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Chapter 4

NURSING 2MM3 Chapter Notes - Chapter 4: Posterior Cerebral Artery, Cerebral Circulation, Acetylcholinesterase Inhibitor


Department
Nursing
Course Code
NURSING 2MM3
Professor
Tracey Jewiss
Chapter
4

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Neurovascular Coupling, Cerebral White Matter integrity, and
Response to Cocoa in Older People
Abstract
- Objective
o Investigate relationship between neurovascular coupling and cognitive function in
elderly individuals with vascular risk factors and to determine whether neurovascular
coupling could be modified by cocoa consumption
- Methods
o Sixty older people were studied in a parallel-arm, double blind clinical trial of
neurovascular coupling and cognition in response to 24 hours and 30 days of cocoa
consumption
o Cognitive measures included MMSE and Trail making Test A and B
o Neurovascular coupling was measured from the net-to-beat blood-flow velocity
responses in the middle cerebral arteries to the N-back Task
o In a subset of MRI-eligible participants, cerebra white matter structural integrity was
also measured
- Results
o Neurovascular coupling was associated with Trails B scores and performance on
the 2-Back Task
o neurovascular coupling was also associated with fractional anisotropy in
cerebral white matter hyperintensities
o Finally, 30 days of cocoa consumption was associated with neurovascular
coupling and Trails B times in those with impairs neurovascular coupling at
baseline
- Conclusion
o Strong correlation between neurovascular coupling and cognitive function, and both
can be improved by regular cocoa consumption in individuals with baseline
impairments
o Better neurovascular coupling is also associated with white matter structural
integrity
- Neuronal activity is linked to oxygen and glucose delivery
o in metabolic demand leads to blood flow
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o The close functional and spatial relationship between neuronal activity and cerebral
blood flow has been termed neurovascular coupling or functional hyperemia
o NVC has been associated with pathology
- The relationship between NVC and cognition is unknown along with the relationship
between NVC and structural brain changes that occur with aging and vascular disease
o Intact NVC was associated with preserved gait speed despite burden of cerebral
microvascular disease (known to be associated with gait)
o Given the established role of NVC in animal models of human disease, an
understanding of the clinical and brain structural correlates of this process is
needed
- Study was designed to understanding of NVC in older people with vascular disease
o First goal was to determine whether cognition is associated with blood flow
responses to a cognitive task (impaired NVC)
o Second goal was to examine whether impaired NVC is associated with cerebral
white matter disease
o Finally wanted to determine whether NVC was modifiable by flavanol rich cocoa
which has been shown to endothelial and cognitive function
Discussion
- Study shows that NVC is related to cognitive performance and cerebral white matter
structural integrity in an elderly cohort with vascular risk factors
o NVC was associated with cognitive performance and with macro and
microstructure white matter integrity
o Also shows that NVC may be modifiable
o 4 weeks of cocoa consumption resulted in NVC and Trails B scores in those with
impaired function at baseline
- Prior studies have demonstrated pathologic changes involving the neurovascular unit in
both vascular dementia and Alzheimer disease
o These pathologic changes could result in decoupling of cerebral blood flow from
cerebral metabolic demand, and contribute to the resulting brain dysfunction seen in
dementing disorders
o TCD provides a noninvasive measure of blood flow responses to neuronal activation
allowing for the functional assessment of the neurovascular unit
o This approach has helped demonstrate that NVC is in patients with AD, and that
cholinesterase inhibitors can NVC
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