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197
Autonomic Effects of
Expressive Writing in
Individuals with
Elevated Blood
Pressure
KIMBERLY M. BECKWITH MCGUIRE,
Licensed Clinical Psychologist, USA
MELANIE A. GREENBERG, &
RICHARD GEVIRTZ
Alliant International University, USA
KIMBERLEY M. BECKWITH MC GUIRE, PhD, is a
Licensed Clinical Psychologist in private practice in
San Diego and is active in the area of clinical health
psychology.
MELANIE A. GREENBERG (PhD State University of
New York, Stony Brook, NY) is a Professor of Clinical
Psychology at Alliant International University, San
Diego, CA. She has published in the areas of health
psychology, emotional expression interventions and
cognitive-emotional adjustment to life stress.
RICHARD GEVIRTZ (PhD De Paul University,
Chicago, IL) is a Professor of Clinical Psychology at
Alliant International University, San Diego, CA. He
has published in the areas of biofeedback and heart
rate variability.
Journal of Health Psychology
Copyright © 2005 SAGE Publications
London, Thousand Oaks and New Delhi,
www.sagepublications.com
Vol 10(2) 197–209
DOI: 10.1177/1359105305049767
Abstract
We evaluated systolic and
diastolic blood pressure, heart
rate variability and skin
conductance at basline, and 1
and 4 months in 38 participants
with elevated blood pressure,
randomly assigned to expressive
writing or control groups. There
was a significant interaction
such that the very low
frequency wave of heart rate
variability increased over time
only in controls, suggesting
potentially protective buffering
in expressive writing. Systolic
and diastolic blood pressure
also decreased significantly
from baseline to 1 month in
expressive writing. Consistent
with inhibition, Anger-In
moderated effects of writing on
4-month DBP. Overall,
expressive writing
demonstrated short-term
autonomic benefits and
longer-term moderated effects.
Keywords
Anger-In, blood pressure,
expressive writing, heart rate
variability
ACKNOWLEDGEMENTS. The authors would like to thank Gregory
Berkoff, D.O., and Daniel Michaels, M.D., for referring patients to the
study and Jessica Schutte, M.S., and Dawn Dilley, M.S., for their help
with data collection. William Gerin, PhD, provided valuable
information regarding study design and conceptualization.
COMPETING INTERESTS: None declared.
ADDRESS. Correspondence should be directed to:
MELANIE A. GREENBERG, PhD, Clinical PhD Program, Alliant
International University, 10455 Pomerado Rd, San Diego, CA 92131,
USA. [email:
KIMBERLEY M. BECKWITH MC GUIRE at
kbmcguire@cox.net or
MELANIE A. GREENBERG at
mgreenberg@alliant.edu.]
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THIS CONTROLLED study examined the
efficacy of an expressive writing intervention for
individuals with elevated blood pressure (BP).
An estimated 50 million adult Americans are
diagnosed with hypertension, yet three-fourths
are unable to control their BP with medication
and/or lifestyle changes (JNC VI, 1997; JNC 7,
2003), resulting in a myriad of health problems.
Complications of elevated BP, including heart
failure, end-stage renal disease, stroke and
coronary heart disease (CHD) have remained
stable or increased in incidence recently (JNC
VI, 1997). Direct and indirect costs of
hypertension were 40.4 billion dollars in 2001
(AHA, 2000). In their 1997 report, the JNC
discussed the importance of non-pharmacologi-
cal interventions, especially in hypertensives
that do not respond to antihypertensive medi-
cation. They acknowledged, ‘Emotional stress
can raise blood pressure acutely’ (JNC VI, 1997,
p. 2423). This provided the impetus for the
current intervention designed to facilitate
emotional expression and resolution of life
stresses.
Recently, the JNC’s seventh report (JNC 7,
2003) has replaced the category of high normal
BP with a prehypertension category. This report
acknowledges that as BP increases, the chance
of cardiovascular disease (CVD) increases. This
represents increasing recognition that indi-
viduals in the high normal/prehypertension
stage are also at risk for hypertension and later
CVD. Therefore, we included this subgroup in
the study as well.
The cause of essential hypertension is yet to
be known, but theories suggest a possible role of
genetics, inadequate nutrition, lack of exercise
and/or emotional stress (e.g. Brosschot &
Thayer, 1998; Guyton, 1991; Ornish, 1992;
Turner & Boerwinkle, 2003). In this study, we
adopted a biopsychosocial approach (Engel,
1977), which suggests the interplay of emotional
stressors and biological reactions plays a signifi-
cant role in establishing and maintaining
elevated BP.
According to Pennebaker’s Inhibition-
Confrontation Theory (Pennebaker, 1982;
Pennebaker & Beall, 1986), an individual’s
inability to confront traumatic/stressful events
produces both chronic physiological inhibition
and intrusive rumination, leading to chronic
activation of the autonomic nervous system,
with resultant increased vulnerability to disease.
Therefore, deliberately confronting these events
and associated thoughts and emotions should
decrease chronically elevated BP. More recent
theories (Greenberg & Lepore, 2004; Green-
berg, Wortman, & Stone, 1996; Lepore,
Greenberg, Bruno, & Smyth, 2002) emphasize
the emotional self-regulatory effects of writing,
including autonomic and cognitive habituation
to trauma stimuli and responses following
repeated confrontation in a safe context. Thus,
trauma-related stimuli should lose their ability
to trigger chronic sympathetic elevations, result-
ing in lower resting levels of BP and other
sympathetic indicators.
Research supports the hypothesized link
between short-term emotional inhibition and
elevated autonomic arousal and between long-
term inhibition and CVD. Controlled studies
demonstrate that experimentally induced
emotional inhibition or behavioral suppression
produces immediate elevations on sympathetic
measures, including finger pulse amplitude,
finger temperature, heart rate (HR) and skin
conductance (SC) (e.g. Gross, 1998; Gross &
Levenson, 1997; Pennebaker & Chew, 1985).
Additionally, expressive writing studies have
demonstrated a decrease in SC levels for those
writing about traumas (Petrie, Booth, Penne-
baker, Davison, & Thomas, 1995). Experi-
mental studies of emotional expression and BP
in healthy populations have, however, shown
mixed results (Lepore, Ragan, & Jones, 2000;
Pennebaker, Hughes, & O’Heeron, 1987).
However, these studies all examined verbal
disclosure in non-medical samples. Therefore,
they do not directly address the effects of
expressive writing in a population at medical
risk.
Another psychophysiological theory (Bross-
chot & Thayer, 1998) suggests that chronic
emotional inhibition leads to persistently low
vagal tone, which increases HR and decreases
heart rate variability (HRV), which in turn
decreases cardiac control of BP and signifies
essential hypertension. These authors theorized
that chronic anger inhibition is associated with
consistently low vagal tone, as well as slow
cardiovascular recovery. Vagal tone is involved
in general emotional expression and emotional
regulation. When there is low vagal tone, an
individual is in a relatively inflexible state, and
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chronic low vagal tone can slow down cardio-
vascular recovery and increase HR and BP
(Brosschot & Thayer, 1998). Low HRV is a
good predictor of all-cause mortality, cardiac
mortality and sudden death (Dekker et al., 1997;
Katz, Liberty, Porath, Ovsyshcher, & Prys-
towsky, 1999; LaRovere, Bigger, Marcus,
Mortara, & Schwartz, 1998).
Yet another model suggests that expressive
techniques can reduce BP for individuals who
have not ‘adequately cognitively integrated
their stressful experience’ (Davidson et al.,
2002, p. 23). These authors hypothesized that
expressive writing should be beneficial for indi-
viduals who are prone to anger or who demon-
strate excessive levels of anger inhibition, anger
expression or both. This theory implies that a
personality style involving chronic anger inhibi-
tion could moderate the effects of the inter-
vention on physiological functioning. In other
words, writing should be more beneficial for
those high in Anger-In than those without
substantial prior anger inhibition.
A growing body of research supports the
efficacy of written expression interventions in
medically ill populations. Expressive writing
has produced improvement in biological
measures (e.g. skin conductance, immune func-
tioning) in healthy participants (Booth &
Petrie, 2002; Petrie et al., 1995; Smyth, 1998)
and in disease status in participants with
rheumatoid arthritis and asthma (Smyth, Stone,
Hurewitz, & Kaell, 1999). This technique has
also decreased fatigue in terminally ill cancer
patients (Moore et al., 2002), and decreased
medical visits for breast cancer patients
(Stanton & Danoff-Burg, 2002).
A recent, controlled study of expressive
writing in normotensives provides preliminary
support for beneficial effects on BP. Crow,
Pennebaker and King (submitted) assessed 52
adult normotensives randomly assigned to
either an expressive writing condition or a non-
emotional writing condition. BP was measured
two times and then averaged, one day prior to
writing and at 6-week follow-up. Results indi-
cated a significant decrease in diastolic BP for
the experimental group relative to the control
group, with an almost significant decrease noted
for systolic BP. These findings, together with
those demonstrating beneficial effects of writing
in medically ill populations, suggest that this
intervention could plausibly decrease BP, and
autonomic arousal in individuals with elevated
BP. There is also theoretical support suggesting
potential decreases in HRV and increases in
vagal tone. Given the high costs and potential
risks of elevated BP and the lack of demon-
stratedly effective non-pharmacoloigcal treat-
ments for this population, this low cost, and
easily administered psychosocial intervention, if
shown to be effective, has the potential for
widespread clinical use.
We hypothesized that a brief expressive
writing intervention would decrease systolic and
diastolic BP and SC levels and increase HRV in
this elevated BP sample. We also hypothesized,
that Anger-In would moderate the effects of
expressive writing on BP.
Methods
Participants
Forty-nine participants were recruited with 38
of these (78% of original sample) included in
the final sample. Participants were 26 males and
12 females, ranging in age from 25 to 60 (M =
43.34, SD = 10.17). A majority (73.7%) was
Caucasian, and 55.2 percent were married.
More than half of the sample (61%) indicated
an education level of college graduate or
graduate school and 61 percent were engaged in
full-time employment. There were no significant
between-group differences in percentage of
participants in each BP category,
2
(d.f. = 2, N
= 38) = .09, NS for systolic BP and
2
(d.f. = 2,
N = 38) = .73, NS for diastolic BP.
1
The sample was recruited from referrals by
local physicians (18), self-referrals (10) and
from advertisements (10) posted at medical
clinics, local colleges and graduate institutions,
pharmacies, a local newspaper and family
centers (e.g. YMCA). The advertisements
invited individuals to participate in a study
on ‘stress and high blood pressure; a non-
medication technique aimed at reducing your
blood pressure’. Participants received US$30.00
for their participation.
Interested individuals were screened by tele-
phone to determine potential eligibility. The
BP guidelines in effect at the time of this study
were derived from the JNC VI report. Indi-
viduals with a reported history of high normal
to moderate hypertension (130–179 mm
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Hg/85–109 mm Hg) were initially eligible to
participate (Table 1). A reported history was
defined as self-reported elevated BP on at least
two visits to a physician’s office within the
previous 12 months. Hypertension history
reports have demonstrated 94.2 percent accu-
racy, when compared with medical records
(sensitivity = 95.4 percent; specificity = 92.4
percent; Page & France, 2001). To be included
in the final data analyses, potential participants
also had to have BP readings of high normal or
above on either systolic BP or diastolic BP at
baseline. At baseline, 39 percent of participants
had high normal BP, 47 percent had mild and 13
percent had moderate hypertension. Means,
standard deviations and ranges for BP at base-
line and both follow-ups are shown in Table 2.
Other inclusion criteria were proficiency in
English and ability to read English at a 7th grade
level. Exclusion criteria were diabetes, co-
morbid heart disease or history of heart disease,
severe psychiatric disorder or illiteracy (unable
to write for 20 minutes).
Attrition and white coat hypertension Eleven
of the recruited participants were not included
in the final sample, due to either white coat
hypertension (6 participants; 12%) or dropout
due to personal reasons (5 participants; 10%).
White coat hypertension was defined as the
average of the 17 baseline systolic and diastolic
BP readings falling below the high normal
range. Two of the five dropouts completed the
one-month follow-up, while the other three
discontinued after baseline. Neither dropout
status,
2
(2, N = 49) = .47, NS, nor white coat
hypertensive status,
2
(2, N = 49) = .37, NS, was
systematically related to group assignment.
Non-completers were more likely than
completers to identify partner status as single,
2
(2, N = 49) = 6.71, p < .05; percentages single
were 66.7 percent of white coat hypertensives,
40 percent of dropouts and 18.4 percent of
completers. Dropouts also had more comorbid
medical conditions (e.g. hepatitis C, hernia),
2
(2, N = 49) = 6.46, p < .05; 60 percent of drop-
outs, 18.4 percent of completers and 0 percent
of white coat hypertensives had comorbid
conditions. White coat hypertensives indicated
significantly more number of times exercised
per week (M = 5.33, SD = 2.42) than completers
(M = 1.95, SD = 1.81), F (2, 46) = 8.72, p < .001.
Measures
Demographics A demographics questionnaire
assessed gender, relationship status, ethnicity,
education, employment, family history of heart
disease, medication consumption, diet, exercise
and medical status. A health questionnaire
assessed consumption of caffeine, nicotine and
involvement in physical exercise during the
hour prior to physiological assessment.
Manipulation checks The Positive and Nega-
tive Affect Schedule (PANAS; Watson, Clark,
& Tellegen, 1988) assessed positive and negative
affect pre- and post-writing. The PANAS has 20
adjectives, 10 positive (PA) and 10 negative
(NA), and respondents rate their present mood
on a 5-point scale ranging from 1 (very slightly/
not at all) to 5 (very much). This measure validly
assesses short-term mood fluctuations, with
consistent psychometric results in varying
populations and over various time-frames
(Watson et al., 1988). Internal consistency
alphas in the current sample were .87 for PA and
.84 for NA.
Subjective responses to essay-writing were
assessed as per Greenberg et al. (1996). Partici-
pants rated the extent to which their essays were
personal, stressful, meaningful and revealing of
their emotions on a unipolar 7-point scale
ranging from ‘not at all’ (1) to ‘a great deal’ (7).
Anger-In The State-Trait Anger Expression
Inventory (STAXI) Anger-In (AX/In) subscale
(Spielberger, 1988) assessed anger suppression.
Anger-In is the characteristic frequency with
which an individual does not express his/her
anger in anger-arousing situations. Individuals
rate on a 4-point scale ranging from 1 (almost
never) to 4 (almost always), how often they
generally react or behave in the manner
JOURNAL OF HEALTH PSYCHOLOGY 10(2)
200
Table 1. Blood pressure guidelines according to the
JNC VI report (1997)
Blood pressure Range
Normal 120 mmHg/80 mmHg
High normal 130–139 mmHg/85–89 mmHg
Mild/borderline 140–159 mmHg/90–99 mmHg
Moderate 160–179 mmHg/100–109 mmHg
Severe 180 mmHg/110 mmHg or higher
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described when they feel angry or furious.
Coefficient alpha for the current sample was .73.
Blood pressure At baseline and each follow-
up, the first author (KB) or research assistant
took three BP readings, separated by two
minutes, using a ReliOn/Omron (HEM412-C)
home BP monitor. Participants also self-
monitored their systolic and diastolic BP at
home for 1 week at baseline, taking daily
measures, one in the morning and one in the
evening, using the same ReliOn/Omron BP
monitor. These 17 measures (3 laboratory, 14
home) were averaged for each participant to
obtain a baseline BP measure.
Skin conductance At baseline and each follow-
up, SC was assessed every 10 seconds, for a 15-
minute period during which the participant was
sitting quietly. The 15-minute sessions were
divided into two parts (time 1 and time 2), to
facilitate examination of within session differ-
ences. These scores were averaged separately for
each assessment period, resulting in three
overall SC scores. An electrode was placed on
the tip of the palmar side of a finger, along with
a grounding electrode on the forefinger. SC
increases as the number of activated sweat
glands increase and is measured in ‘micromhos’.
High test–retest reliability (r = .89) has been
shown for skin conductance (Schwartz, 1995).
Heart rate variability HRV is the rhythmic
activity ‘in the interval between consecutive
heart beats as well as the oscillations [rhythmic
activity] between consecutive instantaneous
heart rates’ (Task Force of the European
Society of Cardiology and the North American
Society of Pacing and Electrophysiology
(TFENA, 1996). HRV measures degree of auto-
nomic modulation and not level of autonomic
tone (TFENA, 1996), has three frequencies:
(very low frequency (VLF), low frequency (LF)
and high frequency (HF), and can be measured
by various methods using electrocardiogram
(ECG) recordings. The method we used was
spectral analysis (i.e. frequency domain
method), which provides information on the
variance distribution of the frequencies. More
specifically, the non-parametric method Fast
Fourier Transform (FFT) was implemented to
analyze the inter-beat-interval data (IBI). IBI is
the time between the R-waves of the QRS
complex of the electrocardiogram, representing
the ventricular activity of the heart (Gevirtz,
Lehrer, & Andrasik, 2003).
The J & J-300 C2 computerized physiological
monitoring system was used. One electrode was
placed on each wrist to produce the recordings
necessary. The device sampled ECG at over
1000 samples per second. Each session’s HRV
data were averaged every 10 seconds, for a
15-minute period in which the participant was
sitting quietly. The 15-minute sessions were
divided into two parts (time 1 and time 2) to
facilitate examination of within-session differ-
ences.
Procedures
To minimize between-group expectancy differ-
ences, all potential participants were told that
the study would examine the effects of stress on
elevated BP. At the first session, participants
met with the first author or trained research
assistant at either a physician’s office (n = 17),
2
or another quiet setting (n = 21), signed
informed consent forms and filled out baseline
questionnaires including the demographic and
medical status questionnaire, and psychosocial
measures (PANAS, STAXI). There were no
effects of setting on baseline measures (all
ps > .05). HRV and SC baselines were also
BECKWITH ET AL.: EXPRESSIVE WRITING AND BLOOD PRESSURE
201
Table 2. Descriptive statistics for blood pressure at three time points
Variable Mean SD Minimum Maximum Range
Baseline SBP 140.66 12.02 125 171 46
Baseline DBP 90.39 6.27 78 106 28
1-month SBP 135.18 15.56 102 167 65
1-month DBP 87.42 9.31 67 107 40
4-month SBP 138.03 13.02 109 168 59
4-month DBP 86.71 8.16 67 99 32
Notes: SBP = systolic blood pressure; DBP = diastolic blood pressure. All values are in mm Hg. N = 38
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measured after a 5-minute period of rest and
recorded for a 15-minute period, using J & J
biofeedback equipment, one week prior to the
first writing session. Participants were scheduled
to begin the intervention one week after base-
line assessment and were randomly assigned to
either the expressive writing or control groups.
Instructions to participants were derived from
previous studies using the expressive writing
intervention (Pennebaker & Beall, 1986; Smyth,
1998; Smyth et al., 1999). Participants had to
write for 20 minutes on each of three consecu-
tive days. To facilitate adherence checks, they
were told to record the dates of each essay.
Expressive writing participants had to express
their deepest thoughts and feelings about a
personally traumatic/stressful life experience
that previously was undisclosed or minimally
disclosed, while controls had to write objectively
(i.e. non-emotionally) about how they spent
their time the day before (day 1), and that day
(day 2), and what their plans were for the next
week (day 3). This was presented as a time-
management exercise. The first author called all
participants the day before writing to remind
them of the study requirements.
Participants completed a brief health status
questionnaire prior to each writing session to
assess possible medication change, the PANAS
before and after each writing session, and a
post-writing questionnaire after each writing
session. At 1- and 4-month follow-ups, BP, SC
and HRV were assessed using the baseline
procedure, and the STAXI was re-administered.
Results
Baseline comparisons and
manipulation checks
At baseline, there were almost significant differ-
ences between groups on marital status,
2
(1, N
= 38) = 3.98, p = .05, with the experimental
group having more married participants (n = 13)
than the control group (n = 8), and on
Asian/Pacific Islander (yes or no);
2
(1, N = 38)
= 4.02, p = .05, with the control group having
more participants identified as Asian/Pacific
Islander (n = 4) than the experimental group (n
= 0). Marital status and Asian/Pacific Islander
ethnicity were not significantly correlated with
any outcomes and therefore were not controlled
in subsequent analyses.
Examination of recorded essay dates
confirmed that 36 participants (95%) adhered to
instructions to write on three consecutive days.
All participants’ essays conformed to the
assigned writing condition topics. EW partici-
pants wrote about a range of stressful/traumatic
experiences, including death of a family member
(33%), extreme job situations (33%), self-
deprecation (17%), marital difficulties (12%)
and childhood stress (5%). Mean essay lengths
were 1.55 pages (SE = .11) and 1.37 pages
(SE = .12) for the EW and control groups
respectively, and these means did not differ
between groups F (1, 36) = 1.26, NS. These
checks established adequate adherence to the
experimental procedures.
A series of three-way ANOVAs (group
writing session time), with two repeated
measures (writing session and time) examined
between-group differences in PANAS PA and
NA from pre- to post-writing. The EW group
reported a significant increase in negative affect,
F (2, 35) = 8.98, p = .01, and no significant differ-
ences in positive affect from pre- to post-writing
task across days, F (2, 35) = .001, p = .97,
compared to controls. There were no signifi-
cant effects of session or session by time inter-
actions.
Daily post-writing assessments were also
analyzed. To reduce Type I error, a three
(session) two (group) MANOVA was
performed on six dependent variables: personal,
meaningful, expression of emotions, stressful,
description of thoughts and/or feelings and
awareness of new thoughts and/or feelings. EW
participants indicated significantly greater
overall involvement in writing (p < .001 for
domains 1–5 and p = .04 for domain 6), relative
to controls ( = .47, p < .001).
Blood pressure effects
Two-way (group time) ANOVAs with one
repeated measure examined between-group
differences in BP from baseline to 1- and 4-
month follow-ups. There was a significant main
effect of time for both systolic, F (2, 72) = 4.57,
p < .02, and diastolic, F (2, 72) = 4.35, p < .02,
indicating that participants decreased in BP
over time, regardless of group (see Table 3). The
hypothesized group time interactions were
not significant for either systolic, F (2, 72) = 1.96,
p = .15,
2
= .05, or diastolic BP, F (2, 72) = .26,
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NS,
2
= .01, however, the former exhibited a
trend in the hypothesized direction.
To further investigate BP data, paired-samples
t-tests were conducted separately within each
group from baseline to 1-month and from 1-
month to 4-month assessments (see Table 3 for
descriptive statistics). These indicated a statisti-
cally significant decrease in systolic BP, t (17) =
3.06, p < .01, d = .36, and in diastolic BP, from
baseline to 1-month follow-up, t (17) = 2.26, p <
.05, d = .21 in the expressive writing group.
Decreases in the control group were not signifi-
cant for either systolic or diastolic BP during
this same time period, t (19) = 1.10, p = .29 and
t (19) = .99, p = .33, respectively. From 1- to 4-
month follow-ups, however, there was a signifi-
cant increase in systolic BP in the expressive
writing group, t (17) = –3.04, p < .01, but no
significant changes in the control group, t (19) =
.49, NS. Neither the expressive writing group,
t (17) = .27, NS, nor the control group, t (19) =
.49, NS, evidenced significant changes in dias-
tolic PB during this period. Thus, there was
some partial support for beneficial effects of
writing on 1-month BP.
Skin conductance and heart
rate variability effects
A series of 3 (time) 2 (session; time 1 and time
2) by 2 (group) ANOVAs evaluated group
differences in SC and HRV.
3
Significant main
effects of session indicated that participants
increased in SC on average from the first half to
the second half of each 15-minute period of
recording biofeedback data, F (1, 31) = 8.82, p <
.01. Contrary to predictions, no significant main
effects of time or group time interactions
were found. Means, standard deviations and
interaction statistics are shown in Table 4.
For heart rate variability, very low frequency
(VLF), low frequency (LF) and high frequency
(HF) waves were analyzed separately. See Table
4 for results. The VLF is considered to be
sympathetically mediated, with lower VLF indi-
cating less arousal and therefore less rumination
and worry (Gevirtz, 2000). The LF correlates
with baroreceptor reflexes, which play an
important role in BP regulation (Gevirtz et al.,
2003). The HF is a measure of vagal tone, which
is parasympathetically mediated, and higher
levels indicate better vagal tone (Gevirtz et al.,
2003).
There was a significant group time inter-
action for VLF such that the control group
increased in VLF from baseline to 1- and 4-
month follow-ups, whereas the expressive
writing group’s VLF scores remained the same
over time, F (2, 29) = 3.50, p < .05; d = .12.
Additionally there was a non-significant trend
(p = .17) indicating increased HF from baseline
to 1-month follow-up in the expressive writing
group and decreased HF in the control group,
which, when accompanied by the concurrent
decreased BP for expressive writing partici-
pants, provides weak support for beneficial
effects of writing on vagal tone.
Moderator effects
To evaluate Anger-In as a moderator of the
relationship between group status and BP, four
multiple regression analyses were performed
using systolic and diastolic BP at 1- and 4-month
follow-ups as the respective dependent vari-
ables. Baseline Anger-In was mean-centered
BECKWITH ET AL.: EXPRESSIVE WRITING AND BLOOD PRESSURE
203
Table 3. Means, standard deviations and ANOVAs for blood pressure
Expressive writing
a
Control
b
F
Variable M (SD) M (SD) Time (T) T X Group
Systolic BP 4.57* (1.96
Baseline 141.79 (10.41) 139.50 (13.08)
1 month 134.11 (11.76) 136.15 (18.58)
4 months 140.78 (13.48) 135.55 (12.40)
Diastolic BP 4.35* ( .26
Baseline 90.26 (5.27) 89.95 (7.16)
1 month 86.94 (7.03) 87.85 (11.14)
4 months 86.44 (8.00) 86.95 (8.50)
Notes: BP = blood pressure. All values are in mmHg.
a
n = 18;
b
n = 20; *p < .05
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to reduce potential multicollinearity prior to
computing the interaction terms. Group was
dummy coded (expressive writing = 1; control =
0). Baseline systolic or diastolic BP (respec-
tively) group, baseline Anger-In and the group
Anger-In interaction term were entered as
predictors. In all four analyses, baseline levels
significantly positively predicted 1- and 4-month
BP. Interactions were not significant for 1-
month diastolic or for systolic BP. Anger-In
interacted significantly with group, however, to
predict 4-month diastolic BP with medium
effect size (sr
2
= .11). Results are shown in Table
5 and Fig. 1. Control group participants who
were high in Anger-In at baseline, had a higher
residualized diastolic BP at 4-month follow-up,
relative to low Anger-In controls. However,
high Anger-In expressive writing group partici-
pants had a lower residualized diastolic BP at
4-months, compared to expressive writing
participants with lower Anger-In.
Discussion
This study evaluated the effects of an expressive
writing intervention on BP in individuals with
elevated BP. The groups were similar at pretest
on all demographics, medications and health
behaviors that were correlated with the
outcomes. Consistent with previous studies
(Greenberg et al., 1996; Pennebaker & Beall,
1986), participants in the expressive writing
group reported an increase in negative mood
from pre- to post-writing task across sessions.
There was no habituation of negative mood
across sessions. The expressive writing group
also rated their essays as more personal and
meaningful, the disclosed events as more stress-
ful and disclosed more thoughts and/or feelings,
as well as becoming aware of more new
thoughts and/or feelings, in comparison with
controls. Adherence checks established that
participants obeyed instructions with respect to
essay content and the timing of essay-writing.
These results suggest that the manipulation
worked mostly as intended.
Although no significant interaction effects
were found for SC, as has been found in
previous studies (Petrie et al., 1995), a signifi-
cant group time interaction was found on one
of three measures of heart rate variability.
Controls increased in the very low frequency
wave of HRV (VLF) from baseline to 1 and 4
month follow-ups, but expressive writing
JOURNAL OF HEALTH PSYCHOLOGY 10(2)
204
Table 4. Means, standard deviations and ANOVAs for skin conductance and heart rate variability
Expressive writing Control
F
Variable M (SD) M (SD) (Time X Group)
VLF HRV (%) 3.50*
Baseline .51 (.01) .48 (.14)
1 month .51 (.01) .53 (.01)
4 months .51 (.01) .54 (.01)
LF HRV (%) 1.09
Baseline .31 (.01) .31 (.01)
1 month .32 (.00) .31 (.01)
4 months .30 (.01) .31 (.01)
HF HRV (%) 1.81
Baseline .18 (.01) .21 (.14)
1 month .23 (.20) .17 (.01)
4 months .19 (.01) .16 (.01)
SC 1.20
Baseline 3.23 (4.62) 2.07 (1.06)
1 month 4.54 (4.59) 2.63 (1.57)
4 months 2.54 (2.37) 2.50 (1.66)
Notes: VLF = very low frequency wave; LF = low frequency wave; HF = high frequency wave; HRV = heart
rate variability. % = percentage of total power for that wave. HRV values are in Hz and SC values are in
micromhos. Expressive writing group ns were 14 for HRV and 16 for SC
Control group ns were 15 for HRV and 17 for skin conductance
*p < .05
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participants maintained a constant level of VLF
over time. The VLF is sympathetically medi-
ated, with lower VLF indicating less arousal.
VLF is also a physiological correlate of rumina-
tion and worry (Gevirtz, 2000). The protective
effects of expressive writing on VLF are
consistent with theories and empirical studies
(Pennebaker & Susman, 1988; Wegner,
BECKWITH ET AL.: EXPRESSIVE WRITING AND BLOOD PRESSURE
205
Table 5. Summary of standard multiple regression analyses for group, Anger–In and their interaction predict-
ing SBP and DBP
Dependent variable Predictor B SE B
sr
2
R
2
1-month SBP
Baseline SBP .79 .18 .61*** .36 .42**
Group –3.76 4.10 –.12 .01
Baseline Anger-In .90 .77 .21 .02
Group Anger-In –1.01 1.14 –.16 .01
4-month SBP
Baseline SBP .65 .14 .60*** .34 .44**
Group 3.56 3.37 .14 .02
Baseline Anger-In .35 .64 .10 .00
Group Anger-In –.94 .94 –.18 .02
1-month DBP
Baseline DBP .78 .22 .53*** .26 .35**
Group –1.14 2.59 –.06 .00
Baseline Anger-In 1.12 .49 .45* .10
Group Anger-In –.47 .72 –.13 .01
4-month DBP
Baseline DBP .49 .20 .38* .13 .28*
Group –1.01 2.39 –.06 .00
Baseline Anger-In .71 .45 .32 .05
Group Anger-In –1.49 .66 –.46* .11
Note: SBP = systolic blood pressure; DBP = diastolic blood pressure; N = 38
*p < .05; **p < .01; ***p < .001
Figure 1. Interaction of mean-centered Anger-In and group predicting residualized 4-month diastolic BP. The
interaction was significant at p < .05.
–1
–0.5
0
0.5
1
Low High
An
g
er-In
Residualized four-month DBP
Expression
Control
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Schneider, Carter, & White, 1987), which
suggest that deliberate cognitive or emotional
inhibition produces chronic rumination and
worry, and with studies by Lepore and
colleagues (e.g. Lepore, 1997; Lepore & Helge-
son, 1998) suggesting that emotional disclosure
inures participants to the negative psychological
and physiological sequelae of intrusive
thoughts. Future research could clarify the
relationship between expressive writing, intru-
sive thoughts and VLF by using a uniform stres-
sor (e.g. a film) and including a measure of
intrusive thoughts at each assessment. Intrusive
thoughts and VLF could be assessed as both
moderators and outcomes of expressive writing.
VLF may also mediate expressive writing
effects on intrusive thoughts.
There were significant time main effects, indi-
cating decreases in both types of BP, regardless
of group, from baseline to the two follow-ups.
The group time interaction for SBP showed a
trend (p < .15) in the hypothesized direction.
Posthoc analyses indicated significant reduc-
tions in both types of BP in the expressive
writing group from baseline to 1 month follow-
up. The effect sizes (d = .36 for systolic BP and
d = .21 for diastolic BP) suggest this finding is
unlikely due just to chance or repeated
measurement. However, expressive writing
group systolic BP increased significantly from 1
to 4 month follow-ups, relative to the control
condition, whereas controls maintained steady
systolic BP levels from 1 to 4 months. There was
also an increase in the high frequency wave
(HF) of HRV from baseline to 1-month follow-
up in the expressive writing group with a
concurrent decrease in the control group. This
trend, together with the simultaneous decrease
in BP, indicates a possible short-term beneficial
increase in vagal tone resulting from expressive
writing and is consistent with psychophysio-
logical theories (Brosschot & Thayer, 1998)
linking chronic emotional inhibition to persist-
ently low vagal tone, decreased HRV and
decreased cardiac control of BP.
How do the reductions in BP in this study
compare to other studies? Crow et al. (submit-
ted), using a normotensive sample, reported a
drop in both systolic and diastolic BP of almost
3 mmHg in the expressive writing group over 6
weeks, whereas between-group differences at 6
weeks in this study were 5.6 mmHg for systolic
and 3.4 mmHg for diastolic BP. In this study,
significant within-group differences were also
found for the expressive writing group from
baseline to 1-month follow-up, systolic BP
decreased 7.68 mmHg and diastolic BP
decreased 3.32 mm Hg. Although the group
time interaction was not significant in this study,
the BP decreases in both groups are similar to
or larger than those found in the Crow et al.
(submitted) study. These decreases are poten-
tially important because the risk for future
cardiac complications, such as stroke or
myocardial infarction, can be reduced with
even small reductions in BP (AHA, 2000).
Anger-In moderated the effects of EWon
autonomic arousal. In the control group, high
Anger-In participants had higher residualized
diastolic BP at 4-month follow-up, relative to
low Anger-In participants. Conversely, expres-
sive writing group participants with higher
Anger-In had lower residualized diastolic BP at
4-month follow-up than low Anger-In partici-
pants. Expressive writing decreased diastolic BP
for characteristic anger inhibitors, yet it
increased diastolic BP for those with low anger
inhibition. Furthermore, control group partici-
pants high in Anger-In, increased their BP more
over time than low Anger-In participants. These
findings are consistent with theoretical asser-
tions regarding the negative physiological
effects of chronic inhibition. Expressive writing
may have inured high Anger-In individuals to
these detrimental effects by providing a safe
context for emotional expression.
The moderating effect of Anger-In and the
protective effects of writing on a physiological
marker of cognitive rumination are consistent
with the theory (Davidson et al., 2002) suggest-
ing that expressive writing is most beneficial for
those with chronic problems in anger modula-
tion or inadequate cognitive integration of
stressful events. This intervention appears less
useful for individuals who do not typically
inhibit emotion. Individuals with undermodu-
lated anger may benefit more from learning how
to decrease emotional arousal or constructively
express anger in an interpersonal context. Those
whose high BP is due to dietary or genetic
factors may do better with medical or health
behavior interventions. Future research might
employ more individualized selection of
appropriate participants.
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Some caveats are in order. First, the relatively
small sample limited the power to detect
outcome differences. Second, there are some
limits to generalizability. Participants were
largely Caucasian (73.7%) and of higher
socioeconomic status (81.6%), although
hypertension is typically more common in
African-Americans (JNC 7, 2003) than Whites.
Dropouts were more likely than completers to
be single and to have comorbid medical
conditions. Third, this was a mixed population
with regard to JNC VI BP category, although all
had elevated BP. Fourth, although these effect
sizes are clinically important, BP decreases in
the expressive writing group were not main-
tained at 4 months and effects were not
consistent across all measures.
Future studies should attempt to replicate
these findings with a larger sample size and
address maintenance issues. Perhaps a greater
frequency or duration of intervention writing
sessions, more structured writing instructions,
booster sessions, or assistance in applying
writing insights to cope with internal or external
stressors are necessary for longer-term main-
tenance of physiological gains in this medical
population. Future research should also include
a no treatment control group to tease apart the
effects of the different conditions.
Conclusions
The immediate effects of expressive writing
were similar to previous studies in that the
expressive writing group reported greater
overall emotional engagement in writing and
had greater pre–post writing NA increases than
controls. Additionally, BP decreased over time
for both groups.
Only expressive writing participants exhib-
ited significant within-group decreases in
systolic and diastolic BP from baseline to 1
month follow-up. The magnitude of effect was
similar to previous studies with normotensives.
These within-group findings, together with a
trend suggesting increased HF HRV in the
expressive writing group at 1 month follow-up,
suggests that expressive writing may have
produced short-term beneficial increases in
vagal tone. Additionally, the significant group
time interaction for VLF indicates that expres-
sive writing may have protected participants
from the increase in sympathetically mediated
arousal and, possibly, cognitive rumination,
found in the control group.
Overall this study found no effects of
expressive writing on SC, and some short-term
beneficial effects on BP and HRV. Longer-term
effects of expressive writing were moderated by
Anger-In, such that expressive writing
increased 4-month diastolic BP for low Anger-
In participants, relative to controls, but
decreased diastolic BP for those high in Anger-
In.
Notes
1. Participants who were physician-referred were of
higher SES and less likely to have a family history
of medical illness than those who were self-
referred or recruited by advertisement/flyers,
2
(4, N = 38) = 13.63, p < .01;
2
(2, N = 38) = 10.13,
p < .01, for SES and family history, respectively.
The expressive writing and control groups did not
differ in the proportion of participants from the
three different referral sources,
2
(2, N = 38) =
1.77, NS, therefore, referral source was not used as
a covariate.
2. One of 18 physician-referred participants chose to
do the writing at his home instead of the
physician’s office.
3. The ns were reduced in these analyses because two
participants at baseline, two participants at 1-
month follow-up and one participant at 4 month
follow-up did not register any SC data. Addition-
ally, the computer did not register the ECG waves
necessary to measure HRV for nine participants.
Therefore, the ns were 33 for SCL (16 expressive
writing, 17 control) and 29 for HRV (14 expressive
writing, 15 control).
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