Glucose and Cognitive Performance

Question 1

What is ketosis?

Answer 1

• Normal response when there is not glucose available e.g. low carb diet or fasting
• In absence of carbs, ketones are produced – additional energy source for brain
• Takes about 3-4 days to go into ketosis
• Fasting or less than 50g of carbs per day

Question 2

What is the main brain fuel?

Answer 2

Glucose

Question 3

How does the push-pull mechanism for energy metabolism work?

Answer 3

• Glucose is pulled into brain – driven by falling glucose levels in brain cells that are doing something – occurs via glucose transported, driven by glucose activity
• Push strategy driven by ketones – when ketones go up they are pushed into brain

Question 4

How does glucose enter the brain cells?

Answer 4

• via GLUT1 transporters.
• Glucose is then taken up by astrocytes;
• either stored briefly as glycogen,
• transported out of astrocytes or transformed into lactate.

Question 5

Under conditions of greater energy demand, what happens?

Answer 5

astrocytic glycogenolysis is activated to provide a rapid energy boos

Question 6

Under low-energy need conditions what happens?

Answer 6

Basal levels of extracellular (ECF) glucose can fulfil neuronal energy requirements

Question 7

What cognitive tasks can be improved with glucose?

Answer 7

information processing and attention, working memory, executive function, long-term memory

Question 8

What populations can benefit from glucose administration?

Answer 8

• Healthy young and older participants
• Alzheimer’s disease
• Down’s syndrome
• Schizophrenia

Question 9

What is the optimal dose of glucose for performance?

Answer 9

25g (for younger populations)

Question 10

Is memory facilitation of glucose dependant on the time of day?

Answer 10

No - robust effect

Question 11

What is a strong moderator of glucose and cog?

Answer 11

Level of task demand (supports brain areas under greater cog load)

Question 12

Is ingestion of a glucose load a valid nutritional intervention?

Answer 12

No

Question 13

What are the mechanisms enabling increased peripheral and/or central glucose availability to influence cognitive processes?

Answer 13

• unclear
• likely to include provision of additional metabolic fuel (ATP), neurotransmitter synthesis and insulin signaling, as well as the possible involvement of peripheral mechanisms.

Question 14

what is glycemic index?

Answer 14

Describes rise in blood glucose levels following intake compared to standard food

Question 15

How are the low GI and high GI curves different?

Answer 15

• Low glycaemic index = slow rise & sustained blood glucose release.
• High glycaemic index = acute large rise, rapid decline

Question 16

Which is better for cognition Low or high GI (adolescents)

Answer 16

• Few studies and results somewhat contradictory

Question 17

Which is better for cognition Low or high GI (adults)

Answer 17

• Few studies and again somewhat contradictory.
• Some show beneficial effects on cognitive performance of low-GI foods, Others show no such effects
• Timing: Effects observed in late postprandial period (75-222 min)
• Aspect of cognitive function that are influenced: memory and attention

Question 18

What is glycemic load?

Answer 18

GL related to the amount of glucose absorbed

Question 19

what factors affect GI?

Answer 19

Individual Factors (Insulin sensitivity, Beta cell function, Gastrointestinal motility – how quickly something passes through gut, Physical activity, Metabolism of previous meals)

Food factors (Presence of fat, protein, fibre, Amount, volume and form of CHO, Source and digestibility of starch, Processing – highly processed foods might be easier to digest so show effect earlier than other food)

Question 20

What is the 2nd meal effect?

Answer 20

• what you have in your first meal has an impact to GI in second meal
• GI of the evening meal influences glycaemic response to breakfast and is associated with memory performance the next day (Lamport et al. 2011)
• If you had high GI meal – primes high Glycaemis response in second meal
• If low GI meal – then have lower glycemic response next meal and even to the next day
  => Overnight fast may not be sufficient.

Question 21

How does palatability affect glycemic response?

Answer 21

Increased response and carb oxidation

Question 22

Hafermann (1955) investigated what?

Answer 22

the effects of glucose administration on school children

Question 23

When blood glucose is low, what happens?

Answer 23

• secretion of the opposing pancreatic hormone glucagon is induced
• Glucagon induces breakdown of liver glycogen to glucose

Question 24

What may the mechanism be for the glucose-cognition association?

Answer 24

• Elevated insulin in response to hyperglycaemia rather than glucose levels per se may moderate memory performance
• Elevated insulin may boost utilization in the hippocampus and result in improved performance

Question 25

What is glycemic control?

Answer 25

• the ability of the body to effectively regulate blood glucose levels and to remove glucose from the blood