Polyphenols and Cognitive Function Flashcards
What are some potential effects of flavonoids on health?
- Reduced cancer risk
- Lower stroke risk
- Reduced bp
- Improved lipid profile
- improved endothelial function
What is an epidemiology study?
groups in a population – e.g. is there evidence they have a cog benefit – to show an association between high intake in polyphenol and physiological/cognitive outcome
How did blueberry supplementation affect mice?
- Mice given blueberries at a young age did not show ageing deficits as controls
- If give older mice blueberries – cog improve and didn’t show deficit like control
- Increase LTP & object recognition (Maher et al 2006)
- Increase hippocampal neurogenesis (more neurons) & spatial memory (Morris Water Maze, Casadesus et al 2004)
What did the Krikorian (2010b) study find about grape juice?
- Significantly better verbal recall at 12 weeks in grape juice group
- But grape juice group were younger than control (75 years vs 80 years – ns)
What did Krikorian (2010) find about blueberries?
- Better Verbal PAL – sig different on verbal task
- No sig effect on CVLT
- used the placebo from grape study in this blueberry study
- both drinks noticeably different
What did the Krikorian fMRI study find?
- Grape juice associated with increased activation in
- right anterior (A) and posterior (B) cortical regions at follow-up
- small sample size
What did the Leeds study find about grape juice flavaniods?
- initial benefit of grape juice and still benefitting when they took the placebo
- Washout wasn’t long enough – hadn’t actually gone back to baseline
- Tower of Hanoi – completion time was greater for grape juice, and not sig different in arm 2 because they still have effect of grape juice
What do effects of crossover designs suggest about polyphenol treatment?
particular carryover effects of active treatments
average = 4 weeks
What does the evidence suggest about the effects of polyphenols on cog function?
- Spatial memory enhanced by PP
- Verbal memory & executive function enduring effects of PP
- Effects on verbal & spatial memory & executive function – commensurate with effects in animal studies
- Effects more apparent in parallel group designs though crossover studies control for individual differences which could influence outcomes of parallel studies
- Also, on indices of psychological state e.g. stress/ anxiety/ mood
What did Kennedy’s study (2010) on Resveratrol find?
- No effects on cognition
- No effects on verbal memory test
- but young sample (is the test hard enough?)
What did Brickman (2015) find when using fMRI and cocoa flavanols?
- CBV increased more with high flavanol chocolate
- On pattern separation task, more dentegyrus engagement with high flavanol chocolate
- Attributed it to more CBV in the detegyrus
In the Lamport study, how is cerebral blood flow affected by cocoa flavonoids
- The HF – LF contrast analysis revealed significantly increased regional perfusion 2 hrs post consumption of the HF drink relative to the LF drink
- anterior cingulate gyrus
Give some possible mechanisms of action of polyphenols?
- protection of neuronal signalling pathways
- modulation of synaptic plasticity
- cerebrovascular effect (improved vasodilation, bf, bp)
What is the effect of soy on cycle length and physical symptoms?
- it increases length of the menstrual cycle (by about 2-3 days)
- Physical symptoms reduce e.g. breast tenderness
What were the effects of Soy/IF on cognitive performance in postmenopausal women?
- No change in memory performance in placebo
- But in women who took soy there was an improvement in week 8
- Hot flushes – constant on placebo, in 5 days, symptoms improved days in women taking soy
Why may taking soy supplements be better or worse than hormone therapy?
Better = less potent Worse = takes longer to take effect
What are the possible mechanisms for soy and isoflavones?
- Direct impact on CNS
(Able to pass through blood-brain barrier and act centrally, mimicking mechanism of oestrogen) - Changes in oestrogenic activity (Bind to ER and have a mixed agonist/antagonist action)
- Antioxidant effects
When may taking soy isoflavones be beneficial for women?
When newly menopausal (when estrogen receptor is still active)
When implementing studies of polyphenols for example what are some considerations?
- Assess habitual dietary intake in as much detail as possible at recruitment, baseline and follow-up
- Ensure washout period is of suitable duration
- Assess Bioavailability of Polyphenols and their metabolites (urine/blood) – ensures people have complied with the protocol – are others able to process it better than others?
Perimenopausal and postmenopausal women commonly report what and what may be responsible for this?
- decline in cognitive functioning, especially regarding memory
- reduction of endogenous oestrogen levels is partly responsible for this susceptibility to neurodegeneration
What gender differences have been observed in rats fed and SPE diet?
- males fed the SPE diet had a negative cognitive response
- In the female rats however, the opposite effect was found so that the SPE fed rats had improved working VSM compared to the SPE-free fed rats
What has been associated with tofu consumption?
- Poorer cognitive test performance
- But, as there is only one longitudinal study into a male and female population, it remains uncertain as to how a long-term high soya diet could impact upon cognitive functioning.
What did File (2001) find when comparing high vs low soya consumption?
- It was found that neither attention nor semantic memory was affected by the diet.
- However, long-term episodic memory (delayed verbal recall of pictures) and short-term non-verbal episodic memory (delayed matching to test sample from CANTAB was significantly enhanced in the high soya group compared to the low soya group
What were some limitations of the file (2001) soya study?
- lack of consideration given to controlling for possible time of day effects on cognitive testing
- precedents of the test session were not stringently controlled (consumption of caffeine between sessions could have confounded results)
- phase of menstrual cycle was not taken into account
In a SR, what type of memory was found to be most sensitive to polyphneol and isoflavones?
polyphenols = immediate verbal memory Isoflavone = delayed spatial memory
