutations:

Answer 3

Presenilin 1 (PSEN1) (Chr 14)
Presenilin 2 (PSEN2) (Chr 1)
Amyloid precursor protein (APP) genes (Chr 21)

Question 4

Familial mutations are associated with which AD?

Answer 4

Early-onset AD

Symptoms beginning 30-70y

Question 5

Genetic ‘clues’ genes that increase the risk of AD are…

Answer 5

Genetic variant of Apolopoprotein E (APOE) gene of chromosome 19 increases a person’s risk of AD

APOE E2 E3 E4
APOE ε3, the most common allele, is believed to play a neutral role in the disease

APOE ε4 increases risk for Alzheimer’s disease and is also associated with an earlier age of disease onset. Having one or two APOE ε4 alleles increases the risk of developing Alzheimer’s.

Question 6

What is the APOE gene responsible for?

Answer 6

Makes proteins that carries cholesterol and other fats in the bloodstream

Question 7

How is Alzheimer’s cognitive function quantified?

Answer 7

Questionnaires:
MOCA
MMSE
ADAS-cog

Question 8

Molecular pathology of AD

Answer 8

Extracellular plaques ‘senile plaques’ -> accumulations of insoluble peptides (ABeta fibrils -> derived from APP)
(Can form plaques around blood vessels)

Tangles of hyper-phosphorylated diseased tau proteins
(a protein encoded by MAPT microtubule associated protein tau)

A beta accumulation is first leading to tau hyper-phosphorylation and tangle formation that CAUSES damage of function
(tau is required for abeta to have its toxic effects)

Question 9

How is Beta cleaved?

Answer 9

From amyloid precursor protein APP by secretes enzymes: Alpha, beta, gamma

*some drugs inhibit b secretase