Lecture 12: Prevention Flashcards
1
Q
Without cure, increasing interest prevention dementia
A
- Individual differences in vulnerability
- no dementia symptoms, despite brain pathology
- modifiable risk factors dementia
- e.g. diet, exercise, leisure activities?
2
Q
no dementia symptoms despite brain pathology:
From: Schneider et al., 2009
A
- > 50% cognitively normal persons had dementia pathology
3
Q
Ageing and AD; Lessons from the Nun-Stud:
- Cognitive reserve (CR)
A
no dementia symptoms despite brain pathology
- Brain structure (pathology) not 1:1 brain function (cognition)
- Characteristics person that protect against effects brain changes
- can help prevent dementia
Cognitive reserve (CR) – theoretical model to explain discrepancy dementia pathology in brain and absence symptoms
4
Q
¤Cognitive reserve (CR)
A
- Brain attempts to cope with brain damage (Stern)
- using preexisting cognitive processing or compensatory approaches
- high CR - better able to copy with same amount of brain damage than low CR
- fewer symptoms with same amount of damage
- CR not specific cognitive skill
- CR attenuate decline in range of cognitive tasks (e.g. information processing speed, flexibility, memory)
5
Q
- Cognitive reserve (CR)
- Brain reserve model
A
- Cognitive reserve (CR)
- CR is an effect of brain function
- Contrasts with brain reserve model
- CR is an effect of brain function
- Brain reserve model – reserve effect of brain size, numbers of neurons
- Bigger brain protects longer against progressing pathology
6
Q
- CR not same as adjusting for education
A
- At baseline, before onset of pathology:
- 70 year old with 8 years of education will recall fewer words than 70 year old with 19 years of education
- After onset pathology:
- 19 years of education needs to sustain more pathology than 8 years of education to reach impaired range
- CR - why person with 19 years of education remains at baseline level longer than person with 8 years
7
Q
Cognitive reserve (CR)
- What contributes to CR?
- (Stern et al., 1994)
A
- Evidence for education, occupation, leisure activities
- Higher education, higher occupation contribute to reserve
(Stern et al., 1994)
- Education: high => 8 yrs, low < 8 yrs
Low occupation: unskilled, skilled trade, clerical
High occupation: managerial, professional
8
Q
Prevalence of MCI
- lower prevalence with more years of education
- From: Petersen et al (2010)
A
9
Q
Cognitive reserve (CR)
- What contributes to CR?
- Evidence for education, occupation, leisure activities
- (Scarmeas et al., 2001)
A
More active leisure activities contribute to reserve
- Community sample, followed up over 7 years
- More leisure activities, reduced risk of dementia
- Most strongly associated with reduced risk:
- Intellectual activities (e.g. reading, playing cards)
- Physical activities (e.g. walking, exercise)
- Social activities (e.g. visiting friends and family, going to movie or restaurants)
- Low leisure group diagnosed dementia at earlier age than high leisure group
10
Q
- Cognitive reserve (CR)
- CBF and CR
- (Stern et al., 1995)
A
CBF and CR
- Negative correlation education/occupation with brain metabolism
- More complex occupations – lower metabolism (matched for AD severity)
- Occupations requiring more interpersonal skills associated with less blood flow in parietal lobe – more pathology
11
Q
Cognitive reserve (CR)
- Amyloid deposition and CR
- (Rentz et al. 2010)
A
- Amyloid deposition and CR
- Cognitively normal older adults
- Amyloid in precuneus correlated negatively with memory performance
- No correlation in high CR
12
Q
How does cognitive reserve protect?
- Puzzling CR - suggests discrepancy brain structure and function
A
- Solution: CR has basis in brain, in differences synaptic organization (networks) or use of specific brain regions
- Life experience associated with CR also affects brain structure
- education associated with microstructure hippocampus, not volume
13
Q
How does cognitive reserve protect?
- Piras et al (2011): 150 healthy adults (18 – 65 years)
- more years in education:
A
- more years in education – fewer microstructural changes in hippocampus (mean diffusivity - MD)
- MD would reflect loss of neurons
14
Q
How does cognitive reserve protect?
- Stern: neural implementation CR - neural reserve and neural compensation
A
- Neural reserve: inter-individual differences in brain networks that underlie task performance
- Neural compensation: persons with brain pathology use brain regions or network not normally used by healthy persons
15
Q
Neural compensation
- Cerebral blood flow (CBF) in location matching task
A
- Less increase rCBF in posterior areas in older adults.
- Increase rCBF in frontal areas in older adults, which is absent in younger adults
16
Q
¨How to estimate CR?
- Individual characteristics
- known to reduce risk of dementia (e.g. education)
- Cumulative life experiences:
A
Cumulative life experiences:
- Range of life experiences - combined for comprehensive estimate CR
- Lifetime of Experiences Questionnaire (LEQ):
- social, academic, occupational, leisure activities at different stages of life
18
Q
- Cognitive reserve (CR)
- cognitive decline
A
- cognitive decline more rapid in persons with high CR than in persons with low CR
19
Q
- Cognitive reserve (CR)
- 312 persons (67-103 yrs) with diagnosis AD
- Repeated testing before and after diagnosis
- (Scarmeas et al., 2006)
A
- More pathology high CR than low CR at time diagnosis.
- Compensation for brain damage no longer possible
27
Q
Common limitation
- Design
- Measures
A
- Design: Cross-sectional / correlational / observational
- Measures: often self report
