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brief report

Cardiac Coherence and PosttraumaticStress Disorderin Combat Veterans
Jay P. Ginsberg,; Melanie E. Berry, ; Donald A. Powell,
PhD

MS

PhD

Background • The need for treatment of posttraumaticstress disorder (PTSD) among combat veterans returningfrom Afghanistan and Iraq is a growing concern. PTSD has
been associated with reduced cardiac coherence (an indicator of heart rate variability [HRV]) and deficits in early stage
information processing (attention and immediate memory)
in different studies. However, the co-occurrence of reduced
coherence and cognition in combat veterans with PTSD has
not been studied before.
Primary Study Objective • A pilot study was undertaken toassess the covariance of coherence and information processing
in combat veterans. An additional study goal was assessment ofeffects of HRV biofeedback (HRVB) on coherence and information processing in these veterans.
Methods/Design • A two-group (combat veterans with and without PTSD), pre-post study of coherence and information processing was employed with baseline psychometric covariates.
Setting • The study was conducted at a VA Medical Center
outpatient mental health clinic.

Participants • Five combat veterans from Iraq or Afghanistanwith PTSD and five active-duty soldiers with comparable combat exposure who were without PTSD.
Intervention • Participants met with an HRVB professional
once weekly for 4 weeks and received visual feedback in HRV
patterns while receiving training in resonance frequency breathing and positive emotion induction.
Primary Outcome Measures • Cardiac coherence, word list
learning, commissions (false alarms) in go–no go reaction time,
digits backward.
Results • Cardiac coherence was achieved in all participants,
and the increase in coherence ratio was significant post-HRVB
training. Significant improvements in the information processing indicators were achieved. Degree of increase in coherence
was the likely mediator of cognitive improvement.
Conclusion • Cardiac coherence is an index of strength of control of parasympathetic cardiac deceleration in an individualthat has cardinal importance for the individual’s attention andaffect regulation.

Jay P. Ginsberg, PhD, is a licensed clinical psychologist andneuropsychologist in the Dorn VA Medical Center (VAMC)
OEF-IF program and a research health scientist in the Shirley
L. Buchanan Neuroscience Laboratory, also at the Dorn
VAMC. Melanie E. Berry, MS, is certified in heart rate variability, electroencephalogram, and electromyography biofeedback by the Biofeedback Certification Institute ofAmerica and has additional professional certifications in theHeartMath Intervention Program for Health Professionals,
Stress Management, and Pain Management. Donald A.
Powell, PhD, is a retired research career scientist with the
Dorn VAMC, where he was a researcher and author. (Altern
Ther Health Med. 2010;16(4):52-60).

mental health problem, but when reassessed 3 to 6 months later,
27% of active duty and 42% of reserve personnel had a mental
health problem.1 The VA has already provided PTSD treatment tomore than 52 000 OEF/OIF veterans. At this time, more than 1.5
million active duty soldiers have deployed to the two conflicts.
Estimates of the incidence of mental health problems, including
PTSD as well as depression and substance abuse, among returning
combat veterans range from 11% to 35%.1-3 The RAND Corporation
estimated that the total number of psychiatric casualties from service in Iraq and Afghanistan by 2006 was 300 000 veterans.4
Heart rate variability (HRV), measured as variance in cardiac inter-beat intervals, or power, has been reported to be reducedin PTSD.5-9 Efferent parasympathetic output from the vagus cranial nerve (vagal tone) is the major contributor to HRV power
and an index of the parasympathetic/sympathetic balance.
Normal vagal tone is necessary for maintenance of the physiological background necessary for initial perception and registrationof environmental stimulation and events, suggesting that PTSD
has an underpinning of physiological abnormality (lower HRV),
which also may adversely affect early-stage information processing. Cardiac coherence, described below and elsewhere in thisissue, is a key measure of HRV that with the appropriate proto-T

he number of returning Afghanistan (Operation
Enduring Freedom, OEF) and Iraq (Operation Iraqi
Freedom, OIF) combat veterans seeking treatment for
posttraumatic stress disorder (PTSD) is expected toincrease in the coming years. A study of OEF/OIF
combat veterans immediately on return from deployment showsthat 5% of active duty and 6% of reserve personnel had a significant

52

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Cardiac Coherence and PTSD

cols can provide a better index of parasympathetic function than
measures such as high-frequency power as well as indicate thedegree of synchronized activity in the autonomic nervous system(ANS) and some higher-level brain systems.10
Several studies have shown that increased HRV power is significantly associated with improved cognitive performance inadults, measured as academic measures in middle school students
with ADHD,11 immediate memory,12 working memory,13 and auditory discrimination reaction time.14 Additional but indirect evidence of this comes from a study of patients with Alzheimer’s
disease who cognitively improved after vagal nerve stimulation.15
Evidence that there are deficits in attention (ATTN) and
immediate memory (IM) associated with PTSD in combat veterans can be found in the literature.16-21 However, the impact of
reduced HRV on ATTN/IM deficits in combat veterans with
PTSD has not been studied. This pilot study aimed to assess theextent to which HRV and ATTN/IM covary in combat veterans.
If normal vago-sympathetic balance is altered in favor of sympathetic tonus in combat-related PTSD (PTSD+), it follows that restoration of a normal balance may lead to amelioration of theeffects of PTSD. The goal of this pilot study was to further test
this idea by assessing the effects of HRV biofeedback, an intervention that is known to improve HRV and increase coherence,on HRV and ATTN/IM in these veterans.
Methods
Study Setting
The study was conducted onsite at Dorn VA Medical
Center, Columbia, South Carolina, after all regulatory approvals were obtained.
Participants
PTSD+ veterans were recruited from the VA Medical
Center’s mental health outpatient clinic. Inclusion criteria for
PTSD+ subjects were combat experience in either Afghanistan or
Iraq, a diagnosis of PTSD, and receiving current treatment for
PTSD. Exclusion criteria for potential participants were known
or suspected histories of acquired neurocognitive deficits including even mild traumatic brain injury; any neurological disorder;
history of PTSD, depression, or alcohol or other substanceabuse/dependence prior to OIF/OEF deployment; history of
diagnosis or treatment for seizure disorder; current prescription
for an acetylcholine esterase inhibitor, beta-blocker, serotoninnorepinephrine reuptake inhibitor, or neuroleptic (typical or
atypical antipsychotic); evidence of active substance abuse ordependence; lifetime history of major depression, bipolar, psychotic, panic and/or obsessive-compulsive disorders; cardiovascular disease including use of pacemakers, bypass surgery, or
heart transplant. Combat veterans without PTSD served as controls. Controls were active-duty soldiers from the nearby Air
National Guard base. Inclusion criteria for controls was combat
experience in Afghanistan or Iraq. Exclusion criteria were thesame as for the PTSD+ subgroup. Five combat PTSD+ veteransand five control veterans were enrolled in the pilot study.

Cardiac Coherence and PTSD

Intervention
Baseline HRV was measured using the emWave HRV monitoring system (HeartMath, LLC, Boulder Creek, California) withapplication software that records and exports R-R interval data.
HRV was measured for 10 minutes during the first session before
any training in the HRV biofeedback (HRVB) technique wasdelivered. During the initial pre-training HRV session, all participants were presented with a scenic picture on the computer
screen during HR recording. Thus, no visual feedback on heart
rate was provided before training. The post-training resting HRV
also was recorded for 10 minutes while participants passively
viewed a scenic picture.
The HRVB training intervention used the emWave system.
HRVB is an interactive procedure using a hardware/software system to monitor and display individuals’ HRV patterns in real time.
During biofeedback training, the participant viewed a split computer screen monitor that shows the HRV power spectrum in real timeso that the participant can visualize the impact of the techniques.
Visual feedback of HRV (either quantitative display of the power
spectrum or as animated challenge games) was provided as participants practiced the techniques of attention focusing, resonant frequency breathing (RFB), and positive emotion induction. As aresult, changes in HRV patterns can be readily seen. The visual feedback enables associations to be formed between the techniques andHRV patterns indicative of shifts toward higher vagal parasympathetic output (0.1 Hz wave), which leads to self-regulation of theability to achieve coherence.
Participants received HRVB training from an HRVB professional during weekly sessions over a 4-week period using the
Quick Coherence Coach method. Before HRVB training, the biofeedback professional (BFP) discussed individual issues (pain,
stress, sleep issues, relationship issues, etc) and goals. During
HRV baseline recording, the BFP observed irregular breathing
patterns, and the physiological connection between RFB and HR(accelerating on inhale, decelerating on exhale) was introduced,
which leads to RFB pattern. The physiological connection
between RFB and HR (accelerating on inhale, decelerating on
exhale) was then introduced, leading to corrective breathing andthe RFB pattern (5-6 breaths per minute).
The BFP then developed a positive emotional state in the subject with the statement, “Engage your emotions by recalling andthinking about something you are grateful for or are appreciativeor proud of or love.” After the positive emotion aspect was introduced, the BFP instructed the visualizer to “experiment” with thevarious positive emotions and find which produced the greatest
0.1 Hz peak. There were occasional shifts between the visualizer
screen and the power spectrum screen so that the actual development of a 0.1 Hz peak could be seen. A home unit Personal Stress
Reliever (PSR) was loaned to the participant to use at home andthroughout the day, enabling them to practice the skills and transfer them to life situations in times of increased stress.
Variables
Baseline psychometric variables were assessed with the

ALTERNATIVE THERAPIES, jul/aug 2010, VOL. 16, NO. 4

53

following instruments. PTSD was assessed with the ClinicianAdministered PTSD Scale (CAPS); depression was assessed with
the Zung Depression Scale; anxiety was assessed with theSpielberger State-Trait Anxiety Inventory. Baseline psychometricvariables were used as potential covariates and were not measured post-HRVB training.
Cardiac coherence was assessed using the latest method.22
Coherence is characterized by a narrow, high-amplitude, easily visualized peak that falls into the upper low-frequency (LF) or lower
high-frequency (HF) bands (0.09-0.14 Hz). Coherence is operationalized by identifying the maximum peak in the 0.04 Hz to 0.26 Hz
range (the frequency range within which coherence and entrainment can occur), calculating the integral in a window 0.030 Hz wide
centered on the highest peak in that region, then calculating thetotal power of the entire spectrum. The coherence ratio is formulated as: coherence = peak power / (total power − peak power)2.22 Thismethod provides an accurate measure of coherence that allows forthe nonlinear nature of the HRV waveform over time.
The ATTN/IM test battery was modeled on Vasterling’s
studies that have shown deficits in PTSD+ combat veterans. 20,21
Sustained attention was assessed with Conners’ Continuous
Performance Test (CPT); registration/encoding of information
was assessed with the Wechsler Adult Intelligence Scale, Digit
Span subtest (DS, total number of trials correctly passed); andIM was assessed with the Rey Auditory-Verbal Learning Test
(RAVLT). The functional aspect of the selected ATTN/IM variables in this small battery is its focus on early-stage information
processing of stimulus information. The CPT is a well-validated
measure of sustained attention that uses the go–no go response
output method to assess response inhibition. Commission (false
alarm) errors were scored when the participant fails to inhibit
responding to the no-go target stimulus. The digit span test is anindicator of attentional capacity for auditory information registration and encoding. List learning is an indicator of immediate
recall of meaningful auditory verbal information.
Data Analysis
Movement artifacts in the recording data were eliminatedbefore outcome variables were computed. Pre-post changes in
ATTN/IM and coherence were analyzed as a mixed model(group x [pre-post]). Changes in HRV power were analyzed using
Mann Whitney U because although HRV power is a reliable
intra-individual physiological indicator, it is not normally distributed and shows large inter-individual differences. The threeway relationship between PTSD, HRV, and ATTN/IM wasanalyzed using univariate (ATTN/IM as outcome) model-building statistical techniques.
Results
The PTSD+ and control subgroups did not significantly differ in composition by sex, race, employment status, or age (Table1). Psychometric scores all reveal moderate to severe psychopathology in the PTSD+ subgroup compared to little or none in thecontrol subgroup.

54

Table 1 Demographics and Baseline Psychometric Scoresof Pilot Study Subjects*
PTSD(n = 5)

Variable

Control(n = 5)P(2-tailed)

Demographics
Sex (% male)

100

100

>.99

Race (% caucasian/AA)

60/40

60/40

>.99

Employed (%)

20

100

.29

Age

29.4 (SE 2.5)

34.2 (SE 2.6)

.22

Psychometrics
PTSD lifetime (CAPS)

104.4 (SE 7.1)

27.0 (SE 11.6)<.01

PTSD current (CAPS)

83.8 (SE 12.1)

6.6 (SE 2.6)<.01

Depression (BD-II)

29.6 (SE 5.8)

4.6 (SE 1.2)<.01

State Anxiety (STAI-S)

47.8 (SE 5.3)

24.4 (SE 2.4)<.01

Trait Anxiety (STAI-T)

57.4 (SE 6.7)

35.2 (SE 4.9)<.01

*AA indicates African American; SE, standard error; CAPS, Clinician-Administered
PTSD Scale; BD, Beck Depression; STAI, State-Trait Anxiety Inventory.

Effects of HRVB Training on Cardiac Coherence and HRV Power
Figure 1 (a-d) illustrates the effect of HRVB training on the
0.1 Hz peak in one study participant (PTSD+ subgroup). These
results are typical of all participants: the average post-training
power peak for all 10 subjects was equal to 0.11 Hz (SD = 0.02, SE= 0.01) and not statistically significantly different from 0.1 Hz(t[9] = 1.6, P [2-tailed] = .15). The coherence ratio in both subgroups increased post-training: PTSD increased from 0.2 to 40.2
and control coherence ratio increased to from 1.2 to 15.0 (Figure2a). The group x pre-post interaction showed a clear trend (P =.06), while pre-post within-subject and group main effects wereboth significant (P = .002 and P = .001, respectively). Overall(average of pre- and post-training), coherence for the PTSD+
subgroup was 20.2 (8.0) and for controls was 8.1 (10.7).
Pre-post HRVB changes in HRV power are shown in Figures
2b and 3. The Wilcoxon Signed Rank Test showed that only theincrease in LF band power was significant within both groups,
and no other pre-post changes in band power within subgroups(very LF, HF, or total) was significant. The increase over baselineof total power among control combat veterans in this study was
122.9% but only 18.2% among the PTSD+ veterans.
Effects of HRVB Training on ATTN/IM
Before training in HRVB, the PTSD+ subgroup was lower on
all measures of ATTN/IM, although none of the differences was
significant (Table 2a). When the pre-post difference in ATTN/IM
for the subgroups was analyzed using a two-factor mixed model
within-subject design (group x pre-post; Table 2b), a significant
interaction between PTSD and training was seen in total numberof words on list learning (P = .03). Inspection of the table ofmeans reveals that the PTSD+ subgroup increased from 54.4 to
59.0 words learned after training, whereas the control subgroup

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Cardiac Coherence and PTSD

60

120

180
Seconds

240

300

Post-training (c)R-R Interval Tachogram

0

60

120
180
Seconds

240

WLF

HF

LF

140
120
100
80
60
40
20
0

0

0.1

0.2

0.3

0.4

0.5

0.4

0.5

Frequency (Hz)Power Spectrum (d)
500
600
700
800
900
1000
1100
1200
1300
1400
1500

Beats Per Minute

120
100
86
75
67
60
55
50
46
43
40

160

300

300

WLF

LF

HF

250
Milliseconds
PSD (ms 2/Hz)

0

500
600
700
800
900
1000
1100
1200
1300
1400
1500

Milliseconds
PSD (ms 2/Hz)

Beats Per Minute

120
100
86
75
67
60
55
50
46
43
40

Power Spectrum (b)Pre-training (a)R-R Interval Tachogram

200
150
100
50
0

0

0.1

0.2
0.3
Frequency (Hz)Figure 1 (a-d) The Pre-Post HRVB Training, the R-R Interval Tachogram, and Power Spectra Density (PSD) of One PTSD+ Subject

declined negligibly from 56.6 to 56.5 words learned. A significant
main effect of training was seen as improvement in commissions
T score (a decrease in commissions means a reduction in dysinhibition) and digits backward (P = .05 and P = .03, respectively).

CAPSA and commissions decreased from .92 to .85 (partial) to.41 (semi-partial), with 1-tailed P going from .01 to .08 to .30,
respectively. This result suggests that percent change in coherence, not CAPSA, is predictive of improvement in commissions.

The Relationship Between PTSD, HRV, and ATTN/IM in
PTSD+ Combat Veterans
The PTSD+ subgroup was analyzed separately for relationships between HRV and ATTN/IM because it is the population ofinterest, and there was a significant PTSD x coherence interaction. Variable selection performed to motivate the model
revealed that CAPS Criterion C (Avoidance, CAPSA) was the only
psychometric measure with acceptable correlations with all psychometric variables. Coherence, quantified as percentage change
from pre-training, was chosen as the indicator of HRV change
because of its physiological significance and because it was significantly intercorrelated with both CAPSA (P = .01) and change
in commissions (P = .02). Partial and semi-partial correlation wasused to assess how controlling for percent change in coherence
affected the relationship between CAPSA and change in commissions. Results revealed that the zero-order correlation between

Clinical vs Statistical Significance of the Pilot Study Results
The HRVB intervention produced statistically significant
outcomes, but as a clinical intervention, the effects must be clinically meaningful also. Review of CPT commissions treatment
effect sizes indicated that the statistically significant improvement in CPT commissions found in the pilot study is comparable
to effect sizes produced by standard treatments. For example, theeffect size of the change in CPT commissions in the PTSD+ subgroup in the pilot study was 0.72, which compares favorably withthe published effect size of 0.39 of methylphenidate treatment on
decreased CPT commissions.23 The effect size of transdermal nicotine patch–reduced CPT commissions was reported to be 1.0.24

Cardiac Coherence and PTSD

Limitations of the Pilot Study
Though the data from the pilot study suggest that HRVB
improves some measures of ATTN/IM, these statistical findings

ALTERNATIVE THERAPIES, jul/aug 2010, VOL. 16, NO. 4

55

(a)

Total HRV Power (ms 2/Hz)
PTSD+

(b)

Coherence

4000

PTSD-

PTSD+

PTSD50
45

3500

40
3000

40.2

35
2500
2546
2000

30
25
20

1500
1142

15

15.0

1000
10

961

813
500

5
0.2

0

Pre-HRVB

Post-HRVB

0

Pre-HRVB

1.2
Post-HRVBFIGURE 2 Pre-Post HRVB Training (a) Coherence and (b) Total HRV Power in PTSD and Control Combat Veterans

may be unstable due to the small subgroup size. The small subgroup size also lowers validity of the results due to limited generalizability. Another limitation of the pilot study is that thephysiological data did not include integrated recording of HRV
with respiration rate and/or pulse transit time, two variables
whose measurement would be necessary to demonstrate that
coherence reflects time-locked physiological entrainment.
Changes in severity of PTSD symptoms were also not assessed
post-HRVB training. Lastly, post-HRVB improvements were only
assessed immediately upon conclusion of the final training session, and so it is not known how persistent over time the observed
effects of HRVB will be on improved coherence and ATTN/IM.
Discussion
The trends of the model tested in this pilot study are promising, and given that the subgroups in this pilot study were small,robust effect sizes large enough to produce statistical significancewere observed for some of the outcomes. Results of our pilot
study indicate that HRVB produces cardiac coherence, shown as
increases in HRV power in the LF frequency band. The beneficial
effects of being in a state of increased coherence were then related to improved performance on ATTN/IM, measured as reduced
commissions on a go–no go test and increased digit span backward and list learning.
Cardiac coherence appears to be central to a range of funda-

56

mental learning and information processing that are part ofeveryday life. We have previously shown that vagal control of cardiac deceleration is critical for acquisition of eye-blink and heart
rate conditioned responding in healthy controls25 and is also significantly related to these forms of associative learning and
ATTN/IM in combat veterans with and without PTSD.12,26
Furthermore, normal cardiac deceleration associated with theimmediate, short-duration registration component of the orienting response appears to be eliminated in PTSD.26 Low tonic vagal
tone, which is associated with PTSD, appears to cause problems
maintaining an adequate level of physiological background necessary for attention to environmental stimulation and events.27
Thus, when sympathetic tonus prevails over normal resting parasympathetic state, vigilance is disrupted.
The relationship between heart rate deceleration and information processing is stated in the intake-rejection hypothesisthat heart and brain form an integrated feedback system of perception, autonomic response, and cognitive processing. 28-31
Cardiac deceleration supports motivated attention to the external environment (vigilance) and response selection; cardiac
acceleration supports motivated inattention to the environment
and internal information processing (sustained attention) and
response output. The greater the initial cardiac deceleration(parasympathetic pulse) after stimulus perception, the greater
the efficiency of processing of stimulus type (eg, life-threatening,

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Cardiac Coherence and PTSD

Pre-Training
PTSD+ (Total Power = 813.3 ms 2/Hz)
Control (Total Power = 1142.2 ms 2/Hz)

Post-Training
PTSD+ (Total Power = 961.1 ms 2/Hz)
Control (Total Power = 2546.5 ms2/Hz)

2500

2500

2000

2000

1500

1500

1000

1000

500

833.6
385.9

527.7

430.3

1870.6

184.2
409.6
253.1

290.1

500

80.4

47.1

150.7
0

0
VLF

LF
Frequency Band

VLF

HF

LF
Frequency Band

HF

FIGURE 3 Pre-Post HRVB Training HRV Frequency Band Power in PTSD+ (n = 5) and Control (n = 5) Combat Veterans**VLF indicates very low frequency (0.010-0.040 Hz); LF, low frequency (0.041-0.140 Hz); HF, high frequency (0.141-0.400 Hz).

warning or danger, safe or neutral) and response selection.
Intake-rejection has been found in humans consistently across awide variety of stimuli and task parameters.32 Cardiac deceleration is now recognized as being a potent marker of the attentionfocusing pre-performance routine found in enhanced
performance output of skilled activities such as rifle marksmanship and golf putting.33 In contrast, during sustained attention to
the response performance itself, there is a marked phasic withdrawal of vagal tone and consequent cardiac acceleration to support response output and performance. Among active duty
military personnel (without combat stress), enhanced performance under conditions of high stress was associated with greater suppression of vagal tone.34
All participants achieved cardiac coherence (0.1 Hz peak) as
result of HRVB training. Both subgroups of participants wereshown to have consolidated HRV power from across the frequency
spectrum into the coherence (LF) frequency band even though
total HRV power did not significantly increase in either subgroup.
The relatively small increase over baseline of total power among
PTSD+ veterans (18.2%) in comparison to controls (122.9%) suggests that PTSD+ veterans, although able to achieve coherence,
were in a state of depletion of total HRV power and limited in

Cardiac Coherence and PTSD

their ability to marshal a full response to the intervention, at least
within the 4-week time frame of this pilot study. In contrast, thesurge in HRV power demonstrated by the controls is a likely indicator of enhanced resilience that will be reflected in attention andmental and emotional flexibility and is expected to predictenhanced self-regulation of affect, greater degree of behavioral
adaptability, and more positive emotions and relationships.
Veterans in the PTSD+ subgroup demonstrated significant
improvements in ATTN/IM accompanied by a significant consolidation of HRV power into the LF frequency band with only asmall (nonsignificant) increase in total HRV power, suggestingthat some additional factors are contributing to the beneficial
effects of cardiac coherence. One possible such factor is increased
neural synchronization. Synchronized brain activity resulting
from cardiac vagal afference (originally thought to be baroreceptor feedback but later understood to be heart rate) constitutes amechanism by which performance of perceptual information
processing can be modulated.22,35 Heart rate deceleration is themodulation mechanism by which the onset of synchronizedalpha activity is prevented when attending to external sensory
information, as synchronized alpha activity interferes with thetransmission and processing of external information. In terms of

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57

Table 2a Pre-Post HRVB Training Changes in Attention and Immediate Memory (ATTN/IM)

Commissions
Pre-

Commissions
Post-

DigitsForward# Trials
Pre-

DigitsForward# Trials
Post-

DigitsBackward# Trials
Pre-

DigitsBackward# Trials
Post-

List
Learning
Trial 1Pre-

List
Learning
Trial 1
Post-

List
Learning
Total Pre-

List
Learning
Total
Post-

PTSD
(n = 5)

Mean

48.5

41.6

10.8

10.8

6.4

8.0

7.0

8.4

54.4

59.0

(SD)

(9.0)

(9.5)

(4.0)

(3.1)

(1.1)

(2.2)

(1.5)

(1.8)

(8.2)

(10.0)

Control(n = 5)

Mean

46.7

45.2

11.2

12.2

7.2

8.2

7.8

8.0

56.6

56.5

(SD)

(12.0)

(4.6)

(1.3)

(2.0)

(1.5)

(0.9)

(2.6)

(3.4)

(9.6)

(13.6)

Total

Mean

47.5

43.2

11.0

11.4

6.8

8.1

7.4

8.2

55.5

57.9

(SD)

(9.2)

(7.5)

(2.9)

(2.6)

(1.3)

(1.6)

(2.1)

(2.4)

(8.5)

(11.0)

Table 2b Significance of Pre-Post HRVB Training Changes in
ATTN/IM (All Comparisons df = 1,8)
ATTN/IM Variable

PTSD

Pre-Post

Pre-Post x PTSD

Commissions

.85

.05

.25

Digit forward # trials

.58

.40

.54

Digit backward # trials

.60

.03

.40

List learning trial 1

.73

.41

.11

List learning total

.91

.31

.03

the synchronizing effect on cortical alpha rhythm (via thalamus),it is the pattern and stability of the vagal afferent input from theheart that is significant and not the strength or number of theseneural afferent signals. In situations involving the intake of sensory information, a decrease in heart rate translates into a reduction in the probability of the occurrence of EEG alpha activity.36
The degree of synchronized activity varies depending on theneeds of the moment. It is this flexibility that allows us to quickly
adapt to changing demands, such as focusing on external sensory
input or an internal process. This is reflected in the alpharhythm, which increases in amplitude and distribution when theneural populations are more tightly coupled—and are not
involved in processing external sensory information.10,22 Under
these circumstances, cognitive performance of tasks involving
the processing of external sensory information is reduced. Whenheart rate increases, the activity and amplitude of the alpha synchronization also tend to increase, the effect of which is to facilitate internal processing and response output at the expense of
intake and processing of external information.36
The preliminary data from this pilot are consistent with thismodel. Increased cardiac coherence reflects incorporation of agreater cardiac deceleration component into HRV due toenhanced output of the parasympathetic arm of the ANS. Intake
and registration of stimulus information should therefore be facilitated, leading to greater efficiency and level of performance of
response output. Prior to HRVB, the tendency (especially among
the PTSD+ veterans) is toward underactivation of vigilance andoveractivation of response output to environmental stimulation.

58

The cardiac coherence–improving effects of HRVB are topromote improved intake of stimulus information and accuracyof response output. This is seen as decreased commissions on
go–no go testing, which demonstrate reduction in dysinhibition,
increased registration on digit span backward, and greater attentional capacity and immediate recall on word list learning. These
improvements in early-stage information processing of stimulus
information have apparent ecological validity and highly beneficial effects on activities of daily living and everyday function in
the real world. There is in addition important and obvious military relevance for fitness and return to duty associated with thebetter attention, reduced dysinhibition, increased accuracy of
responding, and greater registration and immediate recall of
information resulting from HRVB.
The effects of vagal control of cardiac coherence on improvement of intake of environmental information attention are related
to improvements in self-regulation of affect by the individual.37-39
Low vagal tone is associated with poor self-regulation, impaired
environmental responsivity, lack of behavioral flexibility, imbalance of stress hormones, and proneness to disease; high vagal
tone is associated with the ability to self-regulate and thus tohave greater behavioral flexibility and adaptability to the environment.7 HRVB also has been shown to improve symptomatology in clinical groups and heightened well-being in otherwise
healthy individuals: increase in positive affect and decrease incortisol among normal working adults40; improvement in selfreported depression in elderly patients with congestive heart failure41; significant reduction in anxiety in HIV+ patients 42; andreduced blood pressure and improved emotional health in hypertensive employees.43
All 10 of the pilot study participants expressed enthusiasm
about their experience in the HRVB pilot study and their perception of its benefit to everyday living. The PTSD+ veterans wereparticularly enthusiastic about the benefits of HRVB, as shownby this statement that one of the PTSD+ veterans made to study
personnel during the final debriefing:

ALTERNATIVE THERAPIES, jul/aug 2010, VOL. 16, NO. 4

I am an OIF and Gulf War veteran. I recently returned
from Iraq, where I experienced 5 IEDs and 1 RPG explo-

Cardiac Coherence and PTSD

sions. To deal with all the pain I felt after I got back I
self-medicated for several months with alcohol andmarijuana, but after weaning off of both I was determined not to use narcotics of any kind to cope with thepain. Being part of this experimental HRV biofeedback
program has changed my life and given me a practical,
non-medicated way to reduce the pain and handle thestress. One time in particular, stress from [the] relationship with my wife was robbing me of sleep and causing
me to lose control. I remembered the biofeedback tool
and after about 30 minutes of practice I was calm andable to go back to sleep. The benefits of HRVB are somuch better than medication because I am learning a
way to self-regulate anywhere, anytime without risk ofdependency or that drugged feeling. I’m so grateful forbeing part of this pilot study. My last BP reading was
115/76, compared to previously when it was 120/95.
My heart rate has dropped from the 90s to the 70s.

research studies with PTSD+ OIF/OEF combat veterans for symptom reduction of PTSD. The application of HRVB to increase cardiac coherence thus has significance for improvement of everyday
function both for the early stage information processes of attention and immediate memory and for emotional well-being.
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around the United States as a treatment modality and in pilot

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