Stress and Chronic Abdominal Pain 1
IMPACT OF STRESS ON CHRONIC ABDOMINAL PAIN
The Impact of Stress on Autonomic Functioning in Chronic Abdominal Pain Patients
Davlyn M. Tillman
Honors Research Thesis completed in fulfillment
of the requirements of the
Honors Program in Psychological Sciences
Under the Direction of Dr. Lynn Walker
Vanderbilt University
April, 2010
Stress and Chronic Abdominal Pain 2
Abstract
This study examined the effect of social stress on chronic abdominal pain patients.
Chronic abdominal pain (CAP) is a type of chronic pain common in children, experienced by 1015 % of young children. Stress has been noted to influence the experience of CAP by increasing
emotional distress and physical problems. Increased reaction to stress can be assessed by
measuring physiological changes, including changes in blood pressure, and also by comparing
changes in positive and negative affect. Study participants were subjected to laboratory social
stress while their blood pressures were measured. Participants’ levels of positive and negative
affect in response to the stress were also assessed through self-report surveys. The study tested
the hypothesis that non-recovered CAP patients would show greater changes in blood pressure,
lower positive affect, and higher negative affect in response to the stress than recovered CAP
patients and well subjects. The results found no significance difference in blood pressure changes
and self-reports of affect between the non-recovered CAP, recovered CAP, and well participants.
Stress and Chronic Abdominal Pain 3
The Impact of Stress on Autonomic Functioning in Chronic Abdominal Pain Patients
Introduction
General Overview of Chronic Pain
Chronic pain is defined as pain that continues beyond the normal time expected for
resolution of the problem or that recurs for other reasons (American Pain Society, 2008). Chronic
pain is different from acute pain in that acute pain is usually due to bodily injury or caused by a
specific, identifiable disease. Chronic pain is estimated to affect 15% to 20% of children and
includes specific chronic pains such as headache, oral pain, and recurrent abdominal pain
(Goodman & McGrath, 1991). Pediatrician John Apley noted that pediatric chronic pains are
most common in the head, abdomen, and limbs (Apley ,1976). Apley also stated that a common
denominator in the recurrent pains of childhood is that they are expressions of reaction to
emotional stress (Apley, 1958, cited in Apley, 1976).
Chronic abdominal pain (CAP) is a recurring pain in the abdomen that is common in
childhood. The criteria for chronic abdominal pain are three or more episodes of abdominal pain
that occur over at least three months and affect normal daily activities (Apley, 1975). Chronic
abdominal pain is also known as recurrent abdominal pain. The majority of children with
functional CAP do not have a specific physical disorder or organic disease that causes the pain.
CAP is experienced by 10-15% of young children. In early childhood, males and females are
affected by CAP equally, but as children grow older, the incidence of CAP decreases in boys but
not in girls (Boyle, 1997). Children with CAP are more likely to have problems with anxiety and
depression, and also are more likely to have poor school attendance, limited extracurricular
activities, and many changes in normal daily functioning (Banez, 2008). As children with CAP
grow older, they may be recovered CAP patients who no longer meet criteria for chronic
Stress and Chronic Abdominal Pain 4
abdominal pain or functional GI disorders. These children may be non-recovered CAP patients if
they still show symptoms of chronic abdominal pain and meet the criteria for a functional GI
disorder.
Factors Associated with Chronic Abdominal Pain in Children
Impact of Stress on Health
Stress has been known to have negative effects on the health of adults and children,
including children with chronic abdominal pain. According to the Center for Disease Control,
stress is internal or external influences that are capable of affecting health by causing emotional
distress and leading to a variety of physiological changes. These changes include increased heart
rate, elevated blood pressure, and a dramatic rise in hormone levels.
A study by DeLongis, Folkman, and Lazarus (1998) used various assessments of 75
married couples over a six month period to measure their daily stress and illness. By comparing
self-reports of illness, they found a significant relationship between daily stress and the
occurrence of both concurrent and subsequent health problems such as the flu, sore throat,
headaches, and backaches.
Various studies have searched for factors that contribute to the onset of functional CAP,
that increase the symptoms of functional CAP in some children, and that increase the risk of
other health problems in CAP patients as they reach adulthood. There has been a focus on factors
that contribute to a heightened experience of CAP in some patients, causing an increase in
somatic symptoms such as headache and abdominal pains. Many of these factors have been
labeled as biopsychosocial contributors to increased symptoms of functional CAP. An article by
Barad and Saps (2008) suggested that biopsychosocial factors that influence chronic abdominal
pain include genetic susceptibility, early life experiences, sociocultural issues, and coping
Stress and Chronic Abdominal Pain 5
mechanisms.
Impact of Stress on Chronic Abdominal Pain Patients
Previous studies assessed whether children with chronic abdominal pain experience a
greater level of stress and also have an increased reaction to those stressors. There are various
types of stressors that can have ill effects on children’s experience of CAP. One study (Walker,
Garber, Smith, Van Slyke, & Claar, 2001) compared the levels of experienced stressors and the
effect of these stressors on somatic symptoms in children with chronic abdominal pain and well
children. The stressors assessed were related to family, school, peers, and daily stressors in the
health domain. The study found that children with CAP reported more daily stressors than well
children and also experienced more somatic symptoms as a result of stress than the well children,
indicating that stress influences symptoms in children with CAP.
Another cross-sectional study (Hjern, Alfven, & Ostberg, 2007) investigated the level of
psychosomatic pain symptoms in Scandinavian school children in relation to school stressors in
their environment. Researchers found that the children who experienced more of the stressors
had a greater occurrence of psychosomatic pain. They reported that the main psychosomatic
pains experienced were headache and recurrent abdominal pain. A study by Walker, Smith,
Garber, and Claar (2007) also found that pediatric patients with chronic abdominal pain were
less able to effectively deal with stress and less likely to have adequate coping strategies for
stress than were well children. The negative stress appraisals and coping strategies also made the
CAP patients more likely to experience higher levels of symptoms.
The experience of stress in CAP patients may also be affected by environmental factors,
such as family. In a longitudinal study, Hotopf et al. (1998) assessed the reasons children
continue to have abdominal pain and also the risks for later adulthood health problems. A birth
Stress and Chronic Abdominal Pain 6
cohort that was followed over the course of 20 years was used as the source of participants.
Hotopf et al. found that the CAP children were more likely to have parents with ill health and
psychiatric disorders. From these results, they suggested that parental anxiety and preoccupations
with physical health may reinforce the child's pain behavior and increased experience of somatic
symptoms.
Effects of Stress on Autonomic Functioning
The physiological effects of stress on children’s health may be assessed with
measurements of autonomic functioning. Effects of stress on autonomic functioning would
suggest negative effects of stress on the muscular activity of the heart and on the circulatory,
digestive, respiratory, and urogenital systems which are controlled by the autonomic nervous
system. This has implications of a greater risk for cardiovascular problems and high blood
pressure.
Many studies have found that an elevated level of stress in children leads to greater
autonomic responses, including higher blood pressures and heart rates. A study by Ewart and
Jorgensen (2004) interviewed adolescents using a Social Competence Interview and then
measured their blood pressure levels in response to the interview. Researchers found that those
children who were shown through the interview to lack social skills and to have a decreased
ability to express and communicate emotions had elevated blood pressure levels. From these
results, researchers also concluded that these children were at higher risk for cardiovascular
disease.
Ewart and Kolodner (1994) also found that children with more anger, negative expressive
styles, and social stressors in the school setting had a greater increase in blood pressure. Chen,
Matthews, Solomon and Ewart (2002) measured both heart rate and blood pressure in children
Stress and Chronic Abdominal Pain 7
during a social competence interview and found that both of these physiological measures were
elevated in children who lacked expressive skills and were more self-defensive and competitive.
One study measured the physiological reaction to a laboratory social stress interview in children
with chronic abdominal pain and children with anxiety (Dorn et al., 2003). Researchers found
that the CAP and anxiety patients both had elevated heart rate, blood pressure, and salivary
cortisol levels.
Effects of Stress on Positive and Negative Affect
The mental effects of stress on children’s health may be measured by self-report surveys
and questionnaires. These questionnaires include ratings of words that represent levels of
positive and negative affect, such as “happy” and “distressed.” Effects of stress on positive and
negative affect may have implications of future mental issues such as depression, anxiety, and
other behavioral disorders. One study dealt with the effect of perceived stress on mental health in
young adults (Bovier, Chamot, & Pernegerl, 2004). Researchers surveyed about 2000 students at
the University of Geneva on their perceived stress, internal resources, and social support and also
self-reports of mental stress. Researchers found that perceived stress is an important risk factor
for a negative effect on mental health.
Limitations of Current Research
Previous studies on stress and its effect on autonomic functioning and mental health in
pediatric CAP patients have certain limitations. One limitation is in relation to the measurement
of stress in children, especially in children with chronic abdominal pain. Some of the stress
measurements are retrospective reports of past stress. These reports of past stress may not be as
accurate at later times and may be affected by children’s limited memories and the common
Stress and Chronic Abdominal Pain 8
tendency to report more past stress during a time when a major event, such as a negative life
event, occurred.
Another limitation is in relation to the measurement of somatic symptoms in CAP
patients. Many of the measurements are self-reports from the CAP patients themselves and also
their parents. The limitation of self-report measurements of somatic symptoms is that patients
vary in their tolerance of the symptoms, causing some to report worse symptoms even though
there is not much difference in their physical health. Many of the studies’ measurements of
symptoms are in the form of interviews and there are no objective measures of the physiological
impact of stress on the children.
Current literature investigates the effect of stress on autonomic functioning and positive
and negative affect in general samples of children, but there is not much literature that
specifically investigates this effect on children with chronic abdominal pain. The Dorn et al.
(2003) study is one that measures the effect of standard laboratory stress on children with CAP,
but the small sample size limits the generalizability of the studies’ results.
Hypotheses and Research Questions to be Further Tested
A question to be further studied is whether chronic abdominal pain patients respond to
stress with greater autonomic and mental reactivity than well children. Previous studies have
found that chronic abdominal pain patients are more reactive to stress and experience greater
levels of daily stress, so it is important to see how their greater experience of stress makes them
more vulnerable to distressing somatic symptoms and also other mental and physical illnesses
such as anxiety, depression, and headaches.
In this study, standard laboratory stressors were used in pediatric CAP patients to
measure their response to stress. Children with CAP are more likely to experience social stress as
Stress and Chronic Abdominal Pain 9
daily stressors, so there were measurements taken of standard laboratory social stress. The
measurements of the patients’ responses to these stressors were standard physiological measures,
including heart rate and blood pressure. There also were standard mental health measurements in
the form of surveys of positive and negative affect. In relation to the Ewart and Jorgensen (2004)
study which concluded that children with greater social stress and elevated blood pressure levels
are at a higher risk for cardiovascular disease, it is interesting to test whether pediatric CAP
patients are at risk for later developing cardiovascular disease due to a tendency to react more to
stress and to have a greater autonomic reactivity to stress.
This current study tested the hypothesis that non-recovered CAP patients would
experience a greater physiological change in blood pressure levels in response to laboratory
stress than recovered CAP patients and well subjects. A second hypothesis tested was that nonrecovered CAP patients would experience lower positive affect change and higher negative
affect change in response to laboratory stress than recovered CAP patients and well subjects.
Methods
Participants
There were 317 participants recruited from the Middle Tennessee area, including recovered
and non-recovered chronic abdominal pain patients and control (“well”) participants.
CAP patients. Chronic abdominal pain patients were patients referred to the Vanderbilt
Pediatric Gastroenterology Clinic who met the criteria for chronic abdominal pain. The criteria
for abdominal pain are three or more episodes of abdominal pain that occur over at least three
months and affect normal daily activities (Apley, 1975). These participants were recruited from a
database of 850 patients who participated in previous Walker Lab research studies from 19932006 and were between 8 and 16 years of age at the time of the previous studies.
Stress and Chronic Abdominal Pain 10
Recovered CAP patients: There were 143 participants identified as recovered CAP patients.
Participants who were in the CAP database were determined to be recovered if they did not
meet the criteria for any functional GI disorder according to their responses on the Health
Interview.
Non-recovered CAP patients: There were 81 participants identified as non-recovered CAP
patients. Participants who were in the CAP database were determined to be non-recovered if
they did meet criteria for one or more functional GI disorders associated with pain
according to their responses on the Health Interview.
Control (“well”) participants. The 93 control participants were healthy adolescents and adults
recruited from a database of 350 controls who also participated in previous Walker Lab studies
between age 8 and 16 years from 1993-2006. In the previous studies, these participants were
recruited from public schools in the metropolitan Nashville area and schools in near rural areas
(Walker et al., 2001).
Participants were between the ages of 12 and 32. Parents of participants younger than age 18
also participated in the study by providing further information needed for their child. In each of
the CAP patient and control databases, there was an equal proportion of males and females
represented.
Recruitment. Participants were recruited from a database of 850 chronic abdominal pain
patients and 350 control patients who participated in research by the Walker Lab team from
1993-2006. During the initial research studies, participants agreed to provide addresses and
telephone numbers to allow contact for follow-up studies. For this study, participants were sent a
letter that described the study and invited them to participate in the study. If participants decided
not to be a part of the study, they had an option to return a pre-stamped postcard. If the postcard
Stress and Chronic Abdominal Pain 11
was not received within 10 days, participants received a telephone call from a research team
member who further described the study and determined whether the participant was eligible for
the study. Participants were then contacted by telephone for recruitment and to set appointments
to participate in the study.
Measures
Social Competence Interview (SCI) – The Social Competence Interview measures personal
capabilities that affect vulnerability to stress-related illnesses (Ewart et al., 2002). The interview
is used as a laboratory measurement of stress to assess physiological reaction to stress. The
interviews lasted about 8-10 minutes in which participants discussed a stressful life situation in
detail. Participants were given cards that list common stressors: work, school, friend,
neighborhood, family, and money. Participants were instructed to choose the one that caused
them the most stress in the past few months. With a standard set of questions asked by the
interviewer, the participants explained why the situation was stressful and recalled a specific
situation in which the stressor occurred. Participants were also asked how they wished the
stressor or problem to be resolved. After the interview, the interviewer gave ratings of the
participant’s Interpersonal Style, Social Impact, Empathy, Coping Goals, and Personal Strivings.
Symptom Emotion Report (SER) – The SER is a self-report survey that assesses participants’
negative and positive affect. The SER survey was taken by participants on a laptop computer
right before and after the Social Competence Interview. Participants were instructed to give
ratings of how they were feeling before the interview and how they were feeling as they were
discussing the stressful situation during the interview. Words that represent positive affect were:
Excited, Glad, Interested, Full of Energy, Happy, Eager, and Joyful. Words that represent
negative affect were: Mad, Angry, Irritated, Scared, Worried, Annoyed, Nervous, and Tense.
Stress and Chronic Abdominal Pain 12
Feelings for each term were assessed on a five point scale ranging from 1 = “Not at all” to 5 =
“A Whole Lot”. The total scores for negative affect and positive affect were the average ratings
of the terms in each subscale.
Health Interview – The Health Interview is a questionnaire completed by participants by phone.
The interview includes questions about emotions and behavior, physical health, and
gastrointestinal symptoms. Participants’ responses in the Rome III section of the interview were
coded according to whether or not they met the criteria for a functional gastrointestinal disorder
associated with abdominal pain. Functional gastrointestinal disorders include irritable bowel
syndrome, functional dyspepsia, abdominal migraine, and functional abdominal pain. The
answers to the Health Interview were used to determine whether participants with chronic
abdominal pain were recovered or non-recovered.
Physiological Assessment – Participants’ physiological reactions to the stress of the Social
Competence Interview were assessed through blood pressure readings. The blood pressure
readings were taken by a Dinamap machine. Before the SCI, participants’ baseline blood
pressures were measured every 2 minutes while the participant viewed a slideshow of photos.
Blood pressure levels were also measured every 2 minutes during the SCI. After the completion
of the SCI, participants’ blood pressures were measured every 2 minutes in a recovery period
while the participant viewed a second slideshow of photos.
Design
All participants, recovered CAP, non-recovered CAP, and well subjects, participated in
the Social Competence Interview. Each participant discussed their most impactful life stressor
with the experimenter. The quasi-independent variable was the stressor that was discussed in the
interview. The stressor varied for each participant in that the participant chose his or her stressor
Stress and Chronic Abdominal Pain 13
from the given cards of stressors. The dependent variable was the change in blood pressure
measurements from baseline to the active phase of the SCI interview. The blood pressures were
taken by the Dinamap machine and recorded as lab data. A final dependent variable was the
amount of change in ratings on the Symptom Emotion Report for positive and negative affect.
Procedure
Participants first completed the health interview over the phone. Interviewers conducted
the questionnaire which included questions on various subjects such as demographics, daily
behavior, and physical wellness. The interview lasted about forty-five minutes to an hour and
was recorded to be sure that answers to questions could be reviewed if necessary.
Participants came into the research lab of the Vanderbilt Children’s Hospital at a later
date to complete the lab session. After consent and setting up equipment, participants viewed a
slideshow of various sceneries and landscapes for six minutes. Baseline blood pressure
measurements were taken by the Dinamap machine every two minutes for a total of four
measurements. After the six minutes, participants then completed two pages of the SER survey
to measure positive and negative affect at SER Time 1. No blood pressure measurements were
taken during that time. After the two pages of the survey were completed, the next part of the
experiment was the Social Competence Interview. The interview lasted an average of eight to
ten minutes and blood pressure measurements were taken during the interview. Participants were
given cards that listed common stressors and were instructed to choose the one that had caused
them the most stress in the past few months. With a standard set of questions asked by the
interviewer, the participants explained the stressors in great detail. The participant had to explain
why the situation was stressful and a specific situation in which the stressor occurred. The
interviewer continued to ask questions about the stressor during this active phase of the
Stress and Chronic Abdominal Pain 14
interview. There second part of the interview was a cool phase in which the participants were
instructed to envision that they were making a movie of the situation in which they were able to
create their ideal ending. After the participants completed their ideas on the perfect ending to
their stressor, the interview was complete. Then the participants completed two more pages of
the SER survey to report their ratings of positive and negative affect during the interview (SER
Time 2). No blood pressure measurements were taken while they completed the survey. Then the
participants viewed a second slideshow on various sceneries and landscapes for six minutes
during a recovery period in which blood pressures were taken.
Expected Results
It was expected that, from the baseline period to the active phase of the interview
measurement, non-recovered CAP patients would have a greater change in blood pressure
measurements than recovered CAP patients and well subjects. It was expected that this change
would be an increase in blood pressure.
It was also expected that from SER Time 1 to SER Time 2, non-recovered CAP patients
would show a greater decrease in positive affect scores and a greater increase in negative affect
scores than recovered CAP patients and well subjects.
Results
Data Analysis
To test the hypothesis that non-recovered CAP patients would show a greater
physiological response to laboratory stress than recovered CAP patients and well subjects, the
blood pressure measurements were used. There were four main phases in which blood pressure
measurements were taken: the baseline period, the active phase of the social competence
Stress and Chronic Abdominal Pain 15
interview, the cool phase of the social competence interview, and the recovery period. The blood
pressures from the baseline period and the active phase of the interview were used to test the
hypothesis. The measurement to be analyzed was the increase in blood pressure that participants
experienced while completing the SCI. The mean of the four baseline systolic and diastolic BP
measurements and the mean of the two maximum systolic and diastolic BP measurements
reached in the SCI active phase were calculated for each participant. The baseline mean was
subtracted from the active phase mean to determine each participant’s change in blood pressure.
A univariate analysis of variance (UNIANOVA) was used as the statistical test to
determine whether this change in blood pressure was significant for a sub-group of participants.
A univariate analysis of variance was used in order to control for participants’ BMI values,
which was seen as a possible confounding variable. The test was conducted for both the
dependent variables: difference in systolic BP means and difference in diastolic BP means. The
independent variable was CAP Outcome (Non-Recovered CAP, Recovered CAP, & Well). The
covariate variable was BMI.
To test the hypothesis that non-recovered CAP patients would have a greater decrease in
positive affect and a greater increase in negative affect after the stressor than recovered CAP
patients and well subjects, participants’ scores on the positive and negative affect scales of the
SER before and after exposure to laboratory stress were compared. A score of 1-5 was assigned
to the five answers for each positive or negative affect word: Not at all – 1, A Little- 2, Some - 3,
A Lot - 4, A Whole Lot - 5. Therefore, a higher score was associated with higher positive affect
and higher negative affect. Each participant’s mean score for positive and negative affect was
calculated for SER Time 1 before the Social Competence Interview and SER Time 2 after the
Social Competence Interview. The difference between the Time 2 and Time 1 means for positive
Stress and Chronic Abdominal Pain 16
and negative affect scores were calculated to determine the changes in positive and negative
affect.
A one-way analysis of variance (ANOVA) was used as the statistical test to determine
whether this change in positive and negative affect was significant for a sub-group of
participants. The test was conducted separately for both the dependent variables: change in
positive affect means and change in negative affect means. The independent variable was CAP
Outcome (Non-Recovered CAP, Recovered CAP, & Well).
Demographics
There were 317 participants in the study. Participants had a mean age of 20.34 years
(S.D. = 4.37). The minimum age was 12 years and maximum age was 32 years. Participants were
mostly Caucasian (92.7%). Participants were 59.6% female and 40.4% male. There were 93 well
participants, 143 recovered CAP participants, and 81 non-recovered participants. Table 1
provides a breakdown of the sample demographics according to the sub groups of chronic
abdominal pain participants and well participants.
Changes in Blood Pressure for Non-recovered CAP, Recovered CAP, and Well Participants
A univariate analysis of variance was conducted to test the hypothesis that non-recovered
CAP participants would show a greater change in blood pressure form baseline to SCI active in
comparison to recovered CAP and well participants. For the systolic blood pressure changes, no
significant difference was found, indicating that the three sub-groups had similar changes in
systolic blood pressure (F (2,222) =0.76, p<0.47). Also, for the diastolic blood pressure changes,
no significant difference was found, indicating that the three sub-groups had similar changes in
diastolic blood pressure (F (2,222) =2.54, p<0.08).
Stress and Chronic Abdominal Pain 17
Table 2 presents the systolic and diastolic blood pressure means and standard deviations
for the three sub-groups. The baseline is the mean of the four blood pressures taken during
baseline phase. SCI Active represents the mean of all blood pressures taken during the SCI
Active phase (the total number varies for each participant). Maximum BP represents the highest
two blood pressures in the SCI Active phase. Figure 1 is a graphical representation of the
changes in systolic and diastolic blood pressure. The line graph shows that all three sub-groups
had an increase in blood pressure as a result of the laboratory stressor, but the non-recovered
participants had increases similar to recovered and well participants as shown by similar slopes
on the graph.
Changes in Positive and Negative Affect for Non-recovered CAP, Recovered CAP, and Well
Participants
A one-way analysis of variance was conducted to test the hypothesis that non-recovered
CAP participants would show greater decrease in positive affect and greater increase in negative
affect in comparison to recovered CAP and well participants. For positive affect changes, no
significant difference was found, indicating that the three sub-groups had similar changes in
positive affect (F (2,205) =3.00, p<0.052). Also, for the negative affect changes, no significant
difference was found, indicating that the three sub-groups had similar changes in negative affect
(F (2,205) =0.50, p<0.605).
Table 3 presents the means and standard deviations for the positive and negative affect
for the three sub-groups. The scores are for Time 1 at baseline and Time 2 after the Social
Competence Interview stressor. Figure 2 presents a graphical view of the change in positive
affect for the three sub-groups. All groups started and ended at similar levels of positive affect.
All groups did experience a decrease in positive affect in response to the stressor, but this change
Stress and Chronic Abdominal Pain 18
was similar for all groups as seen by the similar slopes in the line graph.
Figure 3 is also a graph of the change in negative affect for the three sub-groups. All
groups experienced an increase in negative affect, but this increase was similar for all of the
groups as seen by the similar slopes. The non-recovered CAP group began and ended at a
slightly higher level of negative affect than the recovered CAP and well participants.
General Discussion
This study tested the effects of laboratory stress on chronic abdominal pain patients in
relation to those who have recovered from chronic abdominal pain and also well participants.
The main goal of the study was to measure blood pressure, positive affect, and negative affect in
response to laboratory stress. The means of the changes in these three dependent variables from
baseline to post-stressor were compared for non-recovered CAP, recovered CAP, and well
participants.
The first hypothesis was that non-recovered CAP patients would experience a greater
physiological change in blood pressure levels in response to laboratory stress than recovered
CAP patients and well subjects. All three groups of participants showed an increase in systolic
and diastolic blood pressure in response to the social competence interview stressor. However,
there was no significant difference in the changes between the three groups and non-recovered
CAP participants did not have significantly greater increases than recovered CAP and well
participants.
The second hypothesis was that non-recovered CAP patients would experience lower
positive affect change and higher negative affect change in response to laboratory stress than
recovered CAP patients and well subjects. All three groups did show a decrease in positive affect
Stress and Chronic Abdominal Pain 19
and slight increase in negative affect in response to the laboratory stressor. However, results
showed that this change in affect was similar for all three groups, and the non-recovered CAP
participants had changes in affect not significantly different from recovered CAP and well
participants.
The results for the blood pressure changes in response to stress give implications for the
true effects of stress on chronic abdominal pain patients. Previous studies have found that
chronic abdominal pain patients report increase reactivity to stress. There were differences found
in symptoms, but the symptoms were measured through self-report. (Walker, Garber, Smith, Van
Slyke, & Claar, 2001) found that chronic abdominal pain patients report more daily stressors and
report more somatic symptoms in response to these stressors. The results of this study found the
same impact for all groups, which was unexpected due to previous findings. Therefore, this
implies that the biological responses to stress may be the same, but the perceptions of the effects
are what differs between the groups. It may be that participants with chronic abdominal pain are
more sensitive to the sensations and are more vigilant due to their abdominal pain.
The results for positive and negative affect suggest that responses to stress do have a
direct affect on positive and negative affect, however non-recovered CAP participants do not
show a greater decrease in positive affect or greater increase in negative affect than the other
groups. According to the means and graphical representation of the changes in negative affect,
well and recovered CAP participants were similar in effect. A further question would be whether
recovered CAP participants would have shown a similar affect to wells when they still had
chronic abdominal pain, or did they show similar effects for wells after they were determined to
have recovered from chronic abdominal pain. If the recovered CAP participants had shown
similar effects only after they recovered, then this may give implications of certain coping
Stress and Chronic Abdominal Pain 20
strategies that were useful for them and that helped them to cope at levels close to those who
never experienced chronic abdominal pain. A future study could test the effect of this laboratory
stressor at baseline and then repeat the lab stressor at a follow-up with a focus on those who had
CAP at baseline but recovered by follow-up.
One limitation of this study is that the changes in positive and negative affect were results
from self-report questionnaires and not more objective measurements of affect. Another
limitation of this study is that even though all subjects participate in the same general format of
the Social Competence Interview, not all subjects discuss the same exact stressor. One
participant may discuss a financial stressor and another may discuss a school stressor, which
means that the results that stress affect emotional and physiological measurements cannot be
generalized to a specific stressor. A possible limitation is the fact that the stressor was a shortterm stressor in which the participants discussed the stressor in the laboratory, and different
results may have been obtained from a chronic stressor.
These results will contribute to existing literature because it will give more insight into
the specific effects of stress in chronic abdominal pain patients. Future directions could include
studies focusing on the cognitive effects of stress on chronic abdominal pain patients such as
differences in perception as opposed to the physiological effects such as blood pressure.
Prospective studies that test types of coping strategies and success of strategies used by those
who have recovered from chronic abdominal pain would be questions to pursue in the future.
Stress and Chronic Abdominal Pain 21
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Stress and Chronic Abdominal Pain 23
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Stress and Chronic Abdominal Pain 24
Tables
Table 1: Demographics
Demographic
Age (Years)
Gender (Percentage):
Female
Male
Race (Percentage):
Caucasian
African-American
Other
CAP
(n = 224)
Mean = 21.51, S.D. = 4.42
WELL
(n = 93)
Mean =17.72 , S.D. =2.88
40.3%
28.4%
18.2%
13.1%
63.0%
3.5%
1.9%
30.2%
0.3%
1.0%
Table 2: Systolic and Diastolic Means and Standard Deviation for Non-Recovered CAP,
Recovered CAP, and Well Groups from Baseline to SCI Active Phase (mmHG)
CAP Outcome
Baseline:
Systolic
Wells
Mean
Std.
Deviation
Recovered
Mean
CAP
Std.
Deviation
Unrecovered Mean
CAP
Std.
Deviation
Baseline:
Diastolic
SCI
Active:
Systolic
SCI
Active:
Diastolic
Maximum
BP:
Systolic
Maximum
BP:
Diastolic
111.2165
10.73407
60.8750
6.81437
123.7179
12.73888
73.3787
8.37415
126.6139
12.82149
78.0633
12.79783
115.5574
13.42059
63.0861
8.12033
128.5705
15.09074
73.6767
8.83537
132.4889
15.96537
77.3389
10.23044
110.8161
11.85341
62.6897
7.75634
123.0537
13.37801
73.9026
10.30038
126.3534
14.15361
77.8966
12.68089
Note: SCI Active represents the mean of all blood pressures taken during the SCI Active phase. Maximum BP
represents the highest two blood pressures in the SCI Active phase.
Table 3: Positive and Negative Affect Scores at Time 1 and 2, Mean and Standard Deviation
CAP Outcome
Positive Negative Positive Negative
Affect
Affect
Affect
Affect
Time 1 Time 1 Time 2 Time 2
Wells
Mean 2.5071
1.1453 1.7057
1.6106
S.D.
.70014
.18853 .70310
.52753
Resolved
CAP
Mean
S.D.
2.4633
.78027
1.1501
.28486
1.9297
.70607
1.5765
.52090
Unresolved Mean
CAP
S.D.
2.4048
.74910
1.3367
.37604
1.7176
.72190
1.8864
.67471
Note: Positive and Negative Affect scores are on a five point scale
Stress and Chronic Abdominal Pain 25
Figures
Figure 1: Changes in BP in Non-recovered and Recovered CAP and Well Groups from Baseline
to SCI Active Phase
Figure 2: Change in Positive Affect from Baseline (Time 1) to Post SCI (Time 2)
Figure 3: Change in Negative Affect from Baseline (Time 1) to Post SCI (Time 2)
Stress and Chronic Abdominal Pain 26
Figure 1
Stress and Chronic Abdominal Pain 27
Figure 2
Stress and Chronic Abdominal Pain 28
Figure 3