Alzheimer's disease: L14

Question 1

what percentage of all dementias are alzheimer’s disease (AD)

Answer 1

50%

Question 2

prevalence

1. 65-70
2. > 80

Answer 2

1. 2%

2. 20%

Question 3

diagnosis of AD

Answer 3

• definitive AD diagnosis only made on pathology (brain biopsy)
• can diagnose dementia of the alzheimer type (DAT) during life

Question 4

AD

• how it arises
• early onset: 3 genes mutate

Answer 4

• sporadically
• APP, PSEN1 & PSEN2
• all alter production of Aβ peptide (principle component of senile plaques)

Question 5

• individuals with downs syndrome are what to AD?

- precipitating factors?

Answer 5

• prone to develop -> occurring in 40s
• unknown: Godbolt suggests head injury
• sudden decompensation

Question 6

clinical features of DAT

1. onset
2. course

Answer 6

1. insidious (gradual)
2. slow deterioration
   - > death M = 8.5 y after onset

Question 7

DAT phase 1 symptoms

Answer 7

• failing memory
• muddled inefficiency in activities of daily living (ADLs)
• spatial disorientation
• mood disturbance

Question 8

DAT phase 2 symptoms

Answer 8

• intellect & personality deteriorate
• focal symptoms appear (speech defects)
• disturbance of posture = increased muscle tone
• delusions/hallucinations

Question 9

DAT phase 3 symptoms

Answer 9

• terminal stage
• profound apathy
• bed ridden
• lose neurological function
• bodily wasting

Question 10

Mckhann criteria

1. probable

Answer 10

• deficits 2+ areas of cognition: Amnestic presentation & non amnestic (language, visuospatial)
• worsening of memory/ cog.functions
• no disturbance of consciousness
• 40-90 y/o
• biomarkers (blood profile)

Question 11

Mckhann criteria

2. possible

Answer 11

• variations in onset, presentation or clinical course

- can be made in the presence of another disorder (not considered the cause of the dementia)

Question 12

Mckhann criteria

3. definite

Answer 12

• histopathological evidence of AD obtained from biopsy or autopsy

Question 13

Pathology

Answer 13

• atrophied brain (shrunk)
• degeneration of neurons
• glial cell proliferation
• extensive senile plaques
• extensive neurofibrillary tangles
• > intensity of features correlates with severity of dementia

Question 14

course of neuropathological changes

Answer 14

1. hippocampus/ MTL
2. spreads posteriorly to parietal cortex
3. spreads to frontal cortex

Question 15

clinical pattern of cognitive impairment in DAT - amnestic presentation

• initially
  1. anterograde
  2. retrograde

Answer 15

MTL memory impairment (hippocampal)

1. anterograde:
   - impaired new learning
   - impaired delayed recall
   - poor recognition memory
2. retrograde
   - intact for remote memories
   - reduced for recent retrograde memories

Question 16

clinical pattern of cognitive impairment in DAT - amnestic presentation

1. Wernicke
2. Visuospatial

Answer 16

1. Wernicke aphasia (temporal lobe)
   - word finding difficulties
2. topographical disorientation (parietal lobes)
   - dyspraxia, agnosia & acalculia

Question 17

clinical pattern of cognitive impairment in DAT - amnestic presentation

1. behaviour
   - > must see what for diagnosis of DAT?

Answer 17

1. behaviour (frontal lobes)
   - apathy + agitation
   - > functional impact, day to day interference

Question 18

Treatment/prevention of AD

1. pharmacological
   - > what does it offer

Answer 18

1. re-balance action of acetylcholine
   - > maintain quality of life for longer (QOL)
   - no clear evidence that anything prevents AD (e.g. diet, cognitive activity)

Question 19

AD vs normal ageing

• similarity
• difference

Answer 19

• similar changes occur in both

- cognitive function in DAT is significantly impaired to same age peers

Question 20

MTL (mild cognitive impairment) does what to chances of developing AD?

Answer 20

raises the likelihood of developing AD

Question 21

AD progression overview

Answer 21

MTL -> posterior TL -> frontal TL