Alzheimer's disease Flashcards

1
Q

What factors contribute to the development of AD?

A
Environmental factors (90% of cases)
Mutations in genes increase risk
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2
Q

What are 5 clinical symptoms of Alzheimer’s disease?

A

Memory loss: esp. recently acquired info
Language problems: stopping mid-sentence
Personality changes: confusion, fear, anxiety
Poor judgement: e.g. when dealing with money
Disorientation/confusion

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3
Q

What is the main risk factor of Alzheimer’s disease?

A

Advancing age

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4
Q

What classes of drugs are used to treat Alzheimer’s disease?

A
  1. Anticholinesterases

2. NMDA receptor antagonists

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5
Q

What are the 3 main theories regarding the underlying pathophysiology of AD?

A
  1. Amyloid hypothesis
  2. Tau hypothesis
  3. Inflammation hypothesis
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6
Q

What is the amyloid hypothesis?

A
  1. APP cleaved by β-secretase
  2. Soluble APPβ released, C99 fragment remains
    3.C99 digested by γ-secretase releasing β-amyloid (Aβ) protein
    Aβ = forms toxic aggregates on neurons + microvasculature
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7
Q

What is the tau hypothesis?

A

Hyperphosphorylated tau is insoluble+ self-aggregates to form neurotoxic intracellular neurofibrillary tangles
Also results in dissociation of tau from microtubules + microtubule instability

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8
Q

What is the inflammation hypothesis?

A

Microglia (specialised CNS immune cells) become activated in AD resulting in:
increased release of inflammatory mediators + cytotoxic proteins
increased phagocytosis
decreased levels of neuroprotective proteins

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9
Q

Compare the anticholinesterases used to treat AD

A

Donepezil: reversible cholinesterase inhibitor, long plasma half-life
Rivastigmine: pseudo-reversible AChE + BChE inhibitor, 8 hour half-life, reformulated as transdermal patch to counteract BChE inhibition side effects
Galantamine: reversible cholinesterase inhibitor, 7-8 hour half-life, α7 nAChR agonist (increases ACh available)

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10
Q

What type of drug is memantine? When is memantine used in AD?

A

NMDA receptor antagonist

Only in moderate to severe AD

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11
Q

Describe memantine

A

Use-dependent non-competitive NMDA receptor blocker
Low channel affinity
Long plasma half-life

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12
Q

What does normal physiological processing of the amyloid precursor protein involve?

A
  1. Amyloid precursor protein (APP) cleaved by α-secretase
  2. Soluble APPα released, C83 fragment remains
  3. C83 digested by γ-secretase
    End-products of this pathways are non-toxic + removed
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13
Q

Describe the normal physiology of Tau

A

Tau = soluble protein associated w/microtubules in neurons

Involved in stabilisation + assembly

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14
Q

What molecules/ processes have been unsuccessful targets in AD?

A

Gamma secretase inhibitors (target both pathophysiological + physiological)
Antibodies against B-amyloid plaques
Tau inhibitors (reduce aggregation)

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