Week 11: Vascular Influence on Brain and Cognitive Ageing

Question 1

What are the types of arteries?

Answer 1

• Systemic, in the heart
• Peripheral, distal, in the brain
• Not all are equally important

Question 2

What are some vascular risk factors?

Answer 2

• Stroke
• Atherosclerosis
• Blood pressure
• Heart disease
• Diabetes
• Dyslipidemia - dysfunction in lipids (high cholesterol)
• Homocysteine

Question 3

What is the vascular pathway of how hypertension leads to dementia?

Answer 3

Hypertension -> Atherosclerosis -> Cerebral hypoperfusion -> Cerebral atrophy -> Dementia

Question 4

Ageing is associated with:

Answer 4

1) Higher prevalence of hypertension
2) Stiffening of systemic and cerebral arteries
3) Reduced cerebral blood flow
4) Greater neurodegeneration
5) Greater cognitive deficits

Question 5

What are markers of poor vascular health?

Answer 5

Systolic hypertension and wide (high) pulse pressure

Question 6

How is pulse pressure calculated?

Answer 6

PP/Pulse amplitude = SYS - DIA

Question 7

What are trends in SBP and DBP?

Answer 7

• Systolic BP increases over lifespan
• Diastolic BP increases then tapers off
• No differences in gender

Question 8

How does ageing relate to arterial elasticity?

Answer 8

Young - Elastic vessels

Old - Inelastic vessels

Question 9

What is the process of blood flow for young elastic vessels?

Answer 9

Systolic phase: Retain cardiac stroke volume

Diastolic phase: Elastic recoil of blood vessels release remaining volume

Question 10

What are the characteristics of blood flow for young elastic vessels?

Answer 10

Smooth flow profile, low pulse pressure

Question 11

What is the process of blood flow for old inelastic vessels?

Answer 11

Systolic phase: Almost all cardiac stroke volume delivered

Diastolic phase: Minimal diastolic flow

Question 12

What are the characteristics of blood flow for old inelastic vessels?

Answer 12

Minimal diastolic flow, increased pulse pressure

Question 13

What is optical neuroimaging?

Answer 13

Measures blood pressure in brain, cerebral elasticity

Question 14

During optical neuroimaging, what occurs at peak systole and peak diastole?

Answer 14

Peak systole: Lowest light intensity, arteries expand and most amount of light absorbed by haemoglobin in blood in arteries

Peak diastole: Highest light intensity, arteries contract and little light is absorbed

Question 15

How does cerebral pulse amplitude vary with pulse pressure?

Answer 15

Pulse pressure in brain is correlated with pulse pressure in body, but not perfectly correlated

Question 16

How does cerebral pulse amplitude vary with age?

Answer 16

As age increases, cerebral blood pressure increases

Question 17

What does the area under graph of cerebral arterial elasticity represent?

Answer 17

Reflects integrated index of vascular damage over time

Question 18

How does arterial elasticity vary with age?

Answer 18

As age increases, arterial elasticity decreases

Question 19

How does arterial elasticity relate to cardiorespiratory fitness?

Answer 19

More fit, more elastic

Question 20

How does regional arterial elasticity relate to working memory?

Answer 20

Frontoparietal regions
- Greater arterial elasticity associated with better performance on working memory task

Global arterial elasticity is NOT associated with performance on working memory task

– Elasticity predicts working memory but only in SPECIFIC regions (i.e. frontoparietal regions)

Question 21

How does regional arterial elasticity relate to age?

Answer 21

Frontoparietal regions:
- Greater arterial elasticity associated with younger age

Visual regions
- Arterial elasticity not associated with age

– Some regional specificity when it comes to arterial elasticity and how it is associated with age

Question 22

What are the take-home messages?

Answer 22

• Vascular risk factors play an impt role in cognitive and brain changes in ageing
• Cerebral arterial aging occurs over the adult lifespan, with a degree of regional specificity
• Optical neuroimaging provides a non-invasive window into the cerebral arteries
• The way forward - exercise intervention studies, nutrition studies, genetic assays, etc