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Resting Heart Rate and Right Prefrontal Cortex Functioning in Trauma Survivors
Christopher S. Immel, M.S., James M. Hadder, M.S., Michael M. Knepp, M.S., Chad L. Stephens, M.S.,
Ryoichi J.P. Noguchi, M.S., Sheri L. Towe, M.S., Jared A. Rowland, M.S., & David W. Harrison, Ph. D.
Virginia Tech, Blacksburg, VA, USA.
INTRODUCTION
METHODOLOGY
Trauma has been shown to have an adverse impact on
mental health outcomes, including Posttraumatic
Stress Disorder PTSD) and Major Depression Disorder
(Norris & Elrod, 2006). Further, research has
demonstrated the impact of exposure to trauma as well
as PTSD symptomology’s influence on health
outcomes. One of the health outcomes extensively
studied in the trauma literature is resting heart rate
and the increased heart rate individuals with PTSD
often exhibit (Buckley & Kaloupek, 2001). Even more
importantly, evidence has demonstrated that
individuals with PTSD may experience long-term
hyperactivity which can result in permanent
physiological alterations (Lovallo & Gerin, 2003).
Through the use of a preexisting dataset, the current project
examined the impact of right frontal lobe functioning on
resting heart rate in a group of participants with self-reported
high PTSD symptomology. The majority of participants
reported the April 16th, 2007, Virginia Tech Shootings as their
primary trauma.
A growing body of literature appears to indicate that
PTSD is the primary pathway to which negative health
outcomes arise following trauma (Green & Kimerling,
2004). Though the relationship between PTSD and
resting heart rate has been widely studied, the causal
mechanism of the relationship between PTSD and
physiological outcomes is less well known (Pole, 2007).
Further research is needed to better understand the
relationship between brain activity, particularly the
right prefrontal cortex and resting heart rate in
individuals with elevated PTSD symptoms.
Electrocardiogram (ECG) was recorded using the BIOPAC
MP30 system (BIOPAC Systems Inc, Goleta, CA) at a
sampling rate of 1000 hertz. Physiological signals were
acquired through three disposable, pre-gelled electrodes. The
attachment sites were prepared using 70% isopropyl alcohol.
Electrodes were placed according recommendation in the
BIOPAC User Manual standard limb lead II placement.
Measures:
As a measure of trauma, the study utilized the Impact of
Events Scale-Revised (IES-R; Weiss & Marmar, 1997). The
IES-R is a 22 item self-report instrument designed to assess
avoidant, hyperarousal, and reexperiencing symptoms of
PTSD. The measure utilizes a 5 point likert scale.
Right prefrontal cortex functioning was measured using the
Ruff Figural Fluency Test (Ruff, Light, & Evans, 1987). This
test consists of five sections containing various presentations of
dot matrices. Each section contains 35 stimuli to be completed
by the participant in a one-minute time period. The
participants were asked to connect the dots within each
stimulus to create as many unique designs as possible in that
section. The RFFT is scored by totaling the unique designs as
well as perseverations, as measured by design repetitions.
Design fluency is then computed by subtracting the total
number of perseverations from the unique design total and
using normative data to produce a T score. A T score for a
participant’s error ratio is also computed using the total
number of perseverations divided by the total number of
unique designs.
PURPOSE/HYPOTHESES
The purpose of the current poster is to examine the link
between right frontal lobe functioning, PTSD
symptomology, and resting heart rate.
It was hypothesized that trauma survivors with
heightened PTSD symptomology and elevated right
prefrontal cortex functioning would demonstrate lower
resting heart rate levels. Additionally, individuals with
less right prefrontal functioning were expected to
demonstrate higher resting heart rates.
REFERENCES
RESULTS
A 2 x 3 design was employed to analyze results. A cubic split
was performed on the data based upon RFFT scores. A
high/low split was then performed based upon scores on the
IES-R scale. A total of 38 participants were included in the
univariate analysis of variance.
Heart Rate
Results
Low error ratio on the
RFFT (17)
Mean = 75.18 bpm
SD = 2.83 bpm
High error ratio on the
RFFT scores (21)
Mean = 84.75 bpm
SD = 2.54 bpm
Results of the project indicate that those with high levels of
PTSD symptomology (as recorded by the Impact of Events
Scale-Revised) and a low error ratio (tested by the Right
Frontal Figural Fluency Task [RUFF]) had significantly
lower resting heart rates than those with a high error ratio, F
(36) = 6.34, p< .05.
DISCUSSION
These results may further clarify the factors which influence
resting heart rate in individuals with PTSD symptoms. The
project may also illustrate the importance of heightened
right frontal lobe function in reducing the negative impact of
PTSD on physiological outcomes, such as heart rate.
Limitations of the project include a limited sample size.
Additionally, a normal population of college students was
utilized. This population may illustrate a group of high
functioning individuals with PTSD, given they are enrolled in
college.
Future research will further investigate the relationship
between PTSD symptomology, heart rate, and right frontal
lobe functioning. Further exploration of PTSD symptom
sub-clusters and their relationships with right frontal lobe
functioning and heart rate will be important.
Norris, F. & Elrod, C. (2006). Psychosocial consequences of disaster: A review of past research. In F. H. Norris, S. Galea, M. j. Friedman, & P. J. Watson. Methods for disaster mental health research. The Guildford Press: New York.
Buckley, T. C., & Kaloupek, D. G. (2001). A meta-analytic examination of basal cardiovascular activity in posttraumatic stress disorder. Psychosomatic Medicine, 63, 585–594.
Lovallo, W. R., & Gerin, W. (2003). Psychophysiological reactivity: Mechanisms and pathways to cardiovascular disease. Psychosomatic Medicine, 65, 36–45.
Green, B. L. & Kimerling, R. (2004). Trauma, posttraumatic stress disorder, and health status. In P. Schnurr & B. Green, (Eds.) (2004). Trauma and health: Physical health consequences of exposure to extreme stress. (2004, pp. 13-42). American Psychological Association: Washington D.C.
Ruff R.M., Light R.H., & Evans R.W. (1987). The Ruff Figural Fluency Test: A normative study with adults. Developmental Neuropsychology, 3, 37-51.
Weiss, D. & Marmar, C. (1997). The Impact of Event Scale -Revised. In J. Wilson & T. Keane (Eds), Assessing psychological trauma and PTSD. New York: Guildford.
-Contact Information: Christopher Immel via [email protected].
International Society of Traumatic Stress Studies
rd
24 Annual
Meeting, Chicago, IL, November 2008