The Relationship Between Ambulatory Blood Pressure and
Cognitive Performance
Jennifer Dalecki2010-2011
AbstractAlthough some research has linked cardiovascular risk factors to declines in
cognitive function; other studies have not demonstrated a relationship. One explanation for discrepant findings are differences in the methods used to measure blood pressure (BP). Most studies acquired a measure of clinical blood pressure (BP), meaning a BP taken in a professional setting by a doctor or clinician. Clinical BP, can vary because of the white-coat effect and various other factors, is often an unreliable indicator of an individual’s actual blood pressure. In contrast, 24-hour ambulatory blood press (ABP) has been shown to be more reliable in studies linking BP to brain changes believed to be caused by hypertension such as white matter abnormalities. The purpose of this study was to examine the relationship between 24-hour ABP and decline in cognitive performance in adults over the age of 75. It is hypothesized that those with higher ABP readings will show more evidence of cognitive decline, whereas those with lower ABP will see less evidence of cognitive deterioration. Using participants 75 years or older from a four year longitudinal study, ABP measures were related to results from cognitive performance testing. Results were analyzed by dividing the participant pool into high, middle, and low BP levels and assessing the decline in cognitive performance over the span of four years. Analysis showed no significant correlation between 24-hour blood pressure and memory and speed of processing measures.
Introduction
The Relationship Between Ambulatory Blood Pressure and Cognitive Performance
• White matter=made up of axons; allow nerves to communicate; enables brain to operate effectively
• WMH associated with increasing age (particularly in frontal and temporal regions)
• WMH= “brain rust”; indicates injury to axons
• WMH linked to hypertension and vascular risk factors (heart attack, stroke, heart disease, etc.)
• WMH linked to decline cognitive performance, especially speed of processing (Wakefield)
• Cannot imply complete transitivity– WMH correlates with vascular risk factors and
cognitive decline ≠ vascular risk factors cause cognitive decline
The Relationship Between Ambulatory Blood Pressure and Cognitive Performance
(Intro cont.)
Clinical BP vs. Ambulatory BP• Research linking vascular factors with cognitive decline
inconclusive• Studies used clinical BP (taken in professional setting);
often poorly reproducible and not rep. of average BP• Ambulatory BP (measures at regular intervals for 24
hours)
The Relationship Between Ambulatory Blood Pressure and Cognitive Performance
ABP Superiority• Compared BP reproducibility of patients over 80• Concluded more consistency in ABP over two years
The Relationship Between Ambulatory Blood Pressure and Cognitive Function
Problem Statement & HypothesesHow do ambulatory blood pressure readings relate to an individual’s capacity for cognitive function ?
Hypotheses:Higher systolic ambulatory blood pressure readings will be associated with more severe decline in cognitive function Lower ambulatory blood pressure readings will be associated with more regular cognitive function
The Relationship Between Ambulatory Blood Pressure and Cognitive Performance
Variables
The Relationship of Ambulatory Blood Pressure and Cognitive Performance
Independent Variable: Systolic ambulatory blood pressureDependent Variable: Decline in performance evaluations of cognitive functions(memory, speed of information processing)Control: None
Methodology
The Relationship of Ambulatory Blood Pressure and Cognitive Performance
Using participants in late 70s and older:• Ambulatory Blood Pressure• Trail Making Test A & B• Stroop Color and Words Test • Wechsler Adult Reading Test (WTAR)
Example of Trail Making Test
The Relationship Between Ambulatory Blood Pressure and Cognitive Performance
Stroop Color and Words Test
The Relationship of Ambulatory Blood Pressure and Cognitive Performance
Data Interpretation
The Relationship Between Ambulatory Blood Pressure and Cognitive Performance
• Split group into three groups (low, middle, high BP)• Compare ABP with cognitive function across
domains
P-Value: .88276
>.05 = NO STATISTICAL SIGNIFICANCE
105.4022
113.98875
111.2946
100
102
104
106
108
110
112
114M
ean
Tra
ils T
est
Sco
re
High Middle Low
Ambulatory Blood Pressure
Trails Test vs. Systolic Ambulatory Blood Pressure
25.47826087
28.75
28.08333333
23.524
24.525
25.526
26.527
27.528
28.529
Mea
n S
tro
op
Co
lor
and
W
ord
Tes
t
High Middle Low
Ambulatory Blood Pressure
Stroop Color and Words Test vs. Systolic Ambulatory Blood Pressure
P-Value: .420308
>.05 = NO STATISTICAL SIGNIFICANCE
113.3043
116.0833
109.9167
106107
108109110
111112113
114115
116117
Sco
re o
n W
TA
R
High Middle Low
Ambulatory Blood Pressure
WTAR Scores vs. Systolic Ambulatory Blood Pressure
P-Value: .161183
>.05 = NO STATISTICAL SIGNIFICANCE
Conclusions
• No statistically significant figures• Suggests minimal relationship between
ambulatory blood pressure and cognitive performance
• Disagrees with hypothesis
Error Analysis/ Future Work
• Volunteer bias• Arbitrary division of subject pool• Data from first year of longitudinal study
• RBANS/ CALCAP• More subjects; more diversity• More specific division of pool
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(2006). Regional white matter and neuropsychological functioning across the adult lifespan. Biological Psychiatry,60, 444–453.
• Kaplan RF, Cohen RA, Moscufo N et al. Demographic and biological influences on cognitive reserve. J Clin Exp Neuropsychol Mar 2009;31:1–9.
• Lashley, K. S. (1931). Mass action in cerebral function.Science, 73, 245–254.• Sakakibara R, Hattori T, Uchiyama T et al. Urinary function in elderly people with and without
leukoaraiosis: Relation to cognitive and gait function. J Neurol Neurosurg Psychiatry 1999;67:658–660.
• Welsh-Bohmer, K. A., & Madden, D. J. (2002). Benign senescent forgetfulness, age-associated memory impairment, and age-related cognitive decline. In J. R. M. Copeland, M. T. Abou-Saleh, & D. G. Blazer (Eds.), Principles and practice of geriatric psychiatry(2nd ed., pp. 303–304). John Wiley & Sons.
The Relationship Between Ambulatory Blood Pressure and Cognitive Performance