Social Help and Stress in Connection to Cardiovascular Health

This study explores the impact of social support on subjective stressful experiences and cardiovascular health. It examines the relationship between social support, stress, and cardiovascular reactivity. The findings suggest that social support does not significantly affect cardiovascular reactivity and blood pressure. The study contradicts previous research and calls for larger sample sizes.

RUNNING HEAD: SOCIAL HELP AND STRESS IN CONNECTION TO CARDIOVASCULAR HEALTH
Social help and Stress in connection to
Cardiovascular Health

Social help and Stress in connection to Cardiovascular Health
Abstract
Little attention was paid to the impact of support on subjective stressful experiences in
stressful situations and the potential impact of stress and excitation on cardiovascular
performance. The study went on with 40 healthy volunteers, with men and women in equal
numbers (N = 20). The present study has not found a significant impact of social support on
the cardiovascular reactivity of participants. Social support also does not need high blood
pressure susceptibility for objects in the sample. Neither Heart rate nor Systolic blood
pressure was affected by social support in the current research. These conclusions contradict
the conclusions of previous investigations and demands for large sample size.
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Social help and Stress in connection to Cardiovascular Health
Table of Contents
Abstract................................................................................................................................................................ 2
Introduction....................................................................................................................................................... 4
Hypotheses..................................................................................................................................................... 5
Method................................................................................................................................................................. 6
Participants.................................................................................................................................................... 6
Apparatus....................................................................................................................................................... 6
Experimental Design.................................................................................................................................. 7
Tasks/Challenges........................................................................................................................................ 7
Results.................................................................................................................................................................. 8
Descriptive Statistics and Assumption Testing............................................................................... 8
............................................................................................................................................................................. 8
Hypotheses testing................................................................................................................................... 10
Discussion........................................................................................................................................................ 12
References........................................................................................................................................................ 12
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Social help and Stress in connection to Cardiovascular Health
Introduction
Evidence shows that social support may be an important determinant of human health,
as measured by a wide variety of indices of mortality, morbidity, and psychological
wellbeing (Kamarck, 1992; Orth-Gomér & Johnson, 1987; Uchino, Cacioppo, & Kiecolt-
Glaser, 1996). Several reviews have reported social support to be inversely related to total
mortality (Eriksen, 1994; Schwarzer & Leppin, 1989), total morbidity (Schwarzer & Leppin,
1989; Smith, Fernengel, Holcroft, Gerald, & Marien, 1994), cardiovascular mortality (Krantz
& McCeney, 2002), cardiovascular morbidity (Krantz & McCeney, 2002; Orth-Gomér,
1994), and changes in cardiovascular reactivity based on the difference between task levels
and baseline levels of cardiovascular indicators (Thorsteinsson & James, 1999).
It is important to understand how social support may influence health so that the
effects of support on health can be optimized. Despite the evidence for the health benefits of
social support, there is still limited knowledge about underlying physiological mechanisms
(Orth-Gomér, 2000). Cardiovascular reactivity has been suggested as a potential underlying
physiological mechanisms (mediator) of the benefits of social support on health such that
social support affects reactivity that in turn affects health, and experimental studies have been
conducted (e.g., Hilmert, Christenfeld, & Kulik, 2002; Kamarck, Manuck, & Jennings, 1990;
Lepore, Allen, & Evans, 1993; Thorsteinsson, James, & Gregg, 1998). Much of this work
derives from the "reactivity" hypothesis, which states that excessive cardiovascular reactivity
and episodic psychological stress contributes to the development of hypertension and
cardiovascular disease (Krantz et al., 1991; Krantz & Manuck, 1984; Lepore, 1998; Manuck,
Kasprowicz, & Muldoon, 1990; Obrist, 1981).
Participants in experimental studies have generally performed “active” laboratory
challenges (e.g., public speaking, mental arithmetic), while receiving either supportive verbal
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Social help and Stress in connection to Cardiovascular Health
(e.g., good, well done, you are doing fine) or silent supportive gestures (e.g., presence of a
friend, smiles, nods) as compared with experiencing a neutral (no-support) silent presence of
a confederate (i.e., an assistant to the researcher) or simply conducting the challenge alone.
Generally, heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP)
reactivity are monitored (see Lepore, 1998; Thorsteinsson & James, 1999), but findings have
been mixed (Thorsteinsson & James, 1999). The trend has been for support to reduce HR,
SBP, and DBP reactivity, but effect sizes have varied from small to large and some studies
have reported that support increased HR reactivity (for a meta-analytic review see
Thorsteinsson & James, 1999). These findings suggest that the effects of social support
manipulations are dependent on several factors such as the type of challenge, type of support,
and the relationship between the participant and the support provider. Little attention has
been given to the effects of support on the subjective experience of stress during stressful
situations and the possible effects stress and arousal may have on cardiovascular indicators,
but there is some indication that subjective stress is affected by support (Thorsteinsson,
James, & Gregg, 1996).
Hypotheses
Hypothesis 1: The stressful task increased the subjective stress rating above a score of
50. This hypothesis was a check to see if the task did what it was supposed to do.
Hypothesis 2: The stressful task increased systolic blood pressure (SBP) of the
participants.
Hypothesis 3: The support condition reduced HR reactivity compared with the no-
support condition.
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Social help and Stress in connection to Cardiovascular Health
Hypothesis 4: The support condition reduced SBP reactivity compared with the no-
support condition.
Hypothesis 5: There was a positive association between subjective stress levels and
cardiovascular reactivity (change in HR, SBP, and DBP).
Method
Participants
The study progressed with 40 healthy volunteers, where males and females were
equal in numbers (N = 20). The participants were selected from the university students who
volunteered to participate in the research. Ethics approval was given by the University's
human ethics committee. The debrief sheets were also provided to the selected candidates.
The average age of male participants was 21.95 years (SD = 2.50), and that for the female
participants was 20.21 years (SD = 2.54). Average BMI for all the participants was 21.77
kg/m2, where males (M = 21.33, SD =2.22) were found to have higher BMI compared to
females (M = 21.06, SD = 2.46). Participants were all healthy and non-smokers based on a
screening of general health and health-behavior status using a questionnaire. Average systolic
blood pressure of the partakers during the screening task was 134.48 mmHg, which ranged
from 115 mmHg to 160 mmHg. Hence, participants were normotensive during screening.
Each participant was paid AU$10 on completion of the laboratory session.
Apparatus
Finapres Continuous Blood Pressure NIBP Monitor; model 2300E (Ohmeda,
Ohmeda House, Hertfordshire, England) in combination with dedicated data-processing
software (‘Modelflo’, FAST -mf system, TNO Biomedical Instrumentation Research Unit,
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Social help and Stress in connection to Cardiovascular Health
Amsterdam, The Netherlands) was used to measure HR, SBP, and DBP. A modified version
of self-report stress and arousal inventory (Mackay, Cox, Burrows, & Lazzerini, 1978) was
employed. Stress during task had a Cronbach’s alpha of .81.
Experimental Design
Participants were randomly assigned to one of two conditions: support or no support.
Participants in the support and no-support conditions were told that a confederate who had
considerable experience in dealing with a computer task would appear on the monitor. In the
support condition, the confederate made positive comments on the participant's performance
while in the no support condition the confederate made no comments. The confederate was
shown sitting in front of a computer screen on which the participant's responses appeared to
be displayed, ostensibly allowing the confederate to monitor the participant's performance. A
pre-recording of the confederate was employed to maintain consistency in the support and
no-support conditions across participants.
Tasks/Challenges
The task involved the Fire Chief Computer challenge which is a computerized
microworld generator used to create an interactive fire-fighting simulation. This challenge
was intended to capture a different type of real-life stress, namely, complex decision making,
not captured by tasks such as mental arithmetic or public speaking that are commonly used as
stressors in this area. Participants used a computer mouse to manipulate computer icons
representing a fire truck and a fire-fighting helicopter to extinguish fires that ignited
spontaneously and spread inexorably throughout a large, sparsely populated forest.
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Social help and Stress in connection to Cardiovascular Health
Results
Descriptive Statistics and Assumption Testing
Average task Stress rating score was 58.49 (SD = 12.16). There was not enough
evidence to reject the null hypothesis of Shapiro-Wilk test that the variable was normally
distributed (W = 0.97, p = 0.34), with skewness S = 0.43 and Kurtosis K = 1.2. An outlier
value of 95 was observed outside the “1.5 IQR “rule.
38 46 54 62 70 78 86 94
0
2
4
6
8
10
12
14
Distribution of Stress Task Score
Stress Task Score
Frequency
Figure 1: Distribution of Task Stress Scores
Before task (M = 113.10, SD = 12.03) and during experiment SBP (M = 134.48, SD
= 10.31) were both found to be normally distributed. The null hypothesis regarding the
supposition of normality failed to get rejected at 5% level of significance. Pre-task SBP (W =
0.98, p = 0.74) and during task SBP (W = 0.98, p = 0.75) both were found to be normally
distributed by Shapiro-Wilk test. No outlier observation was there in pre-task SBP, but,
during the task, a participant had SBP of 160 mmHg, and it was found to be an outlier
observation.
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Social help and Stress in connection to Cardiovascular Health
92.5
97.5
102.5
107.5
112.5
117.5
122.5
127.5
132.5
137.5
142.5
0
2
4
6
8
10
Pre Task Systolic
Blood Pressure
SBP (mmHg)
Frequency
117.5
122.5
127.5
132.5
137.5
142.5
147.5
152.5
157.5
0
2
4
6
8
10
12
During Task Systolic
Blood Pressure
SBP (mmHg)
Frequency
Figure 2: Systolic Blood Pressure in pre-task and duration screening
The change in heart rate (HR), Systolic (SBP) and Diastolic blood pressure (DBP)
corresponding to the two experimental conditions. The Shapiro-Wilk test confirmed that
change in SBP was the only variable, which was normally distributed (W = 0.97, p = 0.16).
Hear rate change was significantly not normal (W = 0.87, p < 0.05), and, so was change in
diastolic pressure (W = 0.92, p = 0.01), at 5% level of significance.
HR DBP SBP
0
5
10
15
20
25
30
HR, SBP, DBP change for Two Experimental Conditions
Support
No-Support
Estimated Marginal Mean Change with 1SE
Figure 3: Comparative analysis of HR, SBP, and DBP change
Relative to two experimental conditions
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Social help and Stress in connection to Cardiovascular Health
Hypotheses testing
To estimate whether the stressful task increased the subjective stress rating above a
score of 50, and to check if the task did what it was supposed to do, a one-sample t-test was
performed. Mean difference in subjective stress due to stressful task was measured to be 8.49
mmHg (95% CI: 4.6, 12.38). The researcher found a statistically significant increase in
subjective stress above 50 (M = 58.49, SD = 12.16), t (39) = 4.42, p < 0.05, d = 0.7 (95%
CI: 0.25, 1.15).
The inference on increase in SBP due to the stressful task was tested with a paired t-
test at 5% level of significance. Decrease (M = -21.38, SD = 10.92, 95% CI:-24.87, -17.88)
in SBP was found to due to the task performed. The researcher found a statistically
significant increase in average SBP during task (M = 134.48, SD = 10.31) compared to SBP
before task (M = 113.10, SD = 12.03) to, t (39) = 12.38, p < 0.05, d = 1.96 (95% CI: 1.52,
2.39).
An independent sample t-test was conducted to review the between-subjects design,
that whether the support condition reduced HR reactivity compared with the no-support
condition. Average difference in HR reactivity score was calculated as 5.15 bpm, and
Levene’s test (F = 14.67, p < 0.05) produced enough statistical evidence for unequal
variances of HR change for two experimental conditions. No statistically significant
difference was found between HR change score for support (M = 12.20, SD = 4.63) and non-
support experimental conditions (M = 17.35, SD = 19.65), t (38) = -1.14, p = 0.27, d = -0.36
(95% CI: -0.99, 0.26).
An independent t-test was used to check the hypothesis whether the support condition
reduced SBP reactivity compared with the no-support condition. The difference in systolic
blood pressure between the pre-task and during task conditions was measured. Levene’s test
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Social help and Stress in connection to Cardiovascular Health
confirmed statistically significant evidence for equality of variances of SBP change in two
experimental conditions (F = 0.13, p = 0.72). The scholar failed to find a statistically
significant difference in SBP change between random allocation to support (M = 18.25, SD =
10.74) and non-support experimental condition (M = 24.5, SD = 10.42), t (38) = -1.87, p =
0.07, d = - 0.59 (95% CI: -1.22, 0.04).
Pearson’s correlation was used to draw an inference about the positive association
between subjective stress levels and cardiovascular reactivity (change in HR, SBP, and DBP).
The study found that there was no statistically significant correlation between changes in
subjective stress levels and HR change score (r = 0.29, p = 0.07). Stress task rating was also
found to have a statistically non-significant positive correlation with change in SBP (r =
0.19, p = 0.24). Change in diastolic blood pressure score was also positively correlated with
SBP change, but the correlation was not statistically significant (r = 0.18, p = 0.26) at 5%
level of significance. Hence, none of the independent factors were significantly correlated to
change in systolic blood pressure.
Table 1: Correlation matrix of experiment variables
Measure M SD 1 2 3 4
1
Task stress rating 0 to 100 visual analog scale
(stress_task) 58.49 12.1
6
1
2
HR change score (task - baseline) bpm (hr_ch) 10.90 11.3
8
.345* 1
3
DBP change score (task - baseline) mmHg
(dbp_ch) 14.78 14.2
9
.232 .16
0
1 .181
4
Change in Systolic blood pressure (sbp_ch) 21.38 10.9
2
.191 .28
6
.181 1
Note: *. Correlation is significant at the 0.05 level (2-tailed).
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Social help and Stress in connection to Cardiovascular Health
Discussion
The present research failed to find any significant impact of social support on
cardiovascular reactivity of the participants. Social support also failed to add any benefit to
the hypertension sensitivity for the subjects in the sample. Neither heart rate nor SBP was
affected by social support in the present research. These conclusions contradict with the
outcome of previous research works (Krantz et al., 1991; Obrist, 1981). Alteration in Heart
rate, diastolic blood pressure, and stress task level failed to have a significant correlation with
the change in systolic blood pressure of the subjects. The correlations were found to be
positive, but for significant support, the sample size needs to be increased (Thorsteinsson &
James, 1999). Interestingly, stress full atmosphere or pressure task environment was able to
increase the SBP to a statistically significant level compared to the pre-task condition. This
conclusion was again in line with the results of Thorsteinsson, James, & Gregg (1996).
The study also had its limitations. In most cases, the effect size was not large enough for
statistically significant results. The measures of SBP and DBP were found to have less
sample size, especially when the comparison analysis with social support was done. For each
group of experimental conditions, the sample size was 20, which created problems for
assumptions of normality. Sample size greater than 30 for each experimental condition would
have been a desired criterion.
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Social help and Stress in connection to Cardiovascular Health
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