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. Author manuscript; available in PMC: 2012 Dec 1.
Published in final edited form as: Mindfulness (N Y). 2011 Dec 1;2(4):219–227. doi: 10.1007/s12671-011-0064-3

Mindful awareness and non-judging in relation to posttraumatic stress disorder symptoms

Helané Wahbeh 1,✉, Mary Lu 2,3, Barry Oken 4
PMCID: PMC3349159  NIHMSID: NIHMS371460  PMID: 22582091

Abstract

The objective of this cross-sectional study was to assess group differences between veterans with and without posttraumatic stress disorder (PTSD) in mindful awareness and mindful non-judging. The relationships between mindfulness and PTSD symptom clusters were also evaluated. Three age and gender-matched groups, 1)15 combat veterans with PTSD, 2)15 combat veterans without PTSD, and 3) 15 non-combat veterans without PTSD, completed the Mindful Attention Awareness Scale and the Accept without Judgment scale. PTSD status was determined with the Clinician Administered PTSD Scale and excluded disorders screened with the Structured Clinical Interview for DSM-IV. Mindfulness scale group differences were assessed with analysis of variance. Mindfulness and the PTSD symptom clusters relationships were assessed with hierarchical regression analysis. There were group differences on mindful non-judging (F(2,44)=7.22, p=.002) but not mindful awareness (p>.05). Combat exposure accounted for significant variation in PTSD symptoms (hyper-arousal 47%; numbing-avoiding 32%; re-experiencing 23%). Mindfulness accounted for a significant percentage variance of PTSD symptoms (re-experiencing 32%; numbing-avoiding 19%, hyper-arousal 16%), beyond combat exposure effects, although only mindful non-judging was significant in the model. This study confirms in a clinical sample that mindful non-judging is associated with PTSD symptoms and could represent a meaningful focus for treatment.

Keywords: Posttraumatic stress disorder, combat veterans, mindfulness, awareness, non-judging

Introduction

PTSD is a serious and growing public health issue. Combat soldiers are especially vulnerable to acquiring PTSD due to high job stress and traumatic event exposure. Vietnam veterans’ lifetime prevalence of PTSD is reported as 30% (Kulka, et al., 1990) and 13–17% of Operation Iraqi Freedom and Operation Enduring Freedom soldiers return with PTSD (Hoge, Terhakopian, Castro, Messer, & Engel, 2007; Tanielian & Jaycox, 2008). The personal and societal costs of PTSD often include chronic symptoms, increased psychiatric and medical disorder co-morbidity, and marked functional impairment (Brunello, et al., 2001; S. D. Solomon & Davidson, 1997). The annual economic cost of PTSD is estimated at $45 billion (Marciniak, et al., 2005).

As a form of mind-body medicine, meditation has a 5,000 year old known history and is currently implemented in structured clinical programs with positive results. Mindfulness meditation has a growing body of scientific literature supporting its efficacy for various physical and mental/emotional conditions (Allen, Chambers, & Knight, 2006; Grossman, Niemann, Schmidt, & Walach, 2004), including growing evidence for a role in PTSD treatment. Mindfulness is clinically incorporated into Mindfulness Based Stress Reduction program (Kabat-Zinn, 1982; Kabat-Zinn, et al., 1992), Mindfulness Based Cognitive Therapy (Teasdale, et al., 2000), Mindfulness Based Relapse Prevention (Bowen, et al., 2009), Dialectical Behavioral Therapy (Linehan, Heard, & Armstrong, 1993), and Acceptance Commitment Therapy (Hayes, Wilson, Gifford, Follette, & Strosahl, 1996). Positive clinical outcomes for symptoms relevant to PTSD are shown in depressive symptoms or relapse (Finucane & Mercer, 2006; Kenny & Williams, 2007; Ma & Teasdale, 2004; Mason & Hargreaves, 2001; Sephton, et al., 2007; Teasdale, et al., 2000), anxiety (Finucane & Mercer, 2006; Kabat-Zinn, et al., 1992; McKee, Zvolensky, Solomon, Bernstein, & Leen-Feldner, 2007; Miller, Fletcher, & Kabat-Zinn, 1995; Tacon, McComb, Caldera, & Randolph, 2003), suicidal behavior (Williams, Duggan, Crane, & Fennell, 2006), sleep disturbances (Carlson & Garland, 2005; Shapiro, Bootzin, Figueredo, Lopez, & Schwartz, 2003), and in veterans with PTSD, anxiety, and depression (Finucane & Mercer, 2006; Price, McBride, Hyerle, & Kivlahan, 2007). There is also evidence indicating that mindfulness techniques may affect the functional relationship between the amygdala and the prefrontal cortex, which may be altered in PTSD (Koenigs & Grafman, 2009; Wyland, Kelley, Macrae, Gordon, & Heatherton, 2003). Meta-analytic findings show that PTSD patients exhibit hypo-activity in the prefrontal cortex and hyperactivity in the amygdale (Etkin & Wager, 2007). Mindfulness meditation neuroimaging and electrophysiological studies have shown increased activity in the prefrontal cortex and a decreased activity in the amygdala (Cahn & Polich, 2006; Chiesa & Serretti, 2009; Lieberman, et al., 2007; Rubia, 2009), increased frontal coherence between and within brain hemispheres (Travis & Arenander, 2004), and stronger activations in the medial prefrontal cortex and anterior cingulate cortex compared to controls, which may relate to greater control over distracting events and engagement in emotional processing (Holzel, et al., 2007). Thus, mindfulness meditation may act by improving overall prefrontal cortex functionality allowing increased top-down control on the emotional reactivity generated by the amygdala.

Mindfulness-based clinical practices revolve around educating the student about mindfulness incorporating two distinct components (Cardaciotto, Herbert, Forman, Moitra, & Farrow, 2008): a mindful awareness component and a mindful non-judging component. The mindful awareness or attention component refers to the self-regulation of attention to focus internally (on bodily sensations, breath, thoughts, emotions) and externally (on sights, sounds) at the current moment on the current experience. It is common and expected that the mind will wander away from this focus and so the practice includes gently bringing the attention back to the present moment. Mindful awareness requires sustained attention and flexibility of attention to switch focus back to the object of interest (Bishop, et al., 2004). The second component of mindfulness, mindful non-judging, is distinct from mindful awareness in that it refers to the attitude and orientation of the process rather than how the attention is being directed or the observation of the experiences themselves (Cardaciotto, et al., 2008). Mindful non-judging embodies an attitude of curiosity and openness (Bishop, et al., 2004). It entails refraining from applying evaluative labels such as good/bad, right/wrong, or worthy/worthless and to allow an experience to be as it is without attempts to avoid, escape, or change it (Baer, Smith, & Allen, 2004). For example, when a practitioner finds that their mind has wandered from their object of attention, they can judge themselves negatively leading to increased negative emotion or stress. Mindfulness practice encourages them to not judge but rather shift their attitude to openness and acceptance of themselves and their process (Shapiro, Carlson, Astin, & Freedman, 2006).

PTSD may occur when a person has been exposed to a traumatic event that involves actual or threatened death or serious injury, threat to the physical integrity of self or others, and the person’s response involves intense fear, helplessness, or horror. People with PTSD experience symptoms of increased arousal and sympathetic nervous system hyperactivity that were not present before the trauma (Buckley, Holohan, Greif, Bedard, & Suvak, 2004; Cohen, et al., 1998; Lakusic, et al., 2007; Mellman, Knorr, Pigeon, Leiter, & Akay, 2004; Muraoka, Carlson, & Chemtob, 1998; Pole, 2007). These symptoms include hyper-vigilance, difficulty concentrating, falling or staying asleep, irritability or outbursts of anger, or exaggerated startle response. People with PTSD may also persistently re-experience their trauma through recurrent and intrusive distressing images, thoughts, perceptions, dreams of the event when exposed to internal or external cues that symbolize or resemble an aspect of the traumatic event (Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV)). Re-experiencing symptoms may be a result of the prefrontal cortex which regulates fear extinction. This concept is supported by multiple neuroimaging studies in people with PTSD found prominent hypo-activations in the prefrontal cortex, ACC, and thalamus, regions associated with the experience or regulation of emotion compared to controls (Etkin & Wager, 2007). Prefrontal cortex reactivity is also inversely correlated with PTSD symptom severity in another neuroimaging study (Shin, Rauch, & Pitman, 2006).

Not much is known about assessing or measuring aspects of mindfulness that patients with PTSD may benefit from, how much mindfulness may contribute to treatment readiness or success, or whether it may be used on its own as an efficacious intervention. There may be a relationship between PTSD symptoms and mindfulness that could inform how to implement clinical interventions in this population. Mindfulness may complement or fill in gaps in the dominant cognitive behavioral paradigms. For example, patients in trauma-processing treatments need to be able to allow/accept feelings, thoughts, and experiences at least to some extent. Patients who are overly dysregulated or suicidal often cannot participate and are referred to therapies that incorporate mindfulness (such as Dialectical Behavior Therapy or Acceptance Commitment Therapy). Mindful non-judging may contribute to treatment readiness by encouraging the practitioner to allow and accept thoughts, emotions, and experiences rather than over-reacting to and avoiding them. We would anticipate that people with increased mindful non-judging would be less avoidant. Also, mindful awareness supports being in the present moment rather than dwelling in the past or future and mindfulness meditation improves pre-frontal cortex function. We also know that re-experiencing symptoms are probably a result of prefrontal cortex failure to regulate emotional content. We would expect that people with increased mindful awareness would be more in the present moment and thus have less re-experiencing symptoms.

Because of the increased positive clinical and neuroimaging evidence that mindfulness interventions may benefit PTSD, this study attempts to examine how mindfulness relates to PTSD symptom clusters in a clinical PTSD population with gold standard assessments, with the intention of conducting a mindfulness meditation intervention trial in combat veterans PTSD in the future. No studies to date have examined the relationship between mindful awareness, mindful non-judging, and PTSD symptoms in a clinical population. In non-clinical populations, one study looked at posttraumatic stress symptoms and mindfulness constructs in a student population without axis 1 psychopathology (Vujanovic, Youngwirth, Johnson, & Zvolensky, 2009). Another study focused on mindfulness and experiential avoidance as predictors of PTSD avoidance symptoms in college students (Thompson & Waltz, 2010). A third study examined the relationship between posttraumatic stress symptom severity and alcohol use coping motives in 153 adults who reported exposure to at least one DSM-IV PTSD Criterion A traumatic life event and alcohol use in the past month (Vujanovic, Bonn-Miller, & Marlatt, 2011). All three studies used self-report PTSD symptom questionnaires rather than clinician administered interviews. The research questions of this cross-sectional study were: 1) are there differences in mindful awareness and mindful non-judging between age and gender-matched combat veterans with PTSD, combat veterans without PTSD, and non-combat veterans without PTSD?; and 2) what is the relationship between mindful awareness and mindful non-judging to the PTSD symptom clusters of re-experiencing, avoidance, and hyper-arousal? We hypothesized that the PTSD group would have decreased mindful awareness and mindful non-judging. We also hypothesized that mindfulness awareness would be associated with re-experiencing and mindful non-judging would be associated with avoidance.

Methods

Study procedures included a telephone screening, a screening visit, and completion of questionnaires. Study procedures, inclusion/exclusion criteria, and the risks and benefits of participating were explained during a telephone screening. The screening visit included informed consent procedures, medical history and demographic data collection, clinical interviews, and questionnaire distribution. Participants returned their questionnaire packets at another visit within one week of the screening visit. Questionnaires were checked for completeness and missing questions answered if necessary.

Participants in the study were included in three age and gender matched groups: 15 combat veterans with PTSD, 15 combat veterans without PTSD, and 15 non-combat veterans without PTSD. Potential participants were recruited through flyers at the Portland Veterans Administration Medical Center, Portland Veterans Center, and other veterans groups throughout the Portland Metropolitan area. Veterans were excluded if they were over the age of 70, had a current significant chronic medical illness, bipolar, schizoaffective, or psychotic disorders; any DSM-IV cognitive disorder; substance dependence disorder within the past 3 months or current illicit substance use. Inclusion and exclusion criteria were determined through self-reported past and current medical history and the clinical interviews. The study was approved by the institutional review boards of Portland Veterans Administration Medical Center and Oregon Health & Science University. Written informed consent was obtained from all subjects.

Clinical Interviews

During the screening visit, potential participants were interviewed by trained clinicians (HW and ML) using the Clinician-Administered PTSD Scale for DSM-IV (CAPS) to validate the presence or absence of PTSD and the Structured Clinical Interview for DSM-IV (SCID-IV) to screen for exclusionary psychiatric conditions.

The CAPS is a structured clinical interview designed to assess PTSD according to DSM-IV criteria and evaluates frequency and intensity of each symptom. Participants in the PTSD group met DSM-IV-TR criteria A–F; criteria B, C, and D were met when the frequency plus intensity score were ≥4. Participants in the non-PTSD groups did not meet full syndrome criteria. The CAPS yields a total score as well as re-experiencing, numbing-avoiding, and hyper-arousal subscores. The CAPs also includes the Life Events Checklist (LEC) which assesses lifetime trauma exposure (i.e. natural disasters, physical assault, sexual assault). The LEC was used to assess group differences on trauma history other than combat exposure. Test-retest reliability is high (.90 to .98) as is internal consistency (.85 to .94) (Blake, et al., 1995).

The SCID-IV is a structured diagnostic interview designed to measure the presence or absence of DSM-IV Axis I mental disorders. The SCID-IV is regarded as the "gold standard" for assessing mental disorders and has demonstrated acceptable inter-rater reliability (overall weighted kappa coefficients = .61 for current diagnoses) (First, Spitzer, Gibbon, & Williams, 2002).

Questionnaires

The Combat Exposure Scale (CES) assessed the amount of combat each participant experienced. The CES is a 7-item self-report measure. Items are rated on a 5-point frequency (1 = “no” or “never” to 5 = “more than 50 times”). Participants were asked to respond based on their exposure to various combat situations, such as firing rounds at the enemy and being on dangerous duty. The total CES score (ranging from 0 to 41) is calculated by using a sum of weighted scores (Keane, et al., 1989).

The Beck Depression Inventory-II (BDI) assessed depression symptoms in the participants. It is a 21-item self-report measure that is widely used and accepted. It is positively correlated with the Hamilton Psychiatric Rating Scale for Depression (r =.71, n = 87) and the Hamilton Rating Scale for Anxiety (r =.47, n = 87) (Beck, Steer, & Brown, 1996).

The Mindfulness Attention Awareness Scale was used to assess the primary tenet of mindfulness: the extent to which each participant was able to be attentive and aware to the present moment. It is a 15-item scale that measures the frequency of both general and specific present awareness mindfulness states in daily life. It includes questions such as “It seems I am running on automatic without much awareness of what I’m doing” and “I could be experiencing some emotion and not be conscious of it until some time later.” It shows strong internal consistency (alpha= .82) and expected convergent and discriminant correlations and has been validated with college, community, and cancer patient samples and in French and Swedish (Brown & Ryan, 2003; Carlson & Brown, 2005; Hansen, Lundh, Homman, & Wangby-Lundh, 2009; Jermann, et al., 2009). This score will be referred to as mindful awareness.

Non-judgmental attitude, the second component of mindfulness, was assessed with the “Accept without Judgment” subscale from the Kentucky Inventory of Mindfulness Skills. It is a 9-item self-report questionnaire that evaluates the non-judgmental acceptance of internal processes aspect of mindfulness. It includes questions like “I tell myself that I shouldn’t be thinking the way I’m thinking” and “I think some of my emotions are bad or inappropriate and I shouldn’t feel them. The Kentucky Inventory of Mindfulness Skills has strong internal consistency (alpha=.76–.91) and shows expected convergent and discriminate correlations. The KIMS has been validated in college, community, and patient samples and in French, Swedish, and German (Baer, et al., 2004; Baer, et al., 2008; Baum, et al., 2009; Hansen, et al., 2009; Nicastro, Jermann, Bondolfi, & McQuillan, 2010). This score will be referred to as mindful non-judging.

Statistics

The confounding factors of age, gender, medications, depression and trauma type were considered in the study design in the following ways. Age and gender were addressed through the matched group design. Trauma type was addressed with combat exposure being the primary PTSD event (determined by clinical interview). Traumatic events prior to the PTSD primary event, such as childhood abuse or sexual trauma, were also recording during the clinical interview. Two control groups, one with and one without combat exposure, were chosen to distinguish effects of combat exposure versus PTSD on mindfulness (Pole, 2006). People with PTSD also frequently have co-morbid depression (Schindel-Allon, Aderka, Shahar, Stein, & Gilboa-Schechtman, 2010) and are on medications. Depression status was accounted for as a continuous covariate (Beck Depression Inventory-II score). Participants on medications were included if their dose was stable for 4 weeks or more and all medications were recorded.

Statistical analysis of primary outcomes were conducted in phases: 1) Means, standard deviations, and box plots were observed for each continuous variable and normality was assessed by the Shapiro-Wilk test; 2) Group differences in continuous variables were assessed with analysis of variance if normally distributed and independent samples Kruskal-Wallis non-parametric test if not normally distributed. If significance was found, covariates (depression, prior to PTSD event trauma history) were entered in the model to see if the results changed. Post-hoc tests for significant values were assessed with least square difference for parametric tests and mean rank paired comparisons for non-parametric tests (Langley, 1979). Categorical variables were assessed with the chi-square test; 3) Hierarchical multiple regression analyses were conducted to assess mindful awareness and mindful non-judging’s ability to predict re-experiencing, numbing-avoiding, and hyper-arousal symptom components beyond combat exposure. Normality, linearity, and outliers were assessed through normal probability plots and scatter plots of the standardized residuals. None of these assumptions were violated. Zero-order Pearson product-moment correlation coefficients were examined to determine any collinearity between measures. For each PTSD symptom component, combat exposure scale score was entered in step 1, then mindful awareness and mindful non-judging were entered in step two. Combat exposure was included in the model first to assess the effect of the PTSD trauma exposure before including the mindfulness scales. A p-value of .002 was considered statistically significant adjusting for multiple comparisons using the Holm-Bonferroni method (Holm, 1979). P-values below .05 are still noted but not considered statistically significant.

Results

Group demographics

Demographics and medical history were similar for all groups (all ps>.05 for years in service, race, education, marital status, exercise, sleep, handedness, past psychiatric history, past major depressive disorder, antidepressant use, past or current drug, alcohol, or cigarette use, gender (all groups 100% male), and age). Era was different between groups reflecting more combat era veterans in the PTSD group (Fisher exact test p=.03). There were no group differences on medications use (p>.05). Medications were also categorized as psychotropic medications (i.e. selective serotonin reuptake inhibitors, monamine oxidase inhibitors, tri-cyclics, anti-psychotics, and anxiolytics) versus medications for other health conditions (i.e. diabetes, hypertension, hypercholesterolemia), with no significant group differences in either (all p’s >.05). As expected, CAPS total score, re-experiencing, numbing-avoiding, and hyper-arousal were significantly different between groups reflecting greater PTSD severity in the PTSD group (Table 1). All veterans in the PTSD group endorsed immediate onset of symptoms after combat trauma exposure. Combat exposure was also significantly different between groups with the two combat groups having higher combat exposure than the non-combat group. There was no difference between the two combat groups in combat exposure (p>.05).

Table 1.

Measures by group

Measure Combat,
PTSDe (n=15)		 Combat,
Non-PTSD (n=15)		 Non-Combat,
Non-PTSD (n=15)		 Statistics
Age 55.9 ± 10.4 51.0 ± 13.0 54.8 ± 9.1 F(2,44)=.81, p=0.45
Mindful Awarenessb 3.0 ± .90f 3.4 ± .75 2.9 ± .79 F(2,44)=1.44, p=0.25
Mindful Non-Judgingc 22.5 ± 8.2 33.5 ± 7.1 30.7 ± 9.5 F(2,44)=7.2, p=.002
Re-experiencing 20.2 ± 7.0 1.7 ± 2.7 4.2 ± 6.0 X2=26.7; p=.0001 a
Numbing-Avoiding 31.5 ± 7.5 5.0 ±6.1 4.4 ± 7.9 X2=28.2; p=.0001 a
Hyper-arousal 23.9 ± 4.0 6.4 ± 5.8 2.3 ± 4.5 X2=0.88; p=.0001 a
CAPS Totald 75.3 ± 13.2 11.6 ± 11.8 10.9 ± 14.1 X2=26.5; p=.0001 a
Combat Exposure Scale 29.6 ± 10.1 18.9 ± 8.8 0.5 ± 1.1 X2=0.88; p=.0001 a
Beck Depression Inventory 19.8 ± 13.7 9.8 ± 8.0 13.0 ± 9.4 X2=5.0; p=.08 a
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a

Independent samples Kruskal-Wallis non-parametric test.

b

Mindful Awareness-The Mindfulness Attention Awareness Scale.

c

Mindful Non-Judging-Accept without Judgment subscale from the Kentucky Inventory of Mindfulness Skills.

d

CAPS-Clinician administered post-traumatic stress disorder scale.

e

PTSD-posttraumatic stress disorder

f

Mean plus or minus standard deviation

Mindfulness and PTSD

The PTSD group scored lower on the mindful non-judging (F(2,44)=7.22, p=.002). This significance remained when co-varying for depression (BDI) and other trauma (LEC). Least square differences post-hoc analysis showed that the PTSD group was different from both the combat control (p=.001) and the non-combat control (p=.01) and the two control groups were not different from each other (p>.05). There was no difference between groups on the mindful awareness scale (p>.05) (Table1).

Relationship between mindfulness and PTSD symptoms

Multicollinearity was assessed for the hierarchical regression. All PTSD symptom clusters were correlated with each other and to combat exposure. Mindful non-judging was negatively correlated with re-experiencing (r=−.62), numbing-avoiding(r=−.50), and hyperarousal (r=−.46) (p’s<.0005). Mindful awareness was not correlated with any other variable. The two mindfulness measures were not correlated with each other (Table 2).

Table 2.

Zero-order Pearson correlations of PTSD symptoms and mindfulness scales

Re-
experiencing		 Numbing-
Avoiding		 Hyper-
arousal		 Combat Mindful
Awareness		 Mindful
Non-judging
Re-experiencing - .82b .76b .48a .02 −.62b
Numbing-Avoiding - - .86b .56b −.01 −.50b
Hyper-arousal - - - .68b −.08 −.46a
Combat Exposure - - - - .09 −.13
Mindful Awareness - - - - - .06
Mean 8.7 13.6 10.8 16.3 28.9 43.1
Standard deviation 9.9 14.6 10.6 14.3 9.4 11.4
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n=45

a

p<.001

b

p<.0005

In step one of the linear regression, combat exposure accounted for a significant amount of variation in all PTSD symptom clusters: re-experiencing (23%, F(1,43)=13.08; p=.001), numbing-avoiding (32%, F (1,43)=20.0, p <.0005), and hyper-arousal (47%, F (1,43)=37.7, p <.0005). Adding the mindfulness scales in step two explained a significant part of the PTSD symptoms variability beyond combat exposure effects: re-experiencing (32%, Fchange (2,41)=14.47, p <.0005), numbing-avoiding (19%, Fchange (2,41)=7.9; p =.001); hyper-arousal (16%, Fchange (2,41)=8.5, p =.001). However, only the mindful non-judging was significant in this model (p <.005)(Table 3).

Table 3.

Regression analyses

Adjusted R2 ΔR2a B SE Bb β p
Re-experiencing
Step 1-Combat Exposure
Step 2-Mindfulness
     Awareness
    Non-Judging
.22
.52
.23
.32
.33

.01
−.60
.09

.09
−.57
.48

.02
−.57
.001

.88
<.005
Numbing-Avoiding
Step 1-Combat Exposure
Step 2-Mindfulness
     Awareness
     Non-judging
.30
.47
.32
.19
57

−.04
−.68
.13

.14
.17
.56

−.03
−.44
<.0005

.78
<.0005
Hyper-arousal
Step 1-Combat Exposure
Step 2-Mindfulness
     Awareness
     Non-Judging
.46
.60
.47
.16
.50

−.11
−.42
.08

.09
.11
.68

−.12
−.37
<.0005

.237
<.0005
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a

Change in R2

b

Standard error B

Discussion

The objective of this study was to assess differences in mindfulness in combat veterans with PTSD and combat and non-combat control groups. The relationship between mindfulness and PTSD symptoms was also assessed. Mindful non-judging was different between groups with the PTSD group having the lowest score, but there was no difference in mindful awareness. Mindful non-judging contributed a significant amount of variation in PTSD symptoms beyond combat exposure effects.

The three study groups were matched on age, gender, depression, other trauma history, and other important demographic measures. Era was different between groups reflecting war time for the combat exposure participants. Medications were also evaluated and were not different between groups. There were significant differences on all PTSD symptom clusters reflecting appropriately defined groups.

Combat exposure distinguished the trauma-exposed versus non-trauma exposed group and also explained a significant amount of variation in all three PTSD symptom clusters. Interestingly, combat exposure explained more variation for the hyper-arousal (47%) symptoms than the numbing-avoiding (32%) and re-experiencing symptoms (23%). Hyper-arousal has been shown to be the best single predictor of subsequent symptom severity in other studies (Schell, Marshall, & Jaycox, 2004; Z. Solomon, Horesh, & Ein-Dor, 2009) and the most stable PTSD symptom. Another study examining hyper-arousal in clinical and non-clinical veterans over 20 years found that hyper-arousal symptom long-term trajectories did not differ between the groups (Z. Solomon, et al., 2009), alluding to the idea that trauma-exposure itself regardless of disease development may produce lasting hyper-arousal symptoms.

Mindful non-judging was different between groups but mindful awareness was not. Including mindful awareness and mindful non-judging in the regression model for PTSD symptom clusters explained additional variation for each PTSD symptom cluster beyond combat trauma exposure (re-experiencing 32%, numbing-avoiding 19%, hyper-arousal 16%). It is striking that these numbers are far greater than previously observed (6%) in non-clinical populations highlighting the importance of looking at this research question in a clinical sample (Thompson & Waltz, 2010; Vujanovic, et al., 2009).

Importantly, the two mindfulness measures were not correlated, supporting the notion that mindful awareness and mindful non-judging represent distinct aspects of mindfulness. Mindful awareness and mindful non-judging may represent different brain networks and are thus being differentially implicated in PTSD. Self-referential behavior, conceptually similar to mindful non-judging behavior, is known to be a function of the medial prefrontal cortex (Herwig, Kaffenberger, Jancke, & Bruhl, 2010; Pan, Hu, Li, & Li, 2009) that is inhibitory on the amygdala, whereas, mindful awareness behavior is associated with a different network (Fassbender, et al., 2004; Oken, Salinsky, & Elsas, 2006). These results also imply that mindful awareness alone may not be sufficient to help reduce symptoms. One might expect that mindful awareness would help mitigate the upsetting intrusive thoughts and memories of their traumatic event, because by being more mindful, the person would engage in the present moment reducing the intrusive thoughts. However, it may be that the attitude one brings to the memory is more important in PTSD than having the thoughts or memories go away. For example, someone with PTSD may have an intrusive memory of a combat trauma. That person may judge the memory as negative (which someone with a lower mindful non-judging score may do) or just observe it as it is (which someone with a higher mindful non-judging score may do). Our results are consistent with the idea that people with more PTSD symptoms are more likely to judge their memories, thoughts, feelings negatively. Other studies in non-clinical populations have also found similar results. One study of 191 college students found that non-judging was a significant predictor on PTSD avoidance, whereas other mindfulness constructs were not(Thompson & Waltz, 2010). Another study of 239 adults who endorsed exposure to traumatic events again found that only the mindful non-judging scale was a significant predictor in all PTSD symptom clusters (Vujanovic, et al., 2009). The same group found that non-judging was predictive of alcohol abuse in a 153 trauma exposed individuals (Vujanovic, et al., 2011). Our study builds upon these previous studies by using a clinical population and using standardized clinically administered interviews rather than questionnaires for PTSD symptom assessment.

Clinical interventions using mindfulness-based therapies in PTSD populations that emphasize the non-judging aspect of mindfulness training may improve outcomes. Since the introduction of MBSR, many adapted mindfulness-based programs have been created specifically for various clinical populations such as Mindfulness-Based Cognitive Therapy (Teasdale, et al., 2000) (major depression disorder relapse prevention), Mindfulness-Based Relapse Prevention (Witkiewitz & Bowen, 2010) (substance abuse relapse prevention), Mindfulness-Based Eating Awareness Training (Kristeller & Wolever, 2011) (binge eating disorder), Mindfulness-Based Childbirth and Parenting (Duncan & Bardacke, 2010). While no specific structured program for people with PTSD yet exists, emphasis on mindful non-judging in mindfulness-based programs being administered to people with PTSD may be helpful. For example, in the MBCT standardized curriculum, the non-judging concept is integrated into multiple modules such as the Dealing with Barriers, Allowing/Letting Be, and Thoughts are Not Facts Modules (Segal, Williams, & Teasdale, 2002). An MBCT teacher who was teaching participants with PTSD could spend more time on the non-judging concepts in these modules. In the MBSR curriculum, class two could incorporate PTSD specific examples of judging/non-judging when discussing “How you see things (or don’t see them) will determine in large measure how you will respond to them” (Kabat-Zinn & Santorelli, 2007). Additionally, a mindfulness teacher may choose to spend more time on the loving kindness meditation that is included in the full-day retreat of MBSR throughout the course to a greater cultivation of non-judging attitude. These are just a few ideas of implementing the knowledge of the mindful non-judging relationship to PTSD symptoms in this study. A prospective clinical study examining this effect longitudinally would help explore the effect of weighting non-judging concepts in mindfulness-based curricula in this population.

There are a number of limitations to this study that can be addressed in future studies. It was a cross-sectional study and does not allow for causal inference. The study was limited to male Vietnam veterans, precluding generalizability of results to women veterans and people with non combat-related PTSD. Future studies should include women and younger combat veterans.

In conclusion, this study extends prior observations that mindful non-judging is more highly correlated than mindful awareness to PTSD symptoms, especially re-experiencing, to a new clinical population, combat veterans with PTSD.

Acknowledgements

This work was supported in part by National Institute of Health grants T32 AT002688, K01 AT004951, U19 AT002656, UL1 RR024140, K24AT005121, and a Tartar Trust Grant. Special thanks to Roger Ellingson, Dan Zajdel, Aisha Kudura, Alex Amen, Irina Fonareva.

Contributor Information

Helané Wahbeh, Email: hwahbeh@ohsu.edu, Department of Neurology, Oregon Health & Science University, Portland, OR.

Mary Lu, Department of Psychiatry, Oregon Health & Science University, Portland, OR; Mental Health & Neuroscience Division, Portland Veterans Administration Medical Center, Portland, OR.

Barry Oken, Department of Neurology, Oregon Health & Science University, Portland, OR.

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